A 73-year-old man was admitted for evaluation of sudden onset of dizziness, bilateral shoulder pain, and brachial diplegia. Neurological examination revealed severe bilateral weakness of the triceps brachii, wrist flexor, and wrist extensor muscles. There was no paresis of the lower limbs. His gait was ataxic. Pinprick and temperature sensations were diminished at the bilateral C6-C8 dermatomes. Vibration and position senses were intact. An MRI of the head revealed a right cerebellar infarction and occlusion of the right vertebral artery. An MRI of the cervical spine on T₂ weighted imaging (T₂WI) showed cord compression at the C3/4-C5/6 level secondary to spondylotic degeneration without any intramedullary signal changes of the cord. On the following day, however, high-signal lesions on T₂WI appeared in the C5-C6 spinal cord, suggesting cord infarction. Unilateral vertebral artery occlusion does not usually result in cervical cord infarction because of anastomosis of arteries. Because of the long-term mechanical compression in our case, it was likely that cervical cord ischemia was present before the onset of symptoms. On the basis of chronic cord compression, our case suggests that occlusion of a unilateral vertebral artery could cause cervical cord infarction.