A Cadaver Study Investigating Structures Encountered by the Needle During a Retroclavicular Approach to Infraclavicular Brachial Plexus Block.

BACKGROUND AND OBJECTIVES: Retroclavicular block is designed to overcome the negative aspects of the commonly utilized ultrasound-guided parasagittal approach to the infraclavicular block. However, this approach necessitates the needle traversing an area posterior to the clavicle inaccessible to ultrasound wave conduction. This study sought to document the structures vulnerable to needle injury during a retroclavicular block.

METHODS: A Tuohy needle was inserted using a retroclavicular approach to the infraclavicular block in 3 lightly embalmed cadavers followed by a catheter insertion 4 cm beyond the needle tip. The process was repeated on the contralateral side. With the needle and catheter in position, the cadavers were dissected and photographed.

RESULTS: In 4 of the 6 dissections, the needle was directly touching the suprascapular nerve deep to the clavicle. In the remaining 2 dissections, the suprascapular nerve was within 2 cm of the needle. In 1 dissection, the suprascapular vein was indented, behind the clavicle. The trapezius was the only muscle layer traversed by the needle in all dissections. In 3 of the 6 dissections, the catheter penetrated the posterior cord. In the remaining 3, the catheter threaded along the neurovascular bundle.

CONCLUSIONS: The suprascapular nerve is consistently in the path of the block needle posterior to the clavicle. This raises the possibility of risk of injury to the suprascapular nerve when using this approach to the brachial plexus. Vascular injury is also possible deep to the clavicle, and because of the noncompressible location, caution is advised in patients with disordered coagulation.