A Sonographically Guided In-Plane Distal-to-Proximal Transligamentous Approach to Carpal Tunnel Injections

Several sonographically guided injection methods have been described to treat carpal tunnel syndrome. In most cases, the medication diffuses through the carpal tunnel to the site of maximum compression of the nerve after being injected proximally. In this article, we describe a novel method of sonographically guided carpal tunnel injection that utilizes a distal-to-proximal, in-plane, and transligamentous approach. This novel method may provide ergonomic as well as safety advantages to both clinicians and patients, and should be considered by those performing carpal tunnel injections.

A distal-to-proximal transligamentous approach is taken, utilizing high-resolution ultrasound guidance. Once the median nerve is sonographically visualized longitudinally within the carpal tunnel, an ulnar shift is made with the transducer. With the median nerve out of view, the needle is inserted in-line and distal to the transducer on the palmar side of the hand, at the ulnar portion of Kaplan's cardinal line. Following a trajectory that is nearly parallel to the median nerve, the needle is sonographically guided to the site of maximum nerve compression.

This novel method provides an alternative to previous carpal tunnel injections. The use of ultrasound guidance allows the clinician to visualize and avoid the neurovascular structures near the median nerve and guide the needle to the site of maximum nerve compression. It is possible that this parallel trajectory with the median nerve will provide a lower risk of damage to the nerve.