Causes of persistent and recurrent symptoms after first-rib resection for neurogenic thoracic outlet syndrome: A narrative review

Neurogenic thoracic outlet syndrome (NTOS) may persist after surgery or recur after an initial period of improvement. These outcomes are clinically important because reoperation is technically more demanding, the anatomical cause is often uncertain, and symptom relief is less predictable than after primary decompression. This narrative review examines the mechanisms, diagnostic work-up, and treatment of persistent and recurrent symptoms after first-rib resection and related thoracic outlet decompression. A targeted review of clinical series, registry studies, long-term outcome studies, and systematic reviews was performed, with particular emphasis on studies describing reoperative findings and outcomes. The literature consistently identifies several overlapping mechanisms: retained or residual first-rib segments, residual or reattached scalene muscle, perineural fibrosis, unrecognized pectoralis minor syndrome, multilevel compression, mixed neurovascular compression, secondary injury, and an incorrect or incomplete original diagnosis. Importantly, recurrent NTOS may occur even after an anatomically complete primary decompression; in such cases, dense perineural scar tissue encasing the brachial plexus can be the principal operative finding. Dynamic arterial compression may coexist with neurogenic symptoms and should be considered when discoloration, exertional ischemic symptoms, a positional bruit, or marked changes in subclavian artery flow are present. Diagnostic injections add functional information: a positive response to ultrasound-guided botulinum toxin injection of the anterior scalene and pectoralis minor muscles has a high positive predictive value for surgical response, although a negative response does not reliably exclude benefit. Reoperation is most defensible when symptoms, examination, imaging, and injection response converge on a correctable anatomical target. Complete supraclavicular reoperation and isolated reoperative brachial plexus neurolysis can improve disability and symptoms in selected patients, but outcomes remain variable and complications may be underestimated by 30-day reporting. Careful phenotyping, exclusion of mimics, and treatment in experienced multidisciplinary centers are central to avoiding unnecessary repeat surgery and improving long-term results.