C5 pure motor spinal cord injury: A case with a rare manifestation of cervical spinal cord injury.

We report an extremely rare case showing a fifth cervical spine (C5) level pure motor cervical spinal cord injury (SCI). A 55-year-old-man lost consciousness and fell into a bathtub. Immediately after regaining consciousness, the patient had right arm drop alone. He was referred to our department for investigation of right arm drop 4 months later. Neurological examination revealed motor weakness of the right deltoid muscle. MRI of the cervical spine revealed a C3-4 level central disc herniation compressing the spinal cord. An electromyogram study revealed bilateral neurogenic discharges in the deltoid, supraspinatus and infraspinatus muscles. We diagnosed a C5 segmental pure motor SCI. We chose conservative therapy for the present patient. At the latest follow-up visit, the patient showed modest recovery of motor weakness. Although it is unusual, this case illustrates the possibility that C5 segmental pure motor palsy can occur as one of the manifestations of cervical SCI.