This case demonstrates the typical MRI findings of Hirayama disease.

Hirayama disease typically affects young males in their 20s. Clinical symptoms are weakness and atrophy of the distal upper extremity muscles.

MRI in the neutral position can show focal atrophy and signal abnormality of the lower cervical spinal cord. MRI in a flexion position is the key to diagnosis and demonstrates forward migration of the posterior wall of the dura mater and an enlarged, crescent-shaped and enhancing posterior epidural space.