In 1997, the American Epilepsy Society, in collaboration with the American Academy of Neurology (AAN), and the American Association of Neurological Surgeons, appointed a committee to prepare evidence-based practice parameters for surgical treatment of epilepsy. The committee decided that there was sufficient literature to assess the efficacy of anterior temporal lobe and localized neocortical resections, and reviewed data reported between 1990 and 1999. Although articles from 24 centers reporting on 1,952 anterior temporal resections, and from eight centers reporting on 298 localized neocortical resections, met rigid criteria for inclusion in this review, all were considered to be only class IV evidence by the AAN Quality Standards Subcommittee (QSS), because none had a masked outcome assessment. Evidence-based recommendations require class I or II evidence. With the addition of the Western Ontario study, however, which the QSS deemed class I evidence, the practice parameters were accepted in 2002, and published in Neurology
in 2003 20, 21
The evidence-based practice parameters concluded that in the RCT, and also in the 24 class IV series of surgery for MTLE, two thirds of patients became free of disabling seizures (in some, auras remained), and 10% to 15% were unimproved after surgery; these outcomes did not change when class IV studies were stratified by geographic region, longer follow-up, or surgery after the advent of magnetic resonance imaging (MRI). Half of patients in eight class IV series of localized neocortical resections were free of disabling seizures, and 15% were unimproved. When combining temporal lobe and neocortical series, there was a positive correlation between degree of seizure improvement and HRQOL scores; there was a trend toward better social function, decreased mortality, and reduced medication regimens after surgery; neuropsychological and psychosocial function could improve or worsen, but worsening was related to persistence of seizures; and surgical morbidity and mortality were small (3% permanent neurologic deficits and no surgically related deaths). When the findings for the temporal lobe series were compared with results from pharmacotherapy trials 13, 14
, it could be recommended that patients with disabling complex partial seizures for whom appropriate treatment with first-line AEDs has failed, and who meet established criteria for anteromesial temporal resection, should be offered surgical therapy. Despite the similarity between published temporal lobe and neocortical series, a definitive recommendation could not be made concerning localized neocortical resections because of the absence of class I evidence for this type of surgical intervention.
These practice parameters did not address the efficacy of surgical intervention for specific types of epilepsy or underlying pathologic substrates, the prognostic value of presurgical diagnostic tests or strategies, or the efficacy of a number of other commonly performed surgical interventions, including multilobar resections, hemispherectomies, corpus callosotomies, lesionectomies, and multiple subpial transections; nor did it address the cost-effectiveness of surgical intervention. Although these practice parameters now clearly recommend surgical treatment for AED-resistant MTLE, no recommendation could be made concerning the timing of surgery. In view of persuasive data suggesting that medical refractoriness can be reliably predicted after failure of only two drugs 22
, the next important question is when
in the course of MTLE is it appropriate to abandon further pharmacotherapy trials and refer a patient to an epilepsy surgery center? This question is now being addressed by the National Institute of Neurological Disorders and Stroke (NINDS)-funded multicenter RCT titled Early Randomized Surgical Epilepsy Trial (ERSET).