[Spasm or dimpling of the hypothenar eminence].

Bilateral hypothenar muscular spasm ("dimpling") was discovered in a 62 year-old man. The spasms consisted of recurrent arrhythmic contractions of the palmaris brevis muscle. E.M.G. showed no signs of denervation but the contractions could be stopped by infiltration of the ulnar nerve by xylocaine. Apparently, this syndrome has previously been reported in only two cases. Its clinical and electromyographic characteristics are similar to hemifacial spasm. Compression of the ulnar nerve after its division at the wrist could be a cause.