View source for Subdural hematoma

{{Short description|Hematoma usually associated with traumatic brain injury}}
{{Infobox medical condition (new)
| name          = Subdural hematoma
| synonyms      = Subdural haematoma, subdural haemorrhage
| image         = Subduralandherniation.PNG
| caption       = Subdural hematoma as marked by the arrow with significant [[midline shift]]
| pronounce     =
| field         = [[Neurosurgery]], [[Neurology]]
| symptoms      =
| complications =
| onset         =
| duration      =
| types         =
| causes        = [[Head injury]], [[alcoholism]], reduction in [[cerebrospinal fluid]] pressure<ref name=":0" /><ref name="UVT" />
| risks         = [[Senescence]], long-term excessive alcohol consumption, [[dementia]], and [[cerebrospinal fluid leak]]<ref name="wagner" /><ref name=":2" />
| diagnosis     =
| differential  =
| prevention    =
| treatment     =
| medication    =
| prognosis     =
| frequency     =
| deaths        =
| image_size    = 270
}}

A '''subdural hematoma''' ('''SDH''') is a type of bleeding in which a [[Hematoma|collection of blood]]—usually but not always associated with a [[traumatic brain injury]]—gathers between the inner layer of the [[dura mater]] and the [[arachnoid mater]] of the [[meninges]] surrounding the [[brain]]. It usually results from rips in [[bridging vein]]s that cross the [[subdural space]].

Subdural hematomas may cause an increase in the [[intracranial pressure|pressure inside the skull]], which in turn can cause compression of and damage to delicate brain tissue. Acute subdural hematomas are often life-threatening. Chronic subdural hematomas have a better [[prognosis]] if properly managed.

In contrast, [[epidural hematoma]]s are usually caused by rips in [[arteries]], resulting in a build-up of blood between the dura mater and the [[skull]]. The third type of brain hemorrhage, known as a [[subarachnoid hemorrhage]] (SAH), causes bleeding into the subarachnoid space between the arachnoid mater and the [[pia mater]]. SAH are often seen in trauma settings, or after rupture of intracranial aneurysms.{{Citation needed|date=January 2023}}

__TOC__
==Signs and symptoms==
The symptoms of a subdural hematoma have a slower onset than those of epidural hematomas because the lower-pressure veins involved bleed more slowly than arteries. [[Signs and symptoms]] of acute hematomas may appear in minutes, if not immediately,<ref>{{Cite web |date=2012-06-28 |title=Subdural hematoma : MedlinePlus Medical Encyclopedia |url=https://www.nlm.nih.gov/medlineplus/ency/article/000713.htm |access-date=2012-07-27 |website=Nlm.nih.gov}}</ref> but can also be delayed as much as two weeks.<ref>{{Cite journal |vauthors=Mezue WC, Ndubuisi CA, Chikani MC, Achebe DS, Ohaegbulam SC |date=July 2012 |title=Traumatic extradural hematoma in enugu, Nigeria |journal=Nigerian Journal of Surgery |volume=18 |issue=2 |pages=80–84 |doi=10.4103/1117-6806.103111 |pmc=3762009 |pmid=24027399 |doi-access=free}}</ref> Symptoms of chronic subdural hematomas are usually delayed more than three weeks after injury.<ref name=":0">{{Cite journal |vauthors=Ko BS, Lee JK, Seo BR, Moon SJ, Kim JH, Kim SH |date=January 2008 |title=Clinical analysis of risk factors related to recurrent chronic subdural hematoma |journal=Journal of Korean Neurosurgical Society |volume=43 |issue=1 |pages=11–15 |doi=10.3340/jkns.2008.43.1.11 |pmc=2588154 |pmid=19096538}}</ref>

If the bleeds are large enough to put pressure on the brain, signs of increased [[intracranial pressure]] or brain damage will be present.<ref name="wagner" /> Other symptoms of subdural hematoma can include any combination of the following:<ref>{{Cite web |title=Subdural Hematoma: Types, Symptoms Treatments, Prevention |url=https://my.clevelandclinic.org/health/diseases/21183-subdural-hematoma |access-date=2022-03-10 |website=Cleveland Clinic}}</ref>

{{div col|colwidth=30em}}
* Loss of [[consciousness]] or fluctuating levels of consciousness
* Irritability
* [[Seizures]]
* Pain
* [[Numbness]]
* [[Headache]] (either constant or fluctuating)
* [[Dizziness]]
* [[Disorientation]]
* [[Amnesia]]
* Weakness or [[lethargy]]
* [[Nausea]] or [[vomiting]]
* Loss of appetite
* Personality changes
* [[aphasia|Inability to speak]] or [[dysarthria|slurred speech]]
* [[Ataxia]], or difficulty walking
* Loss of muscle control
* Altered breathing patterns
* Hearing loss or ringing in the ears ([[tinnitus]])
* Blurred vision
* [[Deviated gaze]], or abnormal movement of the eyes.<ref name="wagner" />
{{div col end}}

==Causes==
Subdural hematomas are most often caused by [[head injury]], in which rapidly changing velocities within the [[Human skull|skull]] may stretch and tear small [[bridging vein]]s. Much more common than [[epidural hemorrhage]]s, subdural hemorrhages generally result from [[shearing injury|shearing injuries]] due to various rotational or linear forces.<ref name="wagner">{{EMedicine|article|344482|Imaging in Subdural Hematoma}}</ref><ref name="UVT">University of Vermont College of Medicine. [https://web.archive.org/web/20030821142023/http://cats.med.uvm.edu/cats_teachingmod/pathology/path302/np/home/neuroindex.html "Neuropathology: Trauma to the CNS."] Accessed through web archive on August 8, 2007.</ref> There are claims that they can occur in cases of [[shaken baby syndrome]], although there is no scientific evidence for this.<ref name=":1">{{Cite journal |vauthors=Lynøe N, Elinder G, Hallberg B, Rosén M, Sundgren P, Eriksson A |date=July 2017 |title=Insufficient evidence for 'shaken baby syndrome' – a systematic review |journal=Acta Paediatrica |volume=106 |issue=7 |pages=1021–1027 |doi=10.1111/apa.13760 |pmid=28130787 |s2cid=4435564 |doi-access=free}}</ref>

They are also commonly seen in the elderly and in people with an [[alcohol use disorder]] who have evidence of [[cerebral atrophy]].<ref name=":0" /> Cerebral atrophy increases the length the bridging veins have to traverse between the two meningeal layers, thus increasing the likelihood of shearing forces causing a tear.<ref>{{Cite journal |vauthors=Oishi M, Toyama M, Tamatani S, Kitazawa T, Saito M |date=August 2001 |title=Clinical factors of recurrent chronic subdural hematoma |journal=Neurologia Medico-Chirurgica |volume=41 |issue=8 |pages=382–386 |doi=10.2176/nmc.41.382 |pmid=11561348 |doi-access=free}}</ref> It is also more common in patients on [[anticoagulant]]s or [[antiplatelet drug|antiplatelet medications]], such as [[warfarin]] and [[aspirin]], respectively.<ref name=":0" /> People on these medications can have a subdural hematoma after a relatively minor traumatic event. Another cause can be a reduction in [[cerebrospinal fluid]] pressure, which can reduce pressure in the subarachnoid space, pulling the arachnoid away from the dura mater and leading to a rupture of the blood vessels.<ref>{{Cite journal |vauthors=Yamamoto H, Hirashima Y, Hamada H, Hayashi N, Origasa H, Endo S |date=June 2003 |title=Independent predictors of recurrence of chronic subdural hematoma: results of multivariate analysis performed using a logistic regression model |journal=Journal of Neurosurgery |volume=98 |issue=6 |pages=1217–1221 |doi=10.3171/jns.2003.98.6.1217 |pmid=12816267}}</ref>

===Risk factors===
Factors increasing the risk of a subdural hematoma include very young or very old [[senescence|age]]. As the brain shrinks with age, the [[subdural space]] enlarges and the [[vein]]s that traverse the space must cover a wider distance, making them more vulnerable to tears. The elderly also have more brittle veins, making chronic subdural bleeds more common.<ref name="Downie" /> Infants, too, have larger subdural spaces and are more predisposed to subdural bleeds than are young adults.<ref name="wagner" /> It is often claimed that subdural hematoma is a common finding in shaken baby syndrome, although there is no science to support this.<ref name=":1" /> In juveniles, an [[arachnoid cyst]] is a risk factor for subdural hematoma.<ref>{{Cite journal |vauthors=Mori K, Yamamoto T, Horinaka N, Maeda M |date=September 2002 |title=Arachnoid cyst is a risk factor for chronic subdural hematoma in juveniles: twelve cases of chronic subdural hematoma associated with arachnoid cyst |journal=Journal of Neurotrauma |volume=19 |issue=9 |pages=1017–1027 |doi=10.1089/089771502760341938 |pmid=12482115}}</ref>

Other risk factors include taking blood thinners (anticoagulants), long-term [[Alcohol use disorder|excessive alcohol consumption]], [[dementia]], and [[cerebrospinal fluid leak]]s.<ref name=":2">{{Cite journal |display-authors=6 |vauthors=Beck J, Gralla J, Fung C, Ulrich CT, Schucht P, Fichtner J, Andereggen L, Gosau M, Hattingen E, Gutbrod K, Z'Graggen WJ, Reinert M, Hüsler J, Ozdoba C, Raabe A |date=December 2014 |title=Spinal cerebrospinal fluid leak as the cause of chronic subdural hematomas in nongeriatric patients |journal=Journal of Neurosurgery |volume=121 |issue=6 |pages=1380–1387 |doi=10.3171/2014.6.JNS14550 |pmid=25036203 |s2cid=207731566 |doi-access=free}}</ref>

==Pathophysiology==

=== Acute ===
Acute subdural hematoma is usually caused by external trauma that creates tension in the wall of a bridging vein as it passes between the arachnoid and dural layers of the brain's lining—i.e., the subdural space. The circumferential arrangement of [[collagen]] surrounding the vein makes it susceptible to such tearing.{{citation needed|date=February 2021}}

[[Intracerebral hemorrhage]] and ruptured cortical vessels (blood vessels on the surface of the brain) can also cause subdural hematoma. In these cases, blood usually accumulates between the two layers of the dura mater. This can cause ischemic brain damage by two mechanisms: one, pressure on the cortical blood vessels,<ref name="JNS Acute">{{Cite journal |vauthors=Miller JD, Nader R |date=June 2014 |title=Acute subdural hematoma from bridging vein rupture: a potential mechanism for growth |journal=Journal of Neurosurgery |volume=120 |issue=6 |pages=1378–1384 |doi=10.3171/2013.10.JNS13272 |pmid=24313607 |s2cid=25404949}}</ref> and two, [[vasoconstriction]] due to the substances released from the hematoma, which causes further [[ischemia]] by restricting blood flow to the brain.<ref name="graham">{{Cite book |title=Head Injury |vauthors=Graham DI, Gennareli TA |date=2000 |publisher=Morgan Hill |veditors=Cooper P, Golfinos G |edition=4th |location=New York |chapter=Chapter 5: Pathology of brain damage after head injury}}</ref> When the brain is denied adequate blood flow, a [[biochemical cascade]] known as the [[ischemic cascade]] is unleashed, and may ultimately lead to brain [[cell death]].<ref>{{Cite journal |vauthors=Tandon PN |date=March 2001 |title=Acute subdural haematoma : a reappraisal |url=http://www.neurologyindia.com/article.asp?issn=0028-3886;year=2001;volume=49;issue=1;spage=3;epage=10;aulast=Tandon |journal=Neurology India |volume=49 |issue=1 |pages=3–10 |pmid=11303234 |access-date=26 November 2017 |quote=. The possibility of direct effect of some vasoactive substances released by the blood clot, being responsible for the ischaemia, seems attractive.}}</ref>

Subdural hematomas grow continually larger as a result of the pressure they place on the brain: As [[intracranial pressure]] rises, blood is squeezed into the [[dural venous sinuses]], raising the dural venous pressure and resulting in more bleeding from the ruptured bridging veins. They stop growing only when the pressure of the hematoma equalizes with the intracranial pressure, as the space for expansion shrinks.<ref name="JNS Acute" />

=== Chronic ===

[[Image:Subdural hematoma - very low mag.jpg|thumb|right|[[Micrograph]] of a chronic subdural hematoma, as demonstrated by thin strands of collagen and neovascularization. [[HPS stain]]]]

In chronic subdural hematomas, blood accumulates in the dural space as a result of damage to the dural border cells.<ref name="Pathophysiology of CSDH" /> The resulting [[inflammation]] leads to new membrane formation through [[fibrosis]] and produces fragile and leaky blood vessels through [[angiogenesis]], permitting the leakage of [[red blood cell]]s, [[white blood cell]]s, and [[Blood plasma|plasma]] into the hematoma cavity. Traumatic tearing of the [[arachnoid mater]] also causes leakage of cerebrospinal fluid into the hematoma cavity, increasing the size of the hematoma over time. Excessive [[fibrinolysis]] also causes continuous bleeding.{{citation needed|date=July 2021}}

Pro-inflammatory mediators active in the hematoma expansion process include Interleukin 1α ([[IL1A]]), [[Interleukin 6]], and [[Interleukin 8]], while the anti-inflammatory mediator is [[Interleukin 10]]. Mediators that promote angiogenesis are [[angiopoietin]] and [[vascular endothelial growth factor]] (VEGF). [[Prostaglandin E2]] promotes the expression of VEGF. [[Matrix metalloproteinase]]s remove surrounding collagen, providing space for new blood vessels to grow.<ref name="Pathophysiology of CSDH">{{Cite journal |vauthors=Edlmann E, Giorgi-Coll S, Whitfield PC, Carpenter KL, Hutchinson PJ |date=May 2017 |title=Pathophysiology of chronic subdural haematoma: inflammation, angiogenesis and implications for pharmacotherapy |journal=Journal of Neuroinflammation |volume=14 |issue=1 |pages=108 |doi=10.1186/s12974-017-0881-y |pmc=5450087 |pmid=28558815 |doi-access=free}}</ref>

[[Craniotomy]] for unruptured [[intracranial aneurysm]] is another risk factor for the development of chronic subdural hematoma. The incision in the arachnoid membrane during the operation causes cerebrospinal fluid to leak into the subdural space, leading to inflammation. This complication usually resolves on its own.<ref>{{Cite journal |vauthors=Tanaka Y, Ohno K |date=June 2013 |title=Chronic subdural hematoma – an up-to-date concept |url=http://lib.tmd.ac.jp/jmd/6002/01_Tanaka.pdf |url-status=dead |journal=Journal of Medical and Dental Sciences |volume=60 |issue=2 |pages=55–61 |pmid=23918031 |archive-url=https://web.archive.org/web/20170813054647/http://lib.tmd.ac.jp/jmd/6002/01_Tanaka.pdf |archive-date=13 August 2017 |access-date=26 November 2017}}</ref>

==Diagnosis==
[[Image:Ct-scan of the brain with an subdural hematoma.jpg|thumb|A subdural hematoma demonstrated by CT]]
[[File:ChronicSubduralPostBurrHoles.jpg|thumb|Chronic subdural after treatment with [[burr hole]]s]]
It is important that a person receive medical assessment, including a complete [[neurology|neurological]] examination, after any head trauma. A [[CT scan]] or [[MRI scan]] will usually detect significant subdural hematomas.{{citation needed|date=February 2021}}

Subdural hematomas occur most often around the tops and sides of the [[frontal lobe|frontal]] and [[parietal lobe]]s.<ref name="wagner" /><ref name="UVT" /> They also occur in the [[posterior cranial fossa]], and near the [[falx cerebri]] and [[tentorium cerebelli]].<ref name="wagner" /> Unlike epidural hematomas, which cannot expand past the [[skull suture|sutures of the skull]], subdural hematomas can expand along the inside of the skull, creating a concave shape that follows the curve of the brain, stopping only at [[dural reflection]]s like the tentorium cerebelli and falx cerebri.{{citation needed|date=February 2021}}

On a CT scan, subdural hematomas are classically crescent-shaped, with a concave surface away from the skull. However, they can have a convex appearance, especially in the early stages of bleeding. This may cause difficulty in distinguishing between subdural and epidural hemorrhages. A more reliable indicator of subdural hemorrhage is its involvement of a larger portion of the cerebral hemisphere. Subdural blood can also be seen as a layering density along the tentorium cerebelli. This can be a chronic, stable process, since the feeding system is low-pressure. In such cases, subtle signs of bleeding—such as effacement of [[sulcus (neuroanatomy)|sulci]] or medial displacement of the junction between [[gray matter]] and [[white matter]]—may be apparent.{{citation needed|date=February 2021}}

{|class="wikitable" align="right"
|-
! Age !! Attenuation ([[Hounsfield units|HU]])
|-
|  First hours || +75 to +100<ref name="Rao2016">Fig 3 in: {{Cite journal |vauthors=Rao MG, Singh D, Khandelwal N, Sharma SK |date=April 2016 |title=Dating of Early Subdural Haematoma: A Correlative Clinico-Radiological Study |journal=Journal of Clinical and Diagnostic Research |volume=10 |issue=4 |pages=HC01–HC05 |doi=10.7860/JCDR/2016/17207.7644 |pmc=4866129 |pmid=27190831}}</ref>
|-
| After 3 days || +65 to +85<ref name="Rao2016" />
|-
| After 10–14 days || +35 to +40<ref>{{Cite web |title=Subdural haemorrhage |url=https://radiopaedia.org/articles/subdural-haemorrhage |access-date=2018-08-14 |website=[[Radiopaedia]] |vauthors=Sharma R, Gaillard F}}</ref>
|}

Fresh subdural bleeding is [[radiodensity|hyperdense]], but becomes more hypodense over time due to dissolution of cellular elements. After 3–14 days, the bleeding becomes isodense with brain tissue and may therefore be missed.<ref>{{Cite web |title=Intracranial Hemorrhage – Subdural Hematomas (SDH) |url=http://www.stritch.luc.edu/lumen/MedEd/Radio/curriculum/Neurology/IC_hemorrhage_2013.htm |access-date=2018-01-06 |website=[[Loyola University Chicago]]}}</ref> Subsequently, it will become more hypodense than brain tissue.<ref name="Schweitzer 2019">{{Cite journal |vauthors=Schweitzer AD, Niogi SN, Whitlow CT, Tsiouris AJ |date=October 2019 |title=Traumatic Brain Injury: Imaging Patterns and Complications |journal=Radiographics |volume=39 |issue=6 |pages=1571–1595 |doi=10.1148/rg.2019190076 |pmid=31589576 |s2cid=203926019}}</ref>

===Classification===
Subdural hematomas are classified as [[Acute (medicine)|acute]], subacute, or [[chronic (medicine)|chronic]], depending on the speed of their onset.<ref>{{EMedicine|article|247472|Subdural Hematoma Surgery}}</ref>

Acute bleeds often develop after high-speed acceleration or deceleration injuries. They are most severe if associated with [[cerebral contusion]]s.<ref name="wagner" /> Though much faster than chronic subdural bleeds, acute subdural bleeding is usually venous and therefore slower than the arterial bleeding of an epidural hemorrhage. Acute subdural hematomas due to trauma are the most lethal of all head injuries and have a high [[mortality rate]] if they are not rapidly treated with surgical decompression.<ref>{{Cite web |last=<!--Staff writer(s); no by-line.--> |title=Acute Subdural Hematomas |url=http://neurosurgery.ucla.edu/body.cfm?id=102 |access-date=21 July 2011 |website=UCLA Health}}</ref> The mortality rate is higher than that of epidural hematomas and [[Focal and diffuse brain injury|diffuse brain injuries]] because the force required to cause subdural hematomas tends to cause other severe injuries as well.<ref>{{EMedicine|article|247664|Penetrating Head Trauma}}</ref>

Chronic subdural bleeds develop over a period of days to weeks, often after minor head trauma, though a cause is not identifiable in 50% of patients.<ref name="Downie">Downie A. 2001. [http://www.radiology.co.uk/srs-x/tutors/cttrauma/tutor.htm "Tutorial: CT in head trauma"] {{Webarchive|url=https://web.archive.org/web/20051106231525/http://www.radiology.co.uk/srs-x/tutors/cttrauma/tutor.htm |date=2005-11-06 }}. Retrieved on August 7, 2007.</ref> They may not be discovered until they present clinically months or years after a head injury.<ref name="Kushner98">{{Cite journal |vauthors=Kushner D |year=1998 |title=Mild traumatic brain injury: toward understanding manifestations and treatment |journal=Archives of Internal Medicine |volume=158 |issue=15 |pages=1617–1624 |doi=10.1001/archinte.158.15.1617 |pmid=9701095 |doi-access=free}}</ref> The bleeding from a chronic hematoma is slow and usually stops by itself.<ref name="UVT" /><ref>{{Cite journal |vauthors=Faried A, Halim D, Widjaya IA, Badri RF, Sulaiman SF, Arifin MZ |date=October 2019 |title=Correlation between the skull base fracture and the incidence of intracranial hemorrhage in patients with traumatic brain injury |journal=Chinese Journal of Traumatology = Zhonghua Chuang Shang Za Zhi |volume=22 |issue=5 |pages=286–289 |doi=10.1016/j.cjtee.2019.05.006 |pmc=6823676 |pmid=31521457}}</ref> Because these hematomas progress slowly, they can more often be stopped before they cause significant damage, especially if they are less than a centimeter wide. In one study, only 22% of patients with chronic subdural bleeds had outcomes worse than "good" or "complete recovery".<ref name="wagner" /> Chronic subdural hematomas are common in the elderly.<ref name="Kushner98" />

===Differential diagnosis===
{{Epidural vs. subdural hematoma}}
{{Clear}}

==Treatment==
Treatment of a subdural hematoma depends on its size and rate of growth. Some small subdural hematomas can be managed by careful monitoring as the [[Thrombus|blood clot]] is eventually resorbed naturally. Others can be treated by inserting a small [[catheter]] through a hole drilled through the skull and sucking out the hematoma.{{citation needed|date=February 2021}}

Large or symptomatic hematomas require a [[craniotomy]]. A surgeon opens the skull and then the dura mater; removes the clot with suction or irrigation; and identifies and controls sites of bleeding.<ref>{{Cite journal |vauthors=Koivisto T, Jääskeläinen JE |date=September 2009 |title=Chronic subdural haematoma – to drain or not to drain? |journal=Lancet |volume=374 |issue=9695 |pages=1040–1041 |doi=10.1016/S0140-6736(09)61682-2 |pmid=19782854 |s2cid=29932520}}</ref><ref>{{Cite journal |display-authors=6 |vauthors=Santarius T, Kirkpatrick PJ, Ganesan D, Chia HL, Jalloh I, Smielewski P, Richards HK, Marcus H, Parker RA, Price SJ, Kirollos RW, Pickard JD, Hutchinson PJ |date=September 2009 |title=Use of drains versus no drains after burr-hole evacuation of chronic subdural haematoma: a randomised controlled trial |journal=Lancet |volume=374 |issue=9695 |pages=1067–1073 |doi=10.1016/S0140-6736(09)61115-6 |pmid=19782872 |s2cid=5206569}}</ref> The injured vessels must be repaired. Postoperative complications can include increased [[intracranial pressure]], brain [[edema]], new or recurrent bleeding, [[infection]], and [[Epileptic seizure|seizures]]. In patients with a chronic subdural hematoma but no history of seizures, it is unclear whether [[anticonvulsant]]s are harmful or beneficial.<ref>{{Cite journal |vauthors=Ratilal BO, Pappamikail L, Costa J, Sampaio C |date=June 2013 |title=Anticonvulsants for preventing seizures in patients with chronic subdural haematoma |journal=The Cochrane Database of Systematic Reviews |volume=2013 |issue=6 |pages=CD004893 |doi=10.1002/14651858.CD004893.pub3 |pmc=7388908 |pmid=23744552}}</ref>

Those with chronic subudural haematoma (CSDH) with few or no symptoms or have high risk of complication during surgery may be treated conservatively with medications such as atorvastatin, dexamethasone,<ref name="pmid26342776">{{Cite journal |vauthors=Thotakura AK, Marabathina NR |date=December 2015 |title=Nonsurgical Treatment of Chronic Subdural Hematoma with Steroids |journal=World Neurosurgery |volume=84 |issue=6 |pages=1968–1972 |doi=10.1016/j.wneu.2015.08.044 |pmid=26342776}}</ref> and mannitol, although supporting conservative treatment is still weak.<ref name="pmid28102879">{{Cite journal |vauthors=Soleman J, Nocera F, Mariani L |date=2017 |title=The conservative and pharmacological management of chronic subdural haematoma |journal=[[Swiss Medical Weekly]] |volume=147 |pages=w14398 |doi=10.4414/smw.2017.14398 |doi-broken-date=1 November 2024 |pmid=28102879}}</ref> [[HMG-CoA reductase inhibitor]] such as [[Atorvastatin]] can reduce the haematoma volume and improving neurological function in eight weeks.<ref name="pmid30073290">{{Cite journal |display-authors=6 |vauthors=Jiang R, Zhao S, Wang R, Feng H, Zhang J, Li X, Mao Y, Yuan X, Fei Z, Zhao Y, Yu X, Poon WS, Zhu X, Liu N, Kang D, Sun T, Jiao B, Liu X, Yu R, Zhang J, Gao G, Hao J, Su N, Yin G, Zhu X, Lu Y, Wei J, Hu J, Hu R, Li J, Wang D, Wei H, Tian Y, Lei P, Dong JF, Zhang J |date=November 2018 |title=Safety and Efficacy of Atorvastatin for Chronic Subdural Hematoma in Chinese Patients: A Randomized ClinicalTrial |journal=JAMA Neurology |volume=75 |issue=11 |pages=1338–1346 |doi=10.1001/jamaneurol.2018.2030 |pmc=6248109 |pmid=30073290}}</ref> HMG-CoA reductase inhibitor may also reduce risk of recurrences in CSDH.<ref name="pmid27695533">{{Cite journal |vauthors=Yadav YR, Parihar V, Namdev H, Bajaj J |date=2016 |title=Chronic subdural hematoma |journal=Asian Journal of Neurosurgery |volume=11 |issue=4 |pages=330–342 |doi=10.4103/1793-5482.145102 |pmc=4974954 |pmid=27695533 |doi-access=free}}</ref> Dexamethasone, when used together with surgical drainage, may reduce the recurrence rate of subdural haematoma.<ref>{{Cite journal |vauthors=Chan DY, Sun TF, Poon WS |date=December 2015 |title=Steroid for chronic subdural hematoma? A prospective phase IIB pilot randomized controlled trial on the use of dexamethasone with surgical drainage for the reduction of recurrence with reoperation |journal=Chinese Neurosurgical Journal |language=en |volume=1 |issue=1 |pages=2 |doi=10.1186/s41016-015-0005-4 |issn=2057-4967 |s2cid=3934313 |doi-access=free}}</ref> Even with surgical evacuation of chronic subdural haematoma, the recurrence rate is high, ranging from 7 to 20%.<ref name="pmid28102879" />

== Prognosis ==
Acute subdural hematomas have one of the highest mortality rates of all head injuries, with 50 to 90 percent of cases resulting in death, depending on the underlying brain injury. About 20 to 30 percent of patients recover brain function.<ref>{{Cite web |title=Acute Subdural Hematomas – UCLA Neurosurgery, Los Angeles, CA |url=http://neurosurgery.ucla.edu/acute-subdural-hematomas |access-date=2019-02-19 |website=neurosurgery.ucla.edu}}</ref> Higher [[Glasgow Coma Scale]] score, younger age and responsive pupils are associated with better outcomes in acute subdural hematomas, while the time between the injury and the surgical evacuation, or the type of surgery, do not have a statistically significant impact on the outcomes.<ref name="Koç">{{Cite journal |last=Koç |first=R. Kemal |last2=Akdemir |first2=Hidayet |last3=Oktem |first3=I. Suat |last4=Meral |first4=Mehmet |last5=Menkü |first5=Ahmet |date=1997 |title=Acute subdural hematoma: Outcome and outcome prediction |url=https://pubmed.ncbi.nlm.nih.gov/9457718/ |journal=Neurosurgical Review |volume=20 |issue=4 |pages=239–244 |doi=10.1007/BF01105894 |pmid=9457718 |s2cid=29824615 |access-date=16 February 2024}}</ref> Additionally, chronic subdural hematomas (CSDHs) have a relatively high mortality rate (up to 16.7% in patients over the age of 65); however, they have an even higher rate of recurrence (as mentioned in the previous section).<ref name="Puerto Rico Recurrence Scale: Predi">{{Cite journal |last=Mignucci-Jiménez |first=Giancarlo |last2=Matos-Cruz |first2=Alejandro J. |last3=Abramov |first3=Irakliy |last4=Hanalioglu |first4=Sahin |last5=Kovacs |first5=Melissa S. |last6=Preul |first6=Mark C. |last7=Feliciano-Valls |first7=Caleb E. |date=3 June 2022 |title=Puerto Rico Recurrence Scale: Predicting chronic subdural hematoma recurrence risk after initial surgical drainage |journal=Surgical Neurology International |volume=13 |pages=230 |doi=10.25259/SNI_240_2022 |pmc=9282733 |pmid=35855136 |s2cid=249359877}}</ref> For the aforementioned reasons, researchers have developed predictive grading scales to identify patients at high risk of CSDH recurrence, one of which is the Puerto Rico Recurrence Scale developed by Mignucci-Jiménez et al.<ref name="Puerto Rico Recurrence Scale: Predi" />

== See also ==
<!-- keep alphabetical -->
* [[Concussion]]
* [[Diffuse axonal injury]]
* [[Extra-axial hemorrhage]]
* [[Intra-axial hemorrhage]]
<!-- keep alphabetical -->

== References ==
{{Reflist}}

== External links ==
{{Medical resources
|   DiseasesDB     = 12614
|   ICD10          = {{ICD10|I|62|0|i|60}}, {{ICD10|P|10|0|p|10}}, {{ICD10|S|06|5|s|00}}
|   ICD9           = {{ICD9|852.2}} - traumatic; {{ICD9|432.1}} - nontraumatic
|   ICDO           =
|   OMIM           =
|   MedlinePlus    = 000713
|   eMedicineSubj  = neuro
|   eMedicineTopic = 575
|   MeshID         = D006408
}}
{{commons category|Subdural hematoma}}
* {{EMedicine|article|1137207|Subdural Hematoma}}
* [https://www.youtube.com/watch?v=jiscvATspCA Imaging and Mechanism of Subdural Hematoma – MedPix]

{{Cerebral hemorrhage}}
{{Injuries, other than fractures, dislocations, sprains and strains}}
{{Cerebrovascular diseases}}

[[Category:Neurotrauma]]
[[Category:Cerebrovascular diseases]]