Fall 2010 Issue
An Underused, Life-Changing Treatment
While medication is usually the first step in the treatment of epilepsy, it is often not the most effective. In fact, for almost one-third of epilepsy patients, medicine cannot adequately control seizures. For many of these individuals, surgery could have a profound impact. An estimated 20,000 to 70,000 people in the United States are considered candidates for epilepsy surgery, yet less than 5,000 have surgery each year.
“Overall, epilepsy surgery is underutilized, even though it can offer dramatic relief for many patients,” said Michael Heafner, MD, of Carolina Neurosurgery & Spine Associates.
In general, a patient with epilepsy should be considered a candidate for epilepsy surgery if seizures are not adequately controlled by drug therapy, and at least two different anti-epileptic drugs have been tried.
Following are the most common types of invasive procedures performed in the diagnosis and treatment of epilepsy:
Invasive Intracranial Electrode Monitoring And Mapping
Seizures associated with epilepsy are caused by electrical activity that spreads uncontrollably from one part of the brain to another. Invasive electrode monitoring is performed in order to determine where this electrical activity originates. It allows physicians to plan for surgery when noninvasive techniques, such as surface EEG, cannot provide enough data to pinpoint the seizure area. During the procedure, intracranial electrodes are placed on the brain, and left there to gather data while the patient is awake, at rest and during seizures. After several days the electrodes are removed and a surgical plan is determined based upon the data retrieved.
When electrode monitoring can determine that the focal-origin of the seizures is located in the temporal lobe, a temporal lobectomy can be used to remove the part of the brain where the focal point is located. This is the most common and most effective epilepsy surgery, with more than 85% of patients experiencing significant improvement in seizure control. After the surgery, some patients continue to take seizure medications, often at a lower dosage.
If electrode monitoring cannot find a seizure focal point in the brain, or if there are multiple points that cannot be removed, a corpus callosotomy may be the best treatment option. With this procedure, the corpus callosum, which connects the two hemispheres of the brain, is cut in order to keep seizure activity from spreading. This procedure can significantly reduce the frequency of seizures.
Corpus callosotomy is most often performed on children who experience atonic seizures that cause them to drop to the floor due to a sudden loss of muscle tone. Patients who suffer from grand mal seizures are also often candidates for a corpus callosotomy.
Vagal Nerve Stimulator (VNS)
For over 50% of patients who are not good candidates for surgery, implantation of a VNS may significantly improve seizure control. A VNS serves as a type of programmable pacemaker for the vagus nerve in the neck. Carolina Neurosurgery & Spine Associates has implanted these devices in patients ranging in age from six months to 40 years. After surgery, the patients’ neurologists follow them closely to make the necessary adjustments in stimulation parameters. VNS completely eliminates seizures in 10% to 15% of patients.
Since the age of three, Daniel had only known a life of epileptic seizures. Although multiple medications and combinations of prescriptions failed to alleviate his seizures, he grew into adulthood achieving a high level of education and employment. When his epileptic events became more frequent, he sought further evaluation by epileptologist Bruce Mayes, MD, at Carolinas Medical Center. Daniel underwent tests to establish whether he was a candidate for surgical treatment.
Brain wave testing (audio-video EEG) demonstrated that the seizures were coming from Daniel’s left temporal lobe. A PET scan showed hypometabolism in the same region of the brain. He then underwent intra-carotid amobarbital testing to determine which side of his brain functioned best in memory recall, speech and reading. Results showed that his speech and memory centers were on the left side of his brain, the same side in which his seizures originated. Daniel was then referred to neurosurgeon Michael Heafner, MD, of Carolina Neurosurgery & Spine Associates.
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