Cerebral infarction related to neck position in an adolescent.

A 16-year-old boy developed a left occipital lobe infarction after falling asleep with his head extended and rotated to the left. He was found to have an anomalous cerebrovascular system, in which the entire blood supply to the left occipital cortex derived from the right vertebral artery. It has been shown that vertebral artery flow can be compromised by physiologic degrees of extension of the neck and rotation of the head to the opposite side. To our knowledge, this is the only reported case of cerebral cortical infarction due to temporary arterial obstruction of the vertebral artery during physiologic hyperextension of the neck and rotation of the head. All previous cases attributed to this mechanism have been brainstem, cerebellar, or cervical spinal cord involvement with thrombosis of the vessel in question. Anomalies of the cerebrobasilar vascular system may place these individuals in jeopardy during otherwise harmless physical activities.