Analgesic Effectiveness of Nefopam in Patients Undergoing Anterior Cervical Spine Surgery

The investigators enroll 50 patient who admitted for ACDF. Standard general anesthesia will be performed in all of the patients. Then, an hour before finishing operation, the patients will be divided into two groups. The first group will receive Nefopam 20 mg infuse for 60 min. The another group or group NSS will receive the same amount of 0.9% sodium chloride. The recorded data include patient demographic data, intraoperative blood loss, hemodynamics and pre and postoperative pain scores and Thai version of the Neuropathic Pain Symptom Inventory (NPSI‐T score).