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- The seizures must come consistently from the same part of the brain.
- There must be one and only one seizure focus.
- The seizure focus must be in a part of the brain that can be removed with minimal risk to important functions like language, memory, vision and movement.
- What tests are needed before surgery?
Epilepsy surgery is a highly individualized procedure. The details of the seizure type and seizure focus must be defined as precisely as possible before surgery. Most patients will undergo a battery of tests and procedures as part of the presurgical workup. These tests are standard procedure at UCSD and at most comprehensive epilepsy centers in the US:
- Consultation with an epileptologist for complete review of all records, past diagnostic studies and past response to medical treatment.
- Video – EEG Monitoring of behavior and brain wave activity during seizures, to identify the seizure focus.
- In selected case, Phase II video-EEG monitoring is performed with electrodes places closer to the brain, such as foramen ovale electrodes, subdural strips or grid electrodes.
- High-resolution MRI with special angles to evaluate the temporal lobes.
- A battery of neuropsychological tests of brain function and memory scores for different types of material. These tests are repeated after surgery.
- Some patients may have psychiatric evaluation to assess the individual attitudes and fears about the surgery, and adaptation to changes that may occur if seizures (and disability) are eliminated by the surgery.
- WADA Test: intracarotid angiography to test language and memory on each side of the brain separately.
- Some patients may have noninvasive tests such as magnetoencephalography, or evoked potentials. They may also be asked to undergo noninvasive tests that help the team to evaluate brain function in and around the seizure focus.
- Presurgical visit with the anesthesiologist and neurosurgeon.
- What is a WADA test?
The test is named for the physician who developed it, Dr. June Wada. The purpose is to test each side of the brain for language and memory. The neurologist wishes to identify the side of the brain responsible for language, and to confirm that the side opposite the seizure focus (the unoperated side) can support memory.
The procedure is performed by a specially trained radiologist, working with the epilepsy team. A sterile catheter is introduced into the femoral artery, near the groin area. The catheter is guided through the artery, past the heart, into the carotid artery on one side of the neck. An angiogram is then performed, using a special liquid dye to take pictures of the blood vessels of the brain on that side. Next, a small amount of short acting anesthesia is injected into that side of the brain. Within seconds, the opposite side of the body may become temporarily weak and numb indicating that the anesthesia is working and it is time to test language and memory. The neuropsychologist will then present a series of pictures and questions. After a few minutes, when the anesthesia has worn off, the weakness and numbness will go away, and the neuropsychologist will ask some follow up questions. The same procedure is then repeated on the other side.
The interventional radiologist will explain the Wada test in detail before the procedure. Informed consent is required, as with all invasive procedures. Most patients remain in the recovery area under observation for six hours after the procedure.
- My doctor said I may be awake during part of the surgery?
Patients with a seizure focus in the language dominant side of the brain (usually the left side) may have intraoperative language testing. This is done to be as sure as possible that language areas are spared during the surgery. The anesthesiologist will waken the patient after the brain surface is exposed.
The epilepsy team will then test different parts of the surface of the brain for evidence of language function. You may be asked to count, talk, or name pictures while the surgeon tests for language function. The procedure is not painful, since the brain itself does not have pain receptors.
Local anesthesia is used throughout the procedure. After language areas are identified, the patient is put back to sleep with general anesthesia for the rest of the procedure.
- What are my chances of becoming seizure-free after surgery?
The UCSD Epilepsy Team has had very good outcomes for epilepsy surgery, comparable to the best centers in the world. Of all patients with temporal lobe epilepsy surgery, 75% are seizure free after surgery, usually on medication. Another 20% are significantly better, but not seizure free. The remaining 5% received no worthwhile improvement. The results for surgery outside the temporal lobe are less satisfactory, with only 38% seizure free, 50% improved and 12% no different. Certain features may improve or reduce the chances for a particular patient. Your doctor can explain the circumstances of your case.
It must be noted that the chances are never 100%, and there is no guarantee that the seizures will go into remission.
- How long will I be in the hospital? How much time will I need to recuperate?
Most patients leave the hospital within one week, many within 3-5 days of surgery. Most recuperate at home for several weeks, gradually easing back into their school, work or home activities over the next few months. You may need more time or less time depending on your general health.
- What are the risks of the operation?
You will meet with the neurosurgeon that will perform the procedure, to have your individual questions answered.
There is always a small risk or a major complication, including complications of anesthesia, intraoperative bleeding, stroke or even death. This is true of any operation in the brain. Epilepsy surgery is a carefully planned procedure, carried out under optimal circumstances to remove the region of brain causing the seizures, and to spare parts of the brain necessary for everyday functions.
After surgery there may be swelling and even bruising of the eye on the side of the surgery. The eye may be puffy for up to several weeks. Some patients do not raise their eyebrow perfectly on the side of surgery. Some have jaw pain or limited jaw movement. Headaches are common, but should not be severe. Some patients complain of fullness in the ear or earache. These problems tend to resolve over weeks to months.
Any surgery leaves a surgical scar. The contours of the skull are usually smooth, but they may not be perfect after surgery. The surgeon makes every effort to place the scar behind the hairline, if possible.
- Women: this means shaving part of the head. Your hair will grow back. There may be ¼ to ½ inch on either side of the scar where the hair does not grow perfectly. There may also be numbness of the scar itself.
- Men: over the years, the hairline may change, and the scar may be more visible with less hair to cover it.
After temporal lobe surgery, some patients may have a small “blind spot” in the upper visual field, which is seldom noticeable to the patient. This is also called a visual field cut. The reason for the blind spot is that nerve fibers travel from the back of the eye to the back of the brain, passing through part of the temporal lobe. To understand the blind spot, imagine staring forward at the center of a huge clock. With the eyes fixed, it may be difficult to see details in the upper portion of the clock, for example from the 10 to 12 o’clock, or from the 12 to 2 o’ clock. Shifting the position of the eyes or head will change the position of the blind spot, so most people are unable to detect this on their own.
Neuropsychological testing before and after surgery shows very satisfying results. Most people experience no change in overall IQ. Patients having left sided surgery are more likely to show a small drop in verbal memory or naming, balanced against some improvement in other test scores. Rarely, for reasons that are not well understood, a patient will experience a greater than expected decline in memory, or behavioral or emotional problems after temporal lobe surgery. The presurgical neuropsychologic testing, psychiatric and Wada tests are very important in screening for patients that might have behavioral or memory problems after surgery.
Occasionally, a patient will experience disappointment after surgery. At the UCSD Epilepsy Center, and nationally, it is recognized that epilepsy surgery is an imperfect science. Every effort is made to select only those patients who stand a very good chance of improvement, and for whom the benefits appear to outweigh the risks of surgery. We do not wish to portray epilepsy surgery as a routine procedure or “cure.” Every case is unique and is evaluated with a great deal of care and consideration – not by one physician – but by the entire epilepsy team. You should proceed with epilepsy surgery only after you have discussed the matter carefully with your physician and family, and have had all of your questions answered.
- Do I need to take antiepileptic medication after surgery?
Yes. We recommend continuing the medication for at least 2 years seizure-free before attempting to wean completely. During this time, your doctor may work with your to lower the dose, or change the number or type of medication. If you continue to have auras on medication, your doctor may advise against an attempt to wean completely from medication.
- If my seizures are eliminated, will I be able to drive?
Driving privileges are granted by the DMV, not the doctor. We advise patients to wait until they are seizure free for six months before applying for driving privileges. Patients who have never driven or patients, who have not driven for many years, are advised to begin with a driver’s training courses and proceed slowly. Your doctor will assist with the medical information required on the California DMV forms. Patients who live outside of California should follow the rules of their local Department of Motor Vehicles.
- Is there an age limit for epilepsy surgery?
Once it is clear that a patient has refractory epilepsy, there is little to gain by waiting. After decades of uncontrolled seizures a patient may develop a lifestyle of restricted activity, and feel unprepared to take advantage of new opportunities even if he or she becomes seizure free after surgery. Thus, age, attitudes, lifestyle, family support and educational background all enter into the equation. The average age at the time of surgery is 20-40 years. The ideal age may be younger still. However, age itself is not a reason for exclusion from surgery: patients less than one year of age and patients 60 and above have been operated successfully.
- What else should I know?
If you wish to meet with a person who already had epilepsy surgery, this can be arranged. Be sure to ask questions. Communication with your doctors is essential.
Epilepsy Center
UCSD Thornton Hospital
9300 Campus Point Drive, Mail Code 7740
La Jolla, CA
(858) 657-6080 |