What is Wartenberg's syndrome?

  • It is an entrapment neuropathy of the superficial radial nerve (SRN), which is a pure sensory nerve.
  • Also known as "cheiralgia paraesthetica".
  • Due to compression by the relative motion of brachioradialis and extensor carpi radialis longus (ECRL) during forearm rotation.
  • The nerve may be entrapped at its exit point to the subcutaneous plane by the intervening fascia. 

Anatomy of Superficial Radial Nerve

  • Pure sensory nerve
  • Radial nerve bifurcates in the proximal forearm to give rise to SRN and posterior interosseous nerve (PIN)
  • SRN travels deep to the brachioradialis and lies on the undersurface of the muscle
  • It emerges between brachioradialis and ECRL in the distal third forearm, to become superficial (under the skin)
  • It bifurcates further proximal to the wrist:
    • Dorsal branch to supply the 1st (autonomous dermatome) and 2nd web spaces
    • Palmar branch to supply dorsoradial thumb

Presentation

Symptoms

  • Vague pain over the dorsoradial hand
  • Paraesthesia (tingling sensation)
  • Numbness
  • Onset may have been precipitated by:
    • tight bracelet, wrist watch, wrist band
    • minor trauma to the wrist
    • repetitive wrist flexion, ulnar deviation or forearm rotation

Signs

  • A positive Tinel's sign over the SRN at the entrapment spot is the most reliable sign
  • A provocative test with repeated wrist flexion, ulnar deviation and pronation (akin to Traction Tinel's sign)

Investigations

  • Nerve conduction studies can be performed however it may be normal
  • Diagnostic local anaesthetic injection is the most useful test:

    • Injection of 1-2ml of fast-acting local anaesthetic (1 or 2% lidocaine) at the Tinel's spot followed by resolution of the above symptoms is regarded as a positive test for nerve entrapment. Should the symptoms return predictably as the local anaesthetic wears off (after 4 hours), that is taken as a further level of confirmation.

Treatment

Nonoperative

  • Removal of tight wrist wear
  • Activity modification
  • Splint
  • Painkillers

Operative

 

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