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Cervical Rib (Thoracic Outlet Syndrome)

Definition

  • Congenital anomaly where-by an extra cervical rib or posteriorly fixed brachial plexus results in ↑ angulation of the subclavian artery & first thoracic nerve over the first rib

Incidence

  • Cervical ribs occur in 0.4% of the population (70% are bilateral)
  • Only symptomatic in 10% of cases

Clinically

  • Although congenital, symptoms rarely develop before the age of 30 years & are more common in women
  • Pain & symptoms usually evident in the distribution of the lower roots of the brachial plexus (C8 & T1)
  • subclavian artery is rarely compressed but may be narrowed by irritation of its sympathetic supply
  • Acute angulation may also result in damage of the arterial lining & production of small emboli
  • Results in no general or local neck symptoms usually
  • Complaint of pain in the ulnar forearm & hand worse after activity & carrying parcels
  • May be weakness & clumsiness & excessive sweating , blueness or coldness of the fingers with wasting of the small muscles of the hand
  • shoulder on the affected side may be lower or both shoulders may sag
  • An abnormally elevated subclavian artery may be evident above the clavicle
  • Thoracic Outlet Stress test
    • putting hand behind head ie ER/Abduction/extension of shoulder produces numbness of fingers
    • positive in 80%
  • Adson's Test
    • neck & shoulder are fully mobile but traction on the arm & lateral flexion of the neck away from the painful side may exacerbate symptoms & obliterate the radial pulse (Adson's Test)
    • positive in ~ 20%

X-Rays

  • An occasional well formed rib is seen
    • yet these are less likely to cause significant symptoms
  • Elongation of the lateral mass of C7
    • likely presence of a fibrous band
    • this sharp fibrous band is more likely to result in symptoms

Investigations

  • EMG
    • not as good as clinical examination in establishing the diagnosis
  • X-Rays
    • demonstrate the abnormality

Differential

  • Carpal tunnel syndrome
    • but the sensory & motor changes are not confined to the distribution of the median nerve
  • Ulnar tunnel syndrome
    • again the changes are not confined to the distribution of the ulna nerve
  • Pancoast syndrome
    • (apical carcinoma of the bronchus) may infiltrate the structures at the root of the neck causing pain numbness & weakness of the hand
    • Clinically, large lump in the neck & chest X-Ray typical features of malignancy
  • Cervical spine lesions
    • eg disc prolapse or spondylosis where neck movements are limited
      • TB & mets- X-Rays usually differentiate the cause
  • Spinal cord lesions
    • such as syringomyelia
    • may cause wasting of the hand but other neurological features suggest diagnosis (dissociated pain & temperature loss)
  • Cuff lesions
    • have painful shoulder & arm movements

Treatment

  • Nonoperative
    • exercises to improve support of shoulder girdle associated with weight reduction are usually adequate
  • Operative
    • excision of the rib or fibrous band
      • indicated if the above fails in the presence of severe symptoms
      • significant neurological or vascular disturbances then
Webpage Last Modified: 18 February, 2010