Seizure outcome after temporal lobectomy: Current research practice and findings

Purpose: The literature regarding seizure outcome and prognostic factors fo r outcome after temporal lobectomy is often contradictory. This is problema tic, as these data are the basis on which surgical decisions and counseling are founded. We sought to clarify inconsistencies in the literature by cri tically examining the methods and findings of recent research. Methods: A systematic review of the 126 articles concerning temporal lobect omy outcome published from 1991 was conducted. Results: Major methodologic issues in the literature were heterogeneous def initions of seizure outcome, a predominance of cross-sectional analyses (83 % of studies), and relatively short follow-up in many studies. The range of seizure freedom was wide (33-93% median, 70%); there was a tendency for be tter outcome in more recent studies. Of 63 factors analyzed, good outcome a ppeared to be associated with several factors including preoperative hippoc ampal sclerosis. anterior temporal localization of interictal epileptiform activity, absence of preoperative generalized seizures, and absence of seiz ures in the first postoperative week. A number of factors had no associatio n with outcome (e.g., age at onset, preoperative seizure frequency, and ext ent or lateral resection). Conclusions: Apparently conflicting results in the literature may be explai ned by the methodologic issues identified here (e.g., sample size, selectio n criteria and method of analysis). To obtain a better understanding of pat terns of long-term outcome, increased emphasis on longitudinal analytic met hods is required. The systematic review of possible risk factors for seizur e recurrence provides a basis for planning further research.