THORACIC OUTLET SYNDROME

  1. Definition and discussion

Condition resulting in compression of neurovascular structures (cords of brachial plexus, subclavian artery and subclavian vein) at the thoracic outlet (inlet), causing symptoms in the upper extremities. When it is present C8-T1 spinal levels are most commonly involved.

  1. Aetiology

    • Neurologic type (90-97%), most common between 20-50 years of age
    • Venous type (3-10%), most common between 20-35 years of age
    • Arterial type (atherosclerosis) (1%), most common in the young adult or over 50 years of age

  1. Potential causes:

    • Prior shoulder/lower cervical trauma or repetitive activity such as typing
    • Upper thoracic neurovascular bundle compression
    • Cervical rib or fibrous band connecting the cervical rib to the 1st Cervical ribs are symptomatic in only about 10% of TOS cases.
    • Elongated C7 transverse process
    • Pancoast’s tumour (upper lung)
    • Atherosclerotic plaques within the vessels
    • Hypertonic subclavian muscle, hypertonic pec minor, hypertonic scalene muscles
    • Callus bone formation from fractured clavicle or first

  1. Risk factors:

    • Postural abnormalities (such as rounded shoulders, scoliosis) and sleeping position (abducted shoulder).
    • Excess callus formation after fracture or exostosis of the clavicle or first rib
    • Body building with increased muscular bulk in the thoracic outlet area
    • Obesity, large pendulous breast tissue

  1. History, signs and symptoms

Diagnosis is often made by clinical presentation and not always confirmed by physical examination findings. Usually unilateral numbness, tingling or paraesthesia of the upper limb and shoulder especially down the medial aspect of the arm and hand (very common)

  • Neurologic:

Pain usually on the medial aspect of the arm, forearm and ring and small digits Paraesthesia often occurring at night, awaking the patient with pain or numbness Loss of dexterity (weakness) and occipital headache (referred pain)

Raynaud phenomenon-hand coldness and colour changes may also be seen usually due to an overactive sympathetic nervous system

Prior history of neck trauma preceding (RTA, stress at work)

  • Venous:

Upper limb pain Swelling or arm cyanosis

Paraesthesia in the fingers and hand

  • Arterial:

Pain, pallor, coldness, paraesthesia.

On observation these patients may have an anterior head carriage with hypertonic scalene muscles.

Late changes may include oedema, Raynaud’s phenomenon, glossy skin, cyanosis, dry skin or excessive swelling.

Usually no evidence of muscle atrophy.

On palpation tenderness over the scalene, pec minor and SCM muscles, brachial plexus, lower cervical spine or above the clavicle may be noted

Hypertonic muscles or myofascial trigger points may be found in the above muscles Abnormalities of the clavicle, ribs etc

  1. Management

    • For most patients conservative treatment is indicated if no vascular involvement is present and/or if no major loss of function is present due to the severity of symptoms
    • Joint adjustments and mobilisation of the cervical and thoracic spine, ribs, clavicle and shoulder
    • Cervical distraction may also offer benefit
    • Soft tissue massage, ischemic compression and myofascial dry needing and stripping massage of the above
    • Passive (stretching) and active range of motion exercises to be performed in a pain free
    • Stretch hypertonic SCM, scalene and pec minor as well as other cervical musculature Home care: Avoid repetitive overhead activities and/or change sleeping Weight loss if

axillary folds are causing compression. Medications such as NSAIDs and analgesics for pain control and muscle relaxants In severe chronic cases that do not respond to conservative care, consultation with an orthopaedic specialist or neurosurgeon may be warranted

If vascular involvement is present and/or if there is loss of function and a course of conservative treatment has been tried then surgery may be required:

  1. Removal of first rib or cervical ribs
  2. Removal of fibrous bands
  3. Anterior scalenectomy

Prognosis

  • 85% of patients will improve with appropriate multidisciplinary conservative management
  • Joint manipulation has been shown to be highly effective in treating TOS, especially in combination with myofascial release of scalene and pec muscles
  • Surgery may be warranted for patients who do not respond to conservative care