Is It Effective to Raise the Irradiation Dose from 80 to 85 Gy in Gamma Knife Radiosurgery for Trigeminal Neuralgia?

Objective: In order to assess the effect of raising gamma knife radiosurgery (GKS) doses from 80 to 85 Gy for the treatment of trigeminal neuralgia (TN), the authors analyzed the outcomes of GKS in each group. Patients and Methods: The authors retrospectively collected follow-up data of 104 GKS procedures conducted for TN. Doses of 80 and 85 Gy were prescribed for 60 and 44 patients, respectively. The target was 2-4 mm anterior to the junction of the trigeminal nerve and pons. Outcomes were quantified based on facial pain levels and classified using the Barrow Neurological Institute scale. Results: Actuarial rates of a favorable pain control outcome at 1 and 3 years after GKS were 75.0 and 61.2% for 80 Gy and 65.9 and 60.3% for 85 Gy. Post-GKS facial sensory loss developed in 20.6%. There was no statistically significant difference in pain control rate between the two groups. Time to maximal pain relief was shorter in the 85-Gy group. Protracted morbidity before GKS was a favorable prognostic factor of pain control in a multivariate analysis. Conclusion: According to our finding that 85 Gy brought more rapid clinical improvement without causing more complications, 85 Gy seems to be preferable to 80 Gy, but prospective randomized trials are mandatory to get a more definite conclusion on the optimal dose for GKS of TN. Copyright (C) 2010 S. Karger AG, Basel