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Identification of Potential Epilepsy Surgery Candidates


In the past 10 years, epilepsy surgery has increasingly been recognized as a viable treatment for patients with medically refractory seizures. At the time of the first Palm Desert Conference, in 1987, only 26 epilepsy surgery centers existed in the United States, having performed approximately 500 therapeutic surgical procedures in 1985. By the time of the second Palm Desert Conference, in 1992, 67 epilepsy surgery programs were operational in the United States, having performed approximately 1500 epilepsy surgeries in 1990.

At present, over 100 epilepsy centers exist in the United States. Unfortunately, it often takes 20 years before patients are referred for an epilepsy surgery evaluation. This delay is likely due to physician’s perception of epilepsy surgery as a “last resort” procedure.

Most epilepsy centers define intractability as failure of at least 2 or 3 first-line antiepileptic medications.
However, many physicians define medical intractability differently. They will often try numerous antiepileptic drugs (AEDs) trials before referral for a presurgical evaluation is even considered, even though the prospect of becoming seizure free is only 5%.

The introduction of newer AEDs with better tolerability and fewer drug-drug interactions has made a significant impact on the treatment of epilepsy, in that efficacy can be optimized with less dose-limiting adverse effects. However, a significant proportion of patients still have intractable epilepsy.

More than 250,000 people in the United States have intractable partial epilepsy, and a conservative estimate is that at least 50% of these patients are potential surgical candidates. These patients are at an increased risk for sudden death and personal injury. They are less likely to be employed than patients with well-controlled seizures.

In addition, the epileptogenic process itself produces interictal dysfunction with adverse consequences on cognition and mood, which can be irreversible, particularly in children. After failure of 2 first-line AEDs, the chance for seizure freedom with additional therapeutic regimens can be as low as 5-10%.

In 2009, Berg and colleagues identified a prospectively identified community-based cohort of children from 1993-1997 and found the frequency of magnetic resonance imaging (MRI) lesions potentially relevant to nonidiopathic epilepsy was 16% and that 8% underwent an epilepsy-related surgical procedure.

On the basis of these data, Berg et al estimated that 127 of 1,000,000 new cases of epilepsy per year would be pharmacoresistent, 52 of 1,000,000 patients with childhood-onset epilepsy would undergo epilepsy surgery evaluations, and 27 of 1,000,000 patients would have an epilepsy-related surgical procedure. As of 2006, there were 74 million children younger than 18 years in the United States.

A study by Engel et al found that early surgical treatment may be beneficial. For patients who had mesial temporal lobe epilepsy and disabling seizures for no more than 2 consecutive years following adequate trials of 2 brand-name AEDs, resective surgery plus AED treatment resulted in a lower probability of seizures for at least 2 years posttreatment, as well as improved health-related quality of life, than continued AED treatment alone.

Certain readily definable, surgically remediable syndromes are easily identified, have an excellent prognosis for seizure control, and have minimal surgical morbidity. Postoperatively, many patients with these syndromes have improved quality of life (QOL), improved cognitive, psychosocial, and occupational outcome. In children with catastrophic epilepsy due to diffuse hemispheric syndromes, early surgical intervention stops seizures and reverses the cognitive decline so that these patients can develop normally, eventually leading relatively normal lives.

For more information, see Epilepsy Surgery and Epilepsy and Seizures.

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