Which physical findings are characteristic of radial mononeuropathy?

Updated: Jun 14, 2018
  • Author: Wayne E Anderson, DO, FAHS, FAAN; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

Radial neuropathy typically presents with weakness of wrist dorsiflexion (ie, wrist drop) and finger extension.

  • If the lesion is in the axilla, all radial-innervated muscles are involved.

    • The triceps and brachioradialis reflexes are decreased.

    • Sensation is decreased occur over the triceps, the posterior part of the forearm, and dorsum of the hand.

  • Acute compression of the radial nerve commonly occurs at the spiral groove. If the lesion is at this level, all radial-innervated muscles distal to the triceps are weak.

    • Triceps reflex is preserved, but brachioradialis is decreased.

    • Sensory loss is over the radial dorsal part of the hand and the posterior part of the forearm.

    • Numbness over the triceps area is variable.

  • In isolated posterior interosseous lesions, sensation is spared and motor involvement occurs in radial muscles distal to the supinator.

    • Brachioradialis reflex is intact.

    • The extensor carpi radialis sometimes is also spared, resulting in radial deviation with wrist extension.

    • Pain may occur with palpation at the proximal forearm and with forceful supination.

  • In distal radial sensory lesions at the wrist, no motor weakness occurs. Numbness of the dorsal hand is noted, sparing the fifth digit.


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