Hirayama disease: an uncommon cause of distal upper extremity deficit.

Hirayama disease is a myelopathy related to flexion movements of the neck that produce ischemic damage in the anterior horn of the cervical cord. The disease affects young people and is characterized by a distal upper extremity deficit that develops gradually. The diagnosis is confirmed by cervical magnetic resonance imaging (MRI) in flexion demonstrating a forward shift of the posterior dural sac and spinal cord compression. On radiology, there should be suggestive signs in neutral position such as cord atrophy, intramedullary bilateral high signal intensity on T2-weighted images, straightening of the cervical spine, and loss of attachment between the posterior dural sac and subjacent lamina. Exploration should be completed by an MR study in neck flexion. We report here on two typical cases of the disease and also include a review of the literature.