Background:
Thoracic outlet syndrome (TOS) is a generic term for neurovascular compression syndromes of the shoulder girdle. Causes may include muscle hypertrophy, cervical ribs and trauma. (1)

Case presentation:
A 20-year-old male patient presented with years of C8-radicular pain that was now increasing. He suffered from motion-dependent claudication. In addition, there had been pulsatile swelling on the left side supraclavicular for years.
The clinical examination showed a cervicothoracic scoliosis with a high left shoulder. Elevation of the arm resulted in loss of pulsation of the left radial artery. A CT angiography showed bilateral cervical ribs from C7. On the left side a pseudarthrosis to the first rib caused an elevation and hypomochlion-like constriction of the subclavian artery. An atypical TOS was diagnosed.
Surgical treatment was not performed through the usual transaxillary approach, but by a trapezoidal approach via the trigonum omoclaviculare by otolaryngology (ENT) together with neurosurgery: Resection of the lateral part of the left cervical rib together with the pseudarthrosis, releasing of the subclavian artery and neurolysis of the brachial plexus with neuromonitoring. Without any complications the patient was symptom-free afterwards.

Conclusion:
A TOS can be caused not only by a cervical rib, but also by its potential pseudoarthrosis to the first rib. A collaboration between ENT and neurosurgery is advisable, as in some cases an axillary approach carries an inadequate accessibility and higher risk of complications.

References:
1. Dengler NF, Pedro MT, Kretschmer T, Heinen C, Rosahl SK, Antoniadis G: Neurogenic thoracic outlet syndrome—presentation, diagnosis, and treatment. Dtsch Arztebl Int 2022; 119: 735–42. DOI: 10.3238/arztebl.m2022.0296

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