Frameless Radiosurgery for Intractable Idiopathic Glossopharyngeal Neuralgia

Abstract

Glossopharyngeal neuralgia (GPN) is a rare disorder of the ninth cranial nerve characterized by severe, paroxysmal episodes of pain localized to the posterior tongue, tonsil, throat, or external ear canal. The pain is similar to that experienced with trigeminal neuralgia (TN) and can be triggered by eating, swallowing, and speaking. The pain of GPN can also be associated with hemodynamic instability and life-threatening syncopal episodes. Though traditional treatment for GPN involves medical management at first and surgery for refractory cases, these therapies are often poorly tolerated in the elderly population. Goal of this study was to evaluate the safety and efficacy of Linac based frameless stereotactic radiosurgery (SRS) for patients with intractable idiopathic glossopharyngeal neuralgia From 20011 to 2017, 7 patients (3 male and 4 female) with median age was 60 years presented with medically refractory GPN and all had a long history of pain, median duration (28-70 mo.). In 4 cases, a neurovascular conflict had been identified on MRI. Three patients had unsuccessful prior surgical procedures, including microvascular decompression (MVD) (n = 2) and balloon compression (n = 1). In 4 cases, a neurovascular conflict had been identified on MRI. For the SRS procedure, all patients underwent double reinforced mask/byte immobilization, planning bone CT, Planning MRI (T2 CISS / FIESTA). The target was located at the glossopharyngeal meatus of the jugular foramen. Treatment was delivered on C arm Linac with 6-DOF couch capabilities, 5mm stereotactic cones and intrafraction imaging to ensure submm and sub degree precision. The median dose administered to the nerve was 80 Gy (range: 80-85gy). Follow-up was planned for 3, 6, and 12 months after the procedure and annually thereafter 5 patients experienced an improvement in their pain. The median length of time from SRS to symptom improvement in this group was 7 weeks (range 2-12 months). At the first follow-up, 5 patients were pain-free (pain intensity scores of I-III, based on an adaptation of the Barrow Neurological Institute scoring system for trigeminal neuralgia), including 4 patients who were also medication-free (I). One patient had partial improvement (IV) and 1 patient had no change. The mean duration of follow-up was 46 months (range 10-50 months). No side effect was observed. No patient developed changes in vocal cord function or swallowing disorders after SRS in this study First paper reported in literature showing efficacy of non-invasive frameless radiosurgery as surgical alternative with very high short- & long-term efficacy and without permanent complications for medically refractory glossopharyngeal neuralgia.