A subdural hematoma, also called a subdural hemorrhage, is a collection of blood between the dura (the outer protective covering of the brain) and the arachnoid (the middle layer of the meninges). Such bleeding often separates these two meningeal layers. Injury to the brain may then result from local pressure, increased intracranial pressure, or related insults. An acute subdural hematoma is a medical emergency.

Subdural hematomas are most often caused by head injury, when rapidly changing velocities within the skull may stretch and tear small bridging veins. Following safety precautions and wearing hard hats, helmets, and seat belts prevents many serious head injuries.

It is important to receive medical assessment, including a complete neurological examination, after any head trauma. A CT scan or MRI scan will detect significant subdural hematomas. Other factors, beside the obvious head trauma, increasing the risk of a subdural hematoma include very young or very old age, the taking of blood thinners (anticoagulants), long-term alcohol abuse, and dementia.

Subdural hematomas are divided into acute, subacute, and chronic, depending on how quickly or slowly they take to form. When a subdural hematoma occurs due to a head injury, it is described as traumatic. Traumatic acute subdural hematomas are the most lethal of all head injuries, with a high mortality rate if not rapidly treated with surgical decompression.

Features

Signs and symptoms of a subdural hematoma include:

• A history of recent head injury (moderately severe to severe)
• Loss of consciousness or fluctuating levels of consciousness
• Seizures
• Numbness
• Headache (either constant or fluctuating)
• Disorientation
• Amnesia
• Weakness or lethargy
• Nausea or vomiting
• Personality changes
• Inability to speak or slurred speech

Treatment

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, which is 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. If surgery is administered, postoperative complications include increased intracranial pressure, brain edema, new or recurrent bleeding, infection, and seizure.