Retrospective analysis of variables favouring good surgical outcome in posterior epilepsies

Aim to determine variables favouring good surgical outcome in posterior epilepsies. Methods Fourteen patients submitted to epilepsy surgery were included in the study. The epileptogenic zone was located in temporo-parieto-occipital areas as assessed by both invasive and non-invasive pre-surgical evaluation. Several variables ( age at first seizure; age at surgery; disease duration; type, frequency and clinical semiology of seizures; presence of lesion; scalp ictal and interictal EEG; localization and extension of epileptogenic zone; completeness of surgical resection) were compared ( Fisher's exact test) with freedom from seizures to determine whether surgical outcome (Engel's classification) could be related to any of them. Results Seven patients were seizure free (Ia) and very satisfying results were obtained for 3 patients ( 2 Ib, 1 Ic). New post-surgical visual deficits occurred only in 3 patients. Surgical outcome was related significantly to two variables: scalp ictal EEG ( focal versus non-focal; p: 0.014) and completeness of surgical resection of epileptogenic zone ( p: 0.0023). A significant trend towards a better outcome for focal interictal intracranial activity versus a nonfocal one ( p: 0.07) was found. Conclusions The correlation between completeness of epileptogenic zone resection and surgical outcome suggests that a presurgical protocol, allowing a precise definition of the area of resection, could help in obtaining more satisfying results in posterior epilepsies.