Motor Neuron Disease P-MN003. Improvement of progressive distal bimelic hirayama disease after surgery: A case report

Abstract

Introduction . Hirayama disease, a benign muscular atrophy of the distal upper extremity, is a rare cervical myelopathy usually characterized by slowly progressive weakness of one hand (monomelic amyotrophy). The pathognomonic finding is a forward-shifted spinal cord during neck flexion by magnetic resonance imaging (MRI), as in this young Thai man with rapidly progressive weakness and muscle atrophy in the bilateral distal upper extremities. In this report, we describe a 16-year-old man who had finger drop then rapidly progressive weakness and wasting of both hands without pain for 6 months, electrophysiological evidences of motor neuronopathy. He was diagnosed as progressive distal bimelic type of Hirayama disease by a neurologist before getting MRI. Radiological findings showed normal study in neutral position but during neck flexion showed cervical compression and venous plexus engorgement dorsal to thecal sac. After three months without improvement by neck collar he underwent surgery to prevent flexion. We will provide detail of clinical findings. electrophysiological findings, interesting radiological findings and detail of operation. Results . There were improvements of muscle power of both hands and muscle wasting at 3 months postoperatively. Conclusion . Although Hirayama disease is benign in nature and frequently self-limiting but radidly progressive weakness in some cases may have benefit from surgery to prevent neck flexion.