Ultrasound-guided third occipital nerve and cervical medial branch nerve blocks

Chronic neck pain following whiplash injury is caused by cervical zygapophysial joints in up to 50% of patients. Diagnostic blocks of nerves supplying the joints are mandatory to diagnose zygapophysial joint pain and are usually done under fluoroscopic (or CT) control. Ultrasound (US) guidance may be a very useful alternative to block the nerves supplying the cervical facet joints lower than C2. In contrast to fluoroscopy or CT, in most patients, the cervical medial branches can be visualized by US. One exception is the nerve at the level of C7, where the superimposed layer of soft tissue does not allow visualizing this small nerve in most patients. The needle tip can be advanced under direct view, and the local anesthetic can be injected close to the targeted nerve. One important advantage of US is the direct visualization of the spread of the injected local anesthetic and therefore no need for contrast injection. If the nerve is not reached by the injected local anesthetic in the first attempt, a minor adjustment of the needle tip position and a second injection can correct this.