Thoracic Outlet Syndrome

Question 1

What is thoracic outlet syndrome?

Answer 1

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

Question 2

What can signs and symptoms be divided into?

Answer 2

Neurological nTOS (most common)

Venous vTOS

Arterial aTOS

Most people affected are between 20-50 yo

Question 3

When does TOS usually occur?

Answer 3

In setting of hyperextension injuries

Repetitive stress injuries

External compressing factors

Can also be secondary to anatomical abnormalities

Question 4

Anatomy of structures by thoracic outlet

Answer 4

Brachial plexus and subclavian artery pass through the scalene traingle

Subclavian vein passes anterior to anterior scalene

Brachial plexus can be compressed between anterior and middle scalene or against the 1st rib or a cervical rib.

Typically it is the lower cord that becomes irritated.

Question 5

Pathophysiology of TOS

Answer 5

Hypertrophy of scalene muscles or abnormality in first rib or presence of a cervical rib can all lead to compression on the brachial plexus or subclavian artery.

Previous clavicle fractures can lead to abnormal bony healing and lead to TOS

Costoclavicular ligmanet can reduce the costoclavicular space leading to vTOS

Question 6

What is a cervical rib?

Answer 6

An extra rib that arises from the seventh cervical vertebra

Happens in 0.2-0.5% of the poopulation and can be partial or complete.

Question 7

RIsk factors

Answer 7

Recent trauma

Repetitive motion occupations

Athletes

Anatomical varitations

Question 8

Clinical features depend on neurological, arterial or venous involvement,

Symptoms may also worsen on certain movements.

Symptoms of nTOS

Answer 8

Paraesthesia and/or motor weakness often in ulnar distribution

Muscle wasting and pain can radiate to the neck and upper part of back.

Question 9

Clinical features of vTOS

Answer 9

DVT and extremity swelling called Paget-Schrötter syndrome

In untreated severe cases there can be prominent veins over the shoulder due to collateralisation

Question 10

Clinical features of aTOS

Answer 10

Claudication symptoms or acute limb ischaemia through either occlusion, distal embolisation or aneurysm formation.

Question 11

Examination findings

Answer 11

Weakness or numbness

Swelling or tenderness

Limb ischaemia features

Tenderness over the scalene muscles

Question 12

Special tests for TOS

Answer 12

Adson’s manoeuvre

Roo’s test

Elvey’s test

Question 13

Explain Adson’s

Answer 13

Palpate radial pulse on the affected side with the arm initially abducted 30 degrees

Ask the patient to then turn their head and look at the affected side’s shoulder.

Fully abduct , extend and laterally rotate the shoulder

+ve = Decrease or loss of pulse

Question 14

Explain Roo’s test

Answer 14

Abduct and externally rotate the shoulder on the affected side to 90 degrees, bend the elbow to 90 degrees and then ask the patient to open and close the hands slowly over a 3 minute period.

+ve = Worsening of symptoms

Question 15

Explain Elvey’s test

Answer 15

Extend the arm to 90 degrees with the elbow extended and wrist dorsiflexed

Tilt the patients ear to each shoulder

+ve = Loss of radial pulse or worsening symptoms

Question 16

Initial blood tests

Answer 16

FBC and clotting screen

Question 17

Initial imaging

Answer 17

CXR to identify any bony abnormalities like

cervical ribs

long transverse cervical processes

Rib/clavicular fracture calluses

Question 18

Special investigation for vTOS or aTOS

Answer 18

Venous and arterial duplex USS

The patient should be at rest with the arm in stress positions

CT or MRI imaging or a venogram may be used as well.

Question 19

Investigations for nTOS

Answer 19

Nerve conduction studies to allow detection of decreased action potential conductance due to nerve compression.

Usually used to rule out carpal tunnel and cubital tunnel syndrome rather than diagnose nTOS

Question 20

nTOS management

Answer 20

First line is physiotherapy for 6 months to improve mobility in the neck and shoudler and strengthen surrounding musculature and relax the scalenes.

Botox can also be effective to help relax the scalenes

Question 21

vTOS management

Answer 21

Thrombolysis and anti-coagulation

Most cases howevere will require surgical management to decompress the thoracic outlet.

Question 22

aTOS management with acute limb ischaemia

Answer 22

Urgent vascular input for embolectomy

Most cases are however due to anatomical abnormalities so elective surgery can be done instead.

Question 23

Indications of surgical management

Answer 23

If conservative measures dont work

Anatomical variations that are symptomatic

Elective surgery in aTOS or vTOS are 90-95% successful

50-70% success in nTOS

Question 24

Explain vTOS surgery

Answer 24

Decompression of thoracic outlet

Venoplasty

Venous reconstruction or placement of a venous stent

It can be done via a supraclavicular or transaxillary approach.

This allows access to excise the first or cervical rib.

Question 25

Complications of TOS surgery

Answer 25

Neurological or vascular damage

Haemothorax

Pneumothorax

Chylothorax

Question 26

Complications of TOS

Answer 26

Further sequelae of the pathology like permanent nerve damage, aneurysma dilation of subclavian artery or loss of limb function