Background: Local steroid injection may be an effective conservative treatment for carpal
tunnel syndrome; however, the use of a blind injection technique can increase the chance of
median nerve or ulnar artery injury due to median nerve swelling or the close proximity of the
median nerve and ulnar artery around the distal wrist crease.
Objectives: The purpose of this study is to investigate the relative location of the median nerve
and ulnar artery to the palmaris longus (PL) tendon around the wrist in carpal tunnel syndrome.
Study Design: An observational study.
Setting: A university outpatient interventional pain management practice in the Republic of
Korea.
Methods: Thirty hands of 15 patients with carpal tunnel syndrome and 30 hands of 15 healthy
subjects were studied. Ultrasonography was performed to determine the relative relationship of
the ulnar artery and median nerve to the PL tendon around the wrist.
Results: There were statistically significant differences both in the distance from the medial
margin of the PL to the medial end of the median nerve and the distance from the medial end
of the median nerve to the lateral end of the ulnar artery at all levels of scanning between the
2 groups.
Limitations: Limitations include the inclusion of a small number of patients with carpal tunnel
syndrome.
Conclusion: It is important to recognize the risk of blind local steroid injection for carpal
tunnel syndrome, which is most likely a result of swelling and/or flattening of the median nerve
around the distal wrist crease. A real time, ultrasound-guided local steroid injection is preferred
as a safe and accurate technique in carpal tunnel syndrome treatment.
Key Words: Carpal tunnel syndrome, median nerve, ulnar artery, injection, steroid, injury,
ultrasonography, risk, cross-sectional area
Anatomical Basis of Ulnar Approach in Carpal
Tunnel Injection
