Definition of Migraine aura

Migraine aura: A sensory phenomenon that may occur before a migraine. Visual auras may include flashing lights, geometric patterns, or distorted vision. Some people may have aural auras that involve hearing sounds (usually buzzing) that are not actually present, olfactory auras that involve smelling odors that are not actually present, or tactile auras that appear as premonitory physical sensations. Auras are caused by unusual activity in the brain. The auras experienced by migraine sufferers are similar to those associated with epilepsy.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=11671
Last Editorial Review: 3/19/2012