Predictors of Class I epilepsy surgery outcome in tumour-related chronic temporal lobe epilepsy in adults.

Abstract

Temporal lobe tumours, especially low-grade gliomas and glioneuronal tumours, are common causes of seizures in patients referred for epilepsy surgery. We here present our experience of surgical treatment of patients with intractable chronic epilepsy associated with temporal lobe tumours, focusing on the long-term surgical outcomes and the features associated with better seizure control. In this study, we retrospectively analysed 44 consecutive patients from a total of 182 with refractory temporal lobe epilepsy presenting with long-term intractable epilepsy due to a temporal lobe tumour who were surgically treated at our institution between 2005 and 2015 with post-surgical follow-up of at least two years. All patients underwent a standard pre-surgical evaluation that included: history and physical examination with a description of the seizure semiology, serial scalp EEG recording, brain MR imaging, and a detailed neuropsychological evaluation. Our surgical strategy comprised tumour resection, and combined mesial temporal and neocortical resection in most cases. No patient died during surgery or the postoperative course. Seven patients had postoperative complications, of whom two had permanent hemiparesis due to ischaemic stroke. At the final follow-up, a favourable seizure outcome (Engel Class I) was found in 37 patients (84%), including 31 (70.5%) in Engel Class IA (excellent result). Two (4.5%) patients presented with an Engel Class II outcome (unfavourable outcome). Five patients (11.5%) were in Engel Classes III or IV (surgical failure). We found that complete resection of the hippocampus along with tumour and temporal pole removal was strongly associated with seizure freedom (p = 0.015). Pathological diagnosis was also a significant prognostic indicator of tumour-related seizure freedom. Patients with a diagnosis of a glioneuronal tumour benefited from more seizure freedom after resection compared to those who had a low-grade glioma (p = 0.024). The most appropriate management of tumour-related chronic temporal lobe epilepsy in adults appears to be tai-lored temporal lobe resection including tumour and hippocampal complex removal. Surgical treatment of tumoural temporal lobe epilepsy demonstrates excellent results in terms of seizure improvement, especially in patients with glioneuronal tumours.