Hirayama disease.

A 17-year-old male, who gave up his favorite sport cricket and started playing football, presented with one-year history of slowly progressive atrophic weakness of forearms and hands. Neurological examination showed weak and wasted arms, forearms and hand but no evidence of pyramidal tract, spinothalmic tract and posterior column lesions. Plain cervical spine radiographs showed no abnormal findings. Cervical magnetic resonance imaging (MRI) showed asymmetric cord atrophy; images obtained with neck flexed showed the anterior shifting of the posterior wall of the lower cervical dural sac resulting in cord compression. These findings suggest Hirayama disease, a kind of cervical myelopathy related to the flexion movements of the neck.