Predictive value of 1H MRSI for outcome in temporal lobectomy

Objective: To investigate the predictive value of H-1 MRSI for outcome in patients with mesial temporal lobe epilepsy (MTLE). Background: H-1 MRSI has been shown to be highly sensitive in the lateralization of temporal lob epilepsy. Methods: The authors analyzed the relationship between the H-1 MRSI findings and surgical outcome in 40 consecutive patients who underwent temporal lobe surgery for MTLE. Outcome at a mean of 24 months (range 18 to 40 months) was classified as seizure free or not seizure free. Results: At follow-up, 78% of patients were seizure fi ee. Correlations showed no predictive value for the creatine/N-acetylated compound (Cr/NA) ratio of the operated temporal lobe and outcome. However, a relationship was found between surgical failure and the Cr/NA ratio of the nonoperated temporal lobe and with a Cr/NA ratio in the nonoperated lobe above 1.21 in patients with bilateral abnormalities (p < 0.01). Conclusions: Preoperative elevations in the Cr/NA ratio in the nonoperated temporal. lobe or the presence of higher metabolic ratios contralateral to the proposed surgery are associated with surgical failure. The predictive value of H-1 MRSI absolute metabolite concentrations for outcome in MTLE requires further investigation.