MODIFIED APPROACH FOR THE SELECTIVE TREATMENT OF TEMPORAL-LOBE EPILEPSY - TRANSSYLVIAN-TRANSCISTERNAL MESIAL EN-BLOC RESECTION

Object. The authors propose a novel surgical approach for amygdalohipp ocampectomy (AH) in patients with temporal lobe epilepsy. Via a transs ylvian-transcisternal route, the parahippocampal gyrus is directly exp osed from its medial aspect, thus allowing a standardized en bloc rese ction of the temporomesial epileptogenic structures-the amygdala, ante rior hippocampus, parahippocampal gyrus, and subiculum. Additional ana tomical studies have been performed for standardization of this approa ch. Methods. From 1990 to 1996. 32 patients presenting with medically intractable mesial temporal lobe epilepsy underwent AH via the transsy lvian-transcisternal approach. Preoperative computerized tomography an d magnetic resonance imaging revealed temporomesial lesions in 16 pati ents. Histopathological examination revealed cavernous malformations i n seven patients, low-grade astrocytomas in four, hamartomas in three, and gangliogliomas in two patients. Specimens obtained in patients wi th no lesions were diagnosed as hippocampal sclerosis in all cases. No patient experienced permanent morbidity. Nine percent of the patients developed a temporary partial oculomotor nerve palsy. Only one patien t developed a postoperative visual field deficit with a contralateral quadrantanopsia. With respect to seizure outcome, all patients benefit ed from surgery. At follow-up evaluation (mean 26.4 months), 80% of th e patients were free from seizures (Engel Class I). Eight patients in this group were no longer receiving medication. Seventeen percent had experienced only one to several seizures since surgery (Engel Class II ) and 3% reported a worthwhile improvement (Engel Class III). Conclusi ons. In contrast to previously described standard techniques for AH, t he transsylvian-transcisternal approach presented in this study offers improved anatomical orientation and intraoperative control over the m esial temporal lobe and preserves the lateral as well as the laterobas al temporal lobe.