Prospective Analysis of the Greater Occipital Nerve Location in Patients Undergoing Occipital Nerve Decompression

Background Migraine surgery and onabotulinumtoxinA injections aim to deactivate neurovascular trigger points implicated in chronic headaches. The greater occipital nerve (GON) is a common trigger point. The depth of this nerve has not been previously described. The purpose of this study was to report the intraoperative location, including depth, of the GON in human subjects undergoing migraine surgery. Methods We reviewed records of patients who underwent GON decompression by a single surgeon. Intraoperative measurement of the GON location lateral to midline, inferior to the occipital protuberance, and deep to the skin was collected for 2 previously described positions: where GON (a) enters, "point #2," and (b) exits, "point #3," the semispinalis muscle as it travels from deep to superficial (Plast Reconstr Surg. 2010;126:1563–1572; Plast Reconstr Surg. 2004;113:693–697). Results Thirty-four subjects (60 nerves) were included. The mean depths of the GON were 20 mm (SD, 4) at point no. 3 and 30 mm (SD, 6) at point no. 2. In 26 subjects who underwent bilateral surgery, there was a difference between right and left nerve position lateral to midline at point no. 3 (P = 0.008). Female sex (P = 0.014) and body mass index of 29 kg/m2 or less (P