Sonographically guided anesthetic injection of anterior scalene muscle for investigation of neurogenic thoracic outlet syndrome.

OBJECTIVE: To describe the technique and complications of sonographically guided anesthetic injection of the anterior scalene muscle in patients being investigated for neurogenic thoracic outlet syndrome.

MATERIAL AND METHODS: Subjects were identified via a retrospective review of medical records. For the procedure a 25-gauge needle was introduced into the anterior scalene muscle under real-time ultrasound guidance followed by injection of local anesthetic. The procedures were evaluated for technical success, which was defined as satisfactory identification of anterior scalene muscle, intramuscular needle placement, and intramuscular delivery of medication. There was a short-term follow-up to determine procedure-related complications and rate of unintended brachial plexus (BP) block, manifested by upper extremity paresthesias and/or weakness.

RESULTS: Twenty-six subjects with suspected neurogenic thoracic outlet syndrome underwent 29 injections (three subjects received bilateral injections). Technical success was achieved in all procedures. The mean duration of the procedure was 30 min, and there were no cases of intravascular needle placement or neurogenic pain during the injection. No major complications occurred. Temporary symptoms of partial BP block occurred after nine injections (9/29, 31%), and a temporary complete BP block occurred after one injection (1/29, 3%).

CONCLUSION: Sonographically guided anesthetic injection of the anterior scalene muscle is a safe and well-tolerated diagnostic test for patients being investigated for neurogenic thoracic outlet syndrome.