Chronic Subdural Hematoma

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The blood is pushing the brain from left to right.

Definition:
This is a brain disorder involving a collection of blood in the space between the inner membranes that cover the brain and the outer membrane covering of the brain, with symptoms occurring 2 weeks or more after the causative injury.

The brain is enclosed in the skull, which is a rigid, solid bone. Surrounding the brain is a tough, leathery outer covering called the dura (door-a). When a person receives a severe blow to the head, the brain bounces within the cavity. This movement of the brain structures may cause shearing or tearing of the blood vessels surrounding the brain. When the blood vessels tear, blood accumulates within the space between the brain and the dura. This is known as a subdural hematoma (sub-door-ul hem-a-to-ma), or blood clot in the brain

Incidence and risk factors:

Subdural means below the dura (the dura mater is the outer membrane covering the brain). Chronic subdural hematoma develops when delicate veins that are located between the membranes covering the brain slowly leak blood after a head injury. The head injury could be as obvious as a motor vehicle accident or as seemingly trivial as a minor bump to the head. In many cases, the head injury may not even be remembered. The blood collects into a mass (hematoma) that presses on the brain tissue. This causes loss of brain function, which may progressively worsen as the hematoma very slowly enlarges. The symptoms develop gradually because the leakage of blood is gradual. Risks include head injury, very young or old age, chronic use of aspirin or blood thinner (anti-coagulant) medication, and alcoholism or chronic alcohol use. Other important factors include a history of any disorder that may increase the risk of falling, and organic brain syndromes where confusion and cognitive impairment are already present and may mask symptoms of chronic subdural.

Chronic subdural hematoma occurs in about 1 out of 10,000 people. It is most common in infants and the elderly, especially people over age 75, but it may occur in people of all ages.

Background: An acute subdural hematoma (SDH) is a rapidly clotting blood collection found below the inner layer of the dura but external to the brain and arachnoid membrane. Two further stages, subacute and chronic, may develop with untreated acute SDH. Each type has distinctly different clinical, pathological, and imaging characteristics.

Generally, the subacute phase begins 3-7 days after acute injury. (Surgical literature favors 3 days; radiological, 7).

The chronic phase begins about 2-3 weeks after acute injury..

Some subdural hematomas are small and can resolve on their own. Others, which may be larger or more severe, may cause serious problems and must be removed.

Causes:

A subdural hematoma can happen to anyone, at any age. A blow to the head is the most common cause. This injury may be a severe traumatic event, or may be so insignificant as to not be remembered by the patient.

Signs and symptoms:

The signs and symptoms of a subdural hematoma include severe headache, dizziness, vomiting, increased size of one pupil or sudden weakness in an arm or leg. As the subdural hematoma swells and the brain structures are compressed, more pronounced signs can occur. A more dangerous sign of subdural hematoma is a decreased level of consciousness, such as drowsiness, confusion or inability to awaken from a very deep sleep. Because the brain controls all functions of the human body, breathing pattern changes also can occur. Shortness of breath, gasping for air or very slow breathing can be a warning sign that the person needs help. A subdural hematoma can be life-threatening; therefore, if any of these signs or symptoms occur, the person should be taken to a medical facility immediately.

Diagnostic tests:

If a subdural hematoma is suspected, a CT or MRI scan will be ordered.

Severe compression and displacement of the brain

Treatment

The treatment for subdural hematoma depends upon the clinical signs and symptoms, as well as the size of the clot and area of the brain involved. Some hematomas can be watched over time to see if the blood clot will resolve on its own. These patients tend to have minor symptoms, which do not include any change in level of consciousness. For patients who show signs of brain compression (i.e. confusion, drowsiness or change in level of consciousness), the treatment of choice may be surgery to remove the clot.. The specific procedure, as well as the risks and benefits, should be discussed in detail by the neurosurgeon performing the procedure.

Generally, I remove chronic subdurals using local anesthesia and some sedation. One or two small holes are placed in the skull bone over the clot and the clot is then washed out. At the conclusion, a drainage catheter is placed and will remain until all drainage has stopped.

Drain in place following drainage of SDH

Recovery after surgery:

After the blood clot has been removed, the patient generally is placed in the intensive care unit (ICU), where specially trained nurses can monitor closely the level of consciousness and any signs of complications. Sometimes a ventilator (breathing machine) is needed until the patient wakes up enough to breathe on his or her own.

Visiting the patient in the intensive care unit can be frightening at first. The unit often is noisy and filled with machines and monitors. These monitors are used to closely watch the heart, blood pressure and pressure inside the head. The ventilator is used to help the patient breathe. Often the patient has several intravenous lines that deliver fluid and nutrition through veins. A dressing may be on the head to cover the surgical area. A tube may be in the nose or mouth to keep the stomach clear or to feed the patient.

Patients who have had a subdural hematoma often appear confused or combative. Some patients may need their hands restrained to keep from pulling out vital tubes, such as the breathing tube. It is important to ask the ICU nurses any questions to help understand the equipment and condition of the patient. To make sure all questions are answered, some families write down questions while waiting to see their loved one. Don't hesitate to ask - even if the question seems silly or you have asked it before.

It is not uncommon for the patients to have worsened mental functions immediately after draining the blood, as the brain re-expands to fill the space. This usually resolves over days or weeks. Remember the brain is changing shape, back to where it belongs. In doing so, it doesn’t function normally. In some patients the initial injury is so severe that the condition of the patient is irreversible.

Depending on the severity of the injury, some patients will require a rehabilitation program to regain their abilities. A uniquely trained team of rehabilitation specialists often includes nurses, physiatrists (rehabilitation doctors), neuropsychologists, speech therapists, physical therapists and occupational therapists.

It is important to keep in mind that recovery from a traumatic brain injury can be very slow. Sometimes several days can go by without seeing any major visible change. This is not unusual, and it is best to ask the staff if any changes have occurred. It is also important to try to get enough rest and nutrition while waiting for the patient to recover. It is normal to feel frustrated, overwhelmed, lonely and worried. Sometimes a friend, or support group can help. Before your stress gets out of control, tell someone who can help

Mortality/Morbidity

Acute SDH is associated with high mortality and morbidity.

-Simple SDH occurs in about half of all cases and implies that no parenchymal injury is present. Simple SDH is associated with a mortality rate of about 20%.

-Complicated SDH occurs in about half of all cases and implies that brain injury (eg, contusion or laceration of a cerebral hemisphere) is present. Complicated SDH is associated with a mortality rate of about 50%.

Links

Subdural Hematoma

EMedicine Chronic Subdural Hematoma

ECure Subdural Hematoma