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'''Ataxia''' (from [[Greek (language)|Greek]] α- [a negative prefix] + -τάξις [order] = "lack of order") is a [[neurological sign]] consisting of lack of voluntary [[Motor coordination|coordination of muscle movements]] that can include [[gait abnormality]], speech changes, and abnormalities in [[eye movement]]s, that indicates dysfunction of parts of the [[nervous system]] that coordinate movement, such as the [[cerebellum]].
'''Ataxia''' (from [[Greek (language)|Greek]] α- [a negative prefix] + -τάξις [order] = "lack of order") is a [[neurological sign]] consisting of lack of voluntary [[Motor coordination|coordination of muscle movements]] that can include [[gait abnormality]], speech changes, and abnormalities in [[eye movement]]s, that indicates dysfunction of parts of the [[nervous system]] that coordinate movement, such as the [[cerebellum]].


These nervous system dysfunctions occur in several different patterns, with different results and different possible causes. Ataxia can be limited to one side of the body, which is referred to as hemiataxia. [[Friedreich's ataxia]] has gait abnormality as the most commonly presented symptom. Dystaxia is a mild degree of ataxia.<ref>{{Cite web |title=Dystaxia Definition & Meaning |url=https://www.dictionary.com/browse/dystaxia |access-date=2023-09-13 |website=Dictionary.com |language=en}}</ref>
These nervous-system dysfunctions occur in several different patterns, with different results and different possible causes. Ataxia can be limited to one side of the body, which is referred to as '''hemiataxia.''' [[Friedreich's ataxia]] has gait abnormality as the most commonly presented symptom. '''Dystaxia''' is a mild degree of ataxia.<ref>{{Cite web |title=Dystaxia Definition & Meaning |url =https://www.dictionary.com/browse/dystaxia |access-date =2023-09-13 |website=Dictionary.com |language=en
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== Types ==
== Types ==
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The term [[cerebellar ataxia]] is used to indicate ataxia due to dysfunction of the cerebellum.<ref>{{cite web | title = Ataxia - Symptoms & Causes | publisher = Mayo Clinic | date = 3 June 2020 | url = https://www.mayoclinic.org/diseases-conditions/ataxia/symptoms-causes/syc-20355652 | access-date = 10 August 2020}}</ref> The cerebellum is responsible for integrating a significant amount of neural information that is used to coordinate smoothly ongoing movements and to participate in [[motor planning]]. Although ataxia is not present with all cerebellar [[lesion]]s, many conditions affecting the cerebellum do produce ataxia.<ref name="Schmahmann">{{cite journal | vauthors = Schmahmann JD | title = Disorders of the cerebellum: ataxia, dysmetria of thought, and the cerebellar cognitive affective syndrome | journal = The Journal of Neuropsychiatry and Clinical Neurosciences | volume = 16 | issue = 3 | pages = 367–378 | year = 2004 | pmid = 15377747 | doi = 10.1176/jnp.16.3.367 | doi-access =  }}</ref> People with cerebellar ataxia may have trouble regulating the force, range, direction, velocity, and rhythm of muscle contractions.<ref name="isbn0-8036-0093-3">{{cite book | vauthors = Fredericks CM | chapter = Disorders of the Cerebellum and Its Connections | veditors = Saladin LK, Fredericks CM | title = Pathophysiology of the motor systems: principles and clinical presentations | publisher = F.A. Davis | location = Philadelphia | year = 1996 | isbn = 0-8036-0093-3 | chapter-url = http://www.hy-q.com/cooper/pdf/NCS%20Exam/208%20Disorders%20of%20the%20Cerebellum%20and%20its%20Connections.pdf | access-date = 6 May 2012 | url-access = registration | url = https://archive.org/details/pathophysiologyo0000unse_a1k6 }}</ref> This results in a characteristic type of irregular, uncoordinated movement that can manifest itself in many possible ways, such as [[asthenia]], [[asynergy]], delayed reaction time, and [[dyschronometria]].<ref>{{cite journal | vauthors = Tada M, Nishizawa M, Onodera O | title = Redefining cerebellar ataxia in degenerative ataxias: lessons from recent research on cerebellar systems | journal = Journal of Neurology, Neurosurgery, and Psychiatry | volume = 86 | issue = 8 | pages = 922–928 | date = August 2015 | pmid = 25637456 | doi = 10.1136/jnnp-2013-307225 | s2cid = 20887739 }}</ref> Individuals with cerebellar ataxia could also display instability of gait, difficulty with eye movements, [[dysarthria]], [[dysphagia]], [[hypotonia]], [[dysmetria]], and [[dysdiadochokinesia]].<ref name="Schmahmann" /> These deficits can vary depending on which cerebellar structures have been damaged, and whether the lesion is bi- or unilateral.{{citation needed|date=August 2021}}
The term [[cerebellar ataxia]] is used to indicate ataxia due to dysfunction of the cerebellum.<ref>{{cite web | title = Ataxia - Symptoms & Causes | publisher = Mayo Clinic | date = 3 June 2020 | url = https://www.mayoclinic.org/diseases-conditions/ataxia/symptoms-causes/syc-20355652 | access-date = 10 August 2020}}</ref> The cerebellum is responsible for integrating a significant amount of neural information that is used to coordinate smoothly ongoing movements and to participate in [[motor planning]]. Although ataxia is not present with all cerebellar [[lesion]]s, many conditions affecting the cerebellum do produce ataxia.<ref name="Schmahmann">{{cite journal | vauthors = Schmahmann JD | title = Disorders of the cerebellum: ataxia, dysmetria of thought, and the cerebellar cognitive affective syndrome | journal = The Journal of Neuropsychiatry and Clinical Neurosciences | volume = 16 | issue = 3 | pages = 367–378 | year = 2004 | pmid = 15377747 | doi = 10.1176/jnp.16.3.367 | doi-access =  }}</ref> People with cerebellar ataxia may have trouble regulating the force, range, direction, velocity, and rhythm of muscle contractions.<ref name="isbn0-8036-0093-3">{{cite book | vauthors = Fredericks CM | chapter = Disorders of the Cerebellum and Its Connections | veditors = Saladin LK, Fredericks CM | title = Pathophysiology of the motor systems: principles and clinical presentations | publisher = F.A. Davis | location = Philadelphia | year = 1996 | isbn = 0-8036-0093-3 | chapter-url = http://www.hy-q.com/cooper/pdf/NCS%20Exam/208%20Disorders%20of%20the%20Cerebellum%20and%20its%20Connections.pdf | access-date = 6 May 2012 | url-access = registration | url = https://archive.org/details/pathophysiologyo0000unse_a1k6 }}</ref> This results in a characteristic type of irregular, uncoordinated movement that can manifest itself in many possible ways, such as [[asthenia]], [[asynergy]], delayed reaction time, and [[dyschronometria]].<ref>{{cite journal | vauthors = Tada M, Nishizawa M, Onodera O | title = Redefining cerebellar ataxia in degenerative ataxias: lessons from recent research on cerebellar systems | journal = Journal of Neurology, Neurosurgery, and Psychiatry | volume = 86 | issue = 8 | pages = 922–928 | date = August 2015 | pmid = 25637456 | doi = 10.1136/jnnp-2013-307225 | s2cid = 20887739 }}</ref> Individuals with cerebellar ataxia could also display instability of gait, difficulty with eye movements, [[dysarthria]], [[dysphagia]], [[hypotonia]], [[dysmetria]], and [[dysdiadochokinesia]].<ref name="Schmahmann" /> These deficits can vary depending on which cerebellar structures have been damaged, and whether the lesion is bi- or unilateral.{{citation needed|date=August 2021}}


People with cerebellar ataxia may initially present with poor balance, which could be demonstrated as an inability to stand on one leg or perform [[tandem gait]]. As the condition progresses, walking is characterized by a widened base and high stepping, as well as staggering and lurching from side to side.<ref name ="Schmahmann" /> Turning is also problematic and could result in falls. As cerebellar ataxia becomes severe, great assistance and effort are needed to stand and walk.<ref name ="Schmahmann" /> [[Dysarthria]], an impairment with articulation, may also be present and is characterized by "scanning" speech that consists of slower rate, irregular rhythm, and variable volume.<ref name ="Schmahmann" /> Also, slurring of speech, tremor of the voice, and [[ataxic respiration]] may occur. Cerebellar ataxia could result with incoordination of movement, particularly in the extremities. Overshooting (or hypermetria) occurs with finger-to-nose testing and heel to shin testing; thus, [[dysmetria]] is evident.<ref name ="Schmahmann" /><ref>{{cite journal | vauthors = Manto M, Godaux E, Jacquy J | title = Cerebellar hypermetria is larger when the inertial load is artificially increased | journal = Annals of Neurology | volume = 35 | issue = 1 | pages = 45–52 | date = January 1994 | pmid = 8285591 | doi = 10.1002/ana.410350108 | s2cid = 19328973 }}</ref> Impairments with alternating movements (dysdiadochokinesia), as well as [[Cardiac dysrhythmia|dysrhythmia]], may also be displayed. Tremor of the head and trunk ([[titubation]]) may be seen in individuals with cerebellar ataxia.<ref name ="Schmahmann" />
People with cerebellar ataxia may initially present with poor balance, which could be demonstrated as an inability to stand on one leg or perform [[tandem gait]]. As the condition progresses, walking is characterized by a widened base and high stepping, as well as staggering and lurching from side to side.<ref name ="Schmahmann" /> Turning is also problematic and could result in falls. As cerebellar ataxia becomes severe, great assistance and effort are needed to stand and walk.<ref name ="Schmahmann" /> [[Dysarthria]], an impairment with articulation, may also be present and is characterized by "scanning" speech that consists of a slower rate, irregular rhythm, and variable volume.<ref name ="Schmahmann" /> Also, slurring of speech, tremor of the voice, and [[ataxic respiration]] may occur. Cerebellar ataxia could result in incoordination of movement, particularly in the extremities. Overshooting (or hypermetria) occurs with finger-to-nose testing and heel-to-shin testing; thus, [[dysmetria]] is evident.<ref name ="Schmahmann" /><ref>{{cite journal | vauthors = Manto M, Godaux E, Jacquy J | title = Cerebellar hypermetria is larger when the inertial load is artificially increased | journal = Annals of Neurology | volume = 35 | issue = 1 | pages = 45–52 | date = January 1994 | pmid = 8285591 | doi = 10.1002/ana.410350108 | s2cid = 19328973 }}</ref> Impairments with alternating movements (dysdiadochokinesia), as well as [[Cardiac dysrhythmia|dysrhythmia]], may also be displayed. Tremor of the head and trunk ([[titubation]]) may be seen in individuals with cerebellar ataxia.<ref name ="Schmahmann" />


Dysmetria is thought to be caused by a deficit in the control of interaction [[torque]]s in multijoint motion.<ref name="pmid10805697">{{cite journal | vauthors = Bastian AJ, Zackowski KM, Thach WT | title = Cerebellar ataxia: torque deficiency or torque mismatch between joints? | journal = Journal of Neurophysiology | volume = 83 | issue = 5 | pages = 3019–3030 | date = May 2000 | pmid = 10805697 | doi = 10.1152/jn.2000.83.5.3019 | s2cid = 10244619 }}</ref> Interaction torques are created at an associated joint when the primary joint is moved. For example, if a movement required reaching to touch a target in front of the body, [[flexion]] at the [[shoulder]] would create a torque at the [[elbow]], while [[extension (kinesiology)|extension]] of the elbow would create a torque at the [[wrist]]. These torques increase as the speed of movement increases and must be compensated and adjusted for to create coordinated movement. This may, therefore, explain decreased coordination at higher movement velocities and accelerations.
Dysmetria is thought to be caused by a deficit in the control of interaction [[torque]]s in multijoint motion.<ref name="pmid10805697">{{cite journal | vauthors = Bastian AJ, Zackowski KM, Thach WT | title = Cerebellar ataxia: torque deficiency or torque mismatch between joints? | journal = Journal of Neurophysiology | volume = 83 | issue = 5 | pages = 3019–3030 | date = May 2000 | pmid = 10805697 | doi = 10.1152/jn.2000.83.5.3019 | s2cid = 10244619 }}</ref> Interaction torques are created at an associated joint when the primary joint is moved. For example, if a movement required reaching to touch a target in front of the body, [[flexion]] at the [[shoulder]] would create a torque at the [[elbow]], while [[extension (kinesiology)|extension]] of the elbow would create a torque at the [[wrist]]. These torques increase as the speed of movement increases and must be compensated for and adjusted to create coordinated movement. This may, therefore, explain decreased coordination at higher movement velocities and accelerations.
* [[Vestibulocerebellar syndrome|Dysfunction of the vestibulocerebellum]] ([[flocculonodular lobe]]) impairs balance and the control of eye movements. This presents itself with [[postural instability]], in which the person tends to separate his/her feet upon standing, to gain a wider base and to avoid titubation (bodily oscillations tending to be forward-backward ones). The instability is, therefore, worsened when standing with the feet together, regardless of whether the eyes are open or closed. This is a negative [[Romberg's test]], or more accurately, it denotes the individual's inability to carry out the test, because the individual feels unstable even with open eyes. {{Citation needed|date=May 2012}}
* [[Vestibulocerebellar syndrome|Dysfunction of the vestibulocerebellum]] ([[flocculonodular lobe]]) impairs balance and the control of eye movements. This presents itself with [[postural instability]], in which the person tends to separate his/her feet upon standing, to gain a wider base and to avoid titubation (bodily oscillations tending to be forward-backward ones). The instability is, therefore, worsened when standing with the feet together, regardless of whether the eyes are open or closed. This is a negative [[Romberg's test]], or more accurately, it denotes the individual's inability to carry out the test, because the individual feels unstable even with open eyes. {{Citation needed|date=May 2012}}
* Dysfunction of the [[Anatomy of the cerebellum#Phylogenetic and functional divisions|spinocerebellum]] ([[vermis]] and associated areas near the midline) presents itself with a wide-based "drunken sailor" [[gait]] (called truncal ataxia),<ref name="Blumenfeld">{{cite book | vauthors = Blumenfeld H | title = Neuroanatomy through clinical cases | url = https://archive.org/details/neuroanatomythro00blum | url-access = limited | publisher = Sinauer | location = Sunderland, Mass | year = 2002 | pages = [https://archive.org/details/neuroanatomythro00blum/page/n342 670]–671 | isbn = 0-87893-060-4 }}</ref> characterised by uncertain starts and stops, lateral deviations, and unequal steps. As a result of this gait impairment, [[falling (accident)|falling]] is a concern in patients with ataxia. Studies examining falls in this population show that 74–93% of patients have fallen at least once in the past year and up to 60% admit to fear of falling.<ref name="pmid20157791">{{cite journal | vauthors = Fonteyn EM, Schmitz-Hübsch T, Verstappen CC, Baliko L, Bloem BR, Boesch S, Bunn L, Charles P, Dürr A, Filla A, Giunti P, Globas C, Klockgether T, Melegh B, Pandolfo M, De Rosa A, Schöls L, Timmann D, Munneke M, Kremer BP, van de Warrenburg BP | title = Falls in spinocerebellar ataxias: Results of the EuroSCA Fall Study | journal = Cerebellum | volume = 9 | issue = 2 | pages = 232–239 | date = June 2010 | pmid = 20157791 | doi = 10.1007/s12311-010-0155-z | s2cid = 23247877 }}</ref><ref name="pmid15645525">{{cite journal | vauthors = van de Warrenburg BP, Steijns JA, Munneke M, Kremer BP, Bloem BR | title = Falls in degenerative cerebellar ataxias | journal = Movement Disorders | volume = 20 | issue = 4 | pages = 497–500 | date = April 2005 | pmid = 15645525 | doi = 10.1002/mds.20375 | s2cid = 35160189 }}</ref>
* Dysfunction of the [[Anatomy of the cerebellum#Phylogenetic and functional divisions|spinocerebellum]] ([[vermis]] and associated areas near the midline) presents itself with a wide-based "drunken sailor" [[gait]] (called truncal ataxia),<ref name="Blumenfeld">{{cite book | vauthors = Blumenfeld H | title = Neuroanatomy through clinical cases | url = https://archive.org/details/neuroanatomythro00blum | url-access = limited | publisher = Sinauer | location = Sunderland, Mass | year = 2002 | pages = [https://archive.org/details/neuroanatomythro00blum/page/n342 670]–671 | isbn = 0-87893-060-4 }}</ref> characterised by uncertain starts and stops, lateral deviations, and unequal steps. As a result of this gait impairment, [[falling (accident)|falling]] is a concern in patients with ataxia. Studies examining falls in this population show that 74–93% of patients have fallen at least once in the past year, and up to 60% admit to fear of falling.<ref name="pmid20157791">{{cite journal | vauthors = Fonteyn EM, Schmitz-Hübsch T, Verstappen CC, Baliko L, Bloem BR, Boesch S, Bunn L, Charles P, Dürr A, Filla A, Giunti P, Globas C, Klockgether T, Melegh B, Pandolfo M, De Rosa A, Schöls L, Timmann D, Munneke M, Kremer BP, van de Warrenburg BP | title = Falls in spinocerebellar ataxias: Results of the EuroSCA Fall Study | journal = Cerebellum | volume = 9 | issue = 2 | pages = 232–239 | date = June 2010 | pmid = 20157791 | doi = 10.1007/s12311-010-0155-z | s2cid = 23247877 }}</ref><ref name="pmid15645525">{{cite journal | vauthors = van de Warrenburg BP, Steijns JA, Munneke M, Kremer BP, Bloem BR | title = Falls in degenerative cerebellar ataxias | journal = Movement Disorders | volume = 20 | issue = 4 | pages = 497–500 | date = April 2005 | pmid = 15645525 | doi = 10.1002/mds.20375 | s2cid = 35160189 }}</ref>
* Dysfunction of the [[Anatomy of the cerebellum#Phylogenetic and functional divisions|cerebrocerebellum]] (lateral hemispheres) presents as disturbances in carrying out voluntary, planned movements by the extremities (called appendicular ataxia).<ref name="Blumenfeld" /> These include:
* Dysfunction of the [[Anatomy of the cerebellum#Phylogenetic and functional divisions|cerebrocerebellum]] (lateral hemispheres) presents as disturbances in carrying out voluntary, planned movements by the extremities (called appendicular ataxia).<ref name="Blumenfeld" /> These include:
** [[Intention tremor]] (coarse trembling, accentuated over the execution of voluntary movements, possibly involving the head and eyes, as well as the limbs and torso)
** [[Intention tremor]] (coarse trembling, accentuated over the execution of voluntary movements, possibly involving the head and eyes, as well as the limbs and torso)
** Peculiar writing abnormalities (large, unequal letters, irregular underlining)
** Peculiar writing abnormalities (large, unequal letters, irregular underlining)
** A peculiar pattern of [[dysarthria]] (slurred speech, sometimes characterised by explosive variations in voice intensity despite a regular rhythm)
** A peculiar pattern of [[dysarthria]] (slurred speech, sometimes characterised by explosive variations in voice intensity despite a regular rhythm)
** Inability to perform rapidly alternating movements, known as dysdiadochokinesia, occurs, and could involve rapidly switching from [[pronation]] to [[supination]] of the forearm. Movements become more irregular with increases of speed.<ref name="Schmitz">{{cite book | chapter = Examination of Coordination |vauthors=Schmitz TJ, O'Sullivan SB | title = Physical rehabilitation | url = https://archive.org/details/physicalrehabili00osul | url-access = limited | publisher = F.A. Davis | location = Philadelphia | year = 2007 | pages = [https://archive.org/details/physicalrehabili00osul/page/n199 193]–225 | isbn = 978-0-8036-1247-1  }}</ref>
** Inability to perform rapidly alternating movements, known as dysdiadochokinesia, occurs, and could involve rapidly switching from [[pronation]] to [[supination]] of the forearm. Movements become more irregular with speed increases.<ref name="Schmitz">{{cite book | chapter = Examination of Coordination |vauthors=Schmitz TJ, O'Sullivan SB | title = Physical rehabilitation | url = https://archive.org/details/physicalrehabili00osul | url-access = limited | publisher = F.A. Davis | location = Philadelphia | year = 2007 | pages = [https://archive.org/details/physicalrehabili00osul/page/n199 193]–225 | isbn = 978-0-8036-1247-1  }}</ref>
** Inability to judge distances or ranges of movement happens. This dysmetria is often seen as undershooting, [[hypometria]], or overshooting, [[hypermetria]], the required distance or range to reach a target. This is sometimes seen when a patient is asked to reach out and touch someone's finger or touch his or her own nose.<ref name="Schmitz" />
** Inability to judge distances or ranges of movement happens. This dysmetria is often seen as undershooting, [[hypometria]], or overshooting, [[hypermetria]], the required distance or range to reach a target. This is sometimes seen when a patient is asked to reach out and touch someone's finger or touch his or her own nose.<ref name="Schmitz" />
** The rebound phenomenon, also known as the loss of the check reflex, is also sometimes seen in patients with cerebellar ataxia, for example, when patients are flexing their elbows isometrically against a resistance. When the resistance is suddenly removed without warning, the patients' arms may swing up and even strike themselves. With an intact check reflex, the patients check and activate the opposing triceps to slow and stop the movement.<ref name="Schmitz" />
** The rebound phenomenon, also known as the loss of the check reflex, is also sometimes seen in patients with cerebellar ataxia, for example, when patients are flexing their elbows isometrically against resistance. When the resistance is suddenly removed without warning, the patients' arms may swing up and even strike themselves. With an intact check reflex, the patients check and activates the opposing triceps to slow and stop the movement.<ref name="Schmitz" />
** Patients may exhibit a constellation of subtle to overt cognitive symptoms, which are gathered under the terminology of [[Cerebellar cognitive affective syndrome|Schmahmann's syndrome]].<ref>{{cite journal | vauthors = Manto M, Mariën P | title = Schmahmann's syndrome - identification of the third cornerstone of clinical ataxiology | journal = Cerebellum & Ataxias | volume = 2 | pages = 2 | date = 2015 | pmid = 26331045 | pmc = 4552302 | doi = 10.1186/s40673-015-0023-1 | doi-access = free }}</ref>
** Patients may exhibit a constellation of subtle to overt cognitive symptoms, which are gathered under the terminology of [[Cerebellar cognitive affective syndrome|Schmahmann's syndrome]].<ref>{{cite journal | vauthors = Manto M, Mariën P | title = Schmahmann's syndrome - identification of the third cornerstone of clinical ataxiology | journal = Cerebellum & Ataxias | volume = 2 | article-number = 2 | date = 2015 | pmid = 26331045 | pmc = 4552302 | doi = 10.1186/s40673-015-0023-1 | doi-access = free }}</ref>


=== Sensory ===
=== Sensory ===
The term [[sensory ataxia]] is used to indicate ataxia due to loss of [[proprioception]], the loss of sensitivity to the positions of joint and body parts. This is generally caused by dysfunction of the [[dorsal columns]] of the spinal cord, because they carry proprioceptive information up to the brain. In some cases, the cause of sensory ataxia may instead be dysfunction of the various parts of the brain that receive positional information, including the cerebellum, [[thalamus]], and [[parietal lobe]]s.<ref name="pmid9184691"/>
The term [[sensory ataxia]] is used to indicate ataxia due to loss of [[proprioception]], the loss of sensitivity to the positions of joint and body parts. This is generally caused by dysfunction of the [[dorsal columns]] of the spinal cord, because they carry proprioceptive information up to the brain. In some cases, the cause of sensory ataxia may instead be dysfunction of the various parts of the brain that receive positional information, including the cerebellum, [[thalamus]], and [[parietal lobe]]s.<ref name="pmid9184691"/>


Sensory ataxia presents itself with an unsteady "stomping" gait with heavy [[heel]] strikes, as well as a postural instability that is usually worsened when the lack of proprioceptive input cannot be compensated for by [[visual perception|visual input]], such as in poorly lit environments.<ref>{{Cite web |title=Sensory Ataxia |url=https://www.physio-pedia.com/Sensory_Ataxia |access-date=2022-10-19 |website=Physiopedia |language=en}}</ref><ref>{{Cite journal | vauthors = Ruppert L, Kendig T  |title=A Pt Intervention for a Patient with Sensory Ataxia in the Acute Care Oncology Setting |date=2012 |url=https://journals.lww.com/rehabonc/Citation/2012/30010/A_PT_INTERVENTION_FOR_A_PATIENT_WITH_SENSORY.10.aspx |journal=Rehabilitation Oncology |language=en-US |volume=30 |issue=1 |pages=24–25 |doi=10.1097/01893697-201230010-00010 |issn=2168-3808|doi-access=free }}</ref>
Sensory ataxia presents itself with an unsteady "stomping" gait with heavy [[heel]] strikes, as well as a postural instability that is usually worsened when the lack of proprioceptive input cannot be compensated for by [[visual perception|visual input]], such as in poorly lit environments.<ref>{{Cite web |title=Sensory Ataxia |url=https://www.physio-pedia.com/Sensory_Ataxia |access-date=2022-10-19 |website=Physiopedia |language=en}}</ref><ref>{{Cite journal | vauthors = Ruppert L, Kendig T  |title=A Pt Intervention for a Patient with Sensory Ataxia in the Acute Care Oncology Setting |date=2012 |journal=Rehabilitation Oncology |language=en-US |volume=30 |issue=1 |pages=24–25 |doi=10.1097/01893697-201230010-00010 |issn=2168-3808|doi-access=free }}</ref>


Physicians can find evidence of sensory ataxia during [[physical examination]] by having patients stand with their feet together and [[Human eye|eye]]s shut. In affected patients, this will cause the instability to worsen markedly, producing wide oscillations and possibly a fall; this is called a positive [[Romberg's test]]. Worsening of the finger-pointing test with the eyes closed is another feature of sensory ataxia. Also, when patients are standing with arms and hands extended toward the physician, if the eyes are closed, the patients' fingers tend to "fall down" and then be restored to the horizontal extended position by sudden muscular contractions (the "ataxic hand").<ref>{{cite journal | vauthors = Halmágyi GM, Curthoys IS | title = Vestibular contributions to the Romberg test: Testing semicircular canal and otolith function | journal = European Journal of Neurology | volume = 28 | issue = 9 | pages = 3211–3219 | date = September 2021 | pmid = 34160115 | doi = 10.1111/ene.14942 }}</ref><ref>{{cite book | vauthors = Forbes J, Munakomi S, Cronovich H | chapter = Romberg Test |date=2024 | title = StatPearls | chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK563187/ |access-date=2024-04-16 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=33085334 }}</ref>
Physicians can find evidence of sensory ataxia during [[physical examination]] by having patients stand with their feet together and [[Human eye|eye]]s shut. In affected patients, this will cause the instability to worsen markedly, producing wide oscillations and possibly a fall; this is called a positive [[Romberg's test]]. Worsening of the finger-pointing test with the eyes closed is another feature of sensory ataxia. Also, when patients are standing with arms and hands extended toward the physician, if the eyes are closed, the patients' fingers tend to "fall down" and then be restored to the horizontal extended position by sudden muscular contractions (the "ataxic hand").<ref>{{cite journal | vauthors = Halmágyi GM, Curthoys IS | title = Vestibular contributions to the Romberg test: Testing semicircular canal and otolith function | journal = European Journal of Neurology | volume = 28 | issue = 9 | pages = 3211–3219 | date = September 2021 | pmid = 34160115 | doi = 10.1111/ene.14942 }}</ref><ref>{{cite book | vauthors = Forbes J, Munakomi S, Cronovich H | chapter = Romberg Test |date=2024 | title = StatPearls | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK563187/ |access-date=2024-04-16 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=33085334 }}</ref>


=== Vestibular ===
=== Vestibular ===
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== Causes ==
== Causes ==
The three types of ataxia have overlapping causes, so can either coexist or occur in isolation. Cerebellar ataxia can have many causes despite normal neuroimaging.<ref>{{Cite web |title=Ataxia: What It Is, Causes, Symptoms, Treatment & Types |url=https://my.clevelandclinic.org/health/symptoms/17748-ataxia |access-date=2024-02-08 |website=Cleveland Clinic |language=en}}</ref>
The three types of ataxia have overlapping causes, so they can either coexist or occur in isolation. Cerebellar ataxia can have many causes despite normal neuroimaging.<ref>{{Cite web |title=Ataxia: What It Is, Causes, Symptoms, Treatment & Types |url=https://my.clevelandclinic.org/health/symptoms/17748-ataxia |access-date=2024-02-08 |website=Cleveland Clinic |language=en}}</ref>


=== Focal lesions ===
=== Focal lesions ===
Any type of focal lesion of the [[central nervous system]] (such as [[stroke]], [[brain tumor]], [[multiple sclerosis]], inflammatory [such as [[sarcoidosis]]], and "chronic lymphocytyc inflammation with pontine perivascular enhancement responsive to steroids syndrome" [CLIPPERS<ref>{{cite journal | vauthors = Maenhoudt W, Ramboer K, Maqueda V | title = A Rare Cause of Dizziness and Gait Ataxia: CLIPPERS Syndrome | journal = Journal of the Belgian Society of Radiology | volume = 100 | issue = 1 | pages = 20 | date = February 2016 | pmid = 30151443 | pmc = 6102946 | doi = 10.5334/jbr-btr.997 | doi-access = free }}</ref>]) will cause the type of ataxia corresponding to the site of the lesion: cerebellar if in the cerebellum; sensory if in the dorsal spinal cord...to include cord compression by thickened ligamentum flavum or stenosis of the boney spinal canal...(and rarely in the [[thalamus]] or [[parietal lobe]]); or vestibular if in the vestibular system (including the vestibular areas of the [[cerebral cortex]]).{{citation needed|date=August 2021}}
Any type of focal lesion of the [[central nervous system]] (such as [[stroke]], [[brain tumor]], [[multiple sclerosis]], inflammatory [such as [[sarcoidosis]]], and "chronic lymphocytyc inflammation with pontine perivascular enhancement responsive to steroids syndrome" [CLIPPERS<ref>{{cite journal | vauthors = Maenhoudt W, Ramboer K, Maqueda V | title = A Rare Cause of Dizziness and Gait Ataxia: CLIPPERS Syndrome | journal = Journal of the Belgian Society of Radiology | volume = 100 | issue = 1 | article-number = 20 | date = February 2016 | pmid = 30151443 | pmc = 6102946 | doi = 10.5334/jbr-btr.997 | doi-access = free }}</ref>]) will cause the type of ataxia corresponding to the site of the lesion: cerebellar if in the cerebellum; sensory if in the dorsal spinal cord...to include cord compression by thickened ligamentum flavum or stenosis of the boney spinal canal...(and rarely in the [[thalamus]] or [[parietal lobe]]); or vestibular if in the vestibular system (including the vestibular areas of the [[cerebral cortex]]).{{citation needed|date=August 2021}}


=== Exogenous substances (metabolic ataxia) ===
=== Exogenous substances (metabolic ataxia) ===
[[Exogenous]] substances that cause ataxia mainly do so because they have a depressant effect on central nervous system function. The most common example is [[ethanol]] (alcohol), which is capable of causing reversible cerebellar and vestibular ataxia. Chronic intake of [[ethanol]] causes atrophy of the [[cerebellum]] by oxidative and endoplasmic reticulum stresses induced by [[thiamine]] deficiency.<ref name="pmid34444449">{{cite journal | vauthors = Mitoma H, Manto M, Shaikh AG | title = Mechanisms of Ethanol-Induced Cerebellar Ataxia: Underpinnings of Neuronal Death in the Cerebellum | journal = International Journal of Environmental Research and Public Health | volume = 18 | issue = 16 | pages = 8678 | date = August 2021 | pmid = 34444449 | pmc = 8391842 | doi = 10.3390/ijerph18168678 | doi-access = free }}</ref>
[[Exogenous]] substances that cause ataxia mainly do so because they have a depressant effect on central nervous system function. The most common example is [[ethanol]] (alcohol), which is capable of causing reversible cerebellar and vestibular ataxia. Chronic intake of [[ethanol]] causes atrophy of the [[cerebellum]] by oxidative and endoplasmic reticulum stresses induced by [[thiamine]] deficiency.<ref name="pmid34444449">{{cite journal | vauthors = Mitoma H, Manto M, Shaikh AG | title = Mechanisms of Ethanol-Induced Cerebellar Ataxia: Underpinnings of Neuronal Death in the Cerebellum | journal = International Journal of Environmental Research and Public Health | volume = 18 | issue = 16 | page = 8678 | date = August 2021 | pmid = 34444449 | pmc = 8391842 | doi = 10.3390/ijerph18168678 | doi-access = free }}</ref>


Other examples include various prescription drugs (e.g. most [[antiepileptic drugs]] have cerebellar ataxia as a possible [[adverse effect (medicine)|adverse effect]]), Lithium level over 1.5mEq/L, [[synthetic cannabinoid]] [[Dexanabinol|HU-211]] ingestion<ref name="Inadvertent Ingestion of Marijuana --- Los Angeles, California, 2009">{{cite web |url=https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5834a2.htm?s_cid=mm5834a2 |title=Inadvertent Ingestion of Marijuana --- Los Angeles, California, 2009 |access-date=3 September 2009 |url-status=live |archive-url=https://web.archive.org/web/20110511211253/http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5834a2.htm?s_cid=mm5834a2 |archive-date=11 May 2011}}</ref> and various other medical and recreational drugs (e.g. [[ketamine]], [[Phencyclidine|PCP]] or [[dextromethorphan]], all of which are [[NMDA receptor antagonist]]s that produce a dissociative state at high doses). A further class of pharmaceuticals which can cause short term ataxia, especially in high doses, are [[benzodiazepine]]s.<ref name="pmid817697">{{cite journal | vauthors = Browne TR | title = Clonazepam. A review of a new anticonvulsant drug | journal = Archives of Neurology | volume = 33 | issue = 5 | pages = 326–332 | date = May 1976 | pmid = 817697 | doi = 10.1001/archneur.1976.00500050012003 }}</ref><ref name="pmid1888441">{{cite journal | vauthors = Gaudreault P, Guay J, Thivierge RL, Verdy I | title = Benzodiazepine poisoning. Clinical and pharmacological considerations and treatment | journal = Drug Safety | volume = 6 | issue = 4 | pages = 247–265 | year = 1991 | pmid = 1888441 | doi = 10.2165/00002018-199106040-00003 | s2cid = 27619795 }}</ref> Exposure to high levels of [[methylmercury]], through consumption of fish with high [[Mercury (element)|mercury]] concentrations, is also a known cause of ataxia and other [[neurological disorders]].<ref name="pmid19253038">{{cite book | vauthors = Díez S | chapter = Human Health Effects of Methylmercury Exposure | title = Reviews of Environmental Contamination and Toxicology Volume 198 | volume = 198 | pages = 111–32 | year = 2009 | pmid = 19253038 | doi = 10.1007/978-0-387-09647-6_3 | isbn = 978-0-387-09646-9 }}</ref>
Other examples include various prescription drugs (e.g. most [[antiepileptic drugs]] have cerebellar ataxia as a possible [[adverse effect (medicine)|adverse effect]]), Lithium level over 1.5mEq/L, [[synthetic cannabinoid]] [[Dexanabinol|HU-211]] ingestion<ref name="Inadvertent Ingestion of Marijuana --- Los Angeles, California, 2009">{{cite web |url=https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5834a2.htm?s_cid=mm5834a2 |title=Inadvertent Ingestion of Marijuana --- Los Angeles, California, 2009 |access-date=3 September 2009 |url-status=live |archive-url=https://web.archive.org/web/20110511211253/http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5834a2.htm?s_cid=mm5834a2 |archive-date=11 May 2011}}</ref> and various other medical and recreational drugs (e.g. [[ketamine]], [[Phencyclidine|PCP]] or [[dextromethorphan]], all of which are [[NMDA receptor antagonist]]s that produce a dissociative state at high doses). A further class of pharmaceuticals which can cause short-term ataxia, especially in high doses, are [[benzodiazepine]]s.<ref name="pmid817697">{{cite journal | vauthors = Browne TR | title = Clonazepam. A review of a new anticonvulsant drug | journal = Archives of Neurology | volume = 33 | issue = 5 | pages = 326–332 | date = May 1976 | pmid = 817697 | doi = 10.1001/archneur.1976.00500050012003 }}</ref><ref name="pmid1888441">{{cite journal | vauthors = Gaudreault P, Guay J, Thivierge RL, Verdy I | title = Benzodiazepine poisoning. Clinical and pharmacological considerations and treatment | journal = Drug Safety | volume = 6 | issue = 4 | pages = 247–265 | year = 1991 | pmid = 1888441 | doi = 10.2165/00002018-199106040-00003 | s2cid = 27619795 }}</ref> Exposure to high levels of [[methylmercury]], through consumption of fish with high [[Mercury (element)|mercury]] concentrations, is also a known cause of ataxia and other [[neurological disorders]].<ref name="pmid19253038">{{cite book | vauthors = Díez S | chapter = Human Health Effects of Methylmercury Exposure | title = Reviews of Environmental Contamination and Toxicology Volume 198 | volume = 198 | pages = 111–32 | year = 2009 | pmid = 19253038 | doi = 10.1007/978-0-387-09647-6_3 | isbn = 978-0-387-09646-9 }}</ref>


=== Radiation poisoning ===
=== Radiation poisoning ===
Ataxia can be induced as a result of severe [[Acute radiation syndrome|acute radiation poisoning]] with an absorbed dose of more than 30 [[Gray (unit)|grays]].<ref>{{cite web |title=Radiation Exposure and Contamination - Injuries; Poisoning |url=https://www.merckmanuals.com/professional/injuries-poisoning/radiation-exposure-and-contamination/radiation-exposure-and-contamination |website=Merck Manuals Professional Edition |access-date=26 December 2022}}</ref> Furthermore, those with [[Ataxia–telangiectasia|ataxia telangiectasia]] may have a high sensitivity towards [[gamma ray]]s and [[x-ray]]s.<ref>{{cite journal | vauthors = Rothblum-Oviatt C, Wright J, Lefton-Greif MA, McGrath-Morrow SA, Crawford TO, Lederman HM | title = Ataxia telangiectasia: a review | journal = Orphanet Journal of Rare Diseases | volume = 11 | issue = 1 | pages = 159 | date = November 2016 | pmid = 27884168 | pmc = 5123280 | doi = 10.1186/s13023-016-0543-7 |doi-access=free}}</ref>
Ataxia can be induced as a result of severe [[Acute radiation syndrome|acute radiation poisoning]] with an absorbed dose of more than 30 [[Gray (unit)|grays]].<ref>{{cite web |title=Radiation Exposure and Contamination - Injuries; Poisoning |url=https://www.merckmanuals.com/professional/injuries-poisoning/radiation-exposure-and-contamination/radiation-exposure-and-contamination |website=Merck Manuals Professional Edition |access-date=26 December 2022}}</ref> Furthermore, those with [[Ataxia–telangiectasia|ataxia telangiectasia]] may have a high sensitivity towards [[gamma ray]]s and [[x-ray]]s.<ref>{{cite journal | vauthors = Rothblum-Oviatt C, Wright J, Lefton-Greif MA, McGrath-Morrow SA, Crawford TO, Lederman HM | title = Ataxia telangiectasia: a review | journal = Orphanet Journal of Rare Diseases | volume = 11 | issue = 1 | article-number = 159 | date = November 2016 | pmid = 27884168 | pmc = 5123280 | doi = 10.1186/s13023-016-0543-7 |doi-access=free}}</ref>


=== Vitamin B<sub>12</sub> deficiency ===
=== Vitamin B<sub>12</sub> deficiency ===
[[Vitamin B12 deficiency|Vitamin B<sub>12</sub> deficiency]] may cause, among several neurological abnormalities, overlapping cerebellar and sensory ataxia.<ref>{{cite journal | vauthors = Crawford JR, Say D | title = Vitamin B12 deficiency presenting as acute ataxia | journal = BMJ Case Reports | volume = 2013 | pages = bcr2013008840 | date = March 2013 | pmid = 23536622 | pmc = 3618829 | doi = 10.1136/bcr-2013-008840 }}</ref> Neuropsychological symptoms may include sense loss, difficulty in [[proprioception]], poor balance, loss of sensation in the feet, changes in [[reflex]]es, dementia, and [[psychosis]], which can be reversible with treatment.<ref>{{cite journal | vauthors = Osimani A, Berger A, Friedman J, Porat-Katz BS, Abarbanel JM | title = Neuropsychology of vitamin B12 deficiency in elderly dementia patients and control subjects | journal = Journal of Geriatric Psychiatry and Neurology | volume = 18 | issue = 1 | pages = 33–38 | date = March 2005 | pmid = 15681626 | doi = 10.1177/0891988704272308 | s2cid = 29983253 }}</ref> Complications may include a neurological complex known as [[subacute combined degeneration of spinal cord]], and other neurological disorders.<ref>{{cite book | vauthors = Qudsiya Z, De Jesus O | chapter = Subacute Combined Degeneration of the Spinal Cord |date=2022 | chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK559316/ | title = StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32644742 |access-date=2022-07-17 }}</ref>
[[Vitamin B12 deficiency|Vitamin B<sub>12</sub> deficiency]] may cause, among several neurological abnormalities, overlapping cerebellar and sensory ataxia.<ref>{{cite journal | vauthors = Crawford JR, Say D | title = Vitamin B12 deficiency presenting as acute ataxia | journal = BMJ Case Reports | volume = 2013 | pages = bcr2013008840 | date = March 2013 | pmid = 23536622 | pmc = 3618829 | doi = 10.1136/bcr-2013-008840 }}</ref> Neuropsychological symptoms may include sense loss, difficulty in [[proprioception]], poor balance, loss of sensation in the feet, changes in [[reflex]]es, dementia, and [[psychosis]], which can be reversible with treatment.<ref>{{cite journal | vauthors = Osimani A, Berger A, Friedman J, Porat-Katz BS, Abarbanel JM | title = Neuropsychology of vitamin B12 deficiency in elderly dementia patients and control subjects | journal = Journal of Geriatric Psychiatry and Neurology | volume = 18 | issue = 1 | pages = 33–38 | date = March 2005 | pmid = 15681626 | doi = 10.1177/0891988704272308 | s2cid = 29983253 }}</ref> Complications may include a neurological complex known as [[subacute combined degeneration of spinal cord]], and other neurological disorders.<ref>{{cite book | vauthors = Qudsiya Z, De Jesus O | chapter = Subacute Combined Degeneration of the Spinal Cord |date=2022 | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK559316/ | title = StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32644742 |access-date=2022-07-17 }}</ref>


=== Hypothyroidism ===
=== Hypothyroidism ===
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=== Causes of isolated sensory ataxia ===
=== Causes of isolated sensory ataxia ===
[[Peripheral neuropathy|Peripheral neuropathies]] may cause generalised or localised sensory ataxia (e.g. a limb only) depending on the extent of the neuropathic involvement. Spinal disorders of various types may cause sensory ataxia from the lesioned level below, when they involve the dorsal columns.<ref>{{cite journal | vauthors = Spinazzi M, Angelini C, Patrini C | title = Subacute sensory ataxia and optic neuropathy with thiamine deficiency | journal = Nature Reviews. Neurology | volume = 6 | issue = 5 | pages = 288–293 | date = May 2010 | pmid = 20308997 | doi = 10.1038/nrneurol.2010.16 | s2cid = 12333200 }}</ref><ref>{{cite journal | vauthors = Sghirlanzoni A, Pareyson D, Lauria G | title = Sensory neuron diseases | journal = The Lancet. Neurology | volume = 4 | issue = 6 | pages = 349–361 | date = June 2005 | pmid = 15907739 | doi = 10.1016/S1474-4422(05)70096-X | s2cid = 35053543 }}</ref><ref>{{cite journal | vauthors = Moeller JJ, Macaulay RJ, Valdmanis PN, Weston LE, Rouleau GA, Dupré N | title = Autosomal dominant sensory ataxia: a neuroaxonal dystrophy | journal = Acta Neuropathologica | volume = 116 | issue = 3 | pages = 331–336 | date = September 2008 | pmid = 18347805 | doi = 10.1007/s00401-008-0362-6 | s2cid = 22881684 }}</ref>
[[Peripheral neuropathy|Peripheral neuropathies]] may cause generalised or localised sensory ataxia (e.g., a limb only) depending on the extent of the neuropathic involvement. Spinal disorders of various types may cause sensory ataxia from the lesioned level below, when they involve the dorsal columns.<ref>{{cite journal | vauthors = Spinazzi M, Angelini C, Patrini C | title = Subacute sensory ataxia and optic neuropathy with thiamine deficiency | journal = Nature Reviews. Neurology | volume = 6 | issue = 5 | pages = 288–293 | date = May 2010 | pmid = 20308997 | doi = 10.1038/nrneurol.2010.16 | s2cid = 12333200 }}</ref><ref>{{cite journal | vauthors = Sghirlanzoni A, Pareyson D, Lauria G | title = Sensory neuron diseases | journal = The Lancet. Neurology | volume = 4 | issue = 6 | pages = 349–361 | date = June 2005 | pmid = 15907739 | doi = 10.1016/S1474-4422(05)70096-X | s2cid = 35053543 }}</ref><ref>{{cite journal | vauthors = Moeller JJ, Macaulay RJ, Valdmanis PN, Weston LE, Rouleau GA, Dupré N | title = Autosomal dominant sensory ataxia: a neuroaxonal dystrophy | journal = Acta Neuropathologica | volume = 116 | issue = 3 | pages = 331–336 | date = September 2008 | pmid = 18347805 | doi = 10.1007/s00401-008-0362-6 | s2cid = 22881684 }}</ref>


=== Non-hereditary cerebellar degeneration ===
=== Non-hereditary cerebellar degeneration ===
Non-hereditary causes of cerebellar degeneration include chronic [[alcohol use disorder]], [[head injury]], [[paraneoplastic cerebellar degeneration|paraneoplastic]] and non-paraneoplastic [[autoimmunity|autoimmune]] ataxia,<ref name="Medusa head ataxia - Part 1">{{cite journal | vauthors = Jarius S, Wildemann B | title = 'Medusa-head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 1: Anti-mGluR1, anti-Homer-3, anti-Sj/ITPR1 and anti-CARP VIII | journal = Journal of Neuroinflammation | volume = 12 | issue = 1 | pages = 166 | date = September 2015 | pmid = 26377085 | pmc = 4574226 | doi = 10.1186/s12974-015-0356-y | doi-access = free }}</ref><ref name="Medusa head ataxia - Part 2">{{cite journal | vauthors = Jarius S, Wildemann B | title = 'Medusa head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 2: Anti-PKC-gamma, anti-GluR-delta2, anti-Ca/ARHGAP26 and anti-VGCC | journal = Journal of Neuroinflammation | volume = 12 | issue = 1 | pages = 167 | date = September 2015 | pmid = 26377184 | pmc = 4574118 | doi = 10.1186/s12974-015-0357-x | doi-access = free }}</ref><ref name="Medusa head ataxia - Part 3">{{cite journal | vauthors = Jarius S, Wildemann B | title = 'Medusa head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 3: Anti-Yo/CDR2, anti-Nb/AP3B2, PCA-2, anti-Tr/DNER, other antibodies, diagnostic pitfalls, summary and outlook | journal = Journal of Neuroinflammation | volume = 12 | issue = 1 | pages = 168 | date = September 2015 | pmid = 26377319 | pmc = 4573944 | doi = 10.1186/s12974-015-0358-9 | doi-access = free }}</ref> [[high-altitude cerebral edema]],<ref name="Sharma_2019">{{cite journal | vauthors = Sharma R, Cramer NP, Perry B, Adahman Z, Murphy EK, Xu X, Dardzinski BJ, Galdzicki Z, Perl DP, Dickstein DL, Iacono D | title = Chronic Exposure to High Altitude: Synaptic, Astroglial and Memory Changes | journal = Scientific Reports | volume = 9 | issue = 1 | pages = 16406 | date = November 2019 | pmid = 31712561 | pmc = 6848138 | doi = 10.1038/s41598-019-52563-1 | bibcode = 2019NatSR...916406S }}</ref> [[celiac disease]],<ref name="Hermaszewski_1991">{{cite journal | vauthors = Hermaszewski RA, Rigby S, Dalgleish AG | title = Coeliac disease presenting with cerebellar degeneration | journal = Postgraduate Medical Journal | volume = 67 | issue = 793 | pages = 1023–1024 | date = November 1991 | pmid = 1775412 | pmc = 2399130 | doi = 10.1136/pgmj.67.793.1023 }}</ref> [[normal-pressure hydrocephalus]],<ref name="Lv_2022">{{cite journal | vauthors = Lv M, Yang X, Zhou X, Chen J, Wei H, Du D, Lin H, Xia J | title = Gray matter volume of cerebellum associated with idiopathic normal pressure hydrocephalus: A cross-sectional analysis | journal = Frontiers in Neurology | volume = 13 | pages = 922199 | date = 2022-09-07 | pmid = 36158963 | pmc = 9489844 | doi = 10.3389/fneur.2022.922199 | doi-access = free }}</ref> and infectious or post-infectious [[Post viral cerebellar ataxia|cerebellitis]].<ref name="Parvez_2022">{{cite journal | vauthors = Parvez MS, Ohtsuki G | title = Acute Cerebellar Inflammation and Related Ataxia: Mechanisms and Pathophysiology | journal = Brain Sciences | volume = 12 | issue = 3 | page = 367 | date = March 2022 | pmid = 35326323 | pmc = 8946185 | doi = 10.3390/brainsci12030367 | doi-access = free }}</ref>
Non-hereditary causes of cerebellar degeneration include chronic [[alcohol use disorder]], [[head injury]], [[paraneoplastic cerebellar degeneration|paraneoplastic]] and non-paraneoplastic [[autoimmunity|autoimmune]] ataxia,<ref name="Medusa head ataxia - Part 1">{{cite journal | vauthors = Jarius S, Wildemann B | title = 'Medusa-head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 1: Anti-mGluR1, anti-Homer-3, anti-Sj/ITPR1 and anti-CARP VIII | journal = Journal of Neuroinflammation | volume = 12 | issue = 1 | article-number = 166 | date = September 2015 | pmid = 26377085 | pmc = 4574226 | doi = 10.1186/s12974-015-0356-y | doi-access = free }}</ref><ref name="Medusa head ataxia - Part 2">{{cite journal | vauthors = Jarius S, Wildemann B | title = 'Medusa head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 2: Anti-PKC-gamma, anti-GluR-delta2, anti-Ca/ARHGAP26 and anti-VGCC | journal = Journal of Neuroinflammation | volume = 12 | issue = 1 | article-number = 167 | date = September 2015 | pmid = 26377184 | pmc = 4574118 | doi = 10.1186/s12974-015-0357-x | doi-access = free }}</ref><ref name="Medusa head ataxia - Part 3">{{cite journal | vauthors = Jarius S, Wildemann B | title = 'Medusa head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 3: Anti-Yo/CDR2, anti-Nb/AP3B2, PCA-2, anti-Tr/DNER, other antibodies, diagnostic pitfalls, summary and outlook | journal = Journal of Neuroinflammation | volume = 12 | issue = 1 | article-number = 168 | date = September 2015 | pmid = 26377319 | pmc = 4573944 | doi = 10.1186/s12974-015-0358-9 | doi-access = free }}</ref> [[high-altitude cerebral edema]],<ref name="Sharma_2019">{{cite journal | vauthors = Sharma R, Cramer NP, Perry B, Adahman Z, Murphy EK, Xu X, Dardzinski BJ, Galdzicki Z, Perl DP, Dickstein DL, Iacono D | title = Chronic Exposure to High Altitude: Synaptic, Astroglial and Memory Changes | journal = Scientific Reports | volume = 9 | issue = 1 | article-number = 16406 | date = November 2019 | pmid = 31712561 | pmc = 6848138 | doi = 10.1038/s41598-019-52563-1 | bibcode = 2019NatSR...916406S }}</ref> [[celiac disease]],<ref name="Hermaszewski_1991">{{cite journal | vauthors = Hermaszewski RA, Rigby S, Dalgleish AG | title = Coeliac disease presenting with cerebellar degeneration | journal = Postgraduate Medical Journal | volume = 67 | issue = 793 | pages = 1023–1024 | date = November 1991 | pmid = 1775412 | pmc = 2399130 | doi = 10.1136/pgmj.67.793.1023 }}</ref> [[normal-pressure hydrocephalus]],<ref name="Lv_2022">{{cite journal | vauthors = Lv M, Yang X, Zhou X, Chen J, Wei H, Du D, Lin H, Xia J | title = Gray matter volume of cerebellum associated with idiopathic normal pressure hydrocephalus: A cross-sectional analysis | journal = Frontiers in Neurology | volume = 13 | article-number = 922199 | date = 2022-09-07 | pmid = 36158963 | pmc = 9489844 | doi = 10.3389/fneur.2022.922199 | doi-access = free }}</ref> and infectious or post-infectious [[Post viral cerebellar ataxia|cerebellitis]].<ref name="Parvez_2022">{{cite journal | vauthors = Parvez MS, Ohtsuki G | title = Acute Cerebellar Inflammation and Related Ataxia: Mechanisms and Pathophysiology | journal = Brain Sciences | volume = 12 | issue = 3 | page = 367 | date = March 2022 | pmid = 35326323 | pmc = 8946185 | doi = 10.3390/brainsci12030367 | doi-access = free }}</ref>


=== Hereditary ataxias ===
=== Hereditary ataxias ===
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=== Wilson's disease ===
=== Wilson's disease ===
[[Wilson's disease]] is an [[autosomal]]-[[recessive gene]] disorder whereby an alteration of the ATP7B gene results in an inability to properly excrete [[copper]] from the body.<ref name="urlwww.birminghammodis.com">{{cite web|url=http://www.birminghammodis.com/handbook/Chapter12.pdf |title=Wilson's Disease | vauthors = Walshe JM | veditors = Clarke CE, Nicholl DJ |work=Birmingham Movement Disorders Coursebook |url-status=dead |archive-url= https://web.archive.org/web/20110910171019/http://www.birminghammodis.com/handbook/Chapter12.pdf |archive-date=10 September 2011}}</ref> Copper accumulates in the [[liver]] and raises the toxicity levels in the nervous system causing demyelination of the nerves.<ref>{{cite journal | vauthors = Ortiz JF, Morillo Cox Á, Tambo W, Eskander N, Wirth M, Valdez M, Niño M | title = Neurological Manifestations of Wilson's Disease: Pathophysiology and Localization of Each Component | journal = Cureus | volume = 12 | issue = 11 | pages = e11509 | date = November 2020 | pmid = 33354453 | pmc = 7744205 | doi = 10.7759/cureus.11509 |doi-access=free}}</ref> This can cause ataxia as well as other [[neurological]] and organ impairments.<ref name="urlWilsons disease2">{{cite web |title=Wilson's disease – PubMed Health |url=https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001789/ |url-status=live |archive-url=https://web.archive.org/web/20140727172514/http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001789/ |archive-date=27 July 2014 |work=PubMed Health |vauthors=Haldeman-Englert C}}</ref>
[[Wilson's disease]] is an [[autosomal]]-[[recessive gene]] disorder whereby an alteration of the ATP7B gene results in an inability to properly excrete [[copper]] from the body.<ref name="urlwww.birminghammodis.com">{{cite web|url=http://www.birminghammodis.com/handbook/Chapter12.pdf |title=Wilson's Disease | vauthors = Walshe JM | veditors = Clarke CE, Nicholl DJ |work=Birmingham Movement Disorders Coursebook |archive-url= https://web.archive.org/web/20110910171019/http://www.birminghammodis.com/handbook/Chapter12.pdf |archive-date=10 September 2011}}</ref> Copper accumulates in the [[liver]] and raises the toxicity levels in the nervous system causing demyelination of the nerves.<ref>{{cite journal | vauthors = Ortiz JF, Morillo Cox Á, Tambo W, Eskander N, Wirth M, Valdez M, Niño M | title = Neurological Manifestations of Wilson's Disease: Pathophysiology and Localization of Each Component | journal = Cureus | volume = 12 | issue = 11 | article-number = e11509 | date = November 2020 | pmid = 33354453 | pmc = 7744205 | doi = 10.7759/cureus.11509 |doi-access=free}}</ref> This can cause ataxia as well as other [[neurological]] and organ impairments.<ref name="urlWilsons disease2">{{cite web |title=Wilson's disease – PubMed Health |url=https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001789/ |archive-url=https://web.archive.org/web/20140727172514/http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001789/ |archive-date=27 July 2014 |work=PubMed Health |vauthors=Haldeman-Englert C}}</ref>


=== Gluten ataxia ===
=== Gluten ataxia ===
[[File:Gluten ataxia eng.ogg|thumb|A male with gluten ataxia: previous situation and evolution after three months of a gluten-free diet]]
[[File:Gluten ataxia eng.ogg|thumb|A male with gluten ataxia: previous situation and evolution after three months of a gluten-free diet]]
Gluten ataxia is an [[autoimmune disease]] derived from [[celiac disease]],<ref>{{cite journal | vauthors = Giuffrè M, Gazzin S, Zoratti C, Llido JP, Lanza G, Tiribelli C, Moretti R | title = Celiac Disease and Neurological Manifestations: From Gluten to Neuroinflammation | journal = International Journal of Molecular Sciences | volume = 23 | issue = 24 | pages = 15564 | date = December 2022 | pmid = 36555205 | pmc = 9779232 | doi = 10.3390/ijms232415564 |doi-access=free}}</ref> which is triggered by the ingestion of [[gluten]].<ref name="MitomaAdhikari2016">{{cite journal | vauthors = Mitoma H, Adhikari K, Aeschlimann D, Chattopadhyay P, Hadjivassiliou M, Hampe CS, Honnorat J, Joubert B, Kakei S, Lee J, Manto M, Matsunaga A, Mizusawa H, Nanri K, Shanmugarajah P, Yoneda M, Yuki N | title = Consensus Paper: Neuroimmune Mechanisms of Cerebellar Ataxias | journal = Cerebellum | volume = 15 | issue = 2 | pages = 213–232 | date = April 2016 | pmid = 25823827 | pmc = 4591117 | doi = 10.1007/s12311-015-0664-x | type = Review }}</ref><ref name="sapone-etal-2010-b">{{cite journal | vauthors = Sapone A, Bai JC, Ciacci C, Dolinsek J, Green PH, Hadjivassiliou M, Kaukinen K, Rostami K, Sanders DS, Schumann M, Ullrich R, Villalta D, Volta U, Catassi C, Fasano A | title = Spectrum of gluten-related disorders: consensus on new nomenclature and classification | journal = BMC Medicine | volume = 10 | pages = 13 | date = February 2012 | pmid = 22313950 | pmc = 3292448 | doi = 10.1186/1741-7015-10-13 | doi-access = free | type = Review }}</ref> Early diagnosis and treatment with a [[gluten-free diet]] can improve ataxia and prevent its progression. The effectiveness of the treatment depends on the elapsed time from the onset of the ataxia until diagnosis, because the death of [[Purkinje cells|neurons in the cerebellum]] as a result of gluten exposure is irreversible.<ref name="MitomaAdhikari2016" /><ref name="HadjivassiliouSanders2015" /> It accounts for 40% of ataxias of unknown origin and 15% of all ataxias.<ref name="HadjivassiliouSanders2015">{{cite journal | vauthors = Hadjivassiliou M, Sanders DD, Aeschlimann DP | title = Gluten-related disorders: gluten ataxia | journal = Digestive Diseases | volume = 33 | issue = 2 | pages = 264–268 | year = 2015 | pmid = 25925933 | doi = 10.1159/000369509 | type = Review | s2cid = 207673823 }}</ref> Less than 10% of people with gluten ataxia present any gastrointestinal symptom and only about 40% have intestinal damage.<ref name="MitomaAdhikari2016" /><ref name="HadjivassiliouSanders2015" /> This entity is classified into primary auto-immune cerebellar ataxias (PACA).<ref>{{cite journal | vauthors = Hadjivassiliou M, Graus F, Honnorat J, Jarius S, Titulaer M, Manto M, Hoggard N, Sarrigiannis P, Mitoma H | title = Diagnostic Criteria for Primary Autoimmune Cerebellar Ataxia-Guidelines from an International Task Force on Immune-Mediated Cerebellar Ataxias | journal = Cerebellum | volume = 19 | issue = 4 | pages = 605–610 | date = August 2020 | pmid = 32328884 | pmc = 7351847 | doi = 10.1007/s12311-020-01132-8 }}</ref> There is a continuum between presymptomatic ataxia and immune ataxias with clinical deficits.<ref>{{cite journal | vauthors = Manto M, Mitoma H | title = Immune Ataxias: The Continuum of Latent Ataxia, Primary Ataxia and Clinical Ataxia | journal = Journal of Integrative Neuroscience | volume = 23 | issue = 79 | date = April 2024 | page = 79 | doi = 10.31083/j.jin2304079 | doi-access = free | pmid = 38682229 }}</ref>
Gluten ataxia is an [[autoimmune disease]] derived from [[celiac disease]],<ref>{{cite journal | vauthors = Giuffrè M, Gazzin S, Zoratti C, Llido JP, Lanza G, Tiribelli C, Moretti R | title = Celiac Disease and Neurological Manifestations: From Gluten to Neuroinflammation | journal = International Journal of Molecular Sciences | volume = 23 | issue = 24 | article-number = 15564 | date = December 2022 | pmid = 36555205 | pmc = 9779232 | doi = 10.3390/ijms232415564 |doi-access=free}}</ref> which is triggered by the ingestion of [[gluten]].<ref name="MitomaAdhikari2016">{{cite journal | vauthors = Mitoma H, Adhikari K, Aeschlimann D, Chattopadhyay P, Hadjivassiliou M, Hampe CS, Honnorat J, Joubert B, Kakei S, Lee J, Manto M, Matsunaga A, Mizusawa H, Nanri K, Shanmugarajah P, Yoneda M, Yuki N | title = Consensus Paper: Neuroimmune Mechanisms of Cerebellar Ataxias | journal = Cerebellum | volume = 15 | issue = 2 | pages = 213–232 | date = April 2016 | pmid = 25823827 | pmc = 4591117 | doi = 10.1007/s12311-015-0664-x | type = Review }}</ref><ref name="sapone-etal-2010-b">{{cite journal | vauthors = Sapone A, Bai JC, Ciacci C, Dolinsek J, Green PH, Hadjivassiliou M, Kaukinen K, Rostami K, Sanders DS, Schumann M, Ullrich R, Villalta D, Volta U, Catassi C, Fasano A | title = Spectrum of gluten-related disorders: consensus on new nomenclature and classification | journal = BMC Medicine | volume = 10 | article-number = 13 | date = February 2012 | pmid = 22313950 | pmc = 3292448 | doi = 10.1186/1741-7015-10-13 | doi-access = free | type = Review }}</ref> Early diagnosis and treatment with a [[gluten-free diet]] can improve ataxia and prevent its progression. The effectiveness of the treatment depends on the elapsed time from the onset of the ataxia until diagnosis, because the death of [[Purkinje cells|neurons in the cerebellum]] as a result of gluten exposure is irreversible.<ref name="MitomaAdhikari2016" /><ref name="HadjivassiliouSanders2015" /> It accounts for 40% of ataxias of unknown origin and 15% of all ataxias.<ref name="HadjivassiliouSanders2015">{{cite journal | vauthors = Hadjivassiliou M, Sanders DD, Aeschlimann DP | title = Gluten-related disorders: gluten ataxia | journal = Digestive Diseases | volume = 33 | issue = 2 | pages = 264–268 | year = 2015 | pmid = 25925933 | doi = 10.1159/000369509 | type = Review | s2cid = 207673823 }}</ref> Less than 10% of people with gluten ataxia present any gastrointestinal symptom and only about 40% have intestinal damage.<ref name="MitomaAdhikari2016" /><ref name="HadjivassiliouSanders2015" /> This entity is classified into primary auto-immune cerebellar ataxias (PACA).<ref>{{cite journal | vauthors = Hadjivassiliou M, Graus F, Honnorat J, Jarius S, Titulaer M, Manto M, Hoggard N, Sarrigiannis P, Mitoma H | title = Diagnostic Criteria for Primary Autoimmune Cerebellar Ataxia-Guidelines from an International Task Force on Immune-Mediated Cerebellar Ataxias | journal = Cerebellum | volume = 19 | issue = 4 | pages = 605–610 | date = August 2020 | pmid = 32328884 | pmc = 7351847 | doi = 10.1007/s12311-020-01132-8 }}</ref> There is a continuum between presymptomatic ataxia and immune ataxias with clinical deficits.<ref>{{cite journal | vauthors = Manto M, Mitoma H | title = Immune Ataxias: The Continuum of Latent Ataxia, Primary Ataxia and Clinical Ataxia | journal = Journal of Integrative Neuroscience | volume = 23 | issue = 79 | date = April 2024 | article-number = 79 | doi = 10.31083/j.jin2304079 | doi-access = free | pmid = 38682229 }}</ref>


=== Potassium pump ===
=== Potassium pump ===
Malfunction of the [[sodium-potassium pump]] may be a factor in some ataxias. The {{chem2|Na+/K+}} pump has been shown to control and set the intrinsic activity mode of [[cerebellar]] [[Purkinje neurons]].<ref>{{cite journal | vauthors = Forrest MD, Wall MJ, Press DA, Feng J | title = The sodium-potassium pump controls the intrinsic firing of the cerebellar Purkinje neuron | journal = PLOS ONE | volume = 7 | issue = 12 | pages = e51169 | date = December 2012 | pmid = 23284664 | pmc = 3527461 | doi = 10.1371/journal.pone.0051169 | doi-access = free | bibcode = 2012PLoSO...751169F }}</ref> This suggests that the pump might not simply be a homeostatic, "housekeeping" molecule for ionic gradients; but could be a computational element in the [[cerebellum]] and the [[brain]].<ref>{{cite journal | vauthors = Forrest MD | title = The sodium-potassium pump is an information processing element in brain computation | journal = Frontiers in Physiology | volume = 5 | issue = 472 | pages = 472 | date = December 2014 | pmid = 25566080 | pmc = 4274886 | doi = 10.3389/fphys.2014.00472 | doi-access = free }}</ref> Indeed, a [[ouabain]] block of {{chem2|Na+/K+}} pumps in the cerebellum of a live [[mouse]] results in it displaying ataxia and [[dystonia]].<ref>{{cite journal | vauthors = Calderon DP, Fremont R, Kraenzlin F, Khodakhah K | title = The neural substrates of rapid-onset Dystonia-Parkinsonism | journal = Nature Neuroscience | volume = 14 | issue = 3 | pages = 357–365 | date = March 2011 | pmid = 21297628 | pmc = 3430603 | doi = 10.1038/nn.2753 }}</ref> Ataxia is observed for lower ouabain concentrations, dystonia is observed at higher ouabain concentrations.
Malfunction of the [[sodium-potassium pump]] may be a factor in some ataxias. The {{chem2|Na+/K+}} pump has been shown to control and set the intrinsic activity mode of [[cerebellar]] [[Purkinje neurons]].<ref>{{cite journal | vauthors = Forrest MD, Wall MJ, Press DA, Feng J | title = The sodium-potassium pump controls the intrinsic firing of the cerebellar Purkinje neuron | journal = PLOS ONE | volume = 7 | issue = 12 | article-number = e51169 | date = December 2012 | pmid = 23284664 | pmc = 3527461 | doi = 10.1371/journal.pone.0051169 | doi-access = free | bibcode = 2012PLoSO...751169F }}</ref> This suggests that the pump might not simply be a homeostatic, "housekeeping" molecule for ionic gradients, but could be a computational element in the [[cerebellum]] and the [[brain]].<ref>{{cite journal | vauthors = Forrest MD | title = The sodium-potassium pump is an information processing element in brain computation | journal = Frontiers in Physiology | volume = 5 | issue = 472 | page = 472 | date = December 2014 | pmid = 25566080 | pmc = 4274886 | doi = 10.3389/fphys.2014.00472 | doi-access = free }}</ref> Indeed, a [[ouabain]] block of {{chem2|Na+/K+}} pumps in the cerebellum of a live [[mouse]] results in it displaying ataxia and [[dystonia]].<ref>{{cite journal | vauthors = Calderon DP, Fremont R, Kraenzlin F, Khodakhah K | title = The neural substrates of rapid-onset Dystonia-Parkinsonism | journal = Nature Neuroscience | volume = 14 | issue = 3 | pages = 357–365 | date = March 2011 | pmid = 21297628 | pmc = 3430603 | doi = 10.1038/nn.2753 }}</ref> Ataxia is observed for lower ouabain concentrations, and dystonia is observed at higher ouabain concentrations.


=== Cerebellar ataxia associated with anti-GAD antibodies ===
=== Cerebellar ataxia associated with anti-GAD antibodies ===
Antibodies against the enzyme glutamic acid decarboxylase (GAD: enzyme changing glutamate into GABA) cause cerebellar deficits.<ref>{{cite journal | vauthors = Mitoma H, Manto M, Hampe CS | title = Pathogenic Roles of Glutamic Acid Decarboxylase 65 Autoantibodies in Cerebellar Ataxias | journal = Journal of Immunology Research | volume = 2017 | pages = 2913297 | date = 2017 | pmid = 28386570 | pmc = 5366212 | doi = 10.1155/2017/2913297 | doi-access = free }}</ref> The antibodies impair motor learning and cause behavioral deficits.<ref>{{cite journal | vauthors = Manto M, Honnorat J, Hampe CS, Guerra-Narbona R, López-Ramos JC, Delgado-García JM, Saitow F, Suzuki H, Yanagawa Y, Mizusawa H, Mitoma H | title = Disease-specific monoclonal antibodies targeting glutamate decarboxylase impair GABAergic neurotransmission and affect motor learning and behavioral functions | journal = Frontiers in Behavioral Neuroscience | volume = 9 | pages = 78 | date = 2015 | pmid = 25870548 | pmc = 4375997 | doi = 10.3389/fnbeh.2015.00078 | doi-access = free }}</ref>
Antibodies against the enzyme glutamic acid decarboxylase (GAD: enzyme changing glutamate into GABA) cause cerebellar deficits.<ref>{{cite journal | vauthors = Mitoma H, Manto M, Hampe CS | title = Pathogenic Roles of Glutamic Acid Decarboxylase 65 Autoantibodies in Cerebellar Ataxias | journal = Journal of Immunology Research | volume = 2017 | article-number = 2913297 | date = 2017 | pmid = 28386570 | pmc = 5366212 | doi = 10.1155/2017/2913297 | doi-access = free }}</ref> The antibodies impair motor learning and cause behavioral deficits.<ref>{{cite journal | vauthors = Manto M, Honnorat J, Hampe CS, Guerra-Narbona R, López-Ramos JC, Delgado-García JM, Saitow F, Suzuki H, Yanagawa Y, Mizusawa H, Mitoma H | title = Disease-specific monoclonal antibodies targeting glutamate decarboxylase impair GABAergic neurotransmission and affect motor learning and behavioral functions | journal = Frontiers in Behavioral Neuroscience | volume = 9 | page = 78 | date = 2015 | pmid = 25870548 | pmc = 4375997 | doi = 10.3389/fnbeh.2015.00078 | doi-access = free }}</ref>
[[Glutamate decarboxylase|GAD antibodies]] related ataxia is part of the group called immune-mediated cerebellar ataxias.<ref>{{cite journal | vauthors = Mitoma H, Manto M, Hampe CS | title = Immune-mediated Cerebellar Ataxias: Practical Guidelines and Therapeutic Challenges | journal = Current Neuropharmacology | volume = 17 | issue = 1 | pages = 33–58 | date = 2019 | pmid = 30221603 | pmc = 6341499 | doi = 10.2174/1570159X16666180917105033 }}</ref> The antibodies induce a synaptopathy.<ref>{{cite journal | vauthors = Mitoma H, Honnorat J, Yamaguchi K, Manto M | title = Fundamental Mechanisms of Autoantibody-Induced Impairments on Ion Channels and Synapses in Immune-Mediated Cerebellar Ataxias | journal = International Journal of Molecular Sciences | volume = 21 | issue = 14 | pages = E4936 | date = July 2020 | pmid = 32668612 | pmc = 6341499 | doi = 10.3390/ijms21144936 | doi-access = free }}</ref> The cerebellum is particularly vulnerable to autoimmune disorders.<ref>{{cite journal | vauthors = Mitoma H, Manto M, Hadjivassiliou M | title = Immune-Mediated Cerebellar Ataxias: Clinical Diagnosis and Treatment Based on Immunological and Physiological Mechanisms | journal = Journal of Movement Disorders | volume = 14 | issue = 1 | pages = 10–28 | date = January 2021 | pmid = 33423437 | pmc = 7840241 | doi = 10.14802/jmd.20040 | doi-access = free }}</ref> Cerebellar circuitry has capacities to compensate and restore function thanks to cerebellar reserve, gathering multiple forms of plasticity. LTDpathies gather immune disorders targeting [[long-term depression]] (LTD), a form of plasticity.<ref>{{cite journal | vauthors = Hirano T | title = Long-term depression and other synaptic plasticity in the cerebellum | journal = Proceedings of the Japan Academy. Series B, Physical and Biological Sciences | volume = 89 | issue = 5 | pages = 183–195 | date = 2013 | pmid = 23666089 | pmc = 3722574 | doi = 10.2183/pjab.89.183 }}</ref>
[[Glutamate decarboxylase|GAD antibodies]] related ataxia is part of the group called immune-mediated cerebellar ataxias.<ref>{{cite journal | vauthors = Mitoma H, Manto M, Hampe CS | title = Immune-mediated Cerebellar Ataxias: Practical Guidelines and Therapeutic Challenges | journal = Current Neuropharmacology | volume = 17 | issue = 1 | pages = 33–58 | date = 2019 | pmid = 30221603 | pmc = 6341499 | doi = 10.2174/1570159X16666180917105033 }}</ref> The antibodies induce a synaptopathy.<ref>{{cite journal | vauthors = Mitoma H, Honnorat J, Yamaguchi K, Manto M | title = Fundamental Mechanisms of Autoantibody-Induced Impairments on Ion Channels and Synapses in Immune-Mediated Cerebellar Ataxias | journal = International Journal of Molecular Sciences | volume = 21 | issue = 14 | article-number = E4936 | date = July 2020 | pmid = 32668612 | pmc = 6341499 | doi = 10.3390/ijms21144936 | doi-access = free }}</ref> The cerebellum is particularly vulnerable to autoimmune disorders.<ref>{{cite journal | vauthors = Mitoma H, Manto M, Hadjivassiliou M | title = Immune-Mediated Cerebellar Ataxias: Clinical Diagnosis and Treatment Based on Immunological and Physiological Mechanisms | journal = Journal of Movement Disorders | volume = 14 | issue = 1 | pages = 10–28 | date = January 2021 | pmid = 33423437 | pmc = 7840241 | doi = 10.14802/jmd.20040 | doi-access = free }}</ref> Cerebellar circuitry has capacities to compensate and restore function thanks to cerebellar reserve, gathering multiple forms of plasticity. LTDpathies gather immune disorders targeting [[long-term depression]] (LTD), a form of plasticity.<ref>{{cite journal | vauthors = Hirano T | title = Long-term depression and other synaptic plasticity in the cerebellum | journal = Proceedings of the Japan Academy. Series B, Physical and Biological Sciences | volume = 89 | issue = 5 | pages = 183–195 | date = 2013 | pmid = 23666089 | pmc = 3722574 | doi = 10.2183/pjab.89.183 | bibcode = 2013PJAB...89..183H }}</ref>


== Diagnosis ==
== Diagnosis ==
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== Treatment ==
== Treatment ==
The treatment of ataxia and its effectiveness depend on the underlying cause. Treatment may limit or reduce the effects of ataxia, but it is unlikely to eliminate them entirely. Recovery tends to be better in individuals with a single focal injury (such as [[stroke]] or a [[benign tumour]]), compared to those who have a neurological degenerative condition.<ref name="can rehabilitation help">{{cite journal | vauthors = Morton SM, Bastian AJ | title = Can rehabilitation help ataxia? | journal = Neurology | volume = 73 | issue = 22 | pages = 1818–1819 | date = December 2009 | pmid = 19864635 | doi = 10.1212/WNL.0b013e3181c33b21 | s2cid = 5481310 }}</ref> A review of the management of degenerative ataxia was published in 2009.<ref name="systematic review">{{cite journal | vauthors = Trujillo-Martín MM, Serrano-Aguilar P, Monton-Alvarez F, Carrillo-Fumero R | title = Effectiveness and safety of treatments for degenerative ataxias: a systematic review | journal = Movement Disorders | volume = 24 | issue = 8 | pages = 1111–1124 | date = June 2009 | pmid = 19412936 | doi = 10.1002/mds.22564 | s2cid = 11008654 }}</ref> A small number of rare conditions presenting with prominent cerebellar ataxia are amenable to specific treatment and recognition of these disorders is critical. Diseases include vitamin E deficiency, abetalipoproteinemia, cerebrotendinous xanthomatosis, Niemann–Pick type C disease, Refsum's disease, glucose transporter type 1 deficiency, episodic ataxia type 2, gluten ataxia, glutamic acid decarboxylase ataxia.<ref>{{cite journal | vauthors = Ramirez-Zamora A, Zeigler W, Desai N, Biller J | title = Treatable causes of cerebellar ataxia | journal = Movement Disorders | volume = 30 | issue = 5 | pages = 614–623 | date = April 2015 | pmid = 25757427 | doi = 10.1002/mds.26158 | s2cid = 9560460 }}</ref> Novel therapies target the RNA defects associated with cerebellar disorders, using in particular anti-sense oligonucleotides.<ref>{{cite journal | vauthors = Manto M, Gandini J, Feil K, Strupp M | title = Cerebellar ataxias: an update | journal = Current Opinion in Neurology | volume = 33 | issue = 1 | pages = 150–160 | date = February 2020 | pmid = 31789706 | doi = 10.1097/WCO.0000000000000774 | s2cid = 208538266 }}</ref>
The treatment of ataxia and its effectiveness depend on the underlying cause. Treatment may limit or reduce the effects of ataxia, but it is unlikely to eliminate them entirely. Recovery tends to be better in individuals with a single focal injury (such as [[stroke]] or a [[benign tumour]]), compared to those who have a neurological degenerative condition.<ref name="can rehabilitation help">{{cite journal | vauthors = Morton SM, Bastian AJ | title = Can rehabilitation help ataxia? | journal = Neurology | volume = 73 | issue = 22 | pages = 1818–1819 | date = December 2009 | pmid = 19864635 | doi = 10.1212/WNL.0b013e3181c33b21 | s2cid = 5481310 }}</ref> A review of the management of degenerative ataxia was published in 2009.<ref name="systematic review">{{cite journal | vauthors = Trujillo-Martín MM, Serrano-Aguilar P, Monton-Alvarez F, Carrillo-Fumero R | title = Effectiveness and safety of treatments for degenerative ataxias: a systematic review | journal = Movement Disorders | volume = 24 | issue = 8 | pages = 1111–1124 | date = June 2009 | pmid = 19412936 | doi = 10.1002/mds.22564 | s2cid = 11008654 | hdl = 10261/212902 | hdl-access = free }}</ref> A small number of rare conditions presenting with prominent cerebellar ataxia are amenable to specific treatment, and recognition of these disorders is critical. Diseases include vitamin E deficiency, abetalipoproteinemia, cerebrotendinous xanthomatosis, Niemann–Pick type C disease, Refsum's disease, glucose transporter type 1 deficiency, episodic ataxia type 2, gluten ataxia, glutamic acid decarboxylase ataxia.<ref>{{cite journal | vauthors = Ramirez-Zamora A, Zeigler W, Desai N, Biller J | title = Treatable causes of cerebellar ataxia | journal = Movement Disorders | volume = 30 | issue = 5 | pages = 614–623 | date = April 2015 | pmid = 25757427 | doi = 10.1002/mds.26158 | s2cid = 9560460 }}</ref> Novel therapies target the RNA defects associated with cerebellar disorders, using in particular anti-sense oligonucleotides.<ref>{{cite journal | vauthors = Manto M, Gandini J, Feil K, Strupp M | title = Cerebellar ataxias: an update | journal = Current Opinion in Neurology | volume = 33 | issue = 1 | pages = 150–160 | date = February 2020 | pmid = 31789706 | doi = 10.1097/WCO.0000000000000774 | s2cid = 208538266 }}</ref>


The movement disorders associated with ataxia can be managed by pharmacological treatments and through [[physical therapy]] and [[occupational therapy]] to reduce [[disability]].<ref name="pmid17000340">{{cite journal | vauthors = Perlman SL | title = Ataxias | journal = Clinics in Geriatric Medicine | volume = 22 | issue = 4 | pages = 859–77, vii | date = November 2006 | pmid = 17000340 | doi = 10.1016/j.cger.2006.06.011 }}</ref> Some drug treatments that have been used to control ataxia include: [[5-hydroxytryptophan]] (5-HTP), [[idebenone]], [[amantadine]], [[physostigmine]], [[L-carnitine]] or derivatives, [[trimethoprim/sulfamethoxazole]], [[vigabatrin]], [[phosphatidylcholine]], [[acetazolamide]], [[4-aminopyridine]], [[buspirone]], and a combination of [[coenzyme Q10|coenzyme Q<sub>10</sub>]] and [[vitamin E]].<ref name="systematic review"/>
The movement disorders associated with ataxia can be managed by pharmacological treatments and through [[physical therapy]] and [[occupational therapy]] to reduce [[disability]].<ref name="pmid17000340">{{cite journal | vauthors = Perlman SL | title = Ataxias | journal = Clinics in Geriatric Medicine | volume = 22 | issue = 4 | pages = 859–77, vii | date = November 2006 | pmid = 17000340 | doi = 10.1016/j.cger.2006.06.011 }}</ref> Some drug treatments that have been used to control ataxia include: [[5-hydroxytryptophan]] (5-HTP), [[idebenone]], [[amantadine]], [[physostigmine]], [[L-carnitine]] or derivatives, [[trimethoprim/sulfamethoxazole]], [[vigabatrin]], [[phosphatidylcholine]], [[acetazolamide]], [[4-aminopyridine]], [[buspirone]], and a combination of [[coenzyme Q10|coenzyme Q<sub>10</sub>]] and [[vitamin E]].<ref name="systematic review"/>
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[[Physical therapy]] requires a focus on adapting activity and facilitating [[motor learning]] for retraining specific functional motor patterns.<ref name="Intensive coordinative training improves motor performance in degenerative cerebellar disease">{{cite journal | vauthors = Ilg W, Synofzik M, Brötz D, Burkard S, Giese MA, Schöls L | title = Intensive coordinative training improves motor performance in degenerative cerebellar disease | journal = Neurology | volume = 73 | issue = 22 | pages = 1823–1830 | date = December 2009 | pmid = 19864636 | doi = 10.1212/WNL.0b013e3181c33adf | s2cid = 2087750 }}</ref> A recent systematic review suggested that physical therapy is effective, but there is only moderate evidence to support this conclusion.<ref name="pmid19114434">{{cite journal | vauthors = Martin CL, Tan D, Bragge P, Bialocerkowski A | title = Effectiveness of physiotherapy for adults with cerebellar dysfunction: a systematic review | journal = Clinical Rehabilitation | volume = 23 | issue = 1 | pages = 15–26 | date = January 2009 | pmid = 19114434 | doi = 10.1177/0269215508097853 | s2cid = 25458915 }}</ref> The most commonly used physical therapy interventions for cerebellar ataxia are vestibular habituation, [[Frenkel exercises]], [[proprioceptive neuromuscular facilitation]] (PNF), and balance training; however, therapy is often highly individualized and gait and coordination training are large components of therapy.<ref>{{cite journal | vauthors = Schatton C, Synofzik M, Fleszar Z, Giese MA, Schöls L, Ilg W | title = Individualized exergame training improves postural control in advanced degenerative spinocerebellar ataxia: A rater-blinded, intra-individually controlled trial | language = English | journal = Parkinsonism & Related Disorders | volume = 39 | pages = 80–84 | date = June 2017 | pmid = 28365204 | doi = 10.1016/j.parkreldis.2017.03.016 }}</ref>
[[Physical therapy]] requires a focus on adapting activity and facilitating [[motor learning]] for retraining specific functional motor patterns.<ref name="Intensive coordinative training improves motor performance in degenerative cerebellar disease">{{cite journal | vauthors = Ilg W, Synofzik M, Brötz D, Burkard S, Giese MA, Schöls L | title = Intensive coordinative training improves motor performance in degenerative cerebellar disease | journal = Neurology | volume = 73 | issue = 22 | pages = 1823–1830 | date = December 2009 | pmid = 19864636 | doi = 10.1212/WNL.0b013e3181c33adf | s2cid = 2087750 }}</ref> A recent systematic review suggested that physical therapy is effective, but there is only moderate evidence to support this conclusion.<ref name="pmid19114434">{{cite journal | vauthors = Martin CL, Tan D, Bragge P, Bialocerkowski A | title = Effectiveness of physiotherapy for adults with cerebellar dysfunction: a systematic review | journal = Clinical Rehabilitation | volume = 23 | issue = 1 | pages = 15–26 | date = January 2009 | pmid = 19114434 | doi = 10.1177/0269215508097853 | s2cid = 25458915 }}</ref> The most commonly used physical therapy interventions for cerebellar ataxia are vestibular habituation, [[Frenkel exercises]], [[proprioceptive neuromuscular facilitation]] (PNF), and balance training; however, therapy is often highly individualized and gait and coordination training are large components of therapy.<ref>{{cite journal | vauthors = Schatton C, Synofzik M, Fleszar Z, Giese MA, Schöls L, Ilg W | title = Individualized exergame training improves postural control in advanced degenerative spinocerebellar ataxia: A rater-blinded, intra-individually controlled trial | language = English | journal = Parkinsonism & Related Disorders | volume = 39 | pages = 80–84 | date = June 2017 | pmid = 28365204 | doi = 10.1016/j.parkreldis.2017.03.016 }}</ref>


Current research suggests that, if a person is able to walk with or without a [[mobility aid]], physical therapy should include an exercise program addressing five components: static balance, dynamic balance, trunk-limb coordination, stairs, and [[contracture]] prevention. Once the physical therapist determines that the individual is able to safely perform parts of the program independently, it is important that the individual be prescribed and regularly engage in a supplementary home exercise program that incorporates these components to further improve long term outcomes. These outcomes include balance tasks, gait, and individual activities of daily living. While the improvements are attributed primarily to changes in the brain and not just the hip or ankle joints, it is still unknown whether the improvements are due to adaptations in the cerebellum or compensation by other areas of the brain.<ref name="Intensive coordinative training improves motor performance in degenerative cerebellar disease"/>
Current research suggests that, if a person can walk with or without a [[mobility aid]], physical therapy should include an exercise program addressing five components: static balance, dynamic balance, trunk-limb coordination, stairs, and [[contracture]] prevention. Once the physical therapist determines that the individual can safely perform parts of the program independently, it is important that the individual be prescribed and regularly engage in a supplementary home exercise program that incorporates these components to improve long-term outcomes further. These outcomes include balance tasks, gait, and individual activities of daily living. While the improvements are attributed primarily to changes in the brain and not just the hip or ankle joints, it is still unknown whether the improvements are due to adaptations in the cerebellum or compensation by other areas of the brain.<ref name="Intensive coordinative training improves motor performance in degenerative cerebellar disease"/>


Decomposition, simplification, or slowing of multijoint movement may also be an effective strategy that therapists may use to improve function in patients with ataxia.<ref name="pmid9184691">{{cite journal | vauthors = Bastian AJ | title = Mechanisms of ataxia | journal = Physical Therapy | volume = 77 | issue = 6 | pages = 672–675 | date = June 1997 | pmid = 9184691 | doi = 10.1093/ptj/77.6.672 | doi-access = free }}</ref> Training likely needs to be intense and focused—as indicated by one study performed with stroke patients experiencing limb ataxia who underwent intensive upper limb retraining.<ref name="stroke ataxia">{{cite journal | vauthors = Richards L, Senesac C, McGuirk T, Woodbury M, Howland D, Davis S, Patterson T | title = Response to intensive upper extremity therapy by individuals with ataxia from stroke | journal = Topics in Stroke Rehabilitation | volume = 15 | issue = 3 | pages = 262–271 | year = 2008 | pmid = 18647730 | doi = 10.1310/tsr1503-262 | s2cid = 207260777 }}</ref> Their therapy consisted of [[constraint-induced movement therapy]] which resulted in improvements of their arm function.<ref name="stroke ataxia" /> Treatment should likely include strategies to manage difficulties with everyday activities such as walking. Gait aids (such as a cane or walker) can be provided to decrease the risk of falls associated with impairment of [[Balance (ability)|balance]] or poor [[Motor coordination|coordination]]. Severe ataxia may eventually lead to the need for a [[wheelchair]]. To obtain better results, possible coexisting motor deficits need to be addressed in addition to those induced by ataxia. For example, muscle weakness and decreased endurance could lead to increasing fatigue and poorer movement patterns.{{citation needed|date=August 2021}}
Decomposition, simplification, or slowing of multijoint movement may also be an effective strategy that therapists may use to improve function in patients with ataxia.<ref name="pmid9184691">{{cite journal | vauthors = Bastian AJ | title = Mechanisms of ataxia | journal = Physical Therapy | volume = 77 | issue = 6 | pages = 672–675 | date = June 1997 | pmid = 9184691 | doi = 10.1093/ptj/77.6.672 | doi-access = free }}</ref> Training likely needs to be intense and focused—as indicated by one study performed with stroke patients experiencing limb ataxia who underwent intensive upper limb retraining.<ref name="stroke ataxia">{{cite journal | vauthors = Richards L, Senesac C, McGuirk T, Woodbury M, Howland D, Davis S, Patterson T | title = Response to intensive upper extremity therapy by individuals with ataxia from stroke | journal = Topics in Stroke Rehabilitation | volume = 15 | issue = 3 | pages = 262–271 | year = 2008 | pmid = 18647730 | doi = 10.1310/tsr1503-262 | s2cid = 207260777 }}</ref> Their therapy consisted of [[constraint-induced movement therapy]] which resulted in improvements of their arm function.<ref name="stroke ataxia" /> Treatment should likely include strategies to manage difficulties with everyday activities such as walking. Gait aids (such as a cane or walker) can be provided to decrease the risk of falls associated with impairment of [[Balance (ability)|balance]] or poor [[Motor coordination|coordination]]. Severe ataxia may eventually lead to the need for a [[wheelchair]]. To obtain better results, possible coexisting motor deficits need to be addressed in addition to those induced by ataxia. For example, muscle weakness and decreased endurance could lead to increased fatigue and poorer movement patterns.{{citation needed|date=August 2021}}


There are several assessment tools available to therapists and health care professionals working with patients with ataxia. The [[International Cooperative Ataxia Rating Scale]] (ICARS) is one of the most widely used and has been proven to have very high reliability and validity.<ref>{{cite journal | vauthors = Schmitz-Hübsch T, Tezenas du Montcel S, Baliko L, Boesch S, Bonato S, Fancellu R, Giunti P, Globas C, Kang JS, Kremer B, Mariotti C, Melegh B, Rakowicz M, Rola R, Romano S, Schöls L, Szymanski S, van de Warrenburg BP, Zdzienicka E, Dürr A, Klockgether T | title = Reliability and validity of the International Cooperative Ataxia Rating Scale: a study in 156 spinocerebellar ataxia patients | journal = Movement Disorders | volume = 21 | issue = 5 | pages = 699–704 | date = May 2006 | pmid = 16450347 | doi = 10.1002/mds.20781 | s2cid = 28633679 }}</ref> Other tools that assess motor function, balance and coordination are also highly valuable to help the therapist track the progress of their patient, as well as to quantify the patient's functionality. These tests include, but are not limited to:
Several assessment tools are available to therapists and healthcare professionals working with patients with ataxia. The [[International Cooperative Ataxia Rating Scale]] (ICARS) is one of the most widely used and has been proven to have very high reliability and validity.<ref>{{cite journal | vauthors = Schmitz-Hübsch T, Tezenas du Montcel S, Baliko L, Boesch S, Bonato S, Fancellu R, Giunti P, Globas C, Kang JS, Kremer B, Mariotti C, Melegh B, Rakowicz M, Rola R, Romano S, Schöls L, Szymanski S, van de Warrenburg BP, Zdzienicka E, Dürr A, Klockgether T | title = Reliability and validity of the International Cooperative Ataxia Rating Scale: a study in 156 spinocerebellar ataxia patients | journal = Movement Disorders | volume = 21 | issue = 5 | pages = 699–704 | date = May 2006 | pmid = 16450347 | doi = 10.1002/mds.20781 | s2cid = 28633679 }}</ref> Other tools that assess motor function, balance and coordination are also highly valuable to help the therapist track the progress of their patient, as well as to quantify the patient's functionality. These tests include, but are not limited to:
* The [[Berg Balance Scale]]
* The [[Berg Balance Scale]]
* Tandem Walking (to test for [[Tandem gait]]ability)
* Tandem Walking (to test for [[Tandem gait]]ability)
* Scale for the Assessment and Rating of Ataxia (SARA)<ref name="pmid16769946">{{cite journal | vauthors = Schmitz-Hübsch T, du Montcel ST, Baliko L, Berciano J, Boesch S, Depondt C, Giunti P, Globas C, Infante J, Kang JS, Kremer B, Mariotti C, Melegh B, Pandolfo M, Rakowicz M, Ribai P, Rola R, Schöls L, Szymanski S, van de Warrenburg BP, Dürr A, Klockgether T, Fancellu R | title = Scale for the assessment and rating of ataxia: development of a new clinical scale | journal = Neurology | volume = 66 | issue = 11 | pages = 1717–1720 | date = June 2006 | pmid = 16769946 | doi = 10.1212/01.wnl.0000219042.60538.92 | s2cid = 24069559 }}</ref>
* Scale for the Assessment and Rating of Ataxia (SARA)<ref name="pmid16769946">{{cite journal | vauthors = Schmitz-Hübsch T, du Montcel ST, Baliko L, Berciano J, Boesch S, Depondt C, Giunti P, Globas C, Infante J, Kang JS, Kremer B, Mariotti C, Melegh B, Pandolfo M, Rakowicz M, Ribai P, Rola R, Schöls L, Szymanski S, van de Warrenburg BP, Dürr A, Klockgether T, Fancellu R | title = Scale for the assessment and rating of ataxia: development of a new clinical scale | journal = Neurology | volume = 66 | issue = 11 | pages = 1717–1720 | date = June 2006 | pmid = 16769946 | doi = 10.1212/01.wnl.0000219042.60538.92 | s2cid = 24069559 }}</ref>
* tapping tests – The person must quickly and repeatedly tap their arm or leg while the therapist monitors the amount of [[dysdiadochokinesia]].<ref name="Notermans_1994">{{cite journal | vauthors = Notermans NC, van Dijk GW, van der Graaf Y, van Gijn J, Wokke JH | title = Measuring ataxia: quantification based on the standard neurological examination | journal = Journal of Neurology, Neurosurgery, and Psychiatry | volume = 57 | issue = 1 | pages = 22–26 | date = January 1994 | pmid = 8301300 | pmc = 485035 | doi = 10.1136/jnnp.57.1.22 }}</ref>
* tapping tests – The person must quickly and repeatedly tap their arm or leg while the therapist monitors the amount of [[dysdiadochokinesia]].<ref name="Notermans_1994">{{cite journal | vauthors = Notermans NC, van Dijk GW, van der Graaf Y, van Gijn J, Wokke JH | title = Measuring ataxia: quantification based on the standard neurological examination | journal = Journal of Neurology, Neurosurgery, and Psychiatry | volume = 57 | issue = 1 | pages = 22–26 | date = January 1994 | pmid = 8301300 | pmc = 485035 | doi = 10.1136/jnnp.57.1.22 }}</ref>
* [[finger-nose testing]]<ref name="Notermans_1994"/> – This test has several variations including finger-to-therapist's finger, finger-to-finger, and alternate nose-to-finger.<ref name="urlOPETA: Neurologic Examination">{{cite web|url=http://medinfo.ufl.edu/other/opeta/neuro/NE_ch3.html |title=OPETA: Neurologic Examination |work=Online physical exam teaching assistant |publisher=The UF College of Medicine Harrell Center |access-date=7 May 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120318005424/http://medinfo.ufl.edu/other/opeta/neuro/NE_ch3.html |archive-date=18 March 2012}}</ref>
* [[finger-nose testing]]<ref name="Notermans_1994"/> – This test has several variations including finger-to-therapist's finger, finger-to-finger, and alternate nose-to-finger.<ref name="urlOPETA: Neurologic Examination">{{cite web|url=http://medinfo.ufl.edu/other/opeta/neuro/NE_ch3.html |title=OPETA: Neurologic Examination |work=Online physical exam teaching assistant |publisher=The UF College of Medicine Harrell Center |access-date=7 May 2012 |archive-url=https://web.archive.org/web/20120318005424/http://medinfo.ufl.edu/other/opeta/neuro/NE_ch3.html |archive-date=18 March 2012}}</ref>


== Other uses ==
== Other uses ==
The term "ataxia" is sometimes used in a broader sense to indicate lack of coordination in some physiological process. Examples include '''optic ataxia''' (lack of coordination between visual inputs and hand movements, resulting in inability to reach and grab objects) and [[ataxic respiration]] (lack of coordination in respiratory movements, usually due to dysfunction of the respiratory centres in the [[medulla oblongata]]).
The term "ataxia" is sometimes used in a broader sense to indicate a lack of coordination in some physiological process. Examples include '''optic ataxia''' (lack of coordination between visual inputs and hand movements, resulting in inability to reach and grab objects) and [[ataxic respiration]] (lack of coordination in respiratory movements, usually due to dysfunction of the respiratory centres in the [[medulla oblongata]]).


Optic ataxia may be caused by lesions to the [[posterior parietal cortex]], which is responsible for combining and expressing positional information and relating it to movement. Outputs of the posterior parietal cortex include the spinal cord, brain stem motor pathways, pre-motor and pre-frontal cortex, basal ganglia and the cerebellum. Some neurons in the posterior parietal cortex are modulated by intention. Optic ataxia is usually part of [[Balint's syndrome]], but can be seen in isolation with injuries to the superior parietal lobule, as it represents a disconnection between visual-association cortex and the frontal premotor and motor cortex.<ref name="pmid17603404">{{cite journal | vauthors = Vallar G | title = Spatial neglect, Balint-Homes' and Gerstmann's syndrome, and other spatial disorders | journal = CNS Spectrums | volume = 12 | issue = 7 | pages = 527–536 | date = July 2007 | pmid = 17603404 | doi = 10.1017/S1092852900021271 | s2cid = 45201083 }}</ref>
Optic ataxia may be caused by lesions to the [[posterior parietal cortex]], which is responsible for combining and expressing positional information and relating it to movement. Outputs of the posterior parietal cortex include the spinal cord, brain stem motor pathways, pre-motor and pre-frontal cortex, basal ganglia, and the cerebellum. Some neurons in the posterior parietal cortex are modulated by intention. Optic ataxia is usually part of [[Balint's syndrome]], but can be seen in isolation with injuries to the superior parietal lobule, as it represents a disconnection between the visual-association cortex and the frontal premotor and motor cortex.<ref name="pmid17603404">{{cite journal | vauthors = Vallar G | title = Spatial neglect, Balint-Homes' and Gerstmann's syndrome, and other spatial disorders | journal = CNS Spectrums | volume = 12 | issue = 7 | pages = 527–536 | date = July 2007 | pmid = 17603404 | doi = 10.1017/S1092852900021271 | s2cid = 45201083 }}</ref>


== See also ==
== See also ==
{{Portal|Medicine}}
* [[Ataxic cerebral palsy]]
* [[Ataxic cerebral palsy]]
* [[Locomotor ataxia]]
* [[Locomotor ataxia]]

Latest revision as of 08:00, 27 September 2025

Template:Short description Script error: No such module "other uses". Template:Cs1 config Template:Use dmy dates Template:Infobox medical condition (new) Template:Sister project Ataxia (from Greek α- [a negative prefix] + -τάξις [order] = "lack of order") is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements, that indicates dysfunction of parts of the nervous system that coordinate movement, such as the cerebellum.

These nervous-system dysfunctions occur in several different patterns, with different results and different possible causes. Ataxia can be limited to one side of the body, which is referred to as hemiataxia. Friedreich's ataxia has gait abnormality as the most commonly presented symptom. Dystaxia is a mild degree of ataxia.[1]

Types

Cerebellar

Script error: No such module "Labelled list hatnote". The term cerebellar ataxia is used to indicate ataxia due to dysfunction of the cerebellum.[2] The cerebellum is responsible for integrating a significant amount of neural information that is used to coordinate smoothly ongoing movements and to participate in motor planning. Although ataxia is not present with all cerebellar lesions, many conditions affecting the cerebellum do produce ataxia.[3] People with cerebellar ataxia may have trouble regulating the force, range, direction, velocity, and rhythm of muscle contractions.[4] This results in a characteristic type of irregular, uncoordinated movement that can manifest itself in many possible ways, such as asthenia, asynergy, delayed reaction time, and dyschronometria.[5] Individuals with cerebellar ataxia could also display instability of gait, difficulty with eye movements, dysarthria, dysphagia, hypotonia, dysmetria, and dysdiadochokinesia.[3] These deficits can vary depending on which cerebellar structures have been damaged, and whether the lesion is bi- or unilateral.Script error: No such module "Unsubst".

People with cerebellar ataxia may initially present with poor balance, which could be demonstrated as an inability to stand on one leg or perform tandem gait. As the condition progresses, walking is characterized by a widened base and high stepping, as well as staggering and lurching from side to side.[3] Turning is also problematic and could result in falls. As cerebellar ataxia becomes severe, great assistance and effort are needed to stand and walk.[3] Dysarthria, an impairment with articulation, may also be present and is characterized by "scanning" speech that consists of a slower rate, irregular rhythm, and variable volume.[3] Also, slurring of speech, tremor of the voice, and ataxic respiration may occur. Cerebellar ataxia could result in incoordination of movement, particularly in the extremities. Overshooting (or hypermetria) occurs with finger-to-nose testing and heel-to-shin testing; thus, dysmetria is evident.[3][6] Impairments with alternating movements (dysdiadochokinesia), as well as dysrhythmia, may also be displayed. Tremor of the head and trunk (titubation) may be seen in individuals with cerebellar ataxia.[3]

Dysmetria is thought to be caused by a deficit in the control of interaction torques in multijoint motion.[7] Interaction torques are created at an associated joint when the primary joint is moved. For example, if a movement required reaching to touch a target in front of the body, flexion at the shoulder would create a torque at the elbow, while extension of the elbow would create a torque at the wrist. These torques increase as the speed of movement increases and must be compensated for and adjusted to create coordinated movement. This may, therefore, explain decreased coordination at higher movement velocities and accelerations.

  • Dysfunction of the vestibulocerebellum (flocculonodular lobe) impairs balance and the control of eye movements. This presents itself with postural instability, in which the person tends to separate his/her feet upon standing, to gain a wider base and to avoid titubation (bodily oscillations tending to be forward-backward ones). The instability is, therefore, worsened when standing with the feet together, regardless of whether the eyes are open or closed. This is a negative Romberg's test, or more accurately, it denotes the individual's inability to carry out the test, because the individual feels unstable even with open eyes. Script error: No such module "Unsubst".
  • Dysfunction of the spinocerebellum (vermis and associated areas near the midline) presents itself with a wide-based "drunken sailor" gait (called truncal ataxia),[8] characterised by uncertain starts and stops, lateral deviations, and unequal steps. As a result of this gait impairment, falling is a concern in patients with ataxia. Studies examining falls in this population show that 74–93% of patients have fallen at least once in the past year, and up to 60% admit to fear of falling.[9][10]
  • Dysfunction of the cerebrocerebellum (lateral hemispheres) presents as disturbances in carrying out voluntary, planned movements by the extremities (called appendicular ataxia).[8] These include:
    • Intention tremor (coarse trembling, accentuated over the execution of voluntary movements, possibly involving the head and eyes, as well as the limbs and torso)
    • Peculiar writing abnormalities (large, unequal letters, irregular underlining)
    • A peculiar pattern of dysarthria (slurred speech, sometimes characterised by explosive variations in voice intensity despite a regular rhythm)
    • Inability to perform rapidly alternating movements, known as dysdiadochokinesia, occurs, and could involve rapidly switching from pronation to supination of the forearm. Movements become more irregular with speed increases.[11]
    • Inability to judge distances or ranges of movement happens. This dysmetria is often seen as undershooting, hypometria, or overshooting, hypermetria, the required distance or range to reach a target. This is sometimes seen when a patient is asked to reach out and touch someone's finger or touch his or her own nose.[11]
    • The rebound phenomenon, also known as the loss of the check reflex, is also sometimes seen in patients with cerebellar ataxia, for example, when patients are flexing their elbows isometrically against resistance. When the resistance is suddenly removed without warning, the patients' arms may swing up and even strike themselves. With an intact check reflex, the patients check and activates the opposing triceps to slow and stop the movement.[11]
    • Patients may exhibit a constellation of subtle to overt cognitive symptoms, which are gathered under the terminology of Schmahmann's syndrome.[12]

Sensory

The term sensory ataxia is used to indicate ataxia due to loss of proprioception, the loss of sensitivity to the positions of joint and body parts. This is generally caused by dysfunction of the dorsal columns of the spinal cord, because they carry proprioceptive information up to the brain. In some cases, the cause of sensory ataxia may instead be dysfunction of the various parts of the brain that receive positional information, including the cerebellum, thalamus, and parietal lobes.[13]

Sensory ataxia presents itself with an unsteady "stomping" gait with heavy heel strikes, as well as a postural instability that is usually worsened when the lack of proprioceptive input cannot be compensated for by visual input, such as in poorly lit environments.[14][15]

Physicians can find evidence of sensory ataxia during physical examination by having patients stand with their feet together and eyes shut. In affected patients, this will cause the instability to worsen markedly, producing wide oscillations and possibly a fall; this is called a positive Romberg's test. Worsening of the finger-pointing test with the eyes closed is another feature of sensory ataxia. Also, when patients are standing with arms and hands extended toward the physician, if the eyes are closed, the patients' fingers tend to "fall down" and then be restored to the horizontal extended position by sudden muscular contractions (the "ataxic hand").[16][17]

Vestibular

The term vestibular ataxia is used to indicate ataxia due to dysfunction of the vestibular system, which in acute and unilateral cases is associated with prominent vertigo, nausea, and vomiting. In slow-onset, chronic bilateral cases of vestibular dysfunction, these characteristic manifestations may be absent, and dysequilibrium may be the sole presentation.[18]

Causes

The three types of ataxia have overlapping causes, so they can either coexist or occur in isolation. Cerebellar ataxia can have many causes despite normal neuroimaging.[19]

Focal lesions

Any type of focal lesion of the central nervous system (such as stroke, brain tumor, multiple sclerosis, inflammatory [such as sarcoidosis], and "chronic lymphocytyc inflammation with pontine perivascular enhancement responsive to steroids syndrome" [CLIPPERS[20]]) will cause the type of ataxia corresponding to the site of the lesion: cerebellar if in the cerebellum; sensory if in the dorsal spinal cord...to include cord compression by thickened ligamentum flavum or stenosis of the boney spinal canal...(and rarely in the thalamus or parietal lobe); or vestibular if in the vestibular system (including the vestibular areas of the cerebral cortex).Script error: No such module "Unsubst".

Exogenous substances (metabolic ataxia)

Exogenous substances that cause ataxia mainly do so because they have a depressant effect on central nervous system function. The most common example is ethanol (alcohol), which is capable of causing reversible cerebellar and vestibular ataxia. Chronic intake of ethanol causes atrophy of the cerebellum by oxidative and endoplasmic reticulum stresses induced by thiamine deficiency.[21]

Other examples include various prescription drugs (e.g. most antiepileptic drugs have cerebellar ataxia as a possible adverse effect), Lithium level over 1.5mEq/L, synthetic cannabinoid HU-211 ingestion[22] and various other medical and recreational drugs (e.g. ketamine, PCP or dextromethorphan, all of which are NMDA receptor antagonists that produce a dissociative state at high doses). A further class of pharmaceuticals which can cause short-term ataxia, especially in high doses, are benzodiazepines.[23][24] Exposure to high levels of methylmercury, through consumption of fish with high mercury concentrations, is also a known cause of ataxia and other neurological disorders.[25]

Radiation poisoning

Ataxia can be induced as a result of severe acute radiation poisoning with an absorbed dose of more than 30 grays.[26] Furthermore, those with ataxia telangiectasia may have a high sensitivity towards gamma rays and x-rays.[27]

Vitamin B12 deficiency

Vitamin B12 deficiency may cause, among several neurological abnormalities, overlapping cerebellar and sensory ataxia.[28] Neuropsychological symptoms may include sense loss, difficulty in proprioception, poor balance, loss of sensation in the feet, changes in reflexes, dementia, and psychosis, which can be reversible with treatment.[29] Complications may include a neurological complex known as subacute combined degeneration of spinal cord, and other neurological disorders.[30]

Hypothyroidism

Symptoms of neurological dysfunction may be the presenting feature in some patients with hypothyroidism. These include reversible cerebellar ataxia, dementia, peripheral neuropathy, psychosis and coma. Most of the neurological complications improve completely after thyroid hormone replacement therapy.[31][32]

Causes of isolated sensory ataxia

Peripheral neuropathies may cause generalised or localised sensory ataxia (e.g., a limb only) depending on the extent of the neuropathic involvement. Spinal disorders of various types may cause sensory ataxia from the lesioned level below, when they involve the dorsal columns.[33][34][35]

Non-hereditary cerebellar degeneration

Non-hereditary causes of cerebellar degeneration include chronic alcohol use disorder, head injury, paraneoplastic and non-paraneoplastic autoimmune ataxia,[36][37][38] high-altitude cerebral edema,[39] celiac disease,[40] normal-pressure hydrocephalus,[41] and infectious or post-infectious cerebellitis.[42]

Hereditary ataxias

Ataxia may depend on hereditary disorders consisting of degeneration of the cerebellum or of the spine; most cases feature both to some extent, and therefore present with overlapping cerebellar and sensory ataxia, even though one is often more evident than the other. Hereditary disorders causing ataxia include autosomal dominant ones such as spinocerebellar ataxia, episodic ataxia, and dentatorubropallidoluysian atrophy, as well as autosomal recessive disorders such as Friedreich's ataxia (sensory and cerebellar, with the former predominating) and Niemann–Pick disease, ataxia–telangiectasia (sensory and cerebellar, with the latter predominating), autosomal recessive spinocerebellar ataxia-14[43] and abetalipoproteinaemia. An example of X-linked ataxic condition is the rare fragile X-associated tremor/ataxia syndrome or FXTAS.

Arnold–Chiari malformation (congenital ataxia)

Arnold–Chiari malformation is a malformation of the brain. It consists of a downward displacement of the cerebellar tonsils and the medulla through the foramen magnum, sometimes causing hydrocephalus as a result of obstruction of cerebrospinal fluid outflow.[44]

Succinic semialdehyde dehydrogenase deficiency

Succinic semialdehyde dehydrogenase deficiency is an autosomal-recessive gene disorder where mutations in the ALDH5A1 gene results in the accumulation of gamma-Hydroxybutyric acid (GHB) in the body. GHB accumulates in the nervous system and can cause ataxia as well as other neurological dysfunction.[45]

Wilson's disease

Wilson's disease is an autosomal-recessive gene disorder whereby an alteration of the ATP7B gene results in an inability to properly excrete copper from the body.[46] Copper accumulates in the liver and raises the toxicity levels in the nervous system causing demyelination of the nerves.[47] This can cause ataxia as well as other neurological and organ impairments.[48]

Gluten ataxia

File:Gluten ataxia eng.ogg
A male with gluten ataxia: previous situation and evolution after three months of a gluten-free diet

Gluten ataxia is an autoimmune disease derived from celiac disease,[49] which is triggered by the ingestion of gluten.[50][51] Early diagnosis and treatment with a gluten-free diet can improve ataxia and prevent its progression. The effectiveness of the treatment depends on the elapsed time from the onset of the ataxia until diagnosis, because the death of neurons in the cerebellum as a result of gluten exposure is irreversible.[50][52] It accounts for 40% of ataxias of unknown origin and 15% of all ataxias.[52] Less than 10% of people with gluten ataxia present any gastrointestinal symptom and only about 40% have intestinal damage.[50][52] This entity is classified into primary auto-immune cerebellar ataxias (PACA).[53] There is a continuum between presymptomatic ataxia and immune ataxias with clinical deficits.[54]

Potassium pump

Malfunction of the sodium-potassium pump may be a factor in some ataxias. The Template:Chem2 pump has been shown to control and set the intrinsic activity mode of cerebellar Purkinje neurons.[55] This suggests that the pump might not simply be a homeostatic, "housekeeping" molecule for ionic gradients, but could be a computational element in the cerebellum and the brain.[56] Indeed, a ouabain block of Template:Chem2 pumps in the cerebellum of a live mouse results in it displaying ataxia and dystonia.[57] Ataxia is observed for lower ouabain concentrations, and dystonia is observed at higher ouabain concentrations.

Cerebellar ataxia associated with anti-GAD antibodies

Antibodies against the enzyme glutamic acid decarboxylase (GAD: enzyme changing glutamate into GABA) cause cerebellar deficits.[58] The antibodies impair motor learning and cause behavioral deficits.[59] GAD antibodies related ataxia is part of the group called immune-mediated cerebellar ataxias.[60] The antibodies induce a synaptopathy.[61] The cerebellum is particularly vulnerable to autoimmune disorders.[62] Cerebellar circuitry has capacities to compensate and restore function thanks to cerebellar reserve, gathering multiple forms of plasticity. LTDpathies gather immune disorders targeting long-term depression (LTD), a form of plasticity.[63]

Diagnosis

  • Imaging studies – A CT scan or MRI of the brain might help determine potential causes. An MRI can sometimes show shrinkage of the cerebellum and other brain structures in people with ataxia. It may also show other treatable findings, such as a blood clot or benign tumour, that could be pressing on the cerebellum.
  • Lumbar puncture (spinal tap) – A needle is inserted into the lower back (lumbar region) between two lumbar vertebrae to obtain a sample of cerebrospinal fluid for testing.
  • Genetic testing – Determines whether the mutation that causes one of the hereditary ataxic conditions is present. Tests are available for many but not all of the hereditary ataxias.

Treatment

The treatment of ataxia and its effectiveness depend on the underlying cause. Treatment may limit or reduce the effects of ataxia, but it is unlikely to eliminate them entirely. Recovery tends to be better in individuals with a single focal injury (such as stroke or a benign tumour), compared to those who have a neurological degenerative condition.[64] A review of the management of degenerative ataxia was published in 2009.[65] A small number of rare conditions presenting with prominent cerebellar ataxia are amenable to specific treatment, and recognition of these disorders is critical. Diseases include vitamin E deficiency, abetalipoproteinemia, cerebrotendinous xanthomatosis, Niemann–Pick type C disease, Refsum's disease, glucose transporter type 1 deficiency, episodic ataxia type 2, gluten ataxia, glutamic acid decarboxylase ataxia.[66] Novel therapies target the RNA defects associated with cerebellar disorders, using in particular anti-sense oligonucleotides.[67]

The movement disorders associated with ataxia can be managed by pharmacological treatments and through physical therapy and occupational therapy to reduce disability.[68] Some drug treatments that have been used to control ataxia include: 5-hydroxytryptophan (5-HTP), idebenone, amantadine, physostigmine, L-carnitine or derivatives, trimethoprim/sulfamethoxazole, vigabatrin, phosphatidylcholine, acetazolamide, 4-aminopyridine, buspirone, and a combination of coenzyme Q10 and vitamin E.[65]

Physical therapy requires a focus on adapting activity and facilitating motor learning for retraining specific functional motor patterns.[69] A recent systematic review suggested that physical therapy is effective, but there is only moderate evidence to support this conclusion.[70] The most commonly used physical therapy interventions for cerebellar ataxia are vestibular habituation, Frenkel exercises, proprioceptive neuromuscular facilitation (PNF), and balance training; however, therapy is often highly individualized and gait and coordination training are large components of therapy.[71]

Current research suggests that, if a person can walk with or without a mobility aid, physical therapy should include an exercise program addressing five components: static balance, dynamic balance, trunk-limb coordination, stairs, and contracture prevention. Once the physical therapist determines that the individual can safely perform parts of the program independently, it is important that the individual be prescribed and regularly engage in a supplementary home exercise program that incorporates these components to improve long-term outcomes further. These outcomes include balance tasks, gait, and individual activities of daily living. While the improvements are attributed primarily to changes in the brain and not just the hip or ankle joints, it is still unknown whether the improvements are due to adaptations in the cerebellum or compensation by other areas of the brain.[69]

Decomposition, simplification, or slowing of multijoint movement may also be an effective strategy that therapists may use to improve function in patients with ataxia.[13] Training likely needs to be intense and focused—as indicated by one study performed with stroke patients experiencing limb ataxia who underwent intensive upper limb retraining.[72] Their therapy consisted of constraint-induced movement therapy which resulted in improvements of their arm function.[72] Treatment should likely include strategies to manage difficulties with everyday activities such as walking. Gait aids (such as a cane or walker) can be provided to decrease the risk of falls associated with impairment of balance or poor coordination. Severe ataxia may eventually lead to the need for a wheelchair. To obtain better results, possible coexisting motor deficits need to be addressed in addition to those induced by ataxia. For example, muscle weakness and decreased endurance could lead to increased fatigue and poorer movement patterns.Script error: No such module "Unsubst".

Several assessment tools are available to therapists and healthcare professionals working with patients with ataxia. The International Cooperative Ataxia Rating Scale (ICARS) is one of the most widely used and has been proven to have very high reliability and validity.[73] Other tools that assess motor function, balance and coordination are also highly valuable to help the therapist track the progress of their patient, as well as to quantify the patient's functionality. These tests include, but are not limited to:

Other uses

The term "ataxia" is sometimes used in a broader sense to indicate a lack of coordination in some physiological process. Examples include optic ataxia (lack of coordination between visual inputs and hand movements, resulting in inability to reach and grab objects) and ataxic respiration (lack of coordination in respiratory movements, usually due to dysfunction of the respiratory centres in the medulla oblongata).

Optic ataxia may be caused by lesions to the posterior parietal cortex, which is responsible for combining and expressing positional information and relating it to movement. Outputs of the posterior parietal cortex include the spinal cord, brain stem motor pathways, pre-motor and pre-frontal cortex, basal ganglia, and the cerebellum. Some neurons in the posterior parietal cortex are modulated by intention. Optic ataxia is usually part of Balint's syndrome, but can be seen in isolation with injuries to the superior parietal lobule, as it represents a disconnection between the visual-association cortex and the frontal premotor and motor cortex.[77]

See also

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References

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Further reading

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