CT-only planning for Gamma Knife radiosurgery in the treatment of trigeminal neuralgia: Methodology and outcomes from a single institution

Introduction: Gamma Knife radiosurgery (GKRS) has been established as a safe and effective treatment option for trigeminal neuralgia. Some patients have contraindications to magnetic resonance imaging (MRI), the standard stereotactic imaging used for GKRS treatment planning. Computerized tomography (CT) imaging may be used as an alternative in this scenario. We sought to evaluate the outcomes of our patients treated using this technique. Methods: Between August 2001 and November 2009, 19 patients with trigeminal neuralgia were treated with GKRS using CT-only planning. The course of the trigeminal nerve was determined based upon anatomical landmarks when the nerve was not directly visualized on the treatment-planning CT. Median dose used was 90 Gy (range 8590 Gy). Follow-up data based on Barrow Neurological Institute (BNI) pain score and toxicity were obtained using electronic medical records and by telephone interview. Results: With median follow-up time of 18 months (range 436 months), improvement in quality of life after GKRS was reported in 17 of 19 patients. Freedom from BNI IV-V pain relapse was 82% at 24 months. By 3 months post-GKRS, 50% of patients were able to discontinue medications completely. Three patients reported numbness after GKRS; none of these patients described bothersome numbness. Use of contrast did not affect treatment outcome (P = 0.31). Conclusions: Stereotactic CT-only treatment planning of GKRS for the treatment of trigeminal neuralgia is feasible and safe. Further studies are necessary to determine if the long-term durability of pain relief is comparable to that of MRI-based GKRS planning.