Hirayama disease: A case report.

Hirayama Disease is a spinal muscular atrophy which presents with varying degrees of unilateral or asymmetric bilateral distal muscle weakness of the upper extremity. It is a rare, non-progressive motor neuron disease, mostly affecting young males. Although considered to have a relatively stationary clinical course after a period of initial progression, it can be functionally impairing in some patients. Here, we present a case of a 20-year-old male who complained of weakness of his right upper extremity for 1 year with difficulty performing activities of daily life. This case highlights the role of radiologist in identifying the subtle findings in cervical spine MRI of patients with such presentation. Moreover, it emphasizes the importance of including flexion imaging MRI sequences in a patient with suspicion of Hirayama disease.