Impact of Gamma Knife Radiosurgery on Reduction of Pain and Medication Requirements in Medically Refractory Trigeminal Neuralgia

Summary: Trigeminal Neuralgia is a condition characterized by paroxysmal neuropathic facial pain often triggered by activities such as eating, speaking, or touching the face.1 Following treatment with medication, medically refractory trigeminal neuralgia is debilitating, severely impairing patient quality of life. Of the main surgical interventions for medically refractory trigeminal neuralgia, stereotactic radiosurgery (SRS) is the only modality that is noninvasive. We present long-term results of SRS in a population rigorously examined for pain outcome. We conducted a retrospective review of patients receiving Gamma Knife stereotactic radiosurgery for medically refractory trigeminal neuralgia at the University of Oklahoma Health Sciences Center from 2015-2024. Patient charts were reviewed for data abstraction. The Barrow Neurological Institute Pain Intensity Score2 was used to assess efficacy of treatment. Thirty five patients (22 women, 13 men) with adequate follow-up were evaluated. Mean patient age was 67.9 years (median=69 years; range 33-94). Of these patients, 60% (21/35) had right-sided pain, 34% (12/35) had left-sided pain, and 6% (2/35) had bilateral pain. Forty percent (14/35) of patients experienced pain in the V1 distribution, 77% (27/35) had pain in the V2 distribution, and 66% (23/35) had pain in the V3 distribution. Sixty six percent (23/35) of patients felt pain in multiple distributions of the trigeminal nerve. Prior to undergoing Gamma Knife, 46% (16/35) had undergone a previous surgical procedure for trigeminal neuralgia, most commonly microvascular decompression 26% (9/35) and balloon rhizotomy 17% (6/35). The mean follow-up period was 27.5 months (median = 18 months); the majority of patients were treated to a maximum dose of 85 Gy to the offending trigeminal nerve. At the last follow-up, two patients (6%) were Barrow Class I (no pain, no medications required), 21 (60%) were Class III (some pain, adequately controlled with medications), 9 (26%) were Class IV (some pain, not adequately controlled with medications), and 3 (9%) were Class V (severe pain, no relief). A large cohort of medically refractory trigeminal neuralgia patients treated with Gamma Knife stereotactic radiosurgery experienced a long-term improvement in pain, with a minority of patients experiencing a relief from pain and medication. These results from one of the first radiosurgery series examining pain outcomes using neurosurgery-established criteria firmly establish stereotactic radiosurgery as an efficacious modality in treating medically refractory trigeminal neuralgia with the distinguishing feature of being the only noninvasive treatment modality. Gavin C. Knapp (he/him/his), B.S. (Presenting Author) - University of Oklahoma Health Sciences Center; Laramie Knapp, B.S. (Co-Author) - University of Oklahoma Health Sciences Center; Ozer Algan, MD (Co-Author) - OU Health Stephenson Cancer Center; Tyler Gunter (he/him/his), MD (Co-Author) - OU Health Stephenson Cancer Center; Ian Dunn (he/him/his), MD (Co-Author) - OU Health Stephenson Cancer Center; Jerry Jaboin (he/him/his), MD, PhD, MBA, FACRO (Co-Author) - OU Health Stephenson Cancer Center; Phylicia Gawu, DO, MS (Co-Author) - OU Health Stephenson Cancer Center; Shearwood McClelland (he/him/his), MD (Co-Author) - UH Siedman Cancer Center