Outcomes following single-treatment Gamma Knife surgery for trigeminal neuralgia with a minimum 3-year follow-up.
OBJECTIVE
Gamma Knife surgery (GKS) has been shown to be effective in treating trigeminal neuralgia (TN). Existing studies have demonstrated success rates of 69.1-85% with median follow-up intervals of 19-60 months. However, series with uniform long-term follow-up data for all patients have been lacking. In the present study the authors examined outcomes in a series of patients with TN who underwent a single GKS treatment followed by a minimum follow-up of 36 months. They used a clinical scale that simplifies the reporting of outcome data for patients with TN.


METHODS
Fifty-three consecutive patients with typical, intractable TN received a median maximum radiation dose of 80 Gy applied with a single 4-mm isocenter to the affected trigeminal nerve. Follow-up data were obtained by clinical examination and questionnaire. Outcome results were categorized into the following classes (in order of decreasing success): Class 1A, complete pain relief without medications; 1B, complete pain relief with either a decrease or no change in medications; 1C, > or = 50% pain relief without medications; 1D, > or = 50% pain relief with either a decrease or no change in medications; and Class 2, < 50% pain relief and/or increase in medications. Patients with Class 1A-1D outcome (equivalent to Barrow Neurological Institute Grades I-IIIb) were considered to have a good treatment outcome, whereas in patients with Class 2 outcome (equivalent to Barrow Neurological Institute Grades IV and V) treatment was considered to have failed.


RESULTS
A good treatment outcome from initial GKS was achieved in 31 (58.5%) patients for whom the mean follow-up period was 48 months (range 36-66 months). Outcomes at last follow-up were reflected by class status: Class 1A, 32.1% of patients; 1B, 1.9%; 1C, 3.8%; 1D, 20.8%; and Class 2, 41.5%. Statistical analysis showed no difference in outcomes between patients previously treated with microvascular decompression or rhizotomy compared with patients with no previous surgical treatments. Thirty-six percent of patients reported some degree of posttreatment facial numbness. Anesthesia dolorosa did not develop in any patient.


CONCLUSIONS
Despite a time-dependent deterioration in the success rate of GKS for medically intractable TN, the authors' study showed that > 50% of patients can be expected to have a good outcome based on their scoring system, with approximately 33% having an ideal outcome (pain free with no need for medications). Long-term data, as those presented here, are important when counseling patients on their treatment options.
Boston Gamma Knife Center at Tufts Medical Center, Boston, Massachusetts, USA. rriesenburger@tuftsmedicalcenter.org
Ron I
RI
Riesenburger
Steven W
SW
Hwang
Clemens M
CM
Schirmer
Vasilios
V
Zerris
Julian K
JK
Wu
Kerry
K
Mahn
Paul
P
Klimo
John
J
Mignano
Clinton J
CJ
Thompson
Kevin C
KC
Yao
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005157:Facial Pain; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006987:Hypesthesia; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain; D017060:Patient Satisfaction; D016634:Radiosurgery; D016896:Treatment Outcome; D014277:Trigeminal Neuralgia / Q000601:surgery*