1 Ischemic causes, provided the ischemic threshold is not significantly surpassed, enjoy total recovery. Migrainous types of aura actually involve no detectable tissue pathology as well as little or no expectation of permanent deficit however, migraine with aura has demonstrated increased risk of stroke. For visual scotomas, the primary pathogenesis may occur at the level of the receptors, retinal arterial tree, short posterior ciliary arteries, ophthalmic artery, optic nerve, carotid artery, vertebrobasilar artery or cerebral hemisphere. The differentials for scotoma likewise include migraine and seizure, but the term is more appropriately linked to ischemia, retinal degenerations and inflammations, paraneoplastic syndromes and other neurologic disorders. The definition of visual scotoma is similar to that of visual aura. Visual auras may be transient (e.g., a few seconds) or longstanding (perhaps for months) and, importantly, they may be accompanied by headaches or other types of aura such as vertigo, numbness, tingling or aphasia. Furthermore, an actual image may be adulterated (appears larger, perseverates, etc.). Aura can be defined as either positive (seeing something that is not there) or negative (not seeing something that is there). Visual changes described by patients are often referred to as blur, a word abused by patients as frequently as the word “dizzy.” Blur has different connotative meanings to patients. A visual aura is a transient or longstanding visual perceptual disturbance experienced with migraine or seizure that may originate from the retina or the occipital cortex. With scintillating, or fortification, scotomas, the central scotoma is bordered by a crescent of shimmering zigzags. An understanding of the different types of aura and scotomas and how they present allows eye care practitioners to differentiate causes and order testing appropriately for potentially very different pathologies. Because of this, the complaint of visual aura or scotoma requires a comprehensive evaluation and should not simply be assumed to be migrainous (a diagnosis of exclusion). Nonetheless, each term, when used in the right circumstance, may define remarkably similar visual deficits in one or both eyes.Ī substantial list of differentials must be considered when a patient describes such visual disturbances, some associated with significant morbidity. Likewise, terms such as visual scotomas, amaurosis fugax or transient visual obscurations also represent a disturbance of vision however, they do not classically precede migrainous headache or cortical seizure activity and are associated with other types of pathology.
Although classically preceding migraine or seizure, an aura, simply defined, is a symptom, not a medical condition unto itself. Visual aura represent a type of neurologic deficit familiar to any eye care practitioner.
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