Epilepsy is one of the most common chronic neurological disorders, and close to 3 million Americans have a seizure disorder. Many patients who are treated for epilepsy can live normal lives, but finding the best treatment is critical.
We asked Dr. Gregory D. Cascino, M.D., F.A.A.N., Whitney MacMillan, Jr. Professor of Neuroscience, at the Mayo Clinic College of Medicine, chair of the Division of Epilepsy at Mayo Clinic, and member of the American Academy of Neurology, about treatment guidelines for people with epilepsy, as well as the more promising future treatments.
Q: What is the goal of treatment for epilepsy?
A: Our goals of treatment, for whatever type of seizure disorder the patient has, is for the patient to be seizure-free, not have any adverse effects associated with the treatment, and to be able to do normal activity legally and safely – for many adults that means being able to operate a motor vehicle and get a driver’s license.
Q: How do you decide how to treat epilepsy?
A: We know there are many different types of seizures and seizure disorders, and the evaluation and treatment depends on a number of factors. The type of seizures the patient is experiencing, any co-morbid neurologic disorders they may have, and the age of the patient all need to be considered. We utilize a number of different diagnostic techniques to decide how to evaluate the particular patient.
We also know that the different types of seizure disorders may carry a tremendous difference in prognosis. There are some types of epilepsies that are relatively “benign” and are treated with low doses of medication and the patient is seizure-free and engaged in normal activities. Other types may be more difficult to control. In general terms, you need to know the seizure type and the seizure disorder before you can decide on how to evaluate the patient. Such as, what tests should they have? What medications do you use? And does the patient have a seizure disorder?
Q: What happens during the evaluation?
A: Epilepsy is usually a treatable disorder and the type of evaluation a person has needs to be individualized –we don’t do the same evaluation for all patients. In many adult patients, the evaluation may include seeing a neurologist who compiles a patient history and does an examination.
We do an EEG, which is an electrodiagnostic study that looks at the function of the brain and we do an imaging study in many patients, called an MRI, which looks at the structure of the brain. We take this information together. The tests are done for several reasons. One – does the patient have a seizure disorder? Number two, if they do have a seizure disorder, what type of seizures do they have and what are the appropriate therapies? The medications are not broad-spectrum so that one size fits all - there are many types of medications, which is why there is not one answer to which drug you would use first. The third thing that we do with these studies is try to figure out what is causing the seizure disorder.
What are some causes of epilepsy?
A: In many cases, perhaps one out of every three patients, we can find an etiology or cause. It can be a structural abnormality in the brain, such as a tumor, stroke, blood vessel malformation or a malformation of cortical development, and these are often identified through the MRI. In about two-thirds, the cause is unknown and some of those may have genetic risk factors. Now, after the patient goes through a very careful evaluation - and I have to underscore how important the evaluation is, because many times the patient’s diagnosis, prognosis and treatment plan may change based on the diagnostic study - we then decide if the patient needs to be treated with medication.
Q: How effective are the medications?
A: If a patient does need to be on a medication, we tend to use the drug that’s most appropriate for that individual patient and for their type of seizure. And the goal of therapy is to minimize seizure activity and to try to avoid antiepileptic drug side effects. Most patients who are going to respond to medicines usually respond to the first or second drug that they receive. We try to go at a low dose and increase the dose as needed and tolerated, because many of these drugs may have adverse effects.
But, unfortunately, about a third of patients may have a drug-resistant seizure disorder that does not respond favorably to medication. And in some of those cases, but not all, other treatment options can be considered, such as ketogenic or low glycemic index diet, additional medication trials, epilepsy surgery or electronic stimulation.
Q: How does Vagus Nerve Stimulation (VNS) work?
A: This is an electronic device that is implanted by a surgeon in the chest wall, similar to a cardiac pacemaker. A small wire is led under the skin and it gives intermittent stimulation to the left vagus nerve. It’s been found over time –and it may not be effective initially for six months to one year –to reduce seizure frequency.
Vagus nerve stimulation, or VNS, was approved in 1997, specifically for patients with focal seizures. These devices are mostly used for patients who are not candidates for curative epilepsy surgery or additional medication trials. And this is usually considered a palliative treatment option. Patients who have a vagus nerve stimulator do not have seizures that are well-controlled by medication. The electronic device is likely to reduce seizure frequency, but not render the patient seizure-free.
Q: What about Responsive Neurostimulation (RNS)?
A: The responsive neurostimulation device, or RNS system, was recently approved by the Food and Drug Administration for management of drug-resistant focal epilepsies.
This is an electronic device for direct brain stimulation that may be utilized in patients who are not candidates for curative epilepsy surgery. Patients with RNS may be those who have multifocal seizures, bitemporal seizures or areas of seizure onset that don’t lend themselves to a surgical resection. It has been shown in a pivotal study that RNS may reduce seizure activity and improve the patient’s quality of life.
What are the most promising new treatments on the horizon?
A: There are new surgical techniques that look very promising, and I think they may give the patient a good chance of being seizure-free, and minimize adverse effects. The most effective management for a patient with drug-resistant focal epilepsy remains epilepsy surgery. We constantly concern ourselves with morbidity, which is may be an adverse effect of the surgery. There are new types of therapies being developed, one by a company called Visualase, which involve MRI-guided laser ablation of the epileptic focus (DISCLOSURE: Mayo Clinic is involved in research with Visualase). We don’t know how effective and safe this therapy is relative to epilepsy surgery, but this may be an important treatment option.
Intracranial electronic stimulation is also being done, and not just RNS. Deep brain stimulation trials have been completed that involves stimulation of certain key structures in the brain that are involved with seizure propagation or seizure initiation. Trials show the device to be effective in reducing seizure tendency, but this has not yet been approved by the FDA. Finally, there are new antiepileptic drugs that have been approved by the FDA and will be made available very soon.
Q: What is the takeaway for patients with epilepsy?
A: I think we should emphasize the importance of improving quality of life. We’re not just focusing on the reduction of seizure tendency, because the care and management of these patients goes beyond rendering them seizure-free, but allowing these individuals to be productive members of society.