Gamma Knife surgery for trigeminal pain caused by benign brain tumors

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.

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).

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.

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.