Which physical findings are characteristic of ulnar neuropathy at or distal to the wrist?

Updated: Jun 08, 2018
  • Author: Charles F Guardia, III, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

The following physical findings are significant with respect to ulnar neuropathy at or distal to the wrist:

  • Weakness of the interosseous and hypothenar muscles only, with no sensory loss - This would most likely be due to compression of the deep motor branch in the hand after it had separated from the superficial terminal sensory branch but before the branch to the hypothenar muscles had taken off

  • Interosseous muscle weakness only, with no sensory loss - This would most likely be due to compression of the deep motor branch after the branch to the hypothenar muscles had taken off

  • Weakness of the interosseous and hypothenar muscles, with sensory involvement in the fifth digit - This would suggest involvement in the canal of Guyon with compression of both the deep motor branch and the superficial terminal sensory branch (ie, what might be considered the typical or classic Guyon canal pattern)

  • Pure sensory loss, with normal dorsal ulnar cutaneous sensory nerve, normal palmar cutaneous sensory nerve, and normal motor responses - This would imply injury to the superficial terminal sensory branch alone, probably a compression distal to the canal of Guyon

  • Interosseous weakness and sensory loss, with preserved function in the hypothenar and dorsal ulnar cutaneous territories - This would imply a compression of the deep motor branch and the superficial terminal sensory branch distal to the point where the subbranch to the hypothenar area (eg, the abductor digit minimi) had split off from the deep motor branch


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