Abstracts

Rationale: Oligodendrogliomas (ODs) are the third most common gliomas and account for 2-5% of all brain tumours. A high proportion of patients with ODs present with or eventually develop seizures, that may become refractory to anti-epileptic drugs (AEDs). This study aims to quantify the presence of refractory epilepsy in patients pathologically diagnosed with ODs and identify diagnostic and treatment guidelines as to optimal clinical management. Methods: A retrospective review was conducted using patients pathologically identified as having an OD in the London Health Sciences Centre (LHSC) and London Regional Cancer Program (LRCP) from January 1996 to July 2007. Refractory epilepsy was defined as the failure of 2 appropriately prescribed AEDs. Results: 164 patients were identified that met the inclusion criteria. The population identified thus far was found to hold similar demographic and clinical characteristics to existing populations of oligodendrogliomas in the literature with pre-dominant manifestation in males (89/164; 54.2%) and frontal lobe tumour location (99/164; 60.4%). Refractory epilepsy was found in 58/164 (35.4%). An association (P=0.042) was observed between the occurrences of refractory epilepsy among patients with ODs in the temporal lobe. There was a significant association between tumour contrast enhancement in MRI and final pathological grading (P=0.001). Conclusions: Refractory epilepsy is common among the patients with ODs. The occurrence of ODs within the temporal lobe carries the highest risk for the development of refractory epilepsy.