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Dose-Response and Dose-Complications Relationships in Stereotactic Radiosurgery for Trigeminal Neuralgia Sandra Vermeulen MD, Robert Meier MD, Vivek Mehta MD, Ron Young MD, Francisco Li MS Northwest Gamma Knife Center, Seattle, WA, USA.
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Dose-Response and Dose-Complications Relationships in Stereotactic Radiosurgery for Trigeminal NeuralgiaSandra Vermeulen MD, Robert Meier MD, Vivek Mehta MD, Ron Young MD, Francisco Li MSNorthwest Gamma Knife Center, Seattle, WA, USA
Definition: brief episodic, unilateral face pain, confined to one or more divisions of the 5th nerve. Cause: tumors, vascular compression of the root entry zone, multiple sclerosis and idiopathic causes Pharmacotherapy is the initial treatment modality of choice Annual incidence in the United States: 15,000 Trigeminal Neuralgia: Overview
Purpose/Objective In Patients treated with Gamma Knife Radiosurgery for Trigeminal Neuralgia, to determine if a relationship exists between dose delivered, and the incidence of response, or the incidence of complications
382 patients with either typical or atypical TN were treated between August 1993 and January 2005 None had tumor or Multiple Sclerosis All were treated with a single 4-mm isocenter targeting the ipsilateral trigeminal nerve at the dorsal root entry zone Dose was prescribed at the Dmax Material and Methods
Dose Protocols Three dose protocols were employed using an output factor or 0.87: 76 patients received 76 Gy 179 patients received 87 Gy 127 patients received 98 Gy
Results Treatment outcomes were measured at 6 months, at last follow-up and actuarially “Favorable” responders were patients rendered free of pain, either with or without medication Complications were defined as lasting neurologic deficits attributable to treatment and included numbness or paresthesias
Pain Relief • At 6 months post-treatment, “favorable” outcomes occurred with similar rates in all 3 groups • Log-rank test showed no significant difference in the Kaplan-Meier curves for these three groups (p=0.835)
Complications • The only lasting complication was new numbness or paresthesia • At 6 months, patients treated with higher doses more often developed sensory deficits (p<0.05)
Conclusion In stereotactic radiosurgery for TN, escalation of maximum nerve dose from 76 Gy to 87 Gy to 98 Gy does not significantly improve pain relief, but is associated with a higher incidence of complications