Abstract
A 74-year-old right-handed man who presented with sudden right hemiparesis was transferred to our hospital an hour after onset of symptoms. Upon admission, he exhibited mild unconsciousness, slurred speech, right hemiparesis, and pyramidal signs in both lower extremities. Computed tomography (CT) and magnetic resonance imaging (MRI) showed no lesions, except for the disappearance of the right vertebral artery in magnetic resonance angiography. However, MRI conducted on the next day showed an area of high intensity in a diffusion-weighted image, which ranged from the medial to the right dorsolateral side of the medulla oblongata. Follow-up MRI conducted on day 19 showed that the lesion ranged from the medulla to the upper cervical spine. CT angiography showed a proximal-dominant narrow area in the right vertebral artery. A neurological examination conducted after the improvement of the patient’s unconsciousness revealed weakness in the right sternocleidomastoid muscle, mild left hemiparesis, and sensory impairment on the left side of the body, in addition to the neurological findings that were observed upon admission. Our observations suggest that the ischemic lesion that occurred due to right vertebral artery occlusion included pyramidal decussation, which caused ipsilateral-dominant quadriparesis by impairing the motor fibers both before and after the crossing.
