Hirayama disease, a rare cause of posture related cord compression: a case report from radiological perspective.

Hirayama Disease is a disease of young adults lying in the age group between twenty to thirty years. It is an extremely uncommon disorder. Its other synonyms are juvenile muscular atrophy of the distal upper extremity (JMADUE) or monomelic amyotrophy (MMA). A previously healthy 25-year-old man presented with gradually increasing weakness in both hands for the past few years. There was neither history of trauma nor family history of neuromuscular disease. MRI was advised. Routine cervical sagittal MR images (Non-flexion or extension) revealed cord flattening and atrophy at C5 to C7 levels.There was evidence of syrinx. Flexion MRI was performed later on. Midline sagittal T1- and T2-weighted images of the cervical spine showed anterior displacement of the cervical cord with marked flattening of cord. The patient was advised to modify his posture, avoid flexion and to apply cervical collar. Physiotherapy was started to improve the tone of muscles. In case of deterioration of symptoms he was advised to consult for surgery. The purpose of this case report is to show the importance of dynamic scan in symptomatic patients especially in their second or third decade with progressive upper limb weakness. Mostly the scanning in neutral posture does not reveal any significant cord compression. Similarly a normal looking thecal sac with preserved anterior and posterior thecal sleeves without disc disease dramatically changes on change of posture. This case shows the importance of dynamic scanning in symptomatic patients with progressive upper limb weakness and with no obvious cause of the cord changes on routine MR images. Cervical collar, physiotherapy and in resistant cases surgery is recommended for management.