Decreased vasoreactivity to right cerebral hemisphere pressure in migraine without aura: a near-infrared spectroscopy study.

OBJECTIVE: Several studies have reported changes in cerebrovascular reactivity during the interictal period of migraine. To characterize mechanisms of migraine, we compared changes in total haemoglobin (THbl) and regional oxygen saturation (rSO(2)) of the right and left frontal lobes in response to intracranial pressure changes during the interictal period of migraine. METHODS: Twelve right-handed migraineurs without aura and twelve age- and sex-matched healthy volunteers were asked to perform a head-down maneuver to increase intracranial venous pressure. Initial THbl was designated as 1.0, and all subsequent THbl measurements, which was proportional to the change in cerebral blood flow, were expressed as a value relative to this baseline. RESULTS: The head-down maneuver resulted in a significantly smaller increase in right-sided THbl in migraineurs when compared to volunteers (migraineurs, -0.1+/-0.04; volunteers, 30+/-13; P=0.027), but there was no significant difference in left-sided THbl when comparing migraineurs and volunteers. Further, the head-down maneuver produced a significantly smaller increase in right-sided THbl than in left-sided THbl in migraineurs (right side, -0.1+/-0.04; left side, 0.35+/-0.08; P<0.0001), but produced a significantly greater increase in right-sided THbl than in left-sided THbl in volunteers (right side, 30+/-13; left side, 0.44+/-0.13; P=0.030). The head-down maneuver resulted in a smaller decrease in right-sided rSO(2) in migraineurs when compared to volunteers (migraineurs, -4.1+/-2.2%; volunteers, -16+/-9.1%), but produced a significantly greater decrease in left-sided rSO(2) in migraineurs when compared to volunteers (migraineurs, -1.3+/-1.1%; volunteers, 2.8+/-0.63%; P=0.0037). CONCLUSIONS: These data indicate that pressure-related vasoreactivity is suppressed in the right hemisphere of migraineurs during the interictal period. SIGNIFICANCE: The suppression of vasoreactivity in the right hemisphere might be related to the pathogenesis of migraine.