Subdural Hematoma

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A subdural hematoma is a pool of blood that forms just under the outer covering of the brain (the dura). The hematoma is not in the brain itself, but sits between the brain and the dura. Subdural hematomas put pressure on the brain below, and can cause symptoms and damage as they compress vital brain structures.

Subdural hematomas are usually caused by head trauma that bursts veins in the subdural space. A severe trauma can cause an acute, life-threatening hematoma to form. Any head injury should be evaluated immediately, and a diagnosis of an acute subdural hematoma is a medical emergency that requires immediate treatment.  

Even minor head injuries may sometimes cause enough bleeding to create a small hematoma, which grows slowly and may not cause any immediate symptoms; the potential for developing this kind of chronic subdural hematoma is another reason why all head injuries, regardless of severity, should be evaluated.

A subdural hematoma can also occur spontaneously, especially in infants and the elderly, in those who take blood-thinning medications, in those with a history of alcohol use, and in individuals who have suffered multiple minor head injuries, none of which individually was serious enough to cause the hematoma.

Some small hematomas may be treated with medication, or monitored until they resolve on their own, but larger and symptomatic hematomas have often require surgical treatment. Until recently, most subdural hematomas that needed to be removed surgically required open surgery, but recent advances described in a paper by Dr. Jared Knopman allow neurosurgeons to treat the hematoma using a minimally invasive procedure called middle meningeal embolization. In the embolization procedure, a tiny catheter is threaded up to the arteries feeding the subdural hematoma membrane starting from the femoral artery, accessed by a small needle stick in the groin. Small particles of polyvinyl alcohol are released through the catheter into the middle meningeal artery to shut down the blood supply to the hematoma. This interrupts the blood supply to the hematoma, felt to be involved in the frequent spontaneous re-bleeds observed that account for its growth and development over time. Subsequently, the hematoma can reabsorb on its own and disappear.  (See the abstract of the paper.)

The new minimally invasive approach to treating subdural hematomas is especially helpful in elderly patients, who are most vulnerable to complications when they undergo major open surgery.

Subdural hematomas are best treated in major medical centers by experts with advanced training and extensive experience treating cerebrovascular disorders. Dr. Knopman has pioneered this technique and is the first neurosurgeon in the country to offer it, thus far having treated nearly 50 patients using the new embolization procedure, which spares patients major surgery and prolonged recovery times. (Find out more about this procedure.)

Note that another type of hematoma, epidural hematoma, can form between the dura and the skull, typically when trauma causes the arteries in that space to rupture. The actress Natasha Richardson died of an epidural hematoma after a fall while skiing.  

Reviewed by Jared Knopman, MD
Last reviewed/last updated: December 2017