Abstracts

Resective surgical procedures for epilepsy have proven high rates of seizure control in properly selected patients with an identifyable focus. Intracranial monitoring provides the highest degree of certaintly with regards to the identification of an epileptogenic focus, but it is an invasive additional procedure with associated morbidity. This study aims to examine the morbidity associated with temporal and extratemporal monitoring utilizing intracranial subdural strip and depth electrodes and compare these diagnostic procedures with subsequent resective operations.
We performed a retrospective analysis of all patients between 1991 and 2002 who underwent invasive intracranial monitoring and/or resective surgery for epilepsy of temporal lobe or extratemporal origin. Subdural strip and stereotactically-implanted depth electrode recordings were conducted in appropriate cases for periods of 4 to 21 days. All associated morbidity and mortality within the perioperative period was recorded and patients were followed for a minimum or two years. Visual field testing and neurocognitive examinations were obtained postoperatively in most patiens. Patients were imaged with MRI after electrode monitoring procedures and with CT following resective operations.
Resective temporal lobe surgeries, primarily consisting of anterior temporal lobectomy and amygdalohippocampectomy, was performed on 172 patients and invasive intracranial monitoring was conducted in 72 of these patients. Resective temporal lobe surgeries were generally associated with mild (40%) or transient severe (6%) complications. Many of these included visual field disturbances documented on formal visual testing and temporary mood disturbances. In the monitoring group, complications were infrequently noted but occasionally were severe including hemiplegic infarction (N=1), symptomatic ICH (N=1), and infection (N=1).
Fewer extratemporal monitorings (N=38) and resections (N=27) were performed. There was a higher rate of associated morbidity during these monitoring procedures with symptomatic ICH (N=4), infarction (N=2), and neurologic deficit (N=4) noted. Extratemporal resections usually incurred mild or transient deficits when present.
Intracranial monitoring with subdural strip and stereotacticallly-implanted depth electrodes provides valuable additional information in the localization of an epileptic foci, and resective surgical procedures have proven highly effective with seizure control when applied in these indicated cases. Placement of intracranial electrodes is an invasive, additional procedure with inherent associated morbidity. The rates of severe or permanent complication following resective temporal or extratemporal surgery is low. The risk of perioperative morbidity following intracranial monitoring is much lower with TLE as compared to extratemporal epilepsy.