Hirayama Disease Involving Bilateral Distal Upper Limbs of a Student: A Case Report

Abstract

Hirayama disease is a rare neurological disorder characterized by initially progressive asymmetric muscular weakness and wasting of the distal upper limb(s) in predominantly young men, probably due to sustained or repeated neck flexion causing ischemic changes in the cervical anterior horn. Dynamic MRI (Neutral and flexed) of cervical spine is the mainstay for confirming diagnosis. A 16-year-old boy presented with insidious onset,gradually progressive difficulty in writing and other fine tasks, weakness, tremulousness of fingers,cold paresis and wasting of both hands and medial aspects of forearm(Right & Left) excluding brachioradialis for last 3 months without any trauma, pain , hypopigmented patch or thickened nerve and bladder or bowel involvement. No significant family, past medical or surgical, addiction history were found, but he had been studying for approximately 12 hours/day for last one year in a faulty posture on his bed suggestive of prolong and repetitive neck flexon. General,sensory system and cranial nerves examination showed no abnormality. MMT was normal in both lower and upper limbs except for intrinsic muscles of hands. Signs of UMN or cerebellar leisons were not seen. Dynamic MRI of cervical spine revealed forward displacement of the posterior cervical dural sac at C5-C7. EMG,NCV of both upper limbs suggested denervated and reinnervated potential in C7-T1 muscles. Patient was advised to use Hard cervical collar and counselled regarding maintaining proper posture during studying in a properly configured chair-table. After 3 months, improvement in hand writing was noted without any signs of disease progression.