PR_175: Arterial Micro-Embolism Following Carpal Tunnel Injection: A Case Report

Abstract

Setting: Outpatient hand specialty clinic. Patient: A 51-year-old woman with bilateral carpal tunnel syndrome. Case Description: The patient described paresthesias in her right thumb, index and middle fingers. Examination demonstrated a positive Phalen sign, carpal tunnel compression, and Tinel sign on the right. Electromyography showed bilateral median neuropathies, moderately severe on the right and mild on the left. Using sterile technique, a 25-gauge, 3.2-cm (1.25-in) needle was introduced to the ulnar side of the palmaris longus tendon, proximal to the distal wrist crease. The needle was directed toward the carpal tunnel at a 45° angle. A mixture of 1.5mL of 40mg of triamcinolone (Kenalog) and 1.5mL of lidocaine was injected. After injection, the patient’s right hand exhibited signs of ischemia including coolness and discoloration of the entire hand and all the digits. Her hand was dipped in paraffin 5 times and warmth was maintained for 20 minutes. She regained normal color in the hand but described coolness. Assessment/Results: At follow-up visits, the patient described burning in the hand and blotchiness and superficial skin necrosis of the digits was noted. Magnetic resonance angiogram of the right wrist and vascular medicine consult were normal. She underwent an open carpal tunnel release approximately 6 weeks postinjection. Surgical exploration demonstrated no evidence of needle tracking near the median nerve nor the ulnar or radial arteries. The ischemic changes were presumed to be due to microvascular emboli. Discussion: To our knowledge, this is the first reported case of arterial microembolism following carpal tunnel injection. The exact etiology of the microembolism is unclear, but may be related to vasospasm as has been described in the spine injection literature. Conclusions: This case illustrates an uncommon adverse event in a commonly performed procedure and raises questions for further review.