Subdural hematoma | |
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Subdural hematoma as marked by the arrow with significant midline shift | |
Classification and external resources | |
Specialty | Neurosurgery |
ICD-10 | I62.0, P10.0, S06.5 |
ICD-9-CM | 852.2 - traumatic; 432.1 - nontraumatic |
DiseasesDB | 12614 |
MedlinePlus | 000713 |
eMedicine | neuro/575 |
MeSH | D006408 |
A subdural hematoma or subdural haematoma (alternative spelling), also known as a subdural haemorrhage (SDH), is a type of hematoma, usually associated with traumatic brain injury. Blood gathers between the inner layer of the dura mater and the arachnoid mater. Usually resulting from tears in bridging veins which cross the subdural space, subdural hemorrhages may cause an increase in intracranial pressure (ICP), which can cause compression of and damage to delicate brain tissue. Subdural hematomas are often life-threatening when acute. Chronic subdural hematomas, however, have a better prognosis if properly managed.
In contrast, epidural hematomas are usually caused by tears in arteries, resulting in a build-up of blood between the dura mater and skull. Subarachnoid hemorrhage, the third type of brain hemorrhages, is bleeding into the subarachnoid space — the area between the arachnoid membrane and the pia mater surrounding the brain.
Subdural hematomas are divided into acute, subacute, and chronic, depending on the speed of their onset. Acute subdural hematomas that are 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.
Acute bleeds often develop after high speed acceleration or deceleration injuries and are increasingly severe with larger hematomas. They are most severe if associated with cerebral contusions. Though much faster than chronic subdural bleeds, acute subdural bleeding is usually venous and therefore slower than the typically arterial bleeding of an epidural hemorrhage. Acute subdural bleeds have a high mortality rate, higher even than epidural hematomas and diffuse brain injuries, because the force (acceleration/deceleration) required to cause them causes other severe injuries as well. The mortality rate associated with acute subdural hematoma is around 60 to 80%.