Hirayama-Like Disease In The Thoracic Spine : A Case Report

초록

Hirayama disease is a flexion disorder of spine that involves the lower cervical segment The pathophysiology is unknown but would be due to dynamic compression of spinal cord by forward displacement of the dorsal dura during neck flexion. It usually develops asymmetric motor weakness of forearms in male patients. It should be differentiated from other motor neuron diseases. We reported a young man who had features similar to Hirayama disease in the thoracic spine level at spinal cord MRI and electrophysiologic studies.An eighteen-year-old young man without any past illness visited our clinic with 4 weeks history of slowly progressive left side upper arm weakness. Physical examination revealed weakness of left elbow and wrist extensor muscles, without sensory change. Deep tendon reflex and pathologic reflex examinations revealed no abnormal findings. He visited other clinic a week ago and already did electrodiagnostic study. At that time, the motor, sensory nerve conduction studies (NCS) showed normal responses, including F waves. Needle electromyography (EMG) study revealed abnormal spontaneous activities (ASA) at bilateral upper extremity muscles (extensor digitorum communis (EDC), triceps brachii (TB) and left upper extremity muscles (flexor carpi ulnaris (FCU), abductor pollicis brevis (APB). Polyphasic motor unit action potentials (MUAPs) were observed in the left upper extremity muscles (TB, EDC, FCU, APB). We conducted the follow-up study a month after the previous test. NCS revealed normal motor and sensory nerve responses, including F waves in upper and lower extremities. Needle EMG study showed ASA at right flexor carpi radialis muscle. Neurogenic polyphasic (longer duration and increased amplitude) MUAPs were observed in the left upper extremity muscles (flexor carpi radialis (FCR), FCU, extensor carpi radialis, 1st dorsal interosseous, triceps brachii) and right upper extremity muscles (FCR, 1st dorsal interosseous, EDC). The above findin