Objective: To investigate the prognostic importance of an identified putative underlying risk factor in patients undergoing surgery for intractable temporal lobe epilepsy (TLE). Patients and Methods: A retrospective study of 400 consecutive patients who underwent TLE surgery between December 21, 1987, and September 11, 1996, was performed. Demographic characteristics, history of remote symptomatic neurologic disease, preoperative evaluation, and postoperative outcome data were extracted. Individuals without any risk factors were considered controls. Magnetic resonance imaging findings were used to identify mesial temporal sclerosis (MTS) before surgery. Seizure outcome was classified by a modified Engel classification. Results: Two hundred eighty-one patients had a potential underlying etiology, and 143 patients had more than 1 risk factor. One hundred nineteen patients had no evidence of a putative symptomatic neurologic illness. There was a statistically significant association (P<.05) between the presence of MTS and a favorable operative outcome (odds ratio, 4.28; 95% CI, 2.67-6.87). A history of remote symptomatic neurologic disease was not of prognostic importance unless associated with the development of MTS. Conclusion: These results indicate that the preoperative identification of MTS by neuroimaging is the most important predictor of a favorable operative outcome in patients with TLE. These findings may be useful in the identification and counseling of potential candidates for epilepsy surgery.
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