Palmaris Brevis Spasm

Abstract

Scientific BACKGROUND: Palmaris brevis spasm syndrome is a rare and unusual syndrome with contraction and fasciculations of the palmaris brevis (PB) muscle. Etiology has been postulated as repetetive stretch of the superficial branch of the ulnar nerve or possibly radiculopathy.

CASE: 20-year-old man complained of spontaneous, irregular, nonpainful contractions at the inner side of his left hand and pins-and-needles sensation of the left fifth finger. Neurological examination revealed spontaneous, irregular contractions of the left PB muscle, producing hypothenar dimpling. EMG showed abnormal, spontaneous activity characterized by irregular discharges from the PB muscle only, always associated with visible dimpling of the left hypothenar eminence. Nerve conduction studies revealed mild neuropathy of the ulnar nerve at the elbow in which both sensory and motor fibers were involved with decreased velocities about 30%. We administered 10 units botulinum toxin type A to PB muscle for symptomatic relief and ordered a night elbow splint therapy for ulnar neuropathy with in a conservative behavior. He was called for clinical and electrophysiologic examination after six months from the first visit. He had no spasms, his examination did not reveal any signs of sensory or motor involvement of the left ulnar nerve. His repeated motor and sensory NSC were normal. CONCLUSION: It may be idiopathic or associated with different causes and sites of ulnar nerve lesions. We presume that the PBS was due to ulnar neuropathy at the elbow in our case. To our knowledge this is the first case of PBS reported due to ulnar neuropathy at the elbow.