thoracic outlet syndrome

Question 1

what is thoracic outlet

Answer 1

disorder involving compression of brachial plexus, subclavian artery or vein at the site of the thoracic outlet.

Question 2

aetiology of thoracic outlet

Answer 2

• TOS develops when neck trauma occurs to individuals with anatomical predispositions
• neck trauma can either be a single acute incident or repeated stresses
• anatomical anomalies can either be in the form of soft tissue (70%) or osseous structures (30%)
• a well-known osseous anomaly is the presence of cervical rib
• examples of soft tissue causes are scalene muscle hypertrophy and anomalous bands
• there is usually a history of neck trauma preceding TOS

Question 3

clinical presentation of neurogenic TOS

Answer 3

• painless muscle wasting of hand muscles, with patients complaining of hand weakness e.g. grasping
• sensory symptoms such as numbness and tingling may be present
• if autonomic nerves are involved, the patient may experience cold hands, blanching or swelling

Question 4

clinical presentation of vascular TOS

Answer 4

• subclavian vein compression leads to painful diffuse arm swelling with distended veins
• subclavian artery compression leads to painful arm claudication and in severe cases, ulceration and gangrene

Question 5

Examination of TOS

Answer 5

• neurological examination and musculoskeletal examination are necessary
• stress manoeuvres such as Adson’s manoeuvres may be attempted although they have limited utility
• careful examinations should aim to rule out other pathologies of the cervical spine, the shoulder or peripheral nerves. For instance, cervical radiculopathy, shoulder injuries and carpal tunnel syndrome

Question 6

Ix for TOS

Answer 6

chest and cervical spine plain radiographs to check for any obvious osseous abnormalities e.g. cervical ribs, exclude malignant tumours or other differentials e.g. cervical spine degenerative changes

other imaging modalities may be helpful e.g. CT or MRI to rule out cervical root lesions

venography or angiography may be helpful in vascular TOS
an anterior scalene block may be used to confirm neurogenic TOS and check the likelihood of successful surgical treatment

Question 7

Tx for TOS

Answer 7

conservative management with education, rehabilitation, physiotherapy, or taping is typically the first-line management for neurogenic TOS
surgical decompression is warranted where conservative management has failed especially if there is a physical anomaly. Early intervention may prevent brachial plexus degeneration
in vascular TOS, surgical treatment may be preferred
other therapies being investigated include botox injection