Comparison of the results of 2 targeting methods in Gamma Knife surgery for trigeminal neuralgia

Abstract

Gamma Knife surgery (GKS) is an effective treatment for intractable trigeminal neuralgia (TN). The authors compared results using two major GKS target points, the dorsal root entry zone and the retrogasserian portion, in a series of patients with intractable TN. One hundred patients with medically refractory TN underwent GKS between August 1998 and December 2007. Thirty-seven were men, and 63 were women. The median age at GKS was 74 years. With a single isocenter and use of a 4mm collimator, 51 patients received 80 Gy at the proximal trigeminal nerve (posterior group) and 7 patients received 80 Gy, 1 patient received 85 Gy, and 41 patients received 90 Gy at the retrogasserian portion (anterior group). Follow-up was obtained by clinic visits every 3-6 months after GKS. Data on pain control, complications, and pain recurrence were recorded. The relationships between pain control status, complications, recurrence, and the target portions (anterior vs posterior) were analyzed. The median duration of follow-up was 30 months (range 3-88 months). Initially, 87 patients achieved pain-free status and 64 achieved complete remission. At the final follow-up visit, 68 patients were still in pain-free status and 42 were in complete remission. Recurrence of facial pain occurred in 15 patients. Forty-one patients developed some degree of trigeminal dysfunction. The rate of initial complete remission was higher in the posterior group than in the anterior group (p = 0.003). More complications were observed in the anterior group than in the posterior group (p = 0.009). The posterior targeting group had better pain control and a lower complication rate. The authors recommend the posterior targeting method and use of 80 Gy for treatment of TN with GKS.