A subdural hematoma is a collection of blood on the surface of the brain. It lies beneath the outer covering (the dura) of the brain and the brain's surface.

Subdural hematomas are usually the result of a serious head injury. When this is the cause, they are referred to as "acute" subdural hematomas. Subdural hematomas can also occur spontaneously or after a very minor head injury, especially in the elderly. These go unnoticed for many days to many weeks, and are referred to as "chronic" subdural hematomas. The terms acute, subacute, and chronic reflect how long it takes blood to collect.

Acute traumatic subdural hematomas are among the most lethal of all head injuries (up to 50% lethality). They expand very rapidly, leaving little room for the brain, and are associated with brain injury.

Subdural hematomas occur in about 15% of all head traumas. Tiny veins between the surface of the brain and its outer covering (the dura) stretch and tear, allowing blood to collect. In the elderly, the veins are often already stretched because of brain atrophy (shrinkage).

Risks include:

• Head injury
• Very young or very old age
• Anticoagulant medication (blood thinners)
• Chronic alcohol use

• Recent injury or trauma to the head
• Loss of consciousness after original injury
• Headache, steady or fluctuating
• Weakness, numbness or inability to speak
• Slurred speech
• Nausea and vomiting
• Lethargy
• Seizures

In infants:

• Bulging fontanelles
• Increased head circumference
• Separated sutures
• Irritability
• High-pitched cry
• Focal seizures
• Generalized tonic-clonic seizure

Always seek medical attention following a significant head trauma or mental deterioration in the elderly. The evaluation should include a complete neurologic exam.

Any of the following may prompt the physician to order a brain imaging study:

• Signs of weakness
• Numbness
• Inability to speak
• Slurred speech
• Persistent headache
• Abnormal level of consciousness
• Recent intellectual deterioration in an elderly person, even in the absence of head injury)

A CT scan or MRI scan would likely be done to evaluate for the presence of a subdural hematoma.

A subdural hematoma is an emergency condition! Treatment includes lifesaving measures, controlling symptoms, and minimizing or preventing permanent brain damage.

Medications vary according to the type and severity of symptoms and the extent of brain damage. Diuretics may be used to reduce swelling. Anticonvulsant medications such as phenytoin may be used to control or prevent seizures.

Emergency surgery may be required to reduce pressure within the brain. This may involve drilling a small hole in the skull to relieve pressure and allow the hematoma to drain. Large hematomas or solid blood clots may need to be removed through a larger opening in the skull (craniotomy).

The outlook following a subdural hematoma varies widely depending on the type of head injury, the size of the blood collection, and how quickly treatment is obtained.

Acute subdural hematomas present the largest challenge, with high rates of death and injury. Subacute and chronic subdural hematomas have good outcomes in most cases, with symptoms going away after the blood collection is drained.

There is a high frequency of seizures following a subdural hematoma, but these are usually well controlled with medication.

• Temporary or permanent weakness, numbness, difficulty speaking
• Seizures
• Brain herniation
• Persistent symptoms such as memory loss, dizziness, headache, anxiety, and difficulty concentrating

Serious head injuries and complications like subdural hematoma require emergency medical attention. Call 911 or go immediately to an emergency room. Spinal injuries often accompany head injuries, so always consider immobilizing the patient's neck if the patient must be moved before medics arrive.

Use safety equipment and safety precautions at work and play to minimize the risk of a head injury. For example, use hard hats, bicycle or motorcycle helmets, and seat belts.