Thoracic Outlet Syndrome Quiz

Thoracic Outlet Syndrome (TOS)

• TOS describes compression of neurovascular structures exiting the thoracic outlet.
• The thoracic outlet is a dynamic space bordered by the first rib, clavicle, and scapula.
• Structures in the thoracic outlet include the subclavian vasculature (veins and artery) and brachial plexus.
• TOS is a controversial topic in musculoskeletal medicine and rehabilitation.
• Pain and discomfort are often due to compressed subclavian vein, artery, or brachial plexus.
• The lowest trunk of the brachial plexus (C8 and T1 nerve roots) is the most commonly compressed structure.
• TOS affects approximately 8% of the population, and is more common in women (3-4 times more) between 20-50 years (average age 30s-40s).
• Mostly affects the brachial plexus (95-98%).
• Possible compression sites include the interscalene triangle, costoclavicular space, and subcoracoid tunnel.
• Causes of TOS may include congenital defects, like extra ribs, or fibromuscular bands.

Classification of TOS

• Vascular TOS (vTOS): Accounts for approximately 3% of cases. Compression affects the vascular structures (arteries or veins).
• Neurological TOS (nTOS): Accounts for approximately 97% of cases. Compression affects the neural structures (brachial plexus) which can be further divided into:
  • True Neurological TOS (TOS): Associated with definitive neurological deficits (mostly muscular atrophy).
  • Disputed/Non-specific/Symptomatic TOS (STOS): Associated with TOS symptoms but with no objective neurological, electro-physical or radiological abnormalities.
• TOS causes are anatomical defects (extra ribs, or fibromuscular bands), poor posture, or trauma.

Causes

• Congenital Defects: Presence of extra ribs, or cervical ribs.
  • Often bilateral
  • Affects 0.5-0.6% of people
• Fibromuscular bands connected to the cervical ribs also cause neural compression.
• Poor Posture: Flexed head, depressed and anteriorly shifted shoulders, and protracted scapula contribute to decreased costoclavicular space, increased friction on neurovascular bundle in the subpectoral area, and shortening of the sternocleidomastoid. Scalenes and pectoralis tightening leads to improper head/neck alignment.

Causes (cont.)

• Trauma: Macro-trauma (e.g., motor vehicle accident (MVA)) leading to injury and scarring of the scalene muscle or microtrauma (e.g. repetitive overhead activities like sports) leading to muscle strain in the scapular stabilizers.
• Repetitive Activity: Certain activities (e.g. typing on a computer, lifting heavy objects) can contribute to TOS after years of repetitive movements.

Diagnosis

• Based on a patient history, physical examination, provocative tests, ultrasound, radiological evaluation, and electrodiagnostic evaluation.
• Diagnosis usually involves ruling out other possible causes with similar presentations, such as cervical radiculopathies and upper extremity entrapment neuropathies.
• The clinical presentation is assessed and categorized as either neurogenic (compression of the brachial plexus) or vascular (compression of the subclavian vessels).

Diagnosis (cont)

• Electrodiagnostic evaluation: Nerve conduction studies are helpful and usually reveal decreased ulnar sensory potentials, decreased median action potentials, but often normal ulnar motor and median sensory potentials. Doesn't usually present in dermatomal/myotomal pattern unless nerve roots are involved.
• Imaging Studies: Venography and arteriography are used to identify vascular TOS. Cervical spine and chest x-rays are used to identify bony abnormalities, such as cervical ribs.

Physical Examination

• Assessment of Respiration: Ensure correct Abdominodiaphragmatic breathing.
• Assessment of Thoracic Outlet Closer Muscles: Look for adaptability and shortening of Anterior and middle scalenes, subclavius, pectoralis minor and major muscles.
• Assessment of 1st Rib Position and Mobility: Monitor rib elevation due to scalene hypertonicity or post-fracture callus formation.
• Clavicle Position assessment: Look for prior fracture history and an abnormal callus formation or malalignment.
• Additional tests like cervical rotation-side bending, assessment of scapular position and muscle strength, and acromioclavicular and sternoclavicular joint mobility are usually performed.

Signs and Symptoms

• Present anywhere from neck, face, and occipital region to chest, shoulder, and upper extremity pain.
• Pain and symptoms worsen during arm abduction, overhead, external rotation with head rotated towards affected side.
• Symptoms depend on whether the nerves, blood vessels or both are compressed.
• Neurogenic symptoms include numbness/tingling in the arm/fingers, pain/aches in the neck, shoulder, arm or hand, arm fatigue, and weakness in grip.
• More specific symptoms depend on which nerve is implicated at the upper or lower plexus.

Signs and Symptoms (cont.)

• Vascular TOS: Cyanosis of the hand/fingers; swelling, pain, cold intolerance of hands/arms/fingers. Possible loss of pulse in the affected arm or claudication pain that worsens whilst using affected arm.
• True TOS: Pain, paresthesia (numbness/tingling), and/or weakness, often present both during the day and night and related to the level of compression.

Provocative Testing (e.g.)

• Roos Test: Triggers spontaneously experienced symptoms (pain/numbness/tingling) in the patient within 1 minute. The patient has 90 degrees of abduction with the elbow flexed, while rotating externally, and opening and closing their hands for 3 minutes.
• Scalene Cramp Test: Follow-up to the Roos test to assess scalene muscle contribution to compression. The patient turns their head toward the side of the pain, and pulls their chin into the supraclavicular fossa to cause contraction of scalene muscles. Distal radiation of pain confirms scalene involvement.
• Scalene Relief Test: To further confirm scalene involvement, the patient’s forearm is placed against their forehead on the side of affected shoulder. Increase in space between the clavicle and scalene muscles suggests improved compression.
• Upper limb tension test (ULTT) or Brachial Plexus tension or Elvey's test: Various provocative tests to evaluate brachial plexus compression.

Special Vascular Tests

• Adson's Test: Used to identify vascular compression by compressing the subclavian vessels against the scalene, producing loss of radial pulse - indicative of TOS.
• Wright's Test: Considered the optimal provocative test for assessing costoclavicular compression. Patient's shoulders are externally rotated and abduct up to 180 degrees while maintaining a posterior position and keeping elbow extended.

Treatment

• Medical Management: Nonsteroidal anti-inflammatory drugs (NSAIDs) for pain and inflammation. Botulinum injections (Botox) into the anterior and middle scalene muscles can temporarily reduce pain and spasm.
• Surgical Management: Considered only when conservative management proves ineffective. This may include procedures like supraclavicular scalene surgery and transaxillary first rib resection if all nerve and vascular structures are completely released and when applicable.
• Physiotherapy: First rib mobilization and manipulation, mobilization of sternoclavicular/acromioclavicular joints, Glenohumeral mobilization, Cervical traction, Massage, stretching, and strengthening exercises. Patient education and activity modification.

Postoperative Physical Therapy

• Gentle neural mobilization techniques
• Overhead activities and heavy lifting are avoided for 2-4 weeks
• Exercise programs are designed to address postural abnormalities, and muscle imbalances to prevent re-occurrence of symptoms

Management (cont)

• Patient Education and Activity Modification: Avoiding positions that exacerbate symptoms and adapting work/activities as needed.
• Sleep Positioning: Avoiding sleeping on the affected side and lying on the stomach. Using pillows to support the affected arm and keep it from being abducted overhead.
• Cyriax Release Technique: Position patients with arm rests to actively unload neurovascular structures during sleeping. Gradual increase in symptoms initially, then gradually disappear.