Abstracts

Extratemporal resection is often larger then temporal lobe resection in patients with refractory epilepsy, especially in patients with normal MRI findings. Cortical resection margins could be restricted by the presence of eloquent areas within the planned resection or due to individual vascular, especially venous, anatomy. This paper discusses our experience while performing extratemporal resections in patients with normal MRI regarding the intraoperative factors limiting cortical resection. Sixty-one patients with extratemporal refractory epilepsy and normal MRI were studied (both children and adults). All patients have been submitted to invasive neurophysiological investigation by means of chronically implanted subdural electrodes. Planned cortical resection necessarily included the ictal-onset region and the region from which habitual seizures were elicited by stimulation and, whenever possible, the interictal zone. In 11 patients cortical resection has been limited by the presence of eloquent areas within the planned procedure; in 28 patients the cortical resection has been limited by the patient[apos]s venous drainage pattern and in 6, it has been limited by both. There was no mortality and no unexpected neurological morbidity. Despite the fact the both the presence of eloquent areas and vascular anatomy could limit the actual cortical resection in extratemporal epileptic patients, the venous[apos] drainage pattern appears to be the most important single factor. In 64% of these patients, the cortical resection suggested by invasive neurophysiological findings would be limited by one of these factors, or both.