Gamma Knife surgery for trigeminal pain caused by benign brain tumors

Abstract

Object The authors report the effects of Gamma Knife surgery (GKS) on benign tumor–related trigeminal pain in patients who underwent follow-up for a mean 57.8 months. Methods From 1999 to 2004, 21 patients with benign tumor–related trigeminal pain (12 meningiomas and 9 schwannomas) underwent GKS as a primary or repeated treatment. These patients harbored tumors within the radiosurgical target area. For meningiomas, the mean radiosurgical treatment volume was 8.2 ml (range 1.1–21 ml), and the mean radiosurgical tumor margin dose was 12.7 Gy (range 12–15 Gy); for schwannomas, the mean volume was 5.6 ml (range 2–9.2 ml), and the mean marginal dose was 13 Gy (range 11.5–16 Gy). Seven patients underwent retreatment for recurrent or persistent pain; the ipsilateral trigeminal nerve or ganglion was identified and a mean maximal dose of 60.7 Gy (range 40–70 Gy) was delivered to these targets. In 1 patient undergoing retreatment, the margin dose was 12 Gy. The mean age at the time of radiosurgery was 54.5 years (range 18–79 years). Results The mean follow-up period was 57.8 months (range 36–94 months). Overall, 12 (57%) of 21 patients experienced pain relief without medication after the first GKS and the mean time to drug discontinuation was 10.5 months (range 2–24 months). Initial pain improvement was noted in 17 patients (81%) with a mean time of 3.7 months (range 1 week–10 months) after GKS. Eight patients underwent repeated GKS for persistent and recurrent pain. Four patients (50%) had complete pain relief. The final results of the first and repeated GKS were excellent in 16 patients (76%), and in only 1 patient did GKS fail, and this patient later underwent open surgery. For all 21 patients (100%), control of tumor growth was documented at a mean of 46 months after GKS. Three of 6 patients with pre-GKS facial numbness reported improvement, but 4 suffered new facial numbness after repeated GKS. Conclusions Gamma Knife surgery appears to be an effective tool to treat benign tumor–related trigeminal pain and control tumor growth. Repeated GKS targeting the trigeminal root or ganglion can be considered a tool to enhance the efficacy of pain management if pain persists or recurs, but the optimum treatment dose needs further investigation.