What is the role of a sensory exam in the evaluation of ulnar neuropathy?

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

Although in some patients, the area of the palmar cutaneous sensory nerve can extend a bit farther proximally than is usual, if the sensory involvement extends more than 2.5 cm above the wrist crease along the medial aspect of the forearm, involvement of the nerve roots (C8/T1) or the brachial plexus is likely (possibly in addition to an ulnar injury).

As noted (see Anatomy), both the palmar cutaneous sensory branch of the ulnar nerve and the dorsal ulnar cutaneous branch come off the main ulnar branch above (proximal to) the wrist. Thus, a lesion exclusively at the wrist (at the canal of Guyon) would miss these branches, and the only sensory involvement would be in the superficial terminal branch. However, a physician must be cautious in interpretation.

Typically, neuropathic damage, whether generalized or related to nerve compression, affects (or is perceived to affect) the most distal parts of the nerves preferentially. A compression at the canal of Guyon might be perceived by the patient and might be detectable on examination only in the tips of the fingers. Thus, the compression would appear to be affecting only the superficial terminal branch. [106, 107, 108]


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