Editing Subdural hematoma (section)

==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>