[A case of flexion myelopathy presenting with reversible muscular weakness and atrophy of the unilateral proximal upper limb].

A 16-year-old man visited our clinic because of right-sided weakness of shoulder abduction and elbow flexion. He was well until about three weeks previously. Neurological examination revealed only that he had severe weakness together with mild atrophy of the muscles innervated by the C5 and C6 segments (the deltoid, biceps brachii, brachioradialis), slight hypesthesia on the thumb, and loss of deep reflexes of the biceps brachii on the right. No pyramidal signs were found in the lower extremities. EMG showed neurogenic changes of the atrophied muscles. Neuroradiological studies revealed right-sided atrophy of the spinal cord at C4-5 disk level, anterior shift of the posterior cervical dura mater and congestion of the internal vertebral venous plexus mainly at C4 and C5 vertebral level with his neck flexed. Conservative physiotherapy provided a good recovery within a few months. The clinical and neuroradiological findings of this case resemble those of juvenile type of distal and segmental muscular atrophy of upper extremities excluding distribution of involved muscles because of the different level of the spinal cord lesion. Pathomechanism of this case is considered to be the same as that of juvenile type of distal and segmental muscular atrophy of upper extremities.