Thoracic Outlet Syndrome

Question 1

What is thoracic outlet syndrome and what is it often caused by?

Answer 1

The clinical features that arise from compression of the neurovascular bundle within the thoracic outlet

Neurological (nTOS), Venous (vTOS) and Arterial (aTOS) symptoms

Usualy due to hyperextension injuries, repetitive stress injuries (e.g working over head), external compressive factors (e.g poor posture), anatomical abnormalities (e.g extra cervical rib)

Question 2

What is the pathophysiology of thoracic outlet syndrome?

Answer 2

Brachial plexus and subclavian artery pass through scalene triangle.

Brachial plexus can get compressed between anterior and middle scalene or against the first rib

Usually lower cord that is irritated (ulnar symptoms)

Question 3

What are some risk factors for thoracic outlet syndrome?

Answer 3

• Recent trauma
• Repetitive activity occupations or athletes
• Anatomical variations

Question 4

What are the clinical features of thoracic outlet syndrome?

Answer 4

Depends on arterial, venous and neurological involvement but symptoms often worse with shoulder abduction and extension

On examination look for areas of weakness, numbness, tenderness and any limb ischaemia. Often tenderness over scalene muscles

Question 5

What are some special tests you can do on examination to look for thoracic outlet syndrome?

Answer 5

• Adson’s manouevre
• Roo’s test
• Elvey’s test

Question 6

What investigations are done for suspected thoracic outlet syndrome?

Answer 6

- Initial blood tests (FBC and clotting)

- CXR to look for rib abnormalities (most aTOS have bony issues)

- Venous and Arterial Duplex US at rest and in stress potions for aNOS and vNOS

- CT/MRI or venogram

- Nerve conduction studies for nTOS, often to rule out carpal and cubital tunnel

Question 7

How is each type of TOS treated?

Answer 7

nTOS: physiotherapy to improve mobility in neck and shoulders and relax scalenes. Botulinum toxin injections can help relax scalenes

vTOS: thrombolysis and anticoagulation but most will need surgery to decompress thoracic outlet as well as venoplasty or venous reconstruction

aTOS with acute limb ischaemia: urgent vascular input and embolectomy

Question 8

What are the methods for surgical decompression of the thoracic outlet?

Answer 8

• Supraclavicular or transaxillary approach
• Can excise first or cervical rib
• Can cut any restrictive bands

Question 9

What are some complications of TOS surgery?

Answer 9

• Neurological or vascular damage
• Pneumothorax
• Haemothorax
• Chylothorax especially on left as thoracic duct in the outlet

Question 10

What are some complications of untreated thoracic outlet syndrome?

Answer 10

• Permanent nerve damage
• Aneurysm dilation of subclavian artery leading to embolisation
• Loss of limb function
• Symptom recurrence