Epileptic seizures during follow-up of patients treated for primary brain tumors.

OBJECTIVE: To determine the presentation, incidence, and severity of seizures in follow-up of patients treated for primary brain tumors.
METHODS: A total of 234 consecutive patients attending an outpatient clinic for chemotherapy of a supratentorial brain tumor were examined.
RESULTS: Seizures occurred in 183 patients. All patients with epilepsy were on antiepileptic drugs (AEDs). Compared with patients without epilepsy, patients with epilepsy had a higher proportion of low-grade gliomas (p < 0.001) and cortical tumor location (p < 0.001). In 158 (86.4%) patients, seizures were an early manifestation of the disease, and epilepsy developed in only 25 (13.6%) individuals in the course of the malignant disease. Generalization occurred in 50% of early seizures, but in only 19.1% of patients with seizures persisting after the initiation of AEDs and specific antitumor therapies. The reduction in seizure generalization was significant (p = 0.001). Despite AED and various antitumor treatments, one-half of the patients had a seizure within 1 month and two-thirds within 3 months before the last evaluation.
CONCLUSIONS: Most tumor-related seizures first appear early in the course of disease, usually as a presenting manifestation. Antiepileptic drugs combined with specific antitumor treatments significantly reduce the rate of seizure generalization. However, most patients continue to have focal epilepsy during follow-up.