Epilepsy more common in patients with low-grade glioma

Epileptic seizures in patients with grade II supratentorial gliomas are more common than previously reported and are relatively refractory to treatment, according to a retrospective case-note review that provides the largest case series on the course and prognosis of epilepsy in these patients.

The review also found that antiepileptic agent levetiracetam is the most frequently used add-on drug in patients with refractory epilepsy, and it shows an efficacy that is comparable to that in non-tumour cohorts, according to presenter Rimona S. Weil, MD, clinical research fellow, Institute of Neurology, University College London, London, United Kingdom.Dr. Weil presented the findings here on September 3rd at the 10th Congress of the European Federation of Neurological Societies (EFNS).

Although low-grade glioma has a low incidence, at 2 per 100,000 per year, seizures that are often refractory to medication occur in 70% to 80% of these patients. This study was therefore conducted to determine the prognosis for patients with low-grade glioma and epileptic seizures, and which of the newer antiepileptic agents are most effective and best tolerated?" she detailed.

Study subjects were adults with World Health Organisation grade II supratentorial glioma, as diagnosed according to histology and radiological appearance. Eighty-one patients were included (median age, 36 years; male, 63%), and they had a median follow-up of 4 years (range, 0.8-20.0).Tumour locations were frontal (41%), temporal (22%), frontotemporal (11%), frontoparietal (7%), parietal (6%), temporoparietal (4%), occipital (2%), and other locations (6%). Examination of the histological subtypes indicated: astrocytoma (46%), oligodendroglioma (27%) and oligoastrocytoma (7%); 14% were not biopsied, and 6% were biopsied after transformation.Of patients with low-grade glioma, 27% were seizure free over the previous year.

Age at diagnosis, gender, early resection, tumour location and histological subtype were not associated with an increased probability of seizure freedom.The seizure types seen in this last year of follow-up varied across simple partial seizures (SPS; 44%), complex partial seizures (CPS; 2%), generalised tonic-clonic seizures (GTCS; 14%), SPS + GTCS (11%), SPS + CPS (1%) and unspecified seizures (1%).

The first-line agents were carbamazepine, phenytoin and sodium valproate; 40% of patients also received the newer antiepileptic drugs (AEDs), 31% of which required more than 1 treatment.Changes in seizure control with the various newer AEDs could not be determined due to limited patient numbers, but the researchers did note that levetiracetam was the most frequently used of these agents in patients with treatment failure. In addition, this agent was associated with treatment response (seizure reduction greater than 50%) in 68% of episodes, with 14% of patients remaining seizure free.

The adverse effects profiles of these newer AEDs were generally acceptable in 45% to 70% of patient episodes, according to Dr. Weil.For partial-onset epilepsy, a direct comparison between the relatively small population of 28 evaluable patients with low-grade glioma and the larger non-tumour populations in the literature showed that levetiracetam has similar efficacy rates for seizure reduction and seizure-free status.Dr Weil was the recipient of an unrestricted educational grant from UCB Pharma.