Long Term Follow Up Of 51 Cases Of Idiopathic Trigeminal Neuralgia (itn) Treated With Gamma Knife Surgery.

Keywords: pain, gamma knife, trigeminal neuralgia, outcome, radiosurgery

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     To study the long term efficacy of Gamma Knife surgery for ITN.
     Between 1995 and 2008, 51 patients with ITN were treated at the Hong Kong Gamma Knife Centre. Mean age was 67.6 years (range 39-89). 38 were referred after medical treatment failure. 13 had failed prior surgery and ablation procedures.
     The first 13 patients were treated with the trigeminal nerve (TN) targeted at the root entry zone with 70-80 Gy. For remaining 38 patients, the TN was targeted more distally with 90Gy. Follow up consists of calling patients every 6 to 12 months to check on pain status and side effects. All patients were contacted prior to this study. Responses were classified as pain free without medications (PF); pain free with medications (PFWM); pain relieve with medications (PRWM) and no relieve (NR).
     Overall results were 29 (57%) PF; 7 (14%) PFWM; 13 (25%) PRWM and 2 (4%) NR. 5 patients had a second treatment because of NR.  Pain free onset varied from 0 to 30 months, mean 7.4 months. 16 (33%) patients had numbness – 9 mild and 7 moderate with no significant impact on quality of life. 13 patients had prior surgery and ablation procedures; 5 had microvascular decompression (MVD); 6 had thermal/radiofrequency ablation and 2 had both MVD and ablation procedures. Mean follow up was 7 years. Pain control for this group was similar to that of the overall group. 31 (61%) had more than 5 years follow up, mean 6.6 years. Pain control of this group was also similar to the overall group.
     This is a retrospective study.
     In our series of 51 patients, overall pain control occurred in 49 ( 96% ) with 29 (57% ) achieving pain free without medications. Both the long term follow up group ( > 5years) and more surprisingly, the group with prior surgery and ablation procedures achieved similar pain control.  Average time to pain free was 7.4 months. Side effects were minimal and tolerable. 
     Gamma Knife surgery is an effective treatment for medically and surgically refractory ITN with excellent long term efficacy and minimal side effects.


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