Palmaris brevis spasm syndrome in manual workers using vibratory tools

Palmaris brevis spasm syndrome (PBSS) appears to reflect benign muscle hyperactivity, with unprovoked recurrent spasm of the muscle and consequent dimpling of the hypothenar eminence. Two cases are reported, being the first known report of the condition among manual workers or those using vibratory tools. Each was diagnosed during routine health surveillance for hand-arm vibration syndrome. With hand cramps being a frequent report among vibration-exposed workers, this condition should be considered in such cases, although the lack of reports means that the frequency of the condition is unknown. One of the employees described more frequent episodes of spasm during periods of increased manual work. Diagnosis is possible by witnessing the characteristic spasm, or by viewing photographs of it. Functional impairment is not usual, except for the brief duration of an attack. There is no consensus regarding appropriate treatment.