vertebra-basilar insufficiency.
Vertebrobasilar insufficiency (VBI) is defined by inadequate blood flow through the posterior circulation of the brain, supplied by the 2 vertebral arteries that merge to form the basilar artery. The vertebrobasilar arteries supply the cerebellum, medulla, midbrain, and occipital cortex. When the blood supply to these areas is compromised, it can lead to severe disability and/or death. Because the cerebellum is involved, survivors are often left with dysfunction of many organs including ataxia, hemiplegia, gaze abnormalities, dysarthria, dysphagia and cranial nerve palsies. Fortunarely, many patients have small vessel involvement and thus the neurological deficits are mild and localized.
