Abstracts

Functional Hemispherectomy (FH) is performed in patients with intractable epilepsy and disabling hemiparesis due to diffuse hemispheric pathology such as perinatal stroke or diffuse cortical dysplasia (CD). EEG finding in relation to post-op outcome of FH has not been systematically evaluated in the previous reports., A retrospective analysis included all patients who underwent FH from Sep 91 to June 05 at the Medical College of Georgia. Surgery was performed exclusively by two authors (JRS and MRL) who shared the same surgical technique. Patients were followed at least one yr post-op. Seizure outcome was classified as seizure-free (SF) vs. non seizure-free (NSF). Interictal and ictal EEGs were classified as lateralizing (L) (ipsilateral to the pathology) vs. non-lateralizing (NL) (unlocalizing, contralateral to the pathology, or bilateral-independent onset). Demographic characteristics, etiology, MRI/PET, outcome, and complication were collected from the medical record. Statistical analysis was performed using SPSS 13 package. This study was approved by the institutional review board., Total of 37 patients were included: M 18, F 19. Mean age of seizure onset was 3.4 yrs (0-26 yrs) while mean age of FH was 13.82 yrs (1-40 yrs). Most common etiology was perinatal stroke (40.5%, N=15) followed by diffuse CD (32.4%, 12), RS (21.6%, 8), head trauma (2.7%, 1), and Sturge-Weber Syndrome (2.7%, 1).
Overall surgical outcome was excellent: 81.1% (30/37) SF vs. 18.9% (7/37) NSF. SF outcome was not different between the different etiologies: stroke 73.3% SF (11/5) vs. CD 83.3% SF (10/12) vs. RS 100% SF (8/8). Interictal EEG was nonlateralizing (NL) in 18.9% (7/37) while ictal EEG in 35.1% (13/37). Iinterictal EEG pattern did not predict SF outcome: L 87.5% (21/24) vs. NL 69.2% (9/13), Fisher[apos]s Exact Test; [italic]p[/italic]=0.6. Ictal EEG pattern did not predict SF outcome either: L 87.5% (21/24) vs. 69.2% (9/13), [italic]p=[/italic]0.18. In addition, within the specific etiologic groups, interictal or ictal EEG did not predict the outcome. Age at the time of surgery tended to be younger in the SF group: 13.1 [plusmn] 11.2 (SF) vs. 16.8 [plusmn] 5.8 (NSF), t-test [italic]p[/italic]=0.087., Our data showed that interictal or ictal EEG pattern does not predict the surgical outcome. Our study suggests that selection of candidiates for functional hemispherectomy should be based on clinical and radiological evidence, rather than scalp EEG.,