gms | German Medical Science

Objective: Multilobar resective epilepsy surgery especially in young children poses significant challenges and is often not successful. In 2004 Daniel et al. described operative disconnection of the posterior quadrant of the brain (i.e. the temporal, parietal and occipital lobes) as a surgical option for the treatment of pharmacoresistant focal epilepsy with a presumed epileptogenic zone or lesion in the posterior quadrant. For the present study we have reviewed our 2005-2015 institutional experience with this procedure, to identify predictors of postoperative seizure freedom.

Methods: We retrospectively identified all patients who underwent a posterior disconnection as an epilepsy surgery intervention at our institution. All patients had an epileptological follow-up at 2 years after surgery. Postoperative seizure freedom means freedom from all seizure types including auras (Engel IA). All histopathological findings and neuroimaging data were reviewed. The neuroradiological reviewer was blinded to the clinical and histopathological data and was asked to retrospectively reclassify the extent and borders of the presumed epileptogenic lesion (forced choice between two categories, posterior quadrant only vs. possible extension beyond the posterior quadrant).

Results: Between 2005 and 2015, 26 patients (7f; 19m) underwent posterior disconnection surgery. Median age was 3.4 years. Most patients (N=15; 58%) were histologically diagnosed with malformations of cortical development. 13 of 26 patients (50%) became seizure-free. MR imaging results proved to be the most powerful predictor of the epileptological outcome while there was no significant correlation with lesion histology. 11 of 14 patients (79%) with lesions within the borders of the posterior disconnection became completely seizure-free (Engel class IA). Conversely, only 2 of 12 (17%) cases with possible extension of the epileptogenic lesion beyond the confines of the posterior quadrant had an Engel class IA outcome (p=0.005).

Conclusion: To the best of our knowledge, the present study describes the largest series of epilepsy patients treated with posterior disconnection surgery published so far. Our data show that this procedure constitutes a highly successful treatment for selected patients with pharmacoresistant epilepsy caused by lesions confined to the posterior quadrant. Proper analysis of neuroimaging data is challenging, but also crucial for the identification of appropriate surgical candidates.