Definition An acute subdural haematoma is an accumulation of blood, or a haematoma, between the fibrous membrane called the dura, which covers the brain, and the brain itself.
What are the signs and symptoms of the injury? The classic sign of an acute subdural haematoma is a quick decrease in the level of consciousness after an injury or trauma to the head. As the haematoma gets larger, the pupil of one eye will dilate, or become wider. The eye on the side of the head with the injury is the eye affected. This dilation happens almost at the same time as increasing body weakness. The weakness is usually on the side of the body opposite the haematoma.
If consciousness continues to decrease, the pulse begins to slow. Breathing becomes difficult and the body gets weaker and less responsive to stimulation. Both pupils of the eyes become dilated and unresponsive to light, breathing ceases and finally death occurs.
What are the causes and risks of the injury? Persons travelling at any increased speed are at risk for haematoma whenever the head is struck. During impact, the brain moves around inside the skull. Bridging veins may tear, spilling blood into the subdural space. As people age, brains shrink slightly, so bridging veins are stretched. Thus, the elderly are more susceptible to this type of injury. People who have diabetes, epilepsy, alcoholism or any condition in which consciousness may suddenly be impaired are also more likely to fall. They can develop subdural haematomas.
What can be done to prevent the injury? Seat belts should be worn in motor vehicles. Helmets should be worn when bicycle or motorcycle riding. Remaining under control during activities where speed is inherent, such as skiing, will help prevent head injuries and haematomas. Proper medical treatment of diseases that affect consciousness and balance can help reduce the number of subdural haematomas.
How is the injury recognised? Acute subdural haematomas are usually diagnosed with a CAT scan if people have progressive symptoms. MRI scans and arteriograms, or imaging studies of the arteries, will also show a haematoma. Because time is crucial with this injury, a CAT scan is usually faster.
What are the treatments for the injury? Surgery is the treatment for acute subdural haematoma. The skull is opened and the haematoma is removed. The bleeding vein is clotted if it is still bleeding. Often where there is swelling of the brain, the piece of bone removed so that surgery could be performed is left out. It may be replaced later if the individual recovers enough. It is useful in relieving increased pressure inside the skull that frequently occurs.
Breathing is often controlled with a respirator. Fluids and medications are used to control blood flow in the brain. Medications are often used to prevent seizures. Those who recover from surgery may be mildly or severely neurologically impaired. If so, long-term rehabilitation therapy may be necessary. Unfortunately, some survivors are so neurologically impaired that long-term nursing care in a skilled nursing facility may be necessary.
What are the side effects of the treatments? After surgery, many individuals have neurological impairment in consciousness level, motor skills and activities of daily living. Seizure disorders are common, requiring medications for control. The death rate following even the best treatment has been reported to be as high as 80 percent (80%).
What happens after treatment for the injury? After treatment, many individuals experience impaired motor co-ordination, making them more likely to have future injuries. Psychological counselling may be necessary for both the individual and his or her family. This is because many individuals may have problems with memory, judgment and attention span. Some of these changes may be permanent.
Author: James Warson, MD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
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