The neck crease as a landmark of Chassaignac's tubercle in stellate ganglion block: anatomical and radiological evaluation

Background: Stellate ganglion block (SGB) is most commonly performed at the transverse process of the sixth cervical vertebra, the identification of which could be difficult in patients with short and wide necks. This study was conducted to evaluate whether the neck skin crease is a reliable indicator of the C6 level. Methods: Forty-nine relatively obese pain clinic patients were investigated. They assumed a standard position for SGB. A radiopaque wire was placed along the neck skin crease caudad to the thyroid cartilage. Next, a radiopaque indicator was placed on the skin above the tubercle found to be most prominent by palpation. X-rays of the neck were obtained after each procedure. Results: The probability that the neck crease would cross C5, C6 and C7 was 16%, 71%, and 12%, respectively. The most prominent tubercle corresponded to the C5, C6 and C7 levels in 16%, 69% and 14% of cases, respectively. Conclusion: The studied means to identify the C6 transverse process was found to correlate well with each other (P<0.001). Since in 30% of cases the C6 process could not be identified by any of the studied means, radiological guidance is recommended in order to ensure optimal safety and efficacy of SGB in selected cases.