Cerebrovascular Reactivity Measured By Transcranial Doppler in Migraine Attila Valikovics, MD; Lászió Oláh, MD; Béla Fülesdi, MD; Zoltán Káposzta, MD; Andrea Ficzere, MD; Dániel Bereczki, MD, PhD; László Csiba, MD, PhD From the Department of Neurology and Psychiatry, University Medical School of Debrecen, Hungary. Address all correspondence to Dr. Artilla Valikovics, Department of Neurology and Psychiatry, University Medical School of Debrecen, Debrecen, Nagyerdei krt. 98, H-4012 Debrecen, Hungary. Accepted for publication October 15, 1995. Changes in the diameter of intracranial arteries might have a major role in the pathophysiology of migraine. Though several studies have found alterations in velocity of blood flow and in cerebral vasomotor reactivity of intracranial arteries in migr aineurs in headache-free periods, as well as during migraine attacks, the results are inconclusive. To determine if intracranial hemodynamic characteristics of patients with migraine differ from those of controls, we measured baseline velocity of blo od flow by transcranial Doppler in the middle cerebral arteries in headache-free periods in 51 migraine patients and in 101 age-matched controls. Cerebrovascular reactivity was measured after intravenous administration of acetazolamide in 12 migraino us patients and in 19 controls. Baseline mean velocity was significantly higher in the migraine group (70 versus 65 and 72 versus 65 cm/s with P =0.02 and P =0.0007 on the left and right sides, respectively). The difference stayed significant during ac etazolamide stimulation, but the course of response did not differ between controls and migraineurs. Despite statistical significance, absolute differences were small. Therefore, middle cerebral artery velocity measurements and the acetazolamide test are not useful for the diagnosis of migraine in the interictal period. Key words: migraine, transcranial Doppler, acetazolamide, cerebrovascular reactivity Abbreviations: TCD transcranial Doppler, SPECT single photon emission computed tomography, MCA middle cerebral artery, CR cerebrovascular reactivity, CRC cerebrovascular reserve capacity ( Headache 1996:36;323–328) Several factors contribute to the pathophysiology of migraine headache. According to the concept of a threshold of susceptibility, the brains of migraine patients differ from those of controls in hypothalamic functions and in mechanisms of pain contr ol as well as of vascular regulation. 1 Transcranial Doppler (TCD) measurements have been used by several investigators to study the pathophysiology and the effects of therapeutic interventions in headache. 2,3 Though no difference in blood flow velocity in intracranial arteries was found between migraineurs and controls by some investigators, 4,5 studies involving larger numbers of patients revealed somewhat or significantly higher velocity of flow in intra cranial arteries of migraine patients 6–9 during attack-free periods. Increased blood flow velocity measured by TCD can be the result of either constriction (increased tone) of larger arteries or decreased peripheral resistance (dilatation of arteriol es). Similarly to baseline measurements, stimulation studies were also inconclusive. Zwetsloot et al 10 found normal vasomotor reactivity to carbon dioxide (CO 2 ) in migraineurs. Decreased CO 2 reactivity during the migraine attack was reported by Harer and von Kummer 11 while Sakai and Meyer, 12 Thomas et al, 13 Harer and von Kummer, 11 and Thomsen et al 14 found increased vasomotor reactivity in the headache-free period. The stimuli applied in these studies were varied and hard to standardize. To our knowl edge, the acetazolamide provocation to test cerebral vasomotor reactivity in migraine patients has been used by only one group who measured blood flow by single photon emission computed tomography (SPECT). 15 Based on the contradictory data outlined above, our study posed three questions: (1) Can we find differences in baseline flow velocity in the middle cerebral artery (MCA) between migraineurs and age- and sex-matched controls. (2) Using the standard D iamox ® test (1 g acetazolamide IV), can we detect any difference between vasomotor reactivity of migraineurs and controls. (3) Based on these data, could we recommend baseline TCD measurements or the acetazolamide-TCD test as a reliable tool for the diagnosis of migraine in interictal periods.