Analysis of Factors Predicting for Pain Resolution after Gamma Knife Radiosurgery for Medically Refractory Trigeminal Neuralgia

Materials/Methods: Ninety-five patients underwent GK for TGN between 12/2006-6/2009 at William Beaumont Hospital. Eighty had follow-up $6 weeks and were the subject of this report. Median patient age was 68y (30-92); 58 female, 22 male. 74% of patients had typical trigeminal pain, 11% atypical features and 11% multiple sclerosis. Thirty patients (38%) had undergone prior surgical procedures and 37 (46%) had preexisting sensory complaints. The median dose delivered was 40 Gy (range: 35-45 Gy) to the 50% isodose line (80 Gy max) using either a single (85%) or two (6%) isocenters with a 4 mm collimator, or two isocenters with a 4 and 8 mm collimator (9%). Patients were seen #2 weeks post-GK, then every 3-6 months in addition to periodic mail surveys and telephone interviews. Pain was evaluated using the Barrow Neurological Institute Pain Intensity Scale. Multiple patient and GK factors were analyzed for association with pain relief. Mean follow-up duration was 15.6 months.