Why the lack of shift matters

Likely causes in SSc

1. Distal clavicle or rib resorption (osteolysis).
   • Cecil states that bone resorption in SSc affects "the distal tufts of terminal phalanges (acro-osteolysis), mandibular condyles, ribs, and distal clavicles" - Goldman-Cecil Medicine, Musculoskeletal Complications.
   • Firestein notes that osteolysis of the mandible and clavicle is reported, "suggesting a systemic defect" - Firestein & Kelley's Textbook of Rheumatology, Musculoskeletal Involvement.
   • Rockwood and Green's lists scleroderma among the causes of distal clavicle osteolysis, along with rheumatoid arthritis and hyperparathyroidism.
   • Distal clavicle loss disturbs the strut that holds the shoulder up and out, so the shoulder can sag. Look for this on a shoulder or chest radiograph.
2. Shoulder girdle muscle myopathy or atrophy.
   • SSc causes two kinds. Inflammatory myositis resembles polymyositis and usually appears early. A noninflammatory myopathy with atrophy and fibrosis, with normal muscle enzymes, is common in late disease - Goldman-Cecil Medicine.
   • Weakness or atrophy of the trapezius, levator scapulae and rhomboids lets the scapula and shoulder fall.
   • Disuse atrophy and malnutrition from gut involvement add to this.
   • Myopathy is associated with cardiac disease and a worse outcome - Firestein.
3. Large joint contracture and capsular fibrosis.
   • Diffuse disease can contract the shoulders, along with the wrists, elbows, hips, knees and ankles. This results from fibrosis of the overlying skin, fascia, joint capsule and tendons - Firestein.
   • Tendon friction rubs over the joint suggest aggressive disease.
   • A stiff, retracted shoulder can sit abnormally low or protracted because of altered scapulothoracic and glenohumeral mechanics.
4. Skin and fascial tethering of the neck, chest and upper arm. Tight skin in diffuse cutaneous SSc can fix the shoulder in a depressed or forward position without any skeletal cause.
5. Neuropathic causes, which are not specific to SSc.
   • Spinal accessory nerve palsy gives shoulder droop and scapular winging (listed as a cause in Mulholland and Greenfield's, Table 87.3).
   • Long thoracic nerve palsy and brachial plexopathy are other possibilities.
   • Compression neuropathies are over-represented in SSc: carpal tunnel syndrome can be a presenting feature.
   • Cervical radiculopathy is another possibility.
6. Other bone and soft tissue causes.
   • Osteoporosis with vertebral compression usually causes kyphosis, which would show on the spine.
   • Subcutaneous calcinosis around the shoulder can cause pain and guarding.
   • Rotator cuff tendon or bursal disease, or a prior scapular or clavicular fracture, can also change shoulder position.

Suggested workup

• Shoulder and chest radiographs, looking for distal clavicle, rib and acromion resorption, calcinosis and apical changes.
• Muscle strength testing (trapezius, serratus anterior, deltoid, proximal muscles). Also check CK, aldolase and anti-PM/Scl or Ku antibodies, with EMG and MRI if myositis is suspected.
• Range of motion and palpation for friction rubs.
• Nerve conduction studies and EMG if winging or a focal deficit is present.
• Cervical spine and brachial plexus imaging if there are neurological signs.
• Check for a prior fracture of the clavicle or scapula.

Recent evidence check

1. Loss of volume on one side of the chest

• Lobar collapse or upper lobe fibrosis. Examples are post-TB fibrosis, radiation fibrosis, bronchial obstruction and chronic atelectasis.
• Pleural fibrosis or fibrothorax after empyema or haemothorax, or after pneumonectomy or thoracoplasty.
• Agenesis or hypoplasia of the lung. In this case the chest wall and shoulder may look flattened.

2. Chest wall and bone causes

• Post-thoracotomy or surgical change. Division of the serratus anterior, latissimus dorsi or trapezius can cause winging and a low shoulder. Rib resection also contributes.
• Chest wall tumour or Pancoast (superior sulcus) tumour.
  • It involves the C8-T2 roots and causes shoulder and arm pain, Horner syndrome, and weakness and atrophy of hand muscles - Murray & Nadel's Textbook of Respiratory Medicine, Superior Sulcus Tumors and Pancoast Syndrome.
  • Rib and vertebral destruction can follow. Droop here comes from pain, guarding and lower plexus palsy.
• Rib fractures, flail segment or clavicle and scapula fractures. A fracture of the scapular neck produces drooping of the shoulder with apparent lengthening of the arm - S Das, A Manual on Clinical Surgery, Examination of Injuries about the Shoulder.
• Pectus or other chest wall deformity, or severe kyphoscoliosis. These can lower or round the shoulder, but a spinal deformity would usually be visible.
• Congenital or developmental causes. Poland syndrome is one example. S Das also notes that sagging of the shoulder girdle appears with puberty in some patients, and that thoracic outlet symptoms may follow.

3. Nerve and muscle causes

• Spinal accessory nerve injury (trapezius palsy).
  • This is the classic cause of shoulder droop with scapular winging. Lateral winging increases on arm abduction.
  • The injury can come from carotid endarterectomy (in less than 1% of cases - Mulholland and Greenfield's Surgery, Table 87.3), cervical lymph node biopsy, or neck dissection. Radiation and tumours at the skull base or neck are other causes - Localization in Clinical Neurology; Adams and Victor's Principles of Neurology; Scott-Brown's Otorhinolaryngology.
  • In respiratory patients, think of central venous catheter insertion, neck or mediastinal lymph node biopsy, and lung or head and neck cancer surgery.
• Long thoracic nerve palsy (serratus anterior). It causes medial winging and can follow traction, chest surgery or trauma - Campbell's Operative Orthopaedics, Long Thoracic Nerve. Anaesthesia, thoracic surgery and positioning are risk factors.
• Brachial plexopathy or thoracic outlet compression. Causes include Pancoast tumour, radiation plexopathy and cervical ribs.
• Phrenic nerve palsy. It lifts the hemidiaphragm and gives referred shoulder pain. It does not cause a true droop, but the pain and guarding can look like one.
• Respiratory muscle and neuromuscular disease. Examples are muscular dystrophy (for example facioscapulohumeral, which causes asymmetric shoulder girdle weakness and scapular winging), myopathies, and critical illness myopathy or polyneuropathy.
• Steroid myopathy and cachexia in COPD, cystic fibrosis, ILD and lung cancer. Wasting of the shoulder girdle muscles lowers the shoulder.

4. Adaptation and posture

• Chronic COPD raises the shoulders (accessory muscle use), but late disease with muscle wasting, kyphosis and fatigue can reverse this.
• Chronic pain and guarding from pleuritic pain, cough fractures or post-surgical pain.
• Frozen shoulder after prolonged immobility, for example in ICU or after long hospital stays.

Practical approach

1. Inspect and compare the two sides. Check for winging (at rest and on abduction) and wasting.
2. Test shoulder shrug and external rotation, and arm abduction against resistance. A weak shrug points to the trapezius and spinal accessory nerve. Weak push-up against a wall points to the serratus anterior and long thoracic nerve.
3. Review the history. Check for neck, thoracic or vascular surgery, central lines, radiation, trauma, or a rib or clavicle fracture.
4. Examine the chest. Look for asymmetric expansion, a tracheal shift, dullness and reduced breath sounds.
5. Investigations.
   • Chest and shoulder radiographs, with CT for apical lesions, rib destruction and a Pancoast tumour.
   • EMG and nerve conduction studies if nerve injury is suspected.
   • MRI of the brachial plexus or neck if there are focal deficits.

Evidence check