Subdural means "below the dura" (the dura mater is the outer membrane covering the brain). Subdural hematoma develops when blood veins that are located between the membranes covering the brain (the meninges) leak blood after an injury to the head.

The head injury could be as obvious as a traumatic accident or as trivial as a minor bump to the head. Blood collects as a mass (hematoma) that presses on the tissues of the brain. This pressure damages the brain tissue and causes loss of brain function that may progressively worsen as the hematoma enlarges and as pressure within the head increases.

The injury and the resulting collection of blood cause inflammation of the brain tissues, which leads to swelling (cerebral edema). This swelling further increases the pressure.

Subdural hematoma often develops as a complication after a head injury. Symptoms of subdural hematoma may develop even after symptoms of the head injury (such as decreased consciousness) have improved.

• Acute subdural hematoma progresses rapidly, with symptoms usually appearing within 24 hours of the injury. Rapid deterioration occurs thereafter.
• Subacute subdural hematoma usually develops symptoms within two to 10 days after the injury because of a slightly slower leakage of blood into the subdural area. Typically, symptoms of the original injury improve for a period, followed by development of symptoms of subdural hematoma.

Risks include:

• Head injury
• Very young or very old age
• Chronic use of aspirin
• Chronic use of anticoagulant medication (blood thinners)
• Alcoholism or chronic alcohol use.
• Any disorder that may result in falling (note: if confusion is a symptom of that disorder, it can mask symptoms of acute/subacute subdural hematoma)

Subdural hematoma can occur in people of all ages. Acute/subacute subdural hematoma is less common, but more often fatal, than chronic subdural hematoma.

• Recent injury or trauma to the head
• Loss of consciousness after original injury
  • May or may not regain consciousness for a period of time
  • Decrease in alertness after initial awakening
• Drowsiness
• Headache, steady or fluctuating
• Impaired vision
  • Visual loss (blindness)
  • Left eye
  • Right eye
  • One pupil larger than the other
  • Eyes do not react promptly to sudden bright light
• Eyes retract into the socket (enophthalmos)
• Eyelid drooping on one side only (unilateral)
• Decreased sensation or numbness
  • Lower extremities (right leg or left leg)
  • Upper extremities (right arm or left arm)
  • Face (right side of face or left side of face)
  • Individual is aware of reduced ability to feel (sensory deficit)
• Inattention to environment on the same side as the reduced sensation
• Bleeding or clear fluid emitted from ears or nose (with no obvious external injury to those organs)
• Loss of movement (paralysis)
  • On only one side of the body
  • The individual is aware of movement difficulty (motor deficit)
• Confusion, delirium
• Changes in personality
  • Irritability
  • Apathy
• Decreased memory
• Slowed thought processes
• Impaired speech or language
  • Loss of the ability to read but can still understand speech
  • Unable to repeat a phrase
  • Slurred speech (dysarthria)
  • Unable to use muscles for speech but muscles are not paralyzed
  • Speech is missing, mute
  • Impaired ability to name objects (anomia)
  • Comprehension of spoken word is impaired
• Withdrawal from social interaction
• Absent sweating on one side of the forehead

Symptoms peculiar to infants less than 6 months old:

• Bulging fontanelles
• Increased head circumference
• Separated sutures
• Irritability
• High-pitched cry
• "Setting" sun sign
  • The eyes appear to look downward and there is a small amount of white sclera visible above the iris; it may be easiest to see when the infant is changed from a sitting position to supine (lying face up).
• Focal seizures
• Generalized tonic-clonic seizure

Consult the healthcare provider promptly for any head injury that results in even a brief loss of consciousness, or if other symptoms are present after head injury even without loss of consciousness. Acute/subacute subdural hematoma may be diagnosed after the health-care provider has ruled out other possible causes of symptoms that occur after a head injury, such as intracerebral hemorrhage.

Examination may show focal neurologic deficits (localized, specific brain function changes such as decreased movement or sensation). Reflexes may be abnormal. There may be signs of increased intracranial pressure. The skull may be tender when gently tapped on one or both sides. Examination may reveal a need for emergency surgery to relieve pressure within the head without further testing to pinpoint the location and type of injury.

In abused infants, there may be a history of poor feeding and/or failure to thrive. Retinal hemorrhages are peculiar to infants with subdural bleeding that results from shaking (shaken baby syndrome) or from blows to the head.

Tests:

• A head CT scan confirms the diagnosis of subdural hematoma and will pinpoint the exact location of the hematoma.
• This disease may also alter the results of a cranial MRI.

Acute/subacute subdural hematoma is an emergency condition!

Treatment goals include lifesaving measures, control of symptoms, and minimizing or preventing permanent brain damage. Lifesaving measures may include support of breathing and/or circulation.

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

Emergency or urgent surgery may be required to reduce pressure within the brain. In patients with a subacute hematoma, this may involve drilling a small hole in the skull to relieve pressure and allow drainage of the hematoma. Large hematomas or solid blood clots may need to be removed through a larger opening in the skull (craniotomy). An acute subdural hematoma should be treated with craniotomy (it is difficult to treat an acute subdural hematoma with burr holes because the clot cannot be evacuated well).

Acute subdural hematoma progresses rapidly. The condition has a high death rate, even with prompt treatment because of uncontrollable rapid increase in intracranial pressure.

Subacute subdural hematoma may result in death or in permanent brain damage if untreated or, in some cases, even if treated. This is especially true in the setting of trauma because the mechanism of injury resulting in subdural hematoma is so severe that usually there is other underlying brain injury.

Symptoms such as seizures may persist for several months after treatment. Seizures may begin as late as two years after the injury.

In adults, most recovery occurs in the first six months, with some improvement over approximately two years. Children usually recover more quickly and completely than adults. Incomplete recovery is the result of permanent brain damage.

• Permanent brain damage
• Seizures
• Brain herniation
• Hydrocephalus
• Persistent symptoms such as memory loss, dizziness, headache, anxiety, and difficulty concentrating

Go to the emergency room or call the local emergency number (such as 9-1-1) if symptoms of subdural hematoma occur! Any person with a serious head injury should have his neck immobilized. If vomiting ensues, be prepared to turn victim on his side so he doesn't choke.

Emergency symptoms (that may indicate complications) include:

• Seizures
• Difficulty breathing
• Eyes, pupils different size (one pupil enlarged)
• Weakness
• Paralysis; complete or partial (one or both sides of the body)
• Changes in sensation, any part of the body
• Difficulty speaking
• Difficulty swallowing
• Vision changes
• Eye pain
• Lethargy

A subdural hematoma may not be preventable once a head injury has occurred.