INTRACTABLE NONLESIONAL EPILEPSY OF TEMPORAL-LOBE ORIGIN - LATERALIZATION BY INTERICTAL SPECT VERSUS MRI

We performed a retrospective study of 53 consecutive ''nonlesional'' t emporal lobectomy patients to assess the relative utility of MRI versu s interictal single-photon emission computed tomography (SPECT) in thi s patient population. We compared the seizure lateralizing properties of MRI and SPECT using multiple blinded expert reviewers for both SPEC T and MRI with a test-retest reviewer paradigm and measurements of hip pocampal volume from MRI. The criterion standard for seizure lateraliz ation was satisfactory postoperative seizure control (n = 43). The rat e of correct seizure lateralization was significantly greater for MRI than for SPECT (p less than or equal to 0.01), and the rate of incorre ct lateralization was significantly less for MRI than for SPECT. The m ost accurate MRI measure was hippocampal volume measurements, which co rrectly lateralized the seizures in 86.0% of cases. The correct latera lization rate for SPECT was 45.4%. The MRI and SPECT studies tended to be noncomplementary with respect to seizure lateralization, and SPECT was likely to give an incorrect or indeterminate result in patients w ho were not lateralized by MRI. Concordant MRI-EEG lateralization was a strong predictor of satisfactory postoperative seizure control, whil e no relationship between postoperative seizure control and SPECT find ings was present.