Thoracic outlet syndrome caused by pseudoarticulation of a cervical rib with the scalene tubercle of the first rib

Abstract

A healthy 20-year-old man presented with a bony lump above the left clavicle associated with upper limb pain, numbness, and tingling. Examination in the surrender position elicited left hand weakness and pain with loss of the radial pulse. The patient had paresthesia of the ulnar border of the left hand but no interossei wasting. A lateral neck radiograph identified an unusual bony contour anteriorly at C7/T1 suggesting a cervical rib (A). Duplex ultrasound scan showed widely patent left axillary and subclavian arteries with the arm adducted but severe compression of the subclavian artery on abducting the arm to 90°. A subsequent computed tomography angiogram confirmed bilateral cervical ribs; the left articulating with an extended left transverse process of the seventh cervical vertebra, extending inferiorly to fuse with the first rib (B and C/Cover). The left subclavian artery passed immediately superior to this bony extension whereas the left vertebral artery lay immediately anterior to the origin of the cervical rib at C7. The right cervical rib was much smaller and not in proximity to the vessels. Intraoperatively, the left cervical rib was found to extend from the C7 transverse process to form a true joint with a hypertrophied scalene tubercle on the first rib; both the cervical rib and hypertrophied scalene tubercle were excised via the supraclavicular incision (D). A T1 sensory and motor neuropraxia was noted day 1 postsurgery which, together with his preoperative symptoms, completely resolved within 5 days and continued at 5-month follow-up. Cervical ribs are a known cause of arterial and neurogenic thoracic outlet syndrome. These congenital abnormalities occur in 1% of the population but are bilateral in 50%. Ninety percent are asymptomatic and do not require resection. Complete cervical ribs occur in approximately 25% of patients, most commonly attached to the first rib by a fibrous band, or more rarely, as in this case, via a true joint, often with the scalene tubercle. Surgical management involves removal of the cervical rib; if this does not provide adequate decompression of the subclavian artery and the brachial plexus, removal of the first rib should be done.