Abnormal Cerebrovascular Reactivity in Headache-Free Migraineurs

Abstract

The thermographic finding of a unilateral ''cold patch'' on the forehead of both classic and common migraine sufferers has prompted the suggestion that there is an asymmetry in the vasomotor tone of superficial extracranial arteries that could also be present in cerebral vessels. Transcranial Doppler sonography allows the study of the response of intracranial arteries to variations of blood pCO₂, which may give an estimate of vasomotor tone regulation. Thirty headache-free migraineurs were compared to 30 age-matched controls. The provocative test consisted of a 30-second apnea, followed by hyperventilation for 1 min. End-tidal pCO₂ was assessed by means of a capnometer. The mean flow velocity of the middle cerebral artery was monitored throughout the testing session by means of a 2-MHz transcranial Doppler probe. Baseline mean flow velocities were not statistically different between right and left sides in both controls and migraineurs and between ipsilateral (to the ''cold patch'') and contralateral side in migraineurs. During apnea migraineurs, ipsilaterally to the ''cold patch'', showed a significantly lower increment in mean flow velocity than controls. Following apnea and during maximal hyperventilation, migraineurs showed a bilateral vasoconstriction significantly more pronounced than controls. End-tidal pCO₂ was not statistically different between migraineurs and controls. The findings suggest that the cerebral arterioles of migraineurs are more likely to undergo vasoconstriction when pCO₂ is reduced. In addition, there seems to be a unilaterally more pronounced tendency to resist a vasodilatory stimulation.

Exaggerated Interictal Cerebrovascular Reactivity But Normal Blood Flow Velocities in Migraine Without Aura

“…Others have also found an increased CVR in patients with migraine using different methods but they did not analyse patients with MA and MWOA separately, which makes a healthy comparison difficult (6, 7). On the contrary, studies reporting a normal (8, 9) or attenuated vasodilatory response (10–12) also exist. The great differences in inclusion criteria, diagnostic techniques and timing of study with regard to the last migraine attack make it extremely difficult to pool the results obtained.…”

“…Results of studies measuring cerebrovascular reactivity (CVR) in migraine interictally have also been contradictory. Most studies done on migraine without aura (MWOA) or migraine with aura (MA) showed a normal or increased CVR (6)(7)(8)(9), but studies showing a reduced vasodilatory response also exist (10)(11)(12). The discrepancies in these results can be explained by various factors, including time of measurement with regard to the last migraine attack, inclusion of both MA and MWOA as 'migraine' or differences in techniques used for measuring CVR (i.e.…”