Oligoastrocytoma presenting with intractable epilepsy

Oligoastrocytomas (OA) are mixed gliomas with distinct oligodendroglial and astrocytic neoplastic components. Very little about OA has been reported in the intractable epilepsy population.

We undertook a retrospective review of 923 patients who underwent resective surgery for intractable epilepsy between 1996 and 2004.

6/923 (0.7%) patients were diagnosed with OA. Five patients were female, one was male. Median age at diagnosis was 25 years (range 19-44 years). Tumors arose from the left side in all patients and from the temporal lobe in five patients. Three patients had complex partial seizures. Median length of refractory epilepsy prior to surgery was 10.5 years (range 1-28 years), and the median number of antiepileptic drugs used was 2 (range 1-10). Preoperative WADA testing for language and memory localization was done for three patients; preoperative stereotactical localization was done for three patients. Surgical pathology revealed low-grade OA (WHO II) in five patients, and anaplastic OA in one. There were no surgical complications, clinical or radiographic tumor recurrence at a mean follow up period of 3.2 years (range 2-8). Excellent seizure freedom was achieved in 5/6 patients.

As a result of our small sample size, general conclusions may be imprecise, but this review suggests that OA behave similar to other tumors related to intractable epilepsy: they usually have a preoperative seizure course of many years, an excellent rate of seizure-freedom following surgery, and are in general, low-grade tumors with an indolent course for which serial imaging is sufficient follow-up.