Background: Third occipital nerve block (TONB) is commonly used in the diagnosis and treatment of upper neck pain and cervicogenic headaches. Although fluoroscopy is the current imaging standard for TONB, ultrasound (US) guidance offers a promising, radiation-free alternative. In this randomized, observer-blinded trial, we compared the 2 imaging modalities. Our research hypothesis was that US guidance would result in a shorter performance time.
Methods: Forty patients undergoing TONB were randomized to fluoroscopy or US guidance. A mixture of local anesthetic and radiographic contrast was injected in both groups. The primary outcome was performance time. Secondary outcomes included success rate, pain levels before and after block, area of sensory hypoesthesia, quality of the block (assessed by electrical perceptual threshold), and procedure-related complications.
Results: Ultrasound guidance was associated with a significantly shorter performance time (212.8 vs 396.5 seconds; P = 0.000) and fewer needle passes (2 vs 6; P = 0.000). Both imaging modalities, however, resulted in similar success rates (95%-100%). Furthermore, no intergroup differences were found in preblock and postblock pain scores. In both groups, TONB produced hypoesthesia that was most profound in the suboccipital region. In the fluoroscopy group, C2-C3 intra-articular spread of radiographic contrast and vascular breach were noted in 15% and 10% of patients, respectively. In contrast, no adverse events occurred with US guidance.
Conclusions: Fluoroscopy and US guidance provide similar success rates for TONB. However, ultrasonography is associated with improved efficiency (decreased performance time, fewer needle passes).