Ultrasound-Guided Diagnostic Injections for Neurogenic Thoracic Outlet Syndrome: An Outcomes-Based Cohort Study

OBJECTIVE: Neurogenic thoracic outlet syndrome (NTOS) is an underrecognized problem causing chronic upper extremity symptoms from brachial plexus compression, often affecting overhead athletes. This study evaluated the utility of ultrasound-guided (USG) diagnostic injections for NTOS. DESIGN: This was a retrospective chart review. SETTING: This study was conducted at a single institution. PATIENTS: In total, 203 patients (121 female, 81 male, and 1 nonbinary) with suspected NTOS underwent USG diagnostic blocks. Forty-five were athletes, including 42 overhead athletes. INTERVENTION: A single sports medicine physician performed USG diagnostic injections targeting the pectoralis minor (PM), anterior and middle scalenes, suprascapular nerve (SSN), or quadrilateral space. MAIN OUTCOME MEASURES: Patients reported symptomatic relief >50%. RESULTS: PM blocks were positive in 125/186 (67%) cases and scalene blocks in 85/130 (65%). SSN and quadrilateral space blocks were positive in 34/76 (44%) and 4/11 (36%), respectively. Among 95 nonathletes receiving both PM and scalene blocks, greatest relief was reported with scalene in 40 (42%) and PM in 31 (32.6%), 8 (8.4%) improved with both, 10 (10.5%) with neither, and 6 unreported (6.3%). Among athletes, 36/42 (85.7%) had positive PM blocks and 13/20 (65%) had positive scalene blocks. SSN and quadrilateral space blocks were positive in 9/14 (64%) and 1/3 (33%), respectively. Of 22 athletes receiving both PM and scalene blocks, 16 (73%) reported greatest relief with PM, 4 (18%) with scalene, and 2 (9%) with neither. CONCLUSIONS: PM blocks produced symptom relief comparable with scalene blocks in the general population and were the most effective diagnostic injection in athletes. These results suggest the PM is a more prominent symptom generator in NTOS than previously recognized, particularly in athletes.