Spreading oligemia in the migraine aura--most likely an artifact due to scattered radiation.

The view that "spreading oligemia" reflects spreading depression in the human brain during the migraine aura is based on a defective analysis of CBF data where the most important methodological source of error (scattered radiation) has been ignored. When scattered radiation is taken into account it appears that CBF in the low flow area during the migraine aura is reduced to the ischemic level. There is no reason to believe that "spreading" of the low flow area occurs. Most likely the blood flow decreases in an area of fixed size. All available CBF evidence in fact lends support to "the vascular theory" of migraine pathogenesis.