Vertebrobasilar insufficiency (VBI) describes a temporary set of symptoms due to decreased blood flow (ischemia) in the posterior circulation of the brain.

The term 'vertebrobasilar insufficiency' may be used to describe disease in the vertebral and basilar arteries which predisposes to acute embolic events such as transient ischemic attacks (TIAs) and stroke.

[2] Alternatively it may be used to describe recurrent symptoms which result from narrowing (stenosis) of these arteries in combination with changes of blood pressure or head position.

VBI should also not be confused with beauty parlour syndrome which refers to strokes caused by acute arterial dissection brought on by extreme head positions, such as those maintained during hair washing.

Vertigo is a relatively common symptom that can result from ischemia to the cerebellum, medulla or (rarely) the internal auditory artery which supplies the vestibular system of the inner ear.

[6] A common cause is orthostatic hypotension which results in a fall in blood pressure when the patient changes posture and may be exacerbated by medicines (particularly antihypertensives), dehydration and heat.

The diagnosis of posterior circulation stroke or TIA can be made on the basis of history and physical examination, which should include exclusion of alternative causes for the patient's symptoms and consideration of risk factors for atherosclerosis.

Alternatively, carotid sinus hypersensitivity can cause episodes of dizziness and collapse on head turning if the neck brushes against clothing.