Abstracts

Rationale: Benign lesions of the temporal lobe such as gangliogliomas, cavernous malformations, astrocytomas, and dysembryoplastic neuroepithelial tumors often present with epilepsy. Regardless of pathology, resection of these lesions can offer definitive and long lasting seizure control. However, there is not currently a universally accepted methodology for assessing and surgically treating these patients. Based on our clinical experience and review of the literature, we propose a treatment algorithm to maximize positive surgical outcomes (seizure control) in these patients. Methods: A retrospective review of 464 patients who presented to our institution s comprehensive epilepsy center with seizures and underwent temporal lobe surgery was conducted. Of this patient sample, 70 patients underwent epilepsy surgery for proven benign temporal lobe pathology. Patients usually underwent a relative standard work-up for seizure localization. The Engel Classification system was used to assess seizure reduction rates in these patients post-operatively.Results: Patients with mesial temporal lobe epilepsy (MTLE) usually underwent Wada testing for evaluation of memory asymmetry. Resection of the mesial structures (hippocampus/entorhinal cortex-archicortex) in addition to the lesion was performed in this group of patients if not contraindicated by pre-operative work-up. Patients with neocortical epilepsy underwent intraoperative electrocorticography (ECoG) guided lesionectomy with removal of surrounding epileptic tissue. In patients with neocortical temporal lobe pathology, we obtained an Engel Class I post-surgical outcome in 76% of patients. In patients with mesial-basal temporal lobe pathology, we obtained Engel Class I outcome in 80% of patients. Complete resection of the lesion irrespective of the location was statistically significant for seizure control (p<.05). In addition, patients with new onset seizure had a statistically significant better outcome than patients who presented with chronic epilepsy. No statistical significant difference was identified between histopathology and seizure outcome (p>.05). Nevertheless, mesial temporal lobe sclerosis (MTS) was identified (dual pathology) in 15 out 16 patients who had lesional MTLE and adequate specimen (hippocampus) for pathological diagnosis. However, all patients with suspected MTLE and a basal temporal lesion location (neocortex) failed to demonstrate MTS. Conclusions: Temporal lobe is highly epileptogenic. Lesions within the temporal lobe usually present with intractable epilepsy. A team approach is recommended for the management of these patients. Improved outcomes can be attained by identifying and removing the epileptogenic zone. For neocortical lesions (including basal location), we recommend intraoperative electrocorticography to maximize treatment efficacy. Treatment of mesial temporal lesions (archicortex) should include resection of the mesial temporal structures (not just lesionectomy) for probable MTS (dual pathology) if possible. The use of this treatment algorithm is useful for the education and management of these patients.