<unk>  <unk>  describes a temporary set of symptoms due to decreased blood flow (ischemia) in the posterior circulation of the brain. The posterior circulation supplies the medulla, pons, midbrain, cerebellum and (in 70-80% of people) supplies the posterior cerebellar artery to the thalamus and occipital cortex. As a result, symptoms vary widely depending which brain region is predominantly affected. The term<unk> ' 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. 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.<unk>  should not be confused with other conditions which may relate to the posterior circulation. 25% of strokes and TIAs affect parts of the brain supplied by the posterior circulation, but many of these are embolic from cardiac or other sources.<unk>  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.
Vertebrobasilar insufficiency
Convergence insufficiency
Velopharyngeal insufficiency
Eustachian tube dysfunction
Noise-induced hearing loss
Vibroacoustic disease
Aqueductal stenosis
Subglottic stenosis