Delineation of distal ulnar nerve anatomy using ultrasound in volunteers to identify an optimum approach for neural blockade.

BACKGROUND AND OBJECTIVE

Ultrasound can provide novel approaches to neural blockade independent of surface landmarks. We elucidated the sonoanatomy of the ulnar nerve in the forearm of healthy volunteers in order to identify an optimum site for neural blockade.

METHODS

One hundred forearms were scanned; the shape, depth from skin and cross-sectional area of the nerve were noted at the elbow, forearm and wrist.

RESULTS

The nerve was visualized in all volunteers and had a maximum depth of 18.9 mm from the skin. The mean distance between the nerve and artery, 2 cm proximal to the point where the two structures met in the forearm, was 8.5 mm (95% confidence interval 8.1-8.9 mm). This was approximately at the junction between the proximal 2/5 and distal 3/5 of the forearm.

CONCLUSION

Our study demonstrates that ultrasound can be utilized to identify the ulnar nerve and artery in the forearm. This implies that traditional landmarks will not be required prior to neural blockade. We have suggested a point for blockade of the nerve to reduce risk of vascular puncture.