View source for Neurological disorder

{{Short description|Any disorder of the nervous system}}
'''Neurological disorders''' represent a complex array of medical conditions that fundamentally disrupt the functioning of the nervous system. These [[Disorder of consciousness|disorders]] affect the brain, [[spinal cord]], and nerve networks, presenting unique diagnosis, treatment, and patient care challenges. At their core, they represent disruptions to the intricate communication systems within the [[nervous system]], stemming from genetic predispositions, environmental factors, infections, structural abnormalities, or degenerative processes.

The impact of neurological disorders is profound and far-reaching. Conditions like [[epilepsy]] create recurring [[seizure]]s through abnormal electrical brain activity, while multiple sclerosis damages the protective myelin covering of nerve fibers, interrupting communication between the brain and body. [[Parkinson's disease]] progressively affects movement through the loss of [[dopamine]]-producing nerve cells, and strokes can cause immediate and potentially permanent neurological damage by interrupting blood flow to the brain. Diagnosing these disorders requires sophisticated medical techniques. [[Neuroimaging|Neuroimaging technologies]] like [[Magnetic resonance imaging|MRI]] and CT scans and electroencephalograms provide crucial insights into the intricate changes occurring within the nervous system. Treatment approaches are equally complex, involving multidisciplinary strategies, including medications to manage symptoms, control brain activity, or slow disease progression, coupled with neurological rehabilitation to help patients develop compensatory strategies.{{infobox medical condition (new)
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Ideally, a neurological disorder is any [[Disorder (medicine)#Disorder|disorder]] of the [[nervous system]]. Structural, [[biochemical]] or electrical abnormalities in the [[brain]], [[spinal cord]], or other [[nerves]] can result in a range of [[symptoms]]. Examples of symptoms include [[paralysis]], [[muscle weakness]], poor [[motor coordination|coordination]], loss of [[sensory system|sensation]], [[seizure]]s, [[confusion]], [[pain]], [[Tauopathy|tauopathies]], and [[altered level of consciousness|altered levels of consciousness]]. There are many [[list of neurological disorders|recognized neurological disorders]]; some are relatively common, but many are rare.

Interventions for neurological disorders include preventive measures, [[lifestyle medicine|lifestyle changes]], [[physiotherapy]] or other [[therapy]], neurorehabilitation, [[pain management]], [[medication]], [[Surgery|operations]] performed by [[neurosurgeons]], or a specific diet.<ref name=ThakurAlbanese2016>{{cite book |first1=Thakur |last1= KT |first2=Albanese |last2=E |first3=Giannakopoulos |last3=P |first4=Jette |last4=N |first5=Linde |last5=M |first6=Prince |last6=MJ |first7=Steiner |last7=TM |first8=Dua |last8=T |title=Mental, Neurological, and Substance Use Disorders: Disease Control Priorities, Third Edition (Volume 4). Chapter 5 Neurological Disorders |chapter= Neurological Disorders |date=14 March 2016 |pages= 87–107 |publisher=Patel V, Chisholm D, Dua T, et al. |location=Washington (DC) |doi= 10.1596/978-1-4648-0426-7_ch5 |pmid= 27227247 |isbn= 978-1-4648-0426-7 |url=https://www.ncbi.nlm.nih.gov/books/NBK361950/}}</ref><ref name=ZisHadjivassiliou2019 /> The [[World Health Organization]] estimated in 2006 that neurological disorders and their [[sequelae]] (direct consequences) affect as many as one billion people worldwide and identified [[health inequalities]] and [[social stigma]]/[[discrimination]] as major factors contributing to the associated [[disability]] and their impact.<ref>{{Cite web |url=http://www.who.int/mental_health/neurology/neurodiso/en/index.html |title=WHO &#124; Neurological Disorders: Public Health Challenges |date=March 14, 2007 |website= |archive-url=https://web.archive.org/web/20070314165001/http://www.who.int/mental_health/neurology/neurodiso/en/index.html |archive-date=14 March 2007 |url-status=dead}}</ref>

==Causes==
[[File:APP and LTP in Alzheimer disease.png|thumb|Part of the causal chain leading to [[Alzheimer's disease]]]] Although the brain and spinal cord are surrounded by tough [[meninges|membranes]], enclosed in the bones of the [[human skull|skull]] and spinal [[vertebra]]e, and chemically isolated by the [[blood–brain barrier|blood-brain barrier]], they are very susceptible if compromised. [[Nerve]]s tend to lie deep under the skin but can still become exposed to damage. Individual [[neuron]]s, the [[neural circuit]]s, and the nerves into which they form are susceptible to electrochemical and structural disruption. [[Neuroregeneration]] may occur in the [[peripheral nervous system]] and thus overcome or work around injuries to some extent, but it is thought to be rare in the brain and spinal cord.{{citation needed|date=July 2021}}

The specific causes of neurological problems vary but can include [[genetic disorder]]s, [[congenital abnormality|congenital abnormalities]] or [[congenital disorder|disorders]], [[infection]]s, [[lifestyle (sociology)|lifestyle]], or [[environmental health]] problems such as [[Brain health and pollution|pollution]], [[malnutrition]], [[brain damage]], [[spinal cord injury]], [[nerve injury]], or [[Gluten-related disorders|gluten sensitivity]] (with or without intestinal damage or digestive symptoms).<ref name="ZisHadjivassiliou2019">{{cite journal| vauthors=Zis P, Hadjivassiliou M| title=Treatment of Neurological Manifestations of Gluten Sensitivity and Coeliac Disease. | journal=Curr Treat Options Neurol | date= 26 February 2019 | volume= 21 | issue= 3 | pages= 10 | pmid=30806821 | doi=10.1007/s11940-019-0552-7 | type=Review | doi-access=free }}</ref><ref name="Sanders2009">{{cite journal |pmid=19476290|pmc=2858639|year=2009|last1=Sanders|first1=T.|title= Neurotoxic effects and biomarkers of lead exposure: A review|journal=Reviews on Environmental Health|volume=24|issue=1|pages=15–45|last2=Liu|first2=Y.|last3=Buchner|first3=V.|last4=Tchounwou|first4=P. B.|doi= 10.1515/reveh.2009.24.1.15}}</ref> Metal poisoning, where metals accumulate in the human body and disrupt biological processes, has been reported to induce neurological problems, at least in the case of [[Lead poisoning|lead]].<ref name="Sanders2009" /> The neurological problem may start in another [[body system]] that interacts with the nervous system. For example, [[cerebrovascular disease]] involves brain injury due to problems with the [[blood vessel]]s ([[cardiovascular system]]) supplying the brain; [[Autoimmune disease|autoimmune disorders]] involve damage caused by the body's own [[immune system]]; [[lysosomal storage disease]]s such as [[Niemann–Pick disease]] can lead to neurological deterioration. The [[National Institute for Health and Care Excellence]] recommends considering the evaluation of underlying [[coeliac disease]] in people with unexplained neurological symptoms, particularly [[peripheral neuropathy]] or [[ataxia]].<ref name=NICECD2015>{{cite web|url=https://www.nice.org.uk/guidance/ng20/chapter/Recommendations#referral-of-people-with-suspected-coeliac-disease|title=Coeliac disease: recognition, assessment and management. NICE guideline [NG20]| date=September 2015| website=nice.org.uk|access-date=18 September 2017}}</ref>

In a substantial minority of cases of neurological symptoms, no neurological [[etiology|cause]] can be identified using current testing procedures, and such "[[idiopathic]]" conditions can invite different theories about what is occurring.{{Citation needed|date=October 2017}} Generally speaking, a substantial number of neurological disorders may have originated from a previous clinically not recognized viral infection. For example, it is thought that infection with the [[Hepatitis E]] virus, which is often initially asymptomatic may provoke neurological disorders,<ref>{{cite journal | vauthors = Li Y, Peppelenbosch MP| title =Hepatitis E virus and neurological manifestations | journal = Journal of the Neurological Sciences| volume = 423 | pages = 117388 | date = April 2020 | pmid =33714454 | doi = 10.1016/j.jns.2021.117388 | s2cid =232133206 }}</ref> but there are many other examples as well.

Numerous examples have been described of neurological disorders that are associated with [[mutation|mutated]] [[DNA repair]] genes (for reviews see<ref>{{cite journal |last1=Abugable |first1=Arwa A. |last2=Morris |first2=Julia L.M. |last3=Palminha |first3=Nelma M. |last4=Zaksauskaite |first4=Ringaile |last5=Ray |first5=Swagat |last6=El-Khamisy |first6=Sherif F. | date = Sep 2019 | title = DNA repair and neurological disease: From molecular understanding to the development of diagnostics and model organisms | journal = DNA Repair (Amst.) | volume = 81 | page = 102669 | doi = 10.1016/j.dnarep.2019.102669 | pmid = 31331820 | doi-access = free }}</ref>). Inadequate repair of DNA damages can lead directly to cell death and [[neuron]] depletion as well as disruptions in the pattern of [[epigenetics|epigenetic alterations]] required for normal neuronal function.{{citation needed|date=July 2021}}

===DNA damage===

Neurons are highly oxygenated cells and as a consequence [[DNA damage (naturally occurring)|DNA damage]] caused by chronic exposure to endogenous [[reactive oxygen species]] is a substantial challenge for neurons.<ref name="Wang2017">{{cite journal |vauthors=Wang H, Dharmalingam P, Vasquez V, Mitra J, Boldogh I, Rao KS, Kent TA, Mitra S, Hegde ML |title=Chronic oxidative damage together with genome repair deficiency in the neurons is a double whammy for neurodegeneration: Is damage response signaling a potential therapeutic target? |journal=Mech Ageing Dev |volume=161 |issue=Pt A |pages=163–176 |date=January 2017 |pmid=27663141 |pmc=5316312 |doi=10.1016/j.mad.2016.09.005 }}</ref>  [[Germline mutation]]s deficient in the [[DNA repair|repair of DNA damages]] cause neuronal dysfunction and are etiologically linked to many neurological disorders.<ref name = Wang2017/>  For example, the neurological disorders, [[ALS|amyotrophic lateral sclerosis]] (ALS) and [[frontotemporal dementia]] (FTD) are linked to DNA damage accumulation and DNA repair deficiency.<ref>{{cite journal |vauthors=Wang H, Kodavati M, Britz GW, Hegde ML |title=DNA Damage and Repair Deficiency in ALS/FTD-Associated Neurodegeneration: From Molecular Mechanisms to Therapeutic Implication |journal=Front Mol Neurosci |volume=14 |issue= |pages=784361 |date=2021 |pmid=34975400 |pmc=8716463 |doi=10.3389/fnmol.2021.784361 |doi-access=free }}</ref>

==Classification==
[[File:Neurological conditions world map-Deaths per million persons-WHO2012.svg|thumb|upright=1.3|Deaths due to neurological conditions per million persons 2012 {{Div col|small=yes|colwidth=10em}}{{legend|#ffff20|18-52}}{{legend|#ffe820|53-68}}{{legend|#ffd820|69-84}}{{legend|#ffc020|85-99}}{{legend|#ffa020|100-131}}{{legend|#ff9a20|132-157}}{{legend|#f08015|158-186}}{{legend|#e06815|187-243}}{{legend|#d85010|244-477}}{{legend|#d02010|478-1,482}}{{div col end}}]]
Neurological disorders can be categorized according to the primary location affected, the primary type of dysfunction involved, or the primary type of cause. The broadest division is between [[central nervous system disease|central nervous system disorders]] and [[peripheral nervous system]] disorders. The [[Merck Manual]] lists brain, spinal cord disorders, and nerve disorders in the following overlapping categories:<ref>[http://www.merck.com/mmhe/sec06.html Merck Manual: Brain, Spinal Cord and Nerve Disorders]</ref>

{{Infobox anatomy
| Name        = Nervous system
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* [[Brain]]:
** Brain dysfunction according to type:
*** [[Apraxia]] (patterns or sequences of movements)
*** [[Agnosia]] (identifying things or people)
*** [[Amnesia]] (memory)
*** [[Aphasia]] (language)
*** [[Dysarthria]] (speech)
* [[Spinal cord]] disorders
* Peripheral nervous system disorders (e.g., [[Peripheral neuropathy]])
* [[Cranial nerve disorder]] (e.g., [[trigeminal neuralgia]])
* [[Autonomic nervous system]] disorders (e.g., [[dysautonomia]], [[multiple system atrophy]])
* [[Seizure disorder|Epilepsy]]
* [[Movement disorder]]s of the central and peripheral nervous system such as [[Parkinson's disease]], [[essential tremor]], [[amyotrophic lateral sclerosis]] (ALS),{{failed verification|date=August 2023}} and [[Tourette's syndrome|Tourette syndrome]]{{failed verification|date=August 2023}}
* [[Sleep disorder]]s (e.g., [[narcolepsy]])
* Some [[speech disorder]]s (e.g., [[stuttering]])
* [[Headache]]s (e.g., [[migraines|migraine]], [[cluster headache]], [[tension headache]])
* [[Pain]] (e.g., [[complex regional pain syndrome]], [[fibromyalgia]])
* [[Delirium]]
* [[Dementia]] (e.g., [[Alzheimer's disease]])
* [[Coma]] and [[Disorder of consciousness|impaired consciousness]], (e.g., [[stupor]])
* [[Stroke]]
* [[Tumors]] of the nervous system (e.g., [[cancer]])
* [[Multiple sclerosis]] and other [[demyelinating disease]]s
* Brain [[infection]]s
* [[Meningitis]]
* [[Prion|Prion diseases]] (a type of infectious agent)

Neurological disorders in non-human [[animals]] are treated by [[veterinarians]].<ref>{{Cite web |url=http://www.vetneuro.com/NeurologicalSignsDiseases/tabid/4171/Default.aspx |title=Veterinary Neurological Centre - Neurological Signs and Diseases |access-date=2010-01-27 |archive-url=https://web.archive.org/web/20161102033420/http://vetneuro.com/NeurologicalSignsDiseases/tabid/4171/Default.aspx |archive-date=2016-11-02 |url-status=dead }}</ref><ref>{{Cite web|url=https://www.merckvetmanual.com/?redirectid=18?ruleredirectid=30&cfile=htm/bc/toc_100000.htm|title=Merck Veterinary Manual|website=Merck Veterinary Manual}}</ref>

==Mental functioning==
A [[neurological examination]] can, to some extent, assess the impact of neurological damage and disease on brain function in terms of [[behavior]], [[memory]], or [[cognition]]. [[Behavioral neurology]] specializes in this area. In addition, [[clinical neuropsychology]] uses [[neuropsychological assessment]] to precisely identify and track problems in mental functioning, usually after some sort of brain injury or neurological impairment.{{citation needed|date=July 2021}}

Alternatively, a condition might first be detected through the presence of abnormalities in mental functioning, and further assessment may indicate an underlying neurological disorder. There are sometimes unclear boundaries in the distinction between disorders treated within neurology, and [[mental disorders]] treated within the other medical specialty of [[psychiatry]], or other [[mental health professions]] such as [[clinical psychology]]. In practice, cases may present as one type, but be assessed as more appropriate to the other.<ref>{{cite journal|last=Butler|first=C|title=Neurological syndromes which can be mistaken for psychiatric conditions|journal=Journal of Neurology, Neurosurgery & Psychiatry|date=1 March 2005|volume=76|issue=suppl_1|pages=i31–i38|doi=10.1136/jnnp.2004.060459|url= |pmc=1765684|pmid=15718219}}</ref> [[Neuropsychiatry]] deals with [[mental disorders]] arising from specific identified diseases of the nervous system.{{citation needed|date=July 2021}}

One area that can be contested is in cases of [[idiopathic]] neurological symptoms - conditions where the cause cannot be established. It can be decided in some cases, perhaps by [[diagnosis of exclusion|exclusion of any accepted diagnosis]], that higher-level brain/mental activity is causing symptoms, referred to as [[functional symptom]]s, rather than the symptoms originating in the area of the nervous system from which they may appear to originate. Cases involving these symptoms are classified as [[functional disorder]]s ("functional" in this context is usually contrasted with the old term "[[organic disease]]"). For example, in [[functional neurologic disorder]] (FND), those affected present with various neurological symptoms such as [[Non-epileptic seizure|functional seizures]], [[numbness]], [[paresthesia]], and [[weakness]], among others. Such cases may be contentiously interpreted as being "psychological" rather than "neurological."  [[conversion disorder]], If the onset functional symptoms appear to be causally linked to emotional states or responses to social [[stress (biological)|stress]] or social contexts, it may be referred to as [[conversion disorder]].<ref>{{Cite book|last1=Roelofs|first1=K.|last2=Pasman|first2=J.|chapter=Stress, childhood trauma, and cognitive functions in functional neurologic disorders |date=2016|title=Functional Neurologic Disorders|series=Handbook of Clinical Neurology|volume=139|pages=139–155|doi=10.1016/B978-0-12-801772-2.00013-8|issn=0072-9752|pmid=27719835|isbn=9780128017722|s2cid=8534792 }}</ref>

On the other hand, [[dissociation (psychology)|dissociation]] refers to partial or complete disruption of the integration of a person's conscious functioning, such that a person may feel detached from one's emotions, body and/or immediate surroundings. In extreme cases, this may be diagnosed as [[depersonalization-derealization disorder]]. There are also conditions viewed as neurological where a person appears to consciously register neurological stimuli that cannot possibly be coming from the part of the nervous system to which they would normally be attributed, such as [[phantom pain]] or [[synesthesia]], or where limbs act without conscious direction, as in [[alien hand syndrome]].

[[File:Cognitive science heptagram.svg|thumb|right|300px|Some of the fields that contribute to understanding mental functioning]]

Conditions that are classed as [[mental disorder]]s, [[learning disabilities]], and forms of [[intellectual disability]], are not themselves usually dealt with as neurological disorders. [[Biological psychiatry]] seeks to understand mental disorders in terms of their basis in the nervous system, however. In clinical practice, mental disorders are usually indicated by a [[mental state examination]], or other type of structured interview or questionnaire process. At the present time, [[neuroimaging]] (brain scans) alone cannot accurately diagnose a mental disorder or tell the risk of developing one; however, it can be used to rule out other medical conditions such as a [[brain tumor]].<ref>{{Cite web|url=http://www.nimh.nih.gov/health/publications/neuroimaging-and-mental-illness-a-window-into-the-brain/neuroimaging-and-mental-illness-a-window-into-the-brain.shtml|title=NIMH publications (2009) Neuroimaging and Mental Illness}}</ref> In research, neuroimaging and other neurological tests can show correlations between reported and observed mental difficulties and certain aspects of neural function or differences in brain structure. In general, numerous fields intersect to try to understand the basic processes involved in mental functioning, many of which are brought together in [[cognitive science]]. The distinction between neurological and mental disorders can be a matter of some debate, either in regard to specific facts about the cause of a condition or in regard to the general understanding of brain and [[mind]].{{citation needed|date=July 2021}}

'''<u><big>Impacts</big></u>'''

The consequences of neurological disorders extend beyond medical diagnosis. They profoundly affect patients' psychological well-being, social interactions, and overall life trajectory. Families and caregivers face significant challenges in supporting individuals with these conditions, often requiring extensive resources and emotional resilience (Nur & Kung, 2023). Ongoing research continues to push the boundaries of understanding. Advances in genetic research, neuroimaging, and treatment technologies offer hope for more effective interventions. Emerging fields like neuroplasticity research demonstrate the brain's remarkable ability to adapt, opening new possibilities for treatment and rehabilitation. As medical science progresses, the approach becomes increasingly personalized, recognizing the unique neurological profile of each patient and the incredible complexity of the human nervous system.

==See also==
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* [[Central nervous system]]
* [[European Brain Council]]
* [[Human brain]]
* [[Mental disorder]]
* [[Neuroplasticity]]
* [[Peripheral nervous system]]
* [[Proctalgia fugax]]
* [[Hypokalemic sensory overstimulation]]

{{colend}}

==References==
{{Reflist}}

== External links ==
{{Medical resources
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* [https://www.ninds.nih.gov/health-information/disorders Disorder Index] of the [[National Institute of Neurological Disorders and Stroke]]

{{Nervous system}}
{{Central nervous system disease}}
{{PNS diseases of the nervous system}}
{{Autonomic diseases}}
{{Neuropathic pain and fibromyalgia pharmacotherapies}}
{{Mental and behavioural disorders|selected=neurological}}
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[[Category:Neurological disorders| ]]