Your Guide To....
Epilepsy Surgery
A Guide For Patients
Introduction
Epileptic seizures are produced by abnormal electrical activity in the brain. Surgical removal of seizure-producing areas of the brain has been an accepted form of treatment for over 50 years.
However, because of new surgical techniques and new ways of identifying areas to be removed, more of these operations are being done now than ever before, and with greater success.
Surgery can be performed on both children and adults. However, it is not a suitable treatment for everyone who has epilepsy, or for everyone with poor seizure control.
Brain Surgery
- Brain surgery is a way of treating certain kinds of epilepsy that cannot be controlled with medication.
- Risks and benefits of surgery should be carefully discussed in advance with the doctors who are going to perform the operation.
- Certain testing is necessary before the operation. In some cases, surgery for epilepsy requires two operations.
- Not all patients are good candidates for surgery.
- Having brain surgery does not guarantee that a person will be free of seizures or won't have to take medicine anymore. However, chances are good that most people will have fewer seizures after surgery and many will become seizure-free.
- Not all epilepsy-related surgery is performed on the brain. Therapy which delivers pulses of energy to the brain through a large nerve in the neck (VNS therapy) requires a different type of surgical procedure to set the system in place.
- Brain surgery and VNS implants are accepted treatments for relief of seizures and are covered by most health insurance plans.
Decisions
In trying to decide whether an adult or child will benefit from brain surgery, doctors want to know:
- Is the problem really epilepsy?
- Is it the kind of seizure that can be helped by an operation?
- Have we tried hard enough to control the seizures with medicine, diet, or other treatment?
- Might the condition get better without surgery?
- Might it get worse without surgery?
- Do the benefits outweigh the risks?
- Can surgery be done safely in the affected area of the brain?
These are very individual questions with different answers for each person based on the medical history of the patient or his family; physical examinations; medical records; and a whole battery of pre-surgical tests.
Types of Surgery
All epilepsy surgery involves the brain. However, different types of operations may be done. In general they fall into two main groups:
- Removal of the area of the brain that is producing the seizures.
- Interruption of nerve pathways along which seizure impulses spread.
Lobectomy -- Seizures that begin in one or more areas of the brain are known as simple or complex partial seizures. The seizures can take on different forms, depending on where they originate in the brain. The brain is divided into areas called lobes. There are temporal lobes, frontal lobes, parietal lobes and occipital lobes. There are two of each lobe on either side of the head. An operation to remove all or part of these areas is called a lobectomy. This type of surgery may be performed when a person has seizures that start in the same lobe every time. It is sometimes possible to stop the seizures by removing the seizure-producing area if it can be safely done without damaging vital functions.
Hemispherectomy -- A lobectomy removes a fairly small area of the brain. However, when a child has Rasmussen’s encephalitis, a rare, progressive disease affecting one whole hemisphere of the brain, a hemispherectomy to remove all or almost all of one side of the brain may be performed. While it seems impossible that someone could function with only half a brain (the other side fills up with fluid), children manage to do so because the half that remains takes over many of the functions of the half that was removed. Weakness on the side opposite the operation will continue, however. Hemisperectomies may also be performed when children are born with conditions that cause excessive damage to one side of the brain, such as bleeding in the brain prior to birth.
Corpus Callosotomy -- Another kind of surgery for epilepsy is called a corpus callosotomy (split brain surgery).
The corpus callosotomy operation does not take out brain tissue. Instead, it interrupts the spread of seizures by cutting the nerve fibers connecting one side of the brain to the other. This nerve bridge is called the corpus callosum.
The seizures which may respond to this type of surgery include uncontrolled generalized tonic clonic (grand mal) seizures, drop attacks, or massive jerking movements.
These seizures affect both sides of the brain at once and there is usually no one area which can be removed to stop them from happening.
Seizures are usually not stopped entirely by the operation. Some type of seizure activity on one side of the brain or the other is likely to continue, but the effects are generally less severe than the repeated drop attacks or convulsions.
The corpus callosotomy operation is often done in two steps. The first operation partially separates the two halves of the brain but leaves some connections in place.
If the generalized seizures stop, no further surgery is done. If they continue, the doctors may recommend a second step that completes the separation.
Multiple Subpial Transection -- Some seizures originate in or spread to parts of the brain that are responsible for functions such as movement or language. Removing these areas would lead to paralysis or loss of language function.
A surgical technique called multiple subpial transection (MST) may be performed in these situations. It involves making small incisions in the brain which interfere with the spread of seizure impulses.
This technique may be used alone or in addition to a lobectomy.
Vagus nerve stimulation (VNS) -- is a type of treatment in which short bursts of electrical energy are directed into the brain via the vagus nerve, a large nerve in the neck. The energy comes from a battery, about the size of a silver dollar, which is surgically implanted under the skin, usually on the chest. Leads are threaded under the skin and attached to the vagus nerve in the same procedure. The physician programs the device to deliver small electrical stimulation bursts every few minutes. This is a relatively new type of treatment. It may be tried when other treatment is not effective. Just how it works to prevent seizures is being studied.
Pre-Surgical Testing
Before any operation for epilepsy can be performed, there has to be a period of careful testing and evaluation.
These tests are done to make sure the surgery has a good chance of being successful and won't affect any of the important functions of the brain.
Most of the tests are used to pinpoint the area of the brain where seizures begin or to locate other areas, like speech and memory, that have to be avoided.
How many tests have to be done depends on the kind of operation that is being planned and how much information each test produces.
The following tests are most often used before a decision to operate is made:
- Electroencephalography (EEG) : An electroencephalogram is a non-invasive, diagnostic test which records electrical activity on the surface of the brain, and can identify the location of the abnormally firing neurons. More Info
- Magnetic Resonance Imaging (MRI) :Scans take pictures of the inside of the brain. MRI scans may show tumors, abnormal blood vessels, cysts, and areas of brain cell loss or other brain damage. More Info
- Video EEG :In video-EEG, you are videotaped at the same time as your EEG is recorded. The recording is carried out for a long period of time, often several days. The doctor usually views the video and EEG images side by side on a split screen. In this way the doctor can see precisely how your behavior during seizures is related to the electrical activity in your brain. More Info
- Neurological Exam :A neurological examination looks at how well your brain and the rest of your nervous system are functioning. Every time your doctor taps your knee with a hammer to see if your foot jumps, that's part of a neurological exam. More Info
- Wada Test :The Wada test, also known as the Intracarotid Amobarbital Procedure (IAP), combines neuroimaging and neuropsychological testing methods to examine memory and language functions. It is used to evaluate patients being considered for epilepsy surgery, by examining the independent functions of the brain. More Info
- Positron Emission Tomography (PET) :may be used in certain cases to help identify where seizures are taking place. PET measures how intensely different parts of the brain use up glucose, oxygen, or other substances. More Info
- Single Photon Emission Computed Tomography (SPECT) :Individuals with epilepsy often have changes in blood flow to specific areas of the brain when a seizure begins. The SPECT measures blood flow between seizures and during seizures. The scans are then compared to identify the changes in blood flow in specific areas of the brain, thus identifying where seizures originate. More Info
Tests Using Implants
Even after all the previously described tests are done, additional information may be needed to identify the epileptic area in the brain. This is because the area of seizure activity sometimes can't be found by electrodes attached to the surface of the head.
To obtain that additional information, two separate operations may be required.
The first operation places electrodes in or on the brain itself. These special electrodes are called depth or subdural electrodes.
After they are placed, the patient remains in the hospital with the head wrapped in a large dressing, with wires attached to the electrodes coming out of the dressing. Seizures are then recorded directly from the brain, often on simultaneous video and EEG. This process is called electrocorticography.
Both kinds of recording instruments may be kept in place for some time while doctors monitor signals from within the brain during seizures.
The brain may be stimulated with mild electrical impulses via the electrodes to identify special areas controlling speech, movement and sensation. In addition, further electrical recording to map out the seizure focus (the exact area to be removed) may be done.
If the tests show that there is a single epileptic area and it can be removed safely, a second operation is performed to remove the affected area. If not, surgery is done only to remove the electrodes.
Sometimes all the tests and procedures rule out surgery as a suitable treatment. Other times the tests may fail to give enough information and the doctors may decide not to recommend surgery.
The Operation
Successful epilepsy surgery depends on careful selection of patients and a skilled medical and surgical team.
The operation may take several hours to perform, as surgeons first locate and then remove the area of the brain identified in pre-testing as the source of the seizure activity, or carefully sever the nerve fibers between the two halves of the brain if a split brain operation is being performed, or make the incisions required by the MST procedure.
EEG recordings during the surgery help the physicians map out the exact area of brain to be removed.
The brain may be stimulated with mild electrical impulses during the operation itself to identify special areas controlling speech, movement and sensation.
Sometimes the whole operation is done with the patient awake but under local anesthetic. This is possible because brain tissue is not sensitive to pain.
Benefits and Risks
Lobectomies -- While there are risks in all surgical procedures, including the placement of depth electrodes and grids, most brain surgery for epilepsy appears to be relatively safe. The success rate for epilepsy surgeries depends on the type of operation performed and can usually be predicted after all the test results are available.
- For temporal lobectomies, 65 to 85% of patients will be seizure-free.
Complications occur in about 4 out of every 100 of these operations. Depending on the kind of surgery that's performed, possible complications include: partial losses of vision, motor ability, memory or speech. Infection or temporary swelling of the brain may also sometimes happen.
Corpus Callosotomies -- Among patients having a corpus callosotomy (split brain operation), risks of major and minor complications after surgery are around 20 per 100 operations. Generalized seizures may stop or happen less often than before the operation. Partial seizures (that is, changes in movement, feeling or emotion without loss of consciousness) will probably continue and may even get worse. Still, the uncontrolled drop attacks and generalized tonic clonic seizures that the operation is designed to treat have risks of their own. Decisions to operate take all these possibilities into account.
Hemispherectomies -- Excellent results for this operation, which involve removal of one half or almost one half of the brain, are being reported by the small number of very specialized centers doing these operations. However, there are more risks with hemispherectomies than with other types of epilepsy surgery.
Children who have hemispherectomy operations will continue to have loss of function on the side of the body opposite the side where the brain was removed.
Preparing For Surgery
In preparation for surgery you should do the following:
- Write down any questions you may have. You will see the neurosurgeon for a presurgical visit before you come to the hospital and you will be seen again in the hospital, the day before your operation. The neurosurgeon will explain the details of the operation and answer any questions you have about risks, complications and benefits of surgery. It is important that you fully understand the operation.
- Take your medication in the usual dose.
- You will be admitted to the hospital the day before your operation to prepare you for surgery. Your head will be shaved. You may want to bring a head covering to wear home from the hospital.
- If your surgery involves the side of the brain which controls language (usually the left), brain mapping is done to preserve language function. The procedure involves reading short phrases or naming items presented on slides. The day before the surgery, you will go through a training session to be sure you are familiar with the mapping procedure. You will see the same slides that will be used during the operation so that you will know what to expect and can fully cooperate with the doctors during surgery.
Recovering From Surgery
Good communication between the doctor and the patient is important with all epilepsy treatment, but especially when surgery is being considered.
Although surgery for epilepsy is more common, more successful and safer than ever before, it is still a major operation.
The patient and the family should therefore have a realistic picture of the benefits, the risks, and the chances of complete or partial control of seizures afterwards.
After the operation, most patients are monitored in an intensive care unit for 24 to 48 hours. Possible complications of surgery include death, bleeding, stroke and infection. Patients may also experience effects because of the areas of the brain that were removed. These may be transient or permanent. All the possibilities should be discussed beforehand. The patient stays a few additional days in the hospital and then goes home to recuperate. After about three weeks he or she can usually resume normal activities.
There may be some physical after-effects of epilepsy surgery. Sometimes there are emotional changes as well. People may feel disappointed if their seizures do not stop completely, or if they have to go on taking medicine, at least for a while, after the surgery.
When seizures stop altogether or happen very seldom, there is an understandable feeling of relief and celebration. But sometimes people also feel depressed. It may be stressful and difficult to meet the new expectations that others may have, or to adjust to being a person without seizures after having them for so long.
In most cases, these reactions are temporary. Like other issues that may arise in connection with epilepsy surgery, they can be handled better if both the patient and the family know what to expect and have talked about them with the multidisciplinary medical team (which may include neurologists, surgeons, nurses, and psychologists) before any operation takes place.
- Numbness of the scalp
- Clicking in your ears when you open and close your jaws
- Difficulty opening your mouth fully
- Headaches
- Feeling depressed or tired for several weeks after surgery
- Auras - Some patients find that auras continue for weeks or months after surgery. This does not necessarily mean that your seizures will come back.
- Post-operative seizures. Some patients have a few seizures for 7-10 days after surgery. This does not necessarily mean that your seizures are back permanently.
- Memory or word-finding difficulties - For 2-6 weeks, patients who have had surgery on the dominant or left side of their brain may have difficulty remembering names or words. This problem usually goes away.
- Immediately after surgery, your hair will begin to grow back at a normal rate (approximately 3/4 of an inch per month).
Epilepsy Surgery at Massachusetts General Hospital/Harvard
Theodore H. Schwartz, MD - Epilepsy Surgery
The VNS from a Patient's Point of View
Comprehensive Epilepsy Center
Pediatric Epilepsy Surgery
Surgery : Epilepsy.com
Cyberonics
Epilepsy Surgery Groups on Yahoo!
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