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Thoracic Outlet Syndrome (TOS) is a condition that affects the nerves and/or blood vessels that pass through a narrow space between your collarbone (clavicle) and your first rib, known as the thoracic outlet. These structures include the brachial plexus (a network of nerves that control muscles and sensation in the arm) and the subclavian artery and vein. When these structures become compressed, it can lead to a range of symptoms that can significantly affect everyday activities.

Physiotherapists play a crucial role in identifying, managing and helping clients recover from TOS. Understanding the condition and recognising early signs is vital in preventing chronic symptoms and unnecessary medical interventions.

The symptoms of TOS vary depending on whether nerves or blood vessels are being compressed. It is classified into three main types:

  • Neurogenic TOS – compression of the brachial plexus nerves and accounts for approximately 90% of cases.
  • Venous TOS – compression of the subclavian vein.
  • Arterial TOS – compression of the subclavian artery.

Signs and Symptoms

Neurogenic TOS:

  • Numbness or tingling in the arm, hand, or fingers (especially the ring and little fingers)
  • Weakness in the shoulder or arm
  • Pain or aching in the neck, shoulder, or hand
  • Poor grip strength
  • Muscle wasting in the hand (in chronic cases)
  • Symptoms that follow a non-dermatomal pattern
  • Symptoms that worsen with prolonged positioning or repeated movements.
  • Headaches

Venous TOS:

  • Swelling of the arm or hand
  • Bluish discolouration
  • A feeling of heaviness or fullness in the arm
  • Enlarged veins near the shoulder or chest

Arterial TOS:

  • Pale or cold hand
  • Cramping pain when using the arm
  • Weak or absent pulse in the affected arm
  • In severe cases, ulcers or sores on fingers

Symptoms are often made worse by activities that involve prolonged overhead arm use, poor posture, carrying heavy loads, or repetitive tasks. Clients might describe feeling discomfort after tasks like hanging washing, working at a desk, or carrying a backpack.

Causes and Contributing Factors

TOS usually results from compression in the thoracic outlet due to anatomical or acquired factors. Some common contributors include:

  • Poor posture, particularly rounded shoulders and forward head position
  • Muscle tightness, especially in the scalene or pectoralis minor muscles
  • Repetitive overhead activities (e.g., athletes, manual workers)
  • Anomalies, such as a cervical rib (an extra rib above the first rib) or abnormal fibrous bands
  • Trauma, such as whiplash or clavicle fractures
  • Prolonged sitting, particularly with poor ergonomics

Diagnosis

Assessment tools used by physiotherapists include the Roo’s test and the Elvey’s test. It is important to note that whilst these tests have a sensitivity of 85-94% they have poor sensitivity; meaning clinical reasoning and other diagnostic factors need to be considered before a formal diagnosis is made.

Imaging techniques such as MRI or a nerve conduction study may be considered as tool to exclude other differential diagnosis such as disc herniation, but again is not diagnostic in isolation.

Prognosis

The outlook for TOS depends on the type and how early it is diagnosed. Most individuals with neurogenic TOS respond well to physiotherapy and activity modification. Venous and arterial types may require more urgent medical or surgical interventions but can still have positive outcomes when treated early.

It is likely that neurogenic TOS will resolve within 4-6 months of commencing conservative treatment but for cases in which this does not occur, surgical intervention may be considered.

Treatment

Physiotherapy and Rehabilitation

Physiotherapy is the cornerstone of non-surgical treatment, particularly for neurogenic TOS. Goals include reducing compression, improving mobility and strength, and correcting posture. Key components include:

1. Postural Correction and Activity Modification

  • Education about optimal posture
  • Education on optimal ergonomics and movement patterns
  • Exercises to reduce forward head posture and rounded shoulders (e.g., chin tucks, scapular retraction)
  • Education on activities to avoid and pacing strategies to employ

2. Stretching

  • Specific muscle groups including: Pectoralis minor and major, scalenes, levator scapulae and upper trapezius.
  • General neck and shoulder mobility (manual therapy or home exercises)

3. Strengthening

  • Deep neck flexors
  • Lower trapezius and serratus anterior
  • Rhomboids and thoracic spine extensors

4. Neurodynamic Techniques

  • Gentle nerve gliding (e.g., median nerve sliders) can help reduce neural sensitivity
  • Care is needed to avoid aggravating symptoms

5. Manual Therapy

  • Soft tissue release
  • Joint mobilisation of the cervical spine and first rib
  • Thoracic mobilisation for posture and rib movement

Other Non-Physiotherapy Options

Medication

  • Anti-inflammatories or muscle relaxants may be prescribed by a GP
  • Neuropathic pain medications (e.g., amitriptyline, pregabalin) for severe nerve symptoms

Injections

  • Botulinum toxin or corticosteroid injections into tight muscles (e.g., scalenes or pectoralis minor) can help in resistant cases. They can also be diagnostic for cases that require surgical intervention.

Surgery

  • Reserved for cases that do not improve with conservative management or involve significant vascular compromise
  • May involve first rib resection or scalenectomy aiming for brachial plexus decompression.
  • Surgical management approaches will vary on a case-by case basis and it is important to note that physiotherapy is important both pre and post-operatively.