MeSH

The artery formed by the union of the right and left vertebral arteries; it runs from the lower to the upper border of the pons, where it bifurcates into the two posterior cerebral arteries.

Localized or diffuse reduction in blood flow through the vertebrobasilar arterial system, which supplies the BRAIN STEM; CEREBELLUM; OCCIPITAL LOBE; medial TEMPORAL LOBE; and THALAMUS. Characteristic clinical features include SYNCOPE; lightheadedness; visual disturbances; and VERTIGO. BRAIN STEM INFARCTIONS or other BRAIN INFARCTION may be associated.

Year introduced: 1980

Abnormal outpouching in the wall of intracranial blood vessels. Most common are the saccular (berry) aneurysms located at branch points in CIRCLE OF WILLIS at the base of the brain. Vessel rupture results in SUBARACHNOID HEMORRHAGE or INTRACRANIAL HEMORRHAGES. Giant aneurysms (>2.5 cm in diameter) may compress adjacent structures, including the OCULOMOTOR NERVE. (From Adams et al., Principles of Neurology, 6th ed, p841)

Year introduced: 2000(1969)

A subtype of migraine disorder, characterized by recurrent attacks of reversible neurological symptoms (aura) that precede or accompany the headache. Aura may include a combination of sensory disturbances, such as blurred VISION; HALLUCINATIONS; VERTIGO; NUMBNESS; and difficulty in concentrating and speaking. Aura is usually followed by features of the COMMON MIGRAINE, such as PHOTOPHOBIA; PHONOPHOBIA; and NAUSEA. (International Classification of Headache Disorders, 2nd ed. Cephalalgia 2004: suppl 1)

Year introduced: 2006 (2000)