Prevalence and prognostic significance of epilepsy in patients with gliomas

The aim of this study was to evaluate the prevalence and prognostic significance of epilepsy in 1028 patients diagnosed in the computer tomography (CT) era with histological low- or high-grade intracranial gliomas. Survival analysis included Kaplan-Meier plots, log-rank tests, logistic regression and Cox's analysis as implemented in the SPSS statistical package. Epilepsy was a positive univariate (P < 0.0001) and multivariate, (P < 0.03) prognostic factor for survival in the total patient group (n = 1028, relative risk of death 0.83, 95% confidence interval (CI) 0.70-0.98) as well as in the high-grade patient group (n = 649, relative risk of death 0.80, 95% CI 0.66-0.96), but not in the group of low-grade glioma patients (P > 0.2). The prevalence of epilepsy in glioblastoma patients was 251/512 (49%), 95/137 (69%) in anaplastic gliomas, and 322/379 (85%) in patients with low-grade gliomas, with 97 of the 102 T1 low-grade subgroup (95%) having epilepsy, indicating that the presence of epilepsy may select patients for early radiological diagnosis. The frequency of epilepsy at presentation decreased with age in high-grade glioma patients, and increased with age in low-grade glioma patients to a plateau in the fourth decade of life (P < 0.01). The prevalence of epilepsy in patients with histological intracranial gliomas varied with patient age and tumour histology, with low-grade patients having the highest prevalence. Epilepsy was a significant positive prognostic factor except in patients with low-grade gliomas, and may select low-grade patients for early diagnosis.