Surgical outcomes in patients with epileptogenic tumours and cavernomas in Sweden: good seizure control but late referrals.

PURPOSE: Seizure outcome after epilepsy surgery is to an important extent related to underlying aetiology. In this study of patients who underwent epilepsy surgery with a lesional aetiology in Sweden 1990-2004, the aim was to investigate seizure outcome and prognostic factors.

METHODS: All patients operated on during the time period with a histopathological diagnosis of an epileptogenic tumour (ganglioglioma (GGL), dysembryoblastic neuroepithelial tumour (DNET) and low grade astrocytoma (AST)) or a cavernous haemangioma (CAH) were identified in the population based Swedish National Epilepsy Surgery Register. Univariate and multivariate analyses were performed to determine the independent contribution of the following variables to seizure outcome: age at surgery; epilepsy duration; preoperative seizure frequency; localisation of the resection; and histopathology.

RESULTS: Of the 156 identified patients who had a 2 year follow-up (103 adults and 53 children), 71% had temporal, 16% frontal and 13% parietal and occipital lobe resections. Mean presurgical epilepsy duration was 13 years in adults and 5 years in children. Main histopathological diagnosis was GGL or DNET in 67, CAH in 42 and AST in 47 patients. 77% of patients had sustained seizure freedom (with or without aura) 2 years after surgery. In the multivariate analysis, only diagnosis other than AST was independently associated with becoming seizure free.

CONCLUSION: In this population based series, 120/156 patients (77%) with epileptogenic tumours and cavernomas were seizure free 2 years after surgery. Many had a very long epilepsy history. Seizure outcome can be improved if epilepsy surgery is considered earlier in patients with epileptogenic lesions.