The space between the clavicle and the first rib is relatively small, which is an anatomical weak point where the neurovascular bundle to the upper limb passes through. If the clavicle or first rib undergoes morphological changes, it can further narrow the costoclavicular space, compressing the neurovascular bundle within and causing symptoms, a condition known as costoclavicular syndrome.

bubble_chart Etiology

The pathological causes of the disease include the following four aspects: First, deformity of the first rib. Normally, the first rib curves forward and downward, but in cases of variation, it may lie horizontally or be positioned higher, which can compress the neurovascular bundle above it. Second, scoliosis of the cervicothoracic spine or congenital hemivertebrae can twist the thoracic outlet, causing the first rib to elevate. Third, fractures of the clavicle or first rib, with excessive callus formation or malunion after healing, can reduce the costoclavicular space or even result in displaced fragments of a comminuted clavicular fracture injuring nerves or blood vessels. Fourth, hypertrophy of the subclavius muscle can compress the neurovascular structures.

bubble_chart Clinical Manifestations

The onset of the disease can be gradual or acute.

1. Nerve compression: Pain and discomfort in the neck and shoulder, with radiating numbness and tingling in the ipsilateral upper limb, particularly in the forearm and the inner side of the hand.

2. Vascular compression: Intermittent pain, swelling, and coldness in the hand, along with dry skin, cyanosis, and weakened radial pulse.

During examination, pushing the patient's shoulder backward and hyperextending the neck can exacerbate the numbness and tingling, as well as obstruct venous return in the upper chest and upper limb, leading to venous distension. Sometimes, the radial pulse may weaken or disappear due to compression. Flexing the neck and lowering the upper limb can alleviate the symptoms. Motor dysfunction is rarely observed in this condition. It is difficult to differentiate from cervical rib or anterior scalene syndrome. Cervical ribs can be distinguished using X-rays, while angiography can help identify anterior scalene syndrome.

The conservative treatment is the same as for anterior scalene syndrome. If conservative treatment is ineffective and symptoms are severe, surgical intervention is required. The surgical method involves the transaxillary resection of the first rib: the patient is placed in a lateral position with the affected side up, and a transverse incision is made along the skin fold in the axilla, extending anteriorly beyond the anterior border of the pectoralis major muscle and posteriorly across the posterior border of the axilla. The skin and subcutaneous tissues are incised, and the first and second ribs along with the anterior scalene muscle are exposed deeper. The upper limb is fully elevated when the first rib is identified during upward dissection. The first rib is carefully separated, identifying various structures: the brachial plexus posteriorly, the subclavian vein anteriorly, and the subclavian artery and anterior scalene muscle in between. The anterior and middle scalene muscles are detached from their insertion points, followed by the detachment of the origin of the subclavius muscle. Care must be taken to avoid injuring the internal jugular vein while freeing the anterior scalene muscle. The first rib is subperiosteally dissected, ensuring the pleural membrane is not damaged. The first rib is then transected near the costochondral junction, and a disarticulation is performed posteriorly at the transverse process. If the pleural membrane is accidentally ruptured, a small catheter is placed at the rupture site, the surrounding pleura is closed, and the other end of the catheter is connected to a water-seal bottle for closed drainage.