Repeat Gamma Knife surgery for trigeminal neuralgia: long-term results.
OBJECTIVE
The purpose of this study was to assess the long-term outcome achieved after repeat Gamma Knife surgery (GKS) for trigeminal neuralgia (TN) using a uniform treatment plan.


METHODS
Between 1985 and 2010, 53 patients underwent repeat GKS for refractory TN. In the initial GKS, which involved targeting the root entry zone of the trigeminal nerve, a maximal dose of 80 Gy was used with a 4-mm collimator so that the 50% isodose line abutted the pons. In the second GKS, the treatment plan consisted of a 70-Gy dose directed at a target 4-5 mm distal to the first target on the trigeminal nerve. The mean follow-up duration in these patients was 42 months. Outcomes were defined using the Marseille scale: excellent (Class I or II, no pain with or without medications), good (Class III or IV, ≥ 50% relief), and poor (Class V, < 50% relief).


RESULTS
Trigeminal neuralgia pain was controlled (≥ 50% improvement with or without medications) after repeat GKS in 70% of patients at 1 year, 50% at 3 years, 50% at 5 years, and 50% at 10 years, as defined by a Kaplan-Meier analysis. A correlation was found between facial numbness and pain relief (p = 0.047). No difference was found between patients with Type 1 TN and those with Type 2 TN, and there was no correlation between the best relief obtained and long-term durability of relief from pain. Twenty-two patients (47.8%) described their trigeminal dysfunction in the following manner: numbness (45.6%), dry eye (10.9%), taste change (8.7%), or jaw weakness (2.2%). In only 8.7% of cases did the patient experience facial numbness that was regarded as bothersome.


CONCLUSIONS
Repeat GKS for TN at the doses used provides substantial long-term relief. Treatment failure occurred up to 28 months after the second GKS. Facial numbness correlated with more durable pain relief after repeat GKS in this series.
Department of Neurosurgery, University of Tennessee Health Science Center, Memphis, Tennessee, USA. brentkimballmd@gmail.com
Brent Y
BY
Kimball
Jeffrey M
JM
Sorenson
David
D
Cunningham
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D016634:Radiosurgery / Q000295:instrumentation*; D011879:Radiotherapy Dosage; D012008:Recurrence; D012086:Reoperation / Q000295:instrumentation; D012189:Retrospective Studies; D016896:Treatment Outcome; D014277:Trigeminal Neuralgia / Q000601:surgery*