Clinical Efficacy of an Ultrasound-Guided Greater Occipital Nerve Block at the Level of C2.

Abstract

The purpose of this prospective open-label study was to investigate the analgesic effects of an ultrasound-guided greater occipital nerve (GON) block at the level of C2, as the nerve courses superficially to the obliquus capitis inferior muscle. Patients with a diagnosis of occipital neuralgia or cervicogenic headache were recruited for the study. Ultrasound-guided GON blocks at the level of C2 were performed by experienced clinicians according to a standardized protocol. Numeric rating scale pain scores were recorded preinjection and at 30 minutes, 2 weeks, and 4 weeks after injection. A total of 14 injections were performed with a mean procedure time of 3.75 minutes. Anesthesia in the GON distribution was achieved for 86% of patients at 30 minutes postinjection. Compared with baseline, numeric rating scale scores decreased by a mean of 3.78 at 30 minutes (P < 0.001), 2.64 at 2 weeks (P = 0.006), and 2.21 at 4 weeks (P = 0.01). There were no significant adverse events reported during the study period. This prospective open-label study demonstrated successful blockade of the GON at the level of C2 using a novel ultrasound-guided technique. Significant reductions in pain scores were observed over the 4-week study period, and no adverse events were reported. The observations from this study provide important preliminary data for future randomized trials involving patients with occipital neuralgia and cervicogenic headache.