AMAUROS?S FUGAX (Blackouts)
Posted by recep on April 14th, 2009AMAUROS?S FUGAX(Blackouts)
When unilateral, amaurosis fugax suggests either retinal or optic nerve ischemia. The blackout may present as a dimming of vision with a slow recovery beginning after 5 to 10 min. The restoration of clear vision occurs in the reverse order from the onset pattern. Several episodes of blackout may precede an attack of ischemic optic neuropathy, or episodes may occur for years without serious sequelae. However, patients experiencing such episodes should be under medical care. The blackout can be bilateral if associated with low blood pressure.
Unilateral blackouts are characteristic of carotid artery narrowing,
usually at the bifurcation of the common carotid artery. Because ather
oma is the major cause of vessel narrowing, patients > 50 yr are most
susceptible. Obstruction of the left carotid artery is six times more com
mon than that of the right. f
When blackout is accompanied by hemiplegia on the side opposite the affected eye (transient ischemic attack), carotid stenosis on the side of the affected eye should be strongly suspected. Early recognition of serious carotid stenosis is important because many affected patients will develop permanent visual loss or hemiplegia without appropriate medical and surgical intervention.
The aortic arch syndrome may be suspected if increasingly frequent blackouts are related to changes in posture, such as suddenly sitting up or standing.
