Abstracts

Here we describe a series of patients with MTLE-HS submitted to a progressive presurgical investigation with scalp sphenoidal, followed by FOE and depth temporal electrodes. In addition, a patient with simultaneous FOE and deep temporal electrodes was described. Patients who had phase I investigation suggesting bitemporal epileptogenicity (bitemporal independent interictal epileptiform discharges, nonlateralized ictal onset), or ictal onset initiating in the side contralateral to the temporal lobe having focal abnormalities detected by neuroimaging. The decision to implant FOE was made on the basis of observations in phase I. Patients whose implanted FOE failed to demonstrate an unambiguous unilateral ictal onset were evaluated with depth hippocampal electrodes. Between May 1994 and Dec 2004 64 patients met our inclusion criteria. There were 33 females (51.5%) and 31 males (48.5%). The mean age at enrollment was 37.66 +/- 10.6 years (range 12 to 56 years). The mean age at epilepsy onset was 11.9 +/- 7.4 years (range 1 to 36 years). The epilepsy duration was 24.8 years +/- 10.3 years (range 7 to 48 years). The mean seizure frequency before surgery was 7.1 +/- 4.1 seizures per month. Patients with surface nonlateralized ictal discharge onsets, or those who EEG was not interpretable due to movement artifacts had more lateralized FOE EEGs. Two patients had recrudescence of herpes labialis after FOE implantation, the most common complication. In patients whose ictal FOE discharges were lateralized, the percentage of seizure freedom was 76%, very close to previous descriptions of long-term seizure freedom after surgery of TLE-HS. We found a very good correlation between lateralization data provided by FOE and depth temporal recordings, suggesting that FOE is in fact a safe and reliable method for lateralization of MTLE-HS onset of seizures which are often not clearly recorded by surface EEGs, and that it can be an alternative to invasive depth electrodes. (Supported by FAPESP/CINAPCE Project.)