Teaching NeuroImages: Hirayama Disease With Symmetric Atrophy of Bilateral Distal Upper Extremities.

A 15-year-old boy presented with progressive left to bilateral hand weakness and cold paresis over 1 year. Examination revealed atrophy of upper limb musculature, especially bilateral dorsal interossei muscle. Neutral MRI showed cord thinning and intramedullary hyperintensity at C5–C7 levels. Neck flexion MRI demonstrated bilaterally symmetric spinal cord compression due to dural sac anterior shifting (figure), suggestive of Hirayama disease (HD). HD mimics amyotrophic lateral sclerosis–like symptoms and features an expansion of the dural sac on neck flexion MRI.[1] The majority of HD is unilateral or asymmetric but bilateral symmetric involvement is reported in 10% of patients and indicates more severe affliction.[2]

Figure

Photography of the Patient's Hands and Neck MRI

(A) Wasting of bilateral dorsal interossei muscle. (B) Neutral sagittal T2-weighted MRI shows cord thinning and hyperintense signal at C5 to C7 levels. Neck-flexion sagittal (C) and axial (D) T2-weighted MRI show crescent-shaped enlarged posterior epidural space below C3 with flow void causing bilaterally symmetric flattening of the lower cervical cord.