August 15, 2001
Performs San Diego’s
First Gamma Knife Surgeries for Epilepsy
Epilepsy patients with seizures uncontrolled by medication now have a non-invasive alternative to brain surgery, with finely focused beams of radiation replacing the surgeon’s knife.
|John Alksne, M.D.|
UCSD neurosurgeon John Alksne, M.D., performed San Diego’s first non-invasive Gamma Knife procedures for epilepsy recently on Katrina Corbell, a 23-year-old Clairemont resident, and 57-year-old Gloria Corral, who lives in the South Bay. Both women qualified for the Gamma Knife procedure because of the location of their seizures (the mesial temporal lobe) and the inability of medication to stop the seizures.
With these procedures, “Gamma Knife for epilepsy offers new hope for San Diego area patients with mesial temporal lobe seizures who do not want to accept the risks associated with traditional surgical resection,” Alksne says. “No one knows what tomorrow will bring!”
Not really a knife at all, the Gamma Knife is a medical instrument that emits 201 finely focused beams of radiation that simultaneously intersect at the precise location of a brain disorder. In this case, the device was used to treat the areas of Corbell’s and Corral’s brains that trigger their numerous epileptic seizures. The radiation therapy doesn’t remove abnormal cells, like conventional brain surgery. Rather, it changes the biochemistry enough to stop the spontaneous electrical activity that triggers seizures.
|Vicent Iragui, M.D., Ph.D.|
Vicente Iragui, M.D., Ph.D., director of the Epilepsy Center at UCSD, located at UCSD Thornton Hospital in La Jolla, notes that the Gamma Knife is an outpatient procedure with a short recovery period. And, there are far fewer side effects such as hemorrhage, infection and pain.
“The disadvantage,” Iragui adds, “is that results from the Gamma Knife aren’t immediate. Experience at other Gamma Knife Centers that perform the epilepsy surgery indicates that patients’ seizures gradually diminish over several months, but may not stop completely for nine to 12 months. The results with conventional surgery are usually immediate.”
He explains that it’s not unusual for low-dose radiation therapy, such as that delivered by the Gamma Knife, to have a delayed effect. However, physicians don’t know why the delay occurs and are studying this phenomenon.
The San Diego Gamma Knife Center, located in La Jolla, is used by area neurosurgeons primarily to treat tumors, vascular abnormalities, and functional disorders such as trigeminal neuralgia and epilepsy. Gamma Knife treatment for epilepsy is relatively new in the United States with surgeries performed in the past year at only a handful of medical centers such as the Cleveland and Mayo Clinics. France was the site of the first-ever Gamma Knife epilepsy treatments several years ago by neurosurgeon Jean Regis, M.D., who taught Alksne the procedure and was present for San Diego’s first Gamma Knife epilepsy treatment on June 15.
Following their procedures, patients Corbell and Corral went home that evening and will be followed at the UCSD Epilepsy Center on an outpatient basis.
Both women were evaluated for the Gamma Knife procedure at the Will Sally Epilepsy Telemetry Unit, which provides San Diego’s only inpatient, intensive monitoring of epilepsy. Patients stay for three to five days in private rooms equipped with video and audio, as well as computerized EEG recording systems to precisely localize seizure onsets and evaluate potential treatment options.
Also known as a seizure disorder, epilepsy is a chronic medical condition produced by temporary changes in the electrical function of the brain, causing seizures which affect awareness, movement, or sensation. Even with standard care, usually medication to control seizures, 20 to 30 percent of patients do not adequately respond, and continue to have seizures. These individuals generally have two alternatives for advanced treatment, an implantable nerve stimulator or surgery that removes brain tissue.
Vagus Nerve Stimulation
|Vagus Nerve Stimulator|
The nerve stimulator is a pocketsize implant that was tested at the UCSD Epilepsy Center by Evelyn Tecoma, M.D., Ph.D. and sites nationwide before approval by the Food and Drug Administration in 1997. The device is implanted in the upper left chest wall and small stimulating wires are wrapped around the neck during an outpatient surgical procedure, much like a heart pacemaker. During visits to the neurologist, the device is programmed with a computer to deliver a short electrical pulse to the large vagus nerve in the neck at regular intervals, such as every five minutes. The vagus nerve serves as a natural pathway into the brain, with few side effects.
|Evelyn S. Tecoma, M.D., and associates in the Will Sally Epilepsy Telemetry control room.|
Tecoma, associate director of the UCSD Epilepsy Center, notes that the Vagus Nerve Stimulator reduces seizures in the majority of patients, although most remain on medication to best control the frequency of seizures. “Since we began treatment with the Vagus Nerve Stimulator in 1993, more than 100 patients have received the implant at UCSD,” Tecoma notes.
Candidates for brain surgery and Gamma Knife
Brain surgery for epilepsy has been available at UCSD since 1984. Surgery candidates must be carefully selected after a series of diagnostic procedures to identify the exact source of seizures within the brain. The same careful identification of the exact source of the seizures must be carried out for consideration of Gamma Knife therapy and only those patients with seizures originating in the mesial temporal lobe can undergo treatment with the Gamma Knife.
In initial evaluation at the UCSD Will Sally Telemetry Unit, a patient is fitted with electrodes and then allowed to have typical seizures over several days, in a protected environment. Physicians monitor brain waves and record patient responses with video and audio.
Patients are deemed ineligible for surgery if seizures come from multiple areas of the brain. If the seizures originate within either the left or right temporal lobes (located on the sides of the brain), and additional MRI scans verify the location, patients are potential candidates for surgery. Some patients need a second round of monitoring with electrodes placed inside the skull to more precisely identify the area of disorder. Final testing to verify that the disorder affects only one side of the brain, and not both, will determine the candidate’s eligibility.
Certain individuals who are candidates for conventional brain surgery may also be candidates for the Gamma Knife procedure, and must undergo the same, extensive testing to precisely identify the area of seizure onset.
The morning of the Gamma Knife procedure, the patient is fitted with a stereotaxic head frame, a device that helps identify the three-dimensional location of the disorder with inpute from MRI and CT scans performed at the Gamma Knife Center. The surgeon determines the number of radiation doses needed and the focal points for the radiation. The computer within the Gamma Knife sets the precise coordinates. Once the targeting is completed, the patient receives multiple doses of radiation over two to three hours, with machine adjustments between each treatment. At the end of the day, the patient goes home, with careful follow up over weeks and months.
The UCSD Epilepsy Center continues to evaluate candidates for conventional surgery as well as for the Gamma Knife procedures. Iragui emphasized that each patient is evaluated individually to determine the best treatment plan.
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Media Contact: Sue Pondrom
UCSD Health Sciences Communications HealthBeat: http://health.ucsd.edu/news/