Treatment of Trigeminal Neuralgia with Linac Based Radiosurgery in Patients with Multiple Sclerosis

The aim of this study was to establish if patients with multiple sclerosis (MS) who develop trigeminal neuralgia (TN) have worse outcomes with Linac-based stereotactic radiosurgery (SRS) compared to patients without MS. Between 1996 and 2014, 14 patients with TN treated with SRS had a diagnosis of MS. One patient had bilateral TN treated with SRS, thus there were 15 treatments evaluated. All patients underwent Linac-based SRS. Patients were followed and their pain scores were assessed using the Barrow Neurological Institute scale (BNI), scores I-V. We compared our findings with a literature review of 11 case series of Linac-based SRS for mostly typical TN (Varela-Lema, Pain Physician, 2015, 18:15-27), with response rate (range 75-96%, within mean 8.5 days – 3.8 months), pain recurrence rate (range 5-29%), and incidence of partial numbness (range 7.5-52%) reported as such. Mean follow-up time was 35.2 months (range 0-159.7). Five patients had rhizotomies, one of which had bilateral, before first SRS. All patients had failed medical management with pain scores BNI 4 or 5 at the time of SRS. Median time from surgery to first SRS was 19.5 months (range 1-63). Of the 15 TN SRS treatments, 13 received 90 Gy, 1 received 75 Gy, and 1 received 70 Gy. The BNI scores after SRS for 11/15 treatments ranged from I-IIIa, with median latency of 4 weeks (range 2-7). One patient had no relief and three were not scored. In 4/15 treatments (27%), patients experienced partial numbness on the treatment side, developing 1-7 months post SRS. In total, 8/15 (53%) treatments were successful without pain recurrence at time of last follow-up, 1 patient was lost to follow-up, and 5 (33%) had pain recurrence with a BNI of IV at a median of 12.5 months. The patient with bilateral TN only had recurrence on the right, which had received 70 Gy. Four out of 5 patients with recurrence underwent surgical procedures, 2 with complete relief. One patient underwent successful repeat SRS at 90 Gy, after failure of balloon compression and radiofrequency ablation, 32 months after the first SRS. The patient with bilateral TN with failure on the right received a repeat dose of 70 Gy 22 months after first SRS with pain relief for 8 months; however, this patient failed again on the right and underwent 3 additional rhizotomies without success. Linac-based SRS proved to be an effective, noninvasive treatment for MS patients with TN, with a 73% response rate and a median time to response of 4 weeks, comparable to treatment of patients without MS. Compared to findings in the literature, there was a comparable incidence of partial numbness on the treatment side and only a slightly higher pain recurrence rate in TN patients with MS compared to those without MS. There were no episodes of anesthesia dolorosa noted. Multiple sclerosis should not be considered a contraindication for SRS in patients with TN.