About
- Thoracic Outlet Syndrome (TOS) is a condition that can cause pain, weakness, and atrophy of the thenar muscles. It may affect nerve, vein, or artery function.
Aetiology
- Caused by compression of the lower brachial plexus roots (C8 and T1) by a fibrous band or a cervical rib that extends from the C7 transverse process to the first rib.
Clinical Features
- Primarily affects young adults and is more common in females.
- Pain along the ulnar border of the forearm and T1 sensory loss.
- Thenar muscle wasting, with weakness in the abductor pollicis brevis muscle.
- Associated with ipsilateral Horner syndrome in some cases.
- Potential for subclavian vein or artery compression, leading to arm swelling, coolness, or a bluish hue.
Investigations
- CXR: Cervical rib may be visible.
- CT/MRI: Used to detect a fibrous band or other compression structures.
Symptoms are often exacerbated when the arms are positioned overhead.
Management
- Conservative management:
- Physiotherapy and pain relief measures.
- Avoid carrying heavy bags over the shoulder to reduce pressure on the thoracic outlet.
- Daily stretching exercises focusing on the chest, neck, and shoulders to improve muscle strength and flexibility.
- Weight loss if obesity is a contributing factor.
- Most patients experience improvement with these measures. Surgical intervention may be necessary if symptoms persist.
- Surgical options: May involve scalene muscle release and/or removal of the first rib. This is typically done through an incision above the collarbone or via the armpit, based on the surgeon’s recommendation.