1. 2015;18;E363-E368Cryoablation for the Treatment of Occipital Neuralgia
   Retrospective Evaluation
   Chong H. Kim , MD, Wayne Hu, MD, PhD, Jeff Gao, MD, Kristin Dragan, MD, Thomas Whealton, MD, and Christina Julian, MD.

BACKGROUND: Treatment of occipital neuralgia (ON) can be complex, though many treatment options exist. Cryoablation (CA) is an interventional modality that has been used successfully in chronic neuropathic conditions and is one such option. OBJECTIVE: To study and evaluate the efficacy and safety of cryoablation for treatment of ON. STUDY DESIGN: Retrospective evaluation. SETTING: Academic university-based pain management center. METHODS: All patients received local anesthetic injections for ON. Patients with greater than or equal to 50% relief and less than 2 week duration of relief were treated with CA. RESULTS: Thirty-eight pateitns with an average age of 49.6 years were included. Of the 38 patients, 20 were treated for unilateral greater ON, 10 for unilateral greater and lesser ON, and 8 for bilateral greater ON. There were 10 men and 28 women, with an average age of 45.2 years and 51.1 years, respectively. The average relief for all local anesthetic injections was 71.2%, 58.3% for patients who reported 50 – 74% relief (Group 1) and 82.75% for patients who reported greater than 75% relief (Group 2). The average improvement of pain relief with CA was 57.9% with an average duration of 6.1 months overall. Group 1 reported an average of 45.2% relief for an average of 4.1 months with CA. In comparison, Group 2 reported an average of 70.5% relief for 8.1 months. The percentage of relief (P = 0.007) and duration of relief (P = 0.0006) was significantly improved in those reporting at least 75% relief of pain with local anesthetic injections (Group 2 vs Group 1). Though no significance in improvement from CA was found in men, significance was seen in women with at least 75% benefit with local anesthetic injections in terms of duration (P = 0.03) and percentage (P = 0.001) of pain relief with CA. The average pain score prior to CA was 8 (0 – 10 visual analog scale, VAS), this improved to 4.2, improvement of 3.8 following CA at 6 months (P = 0.03). Of the 38 patients, 3 (7.8%) adverse effects were seen. Two patients reported post procedure neuritis and one was monitored for procedure-related hematoma. LIMITATIONS: Study limitations include the retrospective nature of the study. Additionally, only the percentage of relief, pain score, and duration of relief were collected. CONCLUSIONS: CA is safe, and should be considered in patients with ON.