When Should Epilepsy Surgery Be Considered?

Question:

I have an adult patient who has been on antiepileptic drug therapy for many years and still has seizures. We have tried switching AEDs with no success. Is it time to talk about surgery?

Response from Andrew N. Wilner, MD
Neurohospitalist, Lawrence and Memorial Hospital, New London, Connecticut

Drug-Resistant Epilepsy

Of the approximately 2 million people with epilepsy in the United States, 400,000 to 600,000 experience seizures despite antiepileptic therapy.^[1] Drug resistance has recently been defined by the International League Against Epilepsy (ILAE) as a "failure of adequate trials of 2 tolerated, appropriately chosen and used antiepileptic drug schedules (whether as monotherapy or in combination) to achieve sustained seizure freedom."^[2] Drug-resistant patients are unlikely to become seizure-free through participation in future drug trials and should be evaluated for epilepsy surgery.^[3] "Pharmacoresistant" is a synonym for "drug resistant." Other terms, such as "intractable," "refractory," and "uncontrolled" epilepsy are less strictly defined but describe a patient with continued seizures who warrants further evaluation.

Criteria for Surgery

Epilepsy surgery should be considered for patients with drug-resistant seizures if the seizures significantly interfere with their life.^[4] It is not necessary that the patient have daily or even weekly seizures. For example, a school teacher who has 1 seizure a month despite appropriate antiepileptic medication, but who cannot drive to work or supervise her class, may be a good candidate for epilepsy surgery.

Epilepsy surgery is an underused therapy for people with drug-resistant seizures.^[1] Patients are often referred for surgery after 15 years or more of habitual seizures.^[5] This delay allows seizures to chronically interrupt schooling, employment, and social interactions. People with uncontrolled seizures are at increased risk for death (almost 5 times that of the general population) from status epilepticus, SUDEP (Sudden Unexpected Death in Epilepsy), accidents, and other causes.^[6] After successful surgery, mortality rates return to those of the general population.^[7] Patients who have a single epileptic focus in the anterior temporal lobe are the most amenable to successful epilepsy surgery.

Benefits of Surgery

Approximately two thirds of patients with temporal lobe epilepsy achieve surgical success (are free of disabling seizures) after temporal lobectomy.^[4] A randomized, controlled clinical trial demonstrated that surgery for temporal lobe epilepsy was superior to continued medication trials in drug-resistant patients to achieve seizure control and improve quality of life.^[8]

Epilepsy surgery should be performed at an epilepsy center, where patients can be evaluated by a multidisciplinary team that includes, at a minimum, an epileptologist, a neuropsychologist, a neuroradiologist, and a neurosurgeon. Patients with epilepsy are likely to have medical and psychiatric comorbidities, and these need to be addressed as well in the presurgical and postsurgical settings.^[9] Other team members such as a neuropsychiatrist, epilepsy nurse coordinator, and social worker can help provide more comprehensive care. Benefits and risks must be weighed for each patient with respect to the safety of the surgery and likelihood that the patient will become seizure-free.

Summary of Considerations

Epilepsy surgery has been underused and should be considered in drug-resistant patients.^[10] Patients with drug-resistant epilepsy should be promptly referred to a comprehensive epilepsy center to determine whether they are likely to benefit from epilepsy surgery.^[5] Other therapies for drug-resistant epilepsy, such as the vagus nerve stimulator, may also be considered, but vagus nerve stimulation is rarely curative.^[7] A ketogenic diet may also be tried, but its success has mostly been in children. Successful epilepsy surgery can minimize the risk for injury and death from uncontrolled seizures and prevent the acquired psychosocial disabilities of a lifetime with epilepsy.

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