How to distinguishe a migraine aura from cerebral ischemia and seizures?
Visual or sensory auras from migraine typically spread slowly across the visual field or body part followed by a gradual return to normal function in the areas first affected after 20 to 60 minutes.
The onset of cerebral ischemic events is usually sudden with an equal distribution in the relevant vascular territory, although the affected area can expand stepwise if blood flow drops in additional vessels.
The return of function in areas first affected while symptoms begin in newly affected areas occurs in migraine aura but not in ischemia or seizures.
Migraine aura often begins with positive phenomena such as shimmering lights, zigzags in vision, or tingling.
It is then frequently followed minutes later by negative symptoms such as scotoma, numbness, or a loss of sensation.
This symptom progression can also occur during seizures but usually with a faster progression of symptoms.
This cycle from positive to negative symptoms is not typical of cerebral ischemia.
