Gamma Knife Surgery for Essential Trigeminal Neuralgia: New Treatment Strategy with Robotized Micro-Radiosurgery

Gamma knife surgery (GKS) is a minimally invasive treatment for brain diseases, and is currently used for functional disorders. Moreover, a revised version of Gamma knife system, “Model C-APS (automatic positioning system)” started to be installed in Japan since 2001. This latest model enables us to adjust coordinates by every 0.1 mm, and treat the patient automatically. We have completed a retrospective study of 200 patients suffering from essential trigeminal neuralgia (TGN) treated with GKS in which the target was localized at the retro-gasserian portion of the nerve (We have treated 157 patients with essential TGN by “Model C-APS”). Among the patients, 106 could be followed up more than 6 months, and we evaluated a causeand-effect relationship between the technical development and the clinical results. We categorized patients into three groups based on the term mentioned as follows; 1 st are the patients treated by Model B without completed fusion images (CFI) in between 1999 and 2001, 2 nd are the patients treated by Model B with CFI in 2002, and 3 rd are those treated by model C-APS with CFI since 2003. Clinical result, initial pain free was observed in 62.9% (1st group), 85.7 % (2nd group), 99.1% (3rd group), complete recurrence was observed in 12%, 8.3 %, 0 % for each groups, and postoperative complication was observed in 14.8%, 14.3%, and 9.5% respectively. We believe that precise dose planning, so-called “Robotized Micoro Radiosurgery”, is