Long-Term Outcomes in the Treatment of Classical Trigeminal Neuralgia by Gamma Knife Radiosurgery

Background Gamma knife radiosurgery (GKRS) is one of the alternatives for treatment for classical trigeminal neuralgia (TN). Objective To retrospectively analyze long-term outcomes for TN using GKRS achieved at our institution. Methods One hundred seventeen patients with medically refractory TN treated by GKRS at our institution were followed up between 1993 and 2011. Mean maximum dose was 86.5 Gy (range: 80-90 Gy; median: 90 Gy). Clinical response was defined based on the Burchiel classification. We considered classes I and II as a complete response. For toxicity, we use the Barrow Neurological Institute facial numbness scale. Mean duration of follow-up was 66 months (range: 24-171 months). Results Complete response at last follow-up in our patients was 81%, with an excellent response while off medication in 52%. Pain-free rates without medication (class I) were 85% at 3 years (confidence interval [CI]: 78%-94%), 81% at 5 years (CI: 72%-91%), and 76% at 7 years (CI: 65%-90%). Complete response rates (classes I-II) were 91% at 3 years (CI: 86%-97%), 86% at 5 years (CI: 79%-93%), and 82% at 7 years (CI: 72%-93%). Poor treatment response rates differed significantly between patients who had undergone previous surgery and were refractory to management with medication prior to GKRS. New or worsening facial numbness was reported in 32.5% (30% score II and 2.5% score III). No anesthesia dolorosa was reported. Permanent recurrence pain rate was 12%. Conclusion GKRS achieved favorable outcomes compared with surgery in terms of pain relief and complication rates in our cohort of patients, notwithstanding decreasing pain-free survival rates over time. We consider GKRS to be an initial treatment in the management of medically intractable TN in selected patients. Abbreviations CI, confidence intervalGKRS, gamma knife radiosurgeryMVD, microvascular decompressionRS, radiosurgeryTN, trigeminal neuralgia.