Severe Spinal Injury in Hirayama Disease

Abstract

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.

Keywords: Dynamic myelopathy; Hand atrophy; Hirayama disease; Oblique amyotrophy; Segmental spinal atrophy.

Fig. 1. (A) Hands-palmar view. Wasting of the hands with marked thenar and hypothenar atrophy. (B) Right forearm-midpronation/supination view. Wasting of the forearm with sparing of the brachioradialis muscle (oblique amyotrophy).

Fig. 2. (A) Sagittal fast spin echo T2-weighted images in extension position demonstrates reduced spinal cord diameter at C5-C6 level with a noncompressed elongated central hyperintense lesion. (B) Axial T2-weighted image (433/17 with 20° flip angle) showing loss of attachment between the dural sac and the subjacent laminae with symmetrical hyperintense lesions in the anterior horns of the spinal cord (Owl's eyes sign). (C) Sagittal fast spin echo T2-weighted images in flexion position demonstrate displacement of the dorsal dural sac from the posterior spinal canal wall with enlargement of the epidural space (arrow).