Evaluation of sonoanatomy relevant to performing stellate ganglion blocks using anterior and lateral simulated approaches: an observational study

Stellate (cervicothoracic) ganglion block (SGB) can be associated with serious complications, such as esophageal and vascular injury. The objective of this study was to evaluate the potential for vascular and esophageal injury in healthy subjects by examining the sonoanatomy of the neck relevant to the SGB at the sixth (C6) and seventh (C7) cervical vertebral levels and determining the incidence of blood vessels and esophagi in the simulated path of needle insertion in the conventional and two different ultrasound-guided approaches used to perform a SGB. Ultrasound scanning of the neck at the C6 and C7 cervical vertebral levels was performed in 100 adult subjects, and the following measurements were obtained: the degree of deviation of the esophagus relative to the larynx/trachea; the likelihood of encountering a vessel in the simulated path of needle insertion in the two different approaches to SGB; the incidence of the vertebral artery being situated outside the foramen transversarium at the C6 level; and the distance of the simulated path of needle insertion in the anterior and lateral approaches to SGB at the C6 level. The position of the esophagus was found to be variable but lateral to the airway in 50% and 74% of the subjects at C6 and C7, respectively. The esophagus covered more than half of the distance between the airway and the carotid artery in 14% and 44% of the subjects at the C6 and C7 levels, respectively. With the anterior approach, a major vessel was observed in up to 29% and 43% of patients at the C6 and C7 levels, respectively. The vertebral artery was outside the foramen transversarium in 7% of subjects at the C6 level. Major blood vessels and the esophagus are in close proximity to needle pathways during the anterior approach to SGB performed with either anatomic landmarking or fluoroscopic guidance. An ultrasound-guided lateral approach at the C6 level may possibly confer a greater margin of safety for performing SGB.