Abstracts

Rationale: Although intraoperative electrocorticography (ECoG) has been in clinical use for many decades, the validity of this procedure in guiding resective temporal lobe epilepsy is still uncertain. Currently, is considerate an important additional technique in the tailored temporal lobectomy, superfluous in standard anterior temporal lobectomy, and probably unnecessary in amygdalohippocampectomy. However, there are few papers published about the utility of ECoG in the tailored temporal lobectomy due to mesial temporal sclerosis. These studies have several methodological limitations, including the small number de patients, the missing residual epileptiform activity, the lack of homogeneous diagnosis and preoperative MRI studies. Methods: We retrospectively included 20 patients who underwent tailored temporal epilepsy surgery guided by ECoG at our center from January 2007 through December 2010. We described the clinical characteristics, pathological, neuroimaging, interictal and ictal scalp video-EEG findings, nuclear medicine findings, ECoG abnormalities, anestethics protocols and outcome. We used descriptive statistical analysis. Results: Twenty patients (6 men, 14 women) ranging from 23 to 47 years (mean 36.9 years) were analyzed. Seventeen (85%) patients showed interictal and ictal unilateral temporal onset, mainly right anterior temporal epileptic activity (52%). The ECoG recording showed pre-resection spikes both in mesial temporal lobe (MTL) and lateral temporal lobe (LTL) in 10 (50%) patients, restricted to the LTL in 7 (35%) and only restricted to MTL in 3 (15%) patients. Seventeen (85%) postsurgical ECoG recordings didn t show any remaining epileptiform activity, however, some residual epileptiform abnormalities were seen in 3 (15%) patients, two on the temporal posterior lateral surgical border and one on the third right frontal gyrus. Histopathological evaluation revealed hippocampal sclerosis in all the cases, except in one patient in which an additional cortical temporal dysplasia type IIB were found. Postsurgical follow-up range from 12 months to 2.5 years (mean, 16.3 months), following surgery, 15 (75%) patients were seizure free (IA), two (10%) patients only had auras (IB), two patients (10%) had rare seizures (1; IIA and 1; IIB) and only one patient had IIA outcome. Two patients developed vascular complications. Conclusions: In our study 75% of our patients were seizure free, this outcome maybe is result of a non-standard and tailored neurosurgical approach. To our knowledge this is the first study in this selected population evaluated the role of the maximal residual resection of the epileptiform activity. However, more prospective and randomized studies with larger number of patients are required.