Imaging in Hirayama disease.

Hirayama disease, also known as Sobue disease is a rare nonprogressive spinal muscular atrophy. Here, we report a case series of three young males presenting with atrophy of distal upper limb and Hirayama disease as their clinico-radiological diagnosis. Magnetic resonance imaging (MRI) revealed loss of cervical lordosis with focal areas of lower cervical cord atrophy in a neutral position. MRI in flexion position revealed, anterior displacement of the detached posterior dura from the underlying lamina compressing the thecal sac and widened posterior epidural space with flow voids seen better on 3D-CISS images. All the three patients were managed conservatively.