MRI-guided stereotactic placement of depth electrodes in temporal lobe epilepsy.

Electrodes placed stereotactically in mesial temporal lobe structures may be useful for determining laterality, and extent of the epileptogenic zone in temporal lobe epilepsy. We present and compare our experience with the use of two stereotactic arcs, the Brown-Roberts-Wells (BRW) and Cosman-Roberts-Wells (CRW) for magnetic resonance imaging guided placement of multicontact electrodes in the amygdala, anterior and posterior hippocampus. Out of 101 electrodes, 28 were placed in 6 and 17 patients using the BRW and CRW arcs, respectively. The target-centered design of the CRW arc eliminated the need for trajectory calculations, used uniform 'depth' measurements, and allowed greater operative flexibility and a shortened operating time. The use of depth electrode recording allowed 14 of the 23 patients to be selected for temporal lobectomy.