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Surgery
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When seizures cannot be adequately controlled by medications, doctors may recommend that the person be evaluated for surgery. Surgery for epilepsy is performed by teams of doctors at medical centers. To decide if a person may benefit from surgery, doctors consider the type or types of seizures he or she has. They also take into account the brain region involved and how important that region is for everyday behavior. Surgeons usually avoid operating in areas of the brain that are necessary for speech, language, hearing, or other important abilities. Doctors may perform tests such as a Wada test (administration of the drug amobarbitol into the carotid artery) to find areas of the brain that control speech and memory. They often monitor the patient intensively prior to surgery in order to pinpoint the exact location in the brain where seizures begin. They also may use implanted electrodes to record brain activity from the surface of the brain. This yields better information than an external EEG.
A 1990 National Institutes of Health consensus conference on surgery for epilepsy concluded that there are three broad categories of epilepsy that can be treated successfully with surgery. These include focal seizures, seizures that begin as focal seizures before spreading to the rest of the brain, and unilateral multifocal epilepsy with infantile hemiplegia (such as Rasmussen's encephalitis). Doctors generally recommend surgery only after patients have tried two or three different medications without success, or if there is an identifiable brain lesion--a damaged or dysfunctional area--believed to cause the seizures.
A study published in 2000 compared surgery to an additional year of treatment with antiepileptic drugs in people with longstanding temporal lobe epilepsy. The results showed that 64 percent of patients receiving surgery became seizure-free, compared to 8 percent of those who continued with medication only. Because of this study and other evidence, the American Academy of Neurology (AAN) now recommends surgery for TLE when antiepileptic drugs are not effective. However, the study and the AAN guidelines do not provide guidance on how long seizures should occur, how severe they should be, or how many drugs should be tried before surgery is considered. A nationwide study is now underway to determine how soon surgery for TLE should be performed.
If a person is considered a good candidate for surgery and has seizures that cannot be controlled with available medication, experts generally agree that surgery should be performed as early as possible. It can be difficult for a person who has had years of seizures to fully re-adapt to a seizure-free life if the surgery is successful. The person may never have had an opportunity to develop independence, and he or she may have had difficulties with school and work that could have been avoided with earlier treatment. Surgery should always be performed with support from rehabilitation specialists and counselors who can help the person deal with the many psychological, social, and employment issues he or she may face.
While surgery can significantly reduce or even halt seizures for some people, it is important to remember that any kind of surgery carries some amount of risk (usually small). Surgery for epilepsy does not always successfully reduce seizures and it can result in cognitive or personality changes, even in people who are excellent candidates for surgery. Patients should ask their surgeon about his or her experience, success rates, and complication rates with the procedure they are considering.
Even when surgery completely ends a person's seizures, it is important to continue taking seizure medication for some time to give the brain time to re-adapt. Doctors generally recommend medication for 2 years after a successful operation to avoid new seizures.
Surgery to treat underlying conditions
In cases where seizures are caused by a brain tumor, hydrocephalus, or other conditions that can be treated with surgery, doctors may operate to treat these underlying conditions. In many cases, once the underlying condition is successfully treated, a person's seizures will disappear as well.
Surgery to remove a seizure focus
The most common type of surgery for epilepsy is removal of a seizure focus, or small area of the brain where seizures originate. This type of surgery, which doctors may refer to as a lobectomy or lesionectomy, is appropriate only for focal seizures that originate in just one area of the brain. In general, people have a better chance of becoming seizure-free after surgery if they have a small, well-defined seizure focus. Lobectomies have a 55-70 percent success rate when the type of epilepsy and the seizure focus is well-defined. The most common type of lobectomy is a temporal lobe resection, which is performed for people with temporal lobe epilepsy. Temporal lobe resection leads to a significant reduction or complete cessation of seizures about 70 - 90 percent of the time.
Multiple subpial transection
When seizures originate in part of the brain that cannot be removed, surgeons may perform a procedure called a multiple subpial transection. In this type of operation, which has been commonly performed since 1989, surgeons make a series of cuts that are designed to prevent seizures from spreading into other parts of the brain while leaving the person's normal abilities intact. About 70 percent of patients who undergo a multiple subpial transection have satisfactory improvement in seizure control.
Corpus callosotomy
Corpus callosotomy, or severing the network of neural connections between the right and left halves, or hemispheres, of the brain, is done primarily in children with severe seizures that start in one half of the brain and spread to the other side. Corpus callosotomy can end drop attacks and other generalized seizures. However, the procedure does not stop seizures in the side of the brain where they originate, and these focal seizures may even increase after surgery.
Hemispherectomy and hemispherotomy
These procedures remove half of the brain's cortex, or outer layer. They are used predominantly in children who have seizures that do not respond to medication because of damage that involves only half the brain, as occurs with conditions such as Rasmussen's encephalitis, Sturge-Weber syndrome, and hemimegencephaly. While this type of surgery is very radical and is performed only as a last resort, children often recover very well from the procedure, and their seizures usually cease altogether. With intense rehabilitation, they often recover nearly normal abilities. Since the chance of a full recovery is best in young children, hemispherectomy should be performed as early in a child's life as possible. It is rarely performed in children older than 13.
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