TRANSCRANIAL DOPPLER SONOGRAPHY IN HEADACHE-FREE MIGRAINEURS

We used transcranial Doppler ultrasonography to determine whether intr acranial blood velocities in 182 headache-free migraineurs (60 with au ra, 122 without sura) differed from velocities in 38 nonheadache prone control subjects. During the headache-free period, migraineurs with a nd without aura had significantly elevated mean velocities in all intr acranial arteries except the right internal carotid artery at the leve l of the siphon. Velocities in migraineurs with aura did not differ si gnificantly from velocities in those without aura. Markedly increased velocities were noted in a subset of interictal migraineurs. Two expla nations are possible: 1) Blood flow velocities may increase in respons e to a decrease in the cross sectional area of a vessel at or near the point of insonation. 2) Alterations at the level of the cerebral arte riole may affect regional cerebral blood flow, thereby changing blood flow velocities at the point of insonation. Transcranial Doppler sonog raphy alone cannot sort out which process is responsible for the vascu lar response. This work may have therapeutic as well as diagnostic imp lications. When interictal flow velocities are markedly increased, it is possible that therapeutic agents with vasoconstrictor action might cause an excessive response. Further study is needed to clarify the si tes of vasoreactivity as well as the magnitude of drug-induced vasocon strictor response.