Long-Term Outcome of Gamma Knife Stereotactic Radiosurgery for Multiple Sclerosis Associated Trigeminal Neuralgia

Gamma knife radiosurgery (GKS) has been shown to be a viable treatment for Trigeminal Neuralgia (TN) that provides excellent rates of initial pain relief. There are, however, mixed opinions regarding the efficacy of GKS for multiple sclerosis (MS) -associated TN. This is partly because there has not been enough long-term data to support or reject such a hypothesis. The authors report their long-term experience of 13 patients with MS-TN with GKS. Thirteen patients (14 nerves, n = 14) with MS-TN were treated with GKS at the University of Maryland between 1998 and 2001. The median dose was 75 Gy (range, 70-80 Gy). The median follow-up was 67 months (range, 13-96 months) after GKS. A BNI score of IV characterized 92.9% of nerves prior to GKS treatment, and the remaining one nerve was described as BNI III. Post GKS BNI scores were as follows, BNI I- 57.1%, BNI III- 7.1%, and BNI IV- 35.7%. An improvement in the BNI score, defined as the initial response rate, was observed in 57.1% of the cases. The median time to pain relief was 1 week (range, 1-9 weeks). Six patients were able to discontinue their TN related medications. Of the patients not experiencing relief from their TN symptoms post GKS, none were able to decrease or discontinue medications. The median duration of relief for patients that responded to the first GKS was 36 months (range, 4-78 months). Actuarial freedom from treatment failure at 1-, 3- and 5-years was 42.9%, 42.9% and 28.6%, respectively. There were no major complications noted among the patients undergoing GKS. Only one of patients (7.1%) experienced new facial numbness that was described as moderately bothersome after GKS. One other patient experienced transient numbness following GKS. This study represents the longest follow-up of any series of MS-TN patients treated with GKS. Our data suggest that GKS remains a satisfactory treatment option because of the relatively favorable toxicity profile in MS patients compared to other treatment modalities.