Abstracts

RATIONALE: It is commonly accepted that 50 % or more of patients who undergo temporal or extratemporal resections become completely seizure-free. However, information is inconsistent on the role of the main prognostic predictors of treatment success. The aim of this study was to examine the existing literature and calculate the probability of seizure freedom after surgery in patients with selected prognostic indicators.
METHODS: A Medline search was made of English language original articles published since 1984 that addressed the outcome of epilepsy surgery. Criteria for inclusion were sample size [gt]30, well-defined selection criteria, [gt]90% of patients assessed by MRI, follow-up [gt] 1 year, and outcome measure specified. Each article was reviewed independently by two of the authors. Any disagreement was resolved in conference. Data were recorded on patients[ssquote] and disease characteristics and a list of prognostic factors, including family history of epilepsy and/or febrile seizures, perinatal complications, etiology of epilepsy, MRI, surgical and pathological findings. The primary efficacy outcome was rated as complete vs incomplete seizure control. The probability of success in patients with specific prognostic indicators was quantified with the Risk Ratio (RR) with 95% confidence limits (CL).
RESULTS: In total, 374 papers were selected. Of these, 299 were excluded based on our exclusion criteria, and 48 articles (comprising 3385 patients) have been completely reviewed. The review of the remaining 27 papers is underway. The sample included 3292 adults and 93 children. 73% of cases underwent temporal lobe resection. Complete seizure control was obtained in 66% of cases. Significant predictors of treatment success, shown by univariate analysis, were history of febrile seizures (RR 1.3; 95% CL 1.1-1.4), mesial temporal sclerosis (RR 1.2; 95% CL 1.1-1.3), tumor (RR 1.1; 95% CL 1.0-1.2), EEG/MRI concordance (RR 1.6; 95% CL 1.2-2.0), and large extent of surgical resection (RR 1.5; 95% CL 1.4-1.8).
CONCLUSIONS: In this preliminary analysis, success of epilepsy surgery can be predicted by prior febrile seizures, the presence of mesial temporal sclerosis or other removable structural lesion, EEG/MRI concordance, and extensive resection. The independent role of each of these variables will be assessed by multivatiate analysis and the end of the review.