The course of seizure disorders in patients with malignant gliomas

To describe the morbidity associated with seizures and the efficacy of anticonvulsant therapy in adult patients with malignant gliomas (MGs).

A retrospective review of charts was performed to determine the occurrence of seizures at diagnosis, the frequency and character of subsequent seizures, and the use and toxic side effects of anticonvulsants.

Sixty-five consecutive adult patients with supratentorial MGs who were examined in the neurooncology clinic at a university medical center were studied. The diagnosis was glioblastoma in 47 of the patients, and it was anaplastic astrocytoma in 18 patients. The mean age of the patients was 49.5 years. The median Karnofsky status score was 80. The median survival was 18 months.

Twenty-nine patients presented with seizures, and 21 of these had subsequent (eg, "recurrent") seizures while they were receiving anticonvulsant therapy. Ten of 36 patients who were free of seizures at diagnosis experienced seizures after diagnosis (eg, "late onset") while they were being treated with anticonvulsants, including five patients who had single seizures. Long-term seizure frequency in excess of one per month was observed in 13 patients. Ten patients had episodes of partial motor status epilepticus. Most recurrent and late-onset seizures occurred despite therapeutic anticonvulsant levels, and without evidence of tumor progression. Rash associated with anticonvulsants was observed in 26% of the patients. Other clinically important toxic side effects were observed in 14% of the patients who were receiving long-term anticonvulsant therapy.

Seizures contributed substantially to the neurologic morbidity of MGs in at least 25% of these patients. The occurrence of seizures at diagnosis was a strong predictor of subsequent seizures, and in many patients, seizures proved to be refractory to standard anticonvulsant therapy. Long-term anticonvulsant toxic side effects are relatively common in patients with MGs. The use of long-term seizure prophylaxis for patients with MGs who are free of seizures at presentation is not clearly beneficial and should be studied in a prospective trial.