Compression neuropathy of the radial palmar thumb nerve.

Compression neuropathy of a single digital nerve is a rare entity. We report the case of a patient with numbness in the distribution of the radial digital nerve of the thumb caused by the use of a walking stick. The nerve was compressed between the handle of the stick, the loop and the radial sesamoid bone of the first metacarpophalangeal joint. The site of the lesion was confirmed by electrophysiologic examination. Orthodromic recording of the sensory response from the radial palmar digital nerve of the thumb documented a complete absence of nerve action potential whereas the ulnar digital thumb nerve showed a normal response. Sensory function was restored when a padded ski glove was used to protect the area of the metacarpophalangeal joint whilst using the stick.