Abstracts

For cases of pharmacologically refractory epilepsy in which data from noninvasive diagnostic studies (Phase I) are discordant with respect to the epileptogenic zone, a hypothesis concerning the location of ictal onset is formulated. On the basis of this hypothesis, patients may undergo invasive tests such as ictal EEG recordings via intracerebral depth electrodes (Phase II). The purpose of this study was to assess clinical outcomes (diagnostic and therapeutic) of invasive chronic depth electrode recording for patients with medically intractable epilepsy in a series of 100 patients who underwent operation by a single surgeon at a single institution., Using the UCLA Seizure Disorders Center surgical database, the history, operative course, and clinical outcomes of 100 patients with medically intractable epilepsy who underwent implantation of intracerebral depth electrodes at UCLA Medical Center between January 1993 and August 2005 were retrospectively reviewed., Of the 100 patients reviewed, 54 were males; mean age was 33.2 years; and age range was 12-50 years. All surgeries were performed stereotactically by the same surgeon (I.F.) with pre-operative targeting based on stereotactic cerebral angiography and magnetic resonance imaging. The average number of depth electrodes implanted for each patient was 10 (range 6 to 12). In 60/100 patients, a single epileptogenic zone was localized via the first Phase II study; 10/100 underwent a second Phase II study with subdural grids/strips; and 59/100 underwent Phase III resection. Morbidity secondary to intracerebral depth electrode implantation consisted of: (1) small intracerebral hematoma incidentally revealed on post-implant or post-deplant imaging in three asymptomatic patients; (2) contaminant bacteria on either Gram stain or culture on deplanted electrodes in two asymptomatic patients who were clinically without other evidence of infection; and one episode of fever and cerebrospinal fluid pleiocytosis during implantation in one patient whose deplanted electrodes and cerebrospinal fluid showed negative bacterial cultures. Mortality was zero., These data suggest that chronically implanted intracerebral depth electrodes for electrophysiologic recording are safe and continue to be important in patient selection for Phase III epilepsy surgery, despite the emergence of sophisticated noninvasive diagnostic modalities., (Supported by Epilepsy Foundation Post-Doctoral Research Fellowship.)