Thoracic Outlet Syndrome
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Direct answer
Thoracic outlet syndrome is compression of the brachial plexus or the subclavian vessels as they pass between the first rib, the clavicle and the scalene muscles. The neurogenic form, causing arm pain, paraesthesia and intrinsic hand weakness, is the most common type. Physiotherapy is the first step, and first rib resection is reserved for refractory neurogenic cases and for vascular disease.
What you must remember
- Thoracic outlet spaces: the scalene triangle, the costoclavicular space and the retropectoralis minor space transmit the brachial plexus and the subclavian artery and vein.
- Cervical rib: an extra rib from C7 can compress the lower trunk and subclavian artery, but it is found in only a minority of patients.
- Neurogenic form: the lower trunk (C8 and T1) is most often compressed, producing ulnar-sided forearm pain and paraesthesia.
- Vascular form: arterial compression causes digital ischaemia, while venous effort thrombosis is Paget-Schroetter syndrome in young, active adults.
- Adson test: loss of the radial pulse on head rotation, neck extension and deep inspiration.
- Roos test: the elevated arm stress test reproduces symptoms within about three minutes of repeated hand opening and closing.
- Management: physiotherapy first, first rib resection with scalenectomy for refractory cases, and thrombolysis for venous thrombosis.
A graded pathway from suspicion to surgery
Thoracic outlet syndrome is a clinical diagnosis of exclusion, so the reasoning follows history, provocation tests and targeted imaging in sequence. Each step narrows whether the problem is neurogenic, arterial or venous.
- Sort the symptoms: ulnar-sided arm pain, heaviness and paraesthesia suggest the neurogenic form, while a cold, pale or swollen arm suggests a vascular cause.
- Examine the hand: wasting of the thenar and hypothenar muscles, the classic Gilliatt-Sumner hand, indicates lower trunk involvement.
- Perform provocation tests: the Adson and Roos tests can be positive in healthy people too, so they matter only when they reproduce the patient's own symptoms.
- Image the anatomy: a cervical X-ray detects a cervical rib, while duplex ultrasound or CT angiography assesses the subclavian vessels.
- Confirm the neurogenic form: nerve conduction studies support the diagnosis and exclude other causes of hand weakness.
- Start physiotherapy: posture correction, scalene and pectoral stretching and shoulder strengthening are continued for several months.
- Operate on refractory cases: first rib resection with scalenectomy relieves compression, and venous thrombosis is treated by thrombolysis followed by rib resection.
Where the exam tries to catch you
Most questions hinge on separating the neurogenic form from the vascular form and on knowing which test belongs to which.
- Trap: choosing surgery first for typical neurogenic thoracic outlet syndrome. Correct: physiotherapy is tried first for several months, because many neurogenic patients improve without an operation.
- Trap: treating a swollen, bluish arm in a young athlete as a muscle strain. Correct: this is effort thrombosis, which needs urgent thrombolysis and first rib resection.
- Trap: taking a positive Adson test as proof of the diagnosis. Correct: the test is often positive in asymptomatic people, so it must be read with the history and imaging.
Frequently asked questions
Which provocation tests are used in thoracic outlet syndrome?
The Adson test and the Roos elevated arm stress test are the two most commonly used provocation tests in thoracic outlet syndrome. The Adson test looks for loss of the radial pulse, while the Roos test reproduces the arm symptoms with the arms elevated. Both results must be interpreted together with the patient's history and imaging.
What is Paget-Schroetter syndrome?
Paget-Schroetter syndrome is effort thrombosis of the axillary or subclavian vein, typically seen in young and active individuals. It presents as sudden arm swelling, pain and bluish discolouration. Thrombolysis followed by first rib resection is the usual approach to prevent recurrence.
Why is the lower trunk most often affected in thoracic outlet syndrome?
The lower trunk, formed by the C8 and T1 roots, lies closest to the first rib, so it is most often compressed in thoracic outlet syndrome. Compression produces ulnar-sided forearm pain, paraesthesia in the little finger and weakness of the intrinsic hand muscles. Upper trunk involvement is less common.
What is the first-line treatment for neurogenic thoracic outlet syndrome?
Physiotherapy is the first-line treatment for neurogenic thoracic outlet syndrome. It aims at posture correction, stretching of the scalene and pectoral muscles and strengthening of the shoulder girdle. Surgical decompression by first rib resection is reserved for patients who fail a full course of physiotherapy.