Do epileptic seizures predict outcome in patients with oligodendroglioma?

Many patients with an oligodendroglioma (OD) experience seizures, some of which become refractory to anti-epileptic drugs (AEDs). This study aims (1) to quantify the rate of seizures and medically refractory epilepsy in patients with ODs; and (2) to determine if there is any association between short-term and long-term survival, and the presence and drug-responsiveness of seizures.

A retrospective review was conducted of the medical records of patients who had been pathologically identified as having an OD at the London Health Sciences Centre or the London Regional Cancer Program in London, Ontario from January 1996 to July 2008. Deaths were ascertained by reviewing all hospital records. Survival analysis was performed.

One-hundred sixty-six patients met inclusion criteria. Epileptic seizures were the presenting feature or occurred as part of the initial manifestation of the OD in 75.3% of patients, with 90.4% (n=150) experiencing at least one seizure and 76.5% developing epilepsy over the course of observation. Of the 150 patients with seizures, 23 experienced a single seizure (13.9% of the 166), whereas 127 patients experienced multiple seizures (76.5%). In those with multiple seizures, the epilepsy was refractory to drug treatment slightly more than half the time (54.3%). Survival analysis demonstrated consistently superior survival among those with a single seizure. Those without seizures had the worst survival rates over the first few years post-diagnosis; but then no further deaths occurred. Survival among those with refractory seizures tended to be better than among those whose seizures were drug responsive, over the first 10 years post-diagnosis.

Seizures are common and may influence survival in patients with oligodendogliomas. Those who experience just one seizure appear to do best.