Radiosurgical treatment of intractable epilepsy with low radiation dose.

OBJECTIVE: To localize the epileptic foci with positron emission tomography (PET), and study the principles of target definition and method to determine the optimal range of exposure in radiosurgery for intractable epilepsy. METHODS: This study included 176 patients with intractable epilepsy, who received linear accelerator radiosurgery after (18)F-FDG PET for epileptic foci localization. The patients were divided according to different peripheral doses used in the treatment into Group A in which radiation dose of 9 to 11 Gy was used, Group B with 11 to 13 Gy and Group C with exposure to over 13 Gy. Follow-up study was conducted in all the patients for a period ranging from 3 to 16 months, during which the frequency of seizure after treatment was recorded to evaluate the therapeutic effect. RESULTS: The seizure frequency significantly decreased after radiosurgical treatment in all the groups, but between the groups, the decrement evinced no significant difference. According to Wieser's classification of the effect after operation, 46.9% cases belonged to grade I to II and 41.5% to grade III to IV. Obvious complications were not observed, nor did disability or mortality occurred in these cases. CONCLUSIONS: Stereotactic radiosurgery with low radiation dose under the guidance of PET provides a safe, effective and minimally invasive surgical approach for patients with intractable epilepsy, and peripheral radiation doses of 9 to 11 Gy for the epileptic foci localized by PET is sufficient to ensure good clinical outcome.