Severe Spinal Injury in Hirayama Disease.

Hirayama disease is a rare neurological disorder characterized by an insidious progressive subacute unilateral or bilateral weakness of the hands and forearm muscles leading to a painless amyotrophy. The disease primarily affects young men in the second to third decades of life. It has always been described as a second motor neuron disease, thus sparing the pyramidal and sensitive pathways. It usually has a slow progression course of 3 to 5 years followed by stabilization. Since its initial description by Keyzo Hirayama in 1959, most cases have been reported in Asia, particularly Japan and India, although the disease reportedly has worldwide distribution.