Palmaris brevis spasm syndrome : Is that an occupational syndrome as an army cook ?

초록

Introduction <br> Palmaris brevis (PB) is a small quadrilateral shaped muscle. It arises from the transverse carpal ligament and palmar aponeurosis and is inserted into the skin on the ulnar border of the palm of the hand. Hence its action is to increase dimpling of the hypothenar eminence. The superficial branch ulnar nerve supplies PB whereas most of other intrinsic hand muscles are supplied by deep branch of ulnar nerve. Palmaris brevis spasm syndrome (PBSS) is a rare muscular hyperactivity syndrome confined to a rudimentary muscle. The mechanism is unclear. In some of the previous studies they attributed occupation involving frequent use of mouse and keyboard as possible cause. Most cases of PBSS were due to acquired causes like C8 root compression, ulnar nerve injury or followed by decompressive surgery of ulnar nerve but rest of cases were spontaneous without a known etiology. So far as we know , no cases have been reported for as an army cook in a literature. Here we report the case of a rare PBSS in patient as a army cook. <br> <br>Case <br> A 22 year old man complained of paraesthesia in the right little finger after started cooking as an army cook for 6months. And then, for three months he had experienced spontaneous, slightly painful, contractions in the right hypothenar eminence. (Fig. 1.) Spasms were spontaneous and irregular without stereotyped duration or frequency. On examination there was no weakness of intrinsic muscles of hand, no sensory loss, and deep tendon reflexes were intact. An EMG showed no abnormal spontaneuous activity but fasciculation. Motor unit potentials had a normal configuration with amplitude, recurrent with 5 to 10 Hz frequency. Motor and sensory nerve conduction velocities and F wave latencies were normal. Magnetic resonance imaging showed no particular abnormality and no abnormality at ulnar nerve on scanned images. In ultrasonogram, the right PB muscle's spasm was observed with recurrent and spontaneous activity. (Fig. 2.) So