SUBDURAL HEMATOMA

A subdural hematoma (SDH) is a form of traumatic brain injury in which blood gathers between the dura (the outer protective covering of the brain) and the arachnoid (the middle layer of the meninges). Unlike in epidural hematomas, which are usually caused by tears in arteries, subdural bleeding usually results from tears in veins that cross the subdural space. This bleeding often separates the dura and the arachnoid layers. Subdural hemorrhages may cause an increase in intracranial pressure (ICP), which can cause compression of and damage to delicate brain tissue. Acute subdural hematoma (ASDH) has a high mortality rate and is a severe medical emergency.

Subdural hematomas are most often caused by head injury, when fast changing velocities within the skull may stretch and tear small bridging veins. Subdural hematomas due to head injury are described as traumatic. Much more common than epidural hemorrhages, subdural hemorrhages generally result from shearing injuries due to various rotational or linear forces. It is also commonly seen in the elderly and in alcoholics, who have evidence of brain atrophy. Cerebral atrophy increases the length the bridging veins have to traverse between the two meningeal layers, hence increasing the likelihood of shearing forces causing a tear. It is also more common in patients on anticoagulants, esp Aspirin and Warfarin. Patients on these medications can have a subdural hematoma with a minor injury.

It is important that a patient receive medical assessment, including a complete neurological examination, after any head trauma. A CT scan or MRI scan will usually detect significant subdural hematomas.

Treatment of a subdural hematoma depends on its size and rate of growth. Small subdural hematomas can be managed by careful monitoring until the body heals itself. Large or symptomatic hematomas require a craniotomy, the surgical opening of the skull. A surgeon then opens the dura, removes the blood clot with suction or irrigation, and identifies and controls sites of bleeding. Postoperative complications include increased intracranial pressure, brain edema, new or recurrent bleeding, infection, and seizure.