A Case Report of Juvenile Asymmetric Muscular Atrophy of Bilateral Distal Upper Extremity: Hirayama Disease

J Korean Assoc EMG Electrodiagn Med 2008;10(1):56-60.
Published online June 1, 2008.

Abstract

We report a 17-year-old man, who had been showing progressive weakness in right forearm and hand forthe last 6 months. Nerve conduction studies showed no specific abnormal finding on motor and sensorynerve of both upper and lower extremities. Electromyography of both upper limbs showed significant evidencesof denervation in the both flexor carpi radialis, extensor carpi radialis, triceps brachii, extensorindicis proprius, abductor pollicis brevis, and first dorsal interossei. Both brachioradialis and bicepsbrachii muscles were not affected. Cervical magnetic resonance imaging (MRI) revealed atrophy of thelower cervical cord in a neutral position of neck and a forward displacement of the dural sac with anexpanded venous plexus in a flexed position. We present a Korean case of juvenile muscular atrophysuggesting Hirayama disease with its typical clinical, electrophysiological and neuroradiological findings.

Key Words: Hirayama disease, Juvenile muscular atrophy, Neck flexion