Bilateral Brachial Plexus Injury After MiraDry Procedure for Axillary Hyperhidrosis

Background: Multiple treatments are available for primary axillary hyperhidrosis including noninvasive, microwave-based thermal treatments designed to destroy sweat glands in the axilla. Often these procedures involve local anesthetic injection to the axilla, followed by placement of the microwave emitter onto the skin and applying the heat treatment to varying depths of the subcutaneous tissues. Case Description: A 49-year-old, thin, active woman (body mass index 19.6) underwent microwave-based treatment to the bilateral axillary regions. She experienced an electric sensation into the ulnar digits of the right hand during anesthetic injection and then underwent the microwave thermal treatment. She suffered a bilateral brachial plexus injury with imaging evidence of severe, subcutaneous edema surrounding the nerves of the plexus in the axilla, as well as denervation atrophy of the arm and forearm muscles bilaterally. At the time of evaluation and electromyography, 8 months after treatment, she had recovered significant strength in the left upper extremity but continued to have evidence of a severe radial nerve injury on the right. Electromyography demonstrated some recovery, and observation was recommended followed by secondary reconstruction if required. It is likely that the patient sustained thermal injury to the nerves in the axilla bilaterally, given the close proximity to the skin surface in a patient with a low body mass index. Conclusions: In thin patients undergoing treatment of primary axillary hyperhidrosis, consideration should be given to the distal brachial plexus, which may be at risk of damage with high-powered microwave-based therapy.