Migraine aura precedes the headache in about 20% of patients. The most common type of aura is visual. It consists of flashing lights, sparkles, partial loss of vision, and other visual distortions, which can move across the visual field. Typical duration of the aura is 20 to 60 minutes and it can occur without a headache. Many people get frightened when experiencing an aura for the first time. Thoughts of a brain tumor spring to their minds. Although auras rarely indicate a serious problem, an MRI scan is usually indicated when an aura occurs for the first time.
MRI scans are considered to be safe in pregnancy, but the current guidelines of the FDA require labeling of the MRI devices to indicate that the safety of MRI with respect to the fetus “has not been established”. Not surprisingly, most expecting mothers instinctively try to avoid any testing. So, what to do if a pregnant woman develops an aura? A study by headache specialists at the Montefiore Headache Center in the Bronx suggests that this is not an uncommon occurrence. Of 121 pregnant women presenting with an acute headache, 76 had migraines and a third of these had an aura for the first time in their lives. Two thirds of auras occurred in the third trimester. This report should be reassuring and may help avoid unnecessary MRI scans. However, MRI may still be needed if there are other signs of a more serious neurological problem on examination or by history.
