HORMONAL STATUS AFFECTS THE REACTIVITY OF THE CEREBRAL VASCULATURE

OBJECTIVE: We compared the blood velocity and vascular resistance in t he central retinal and ophthalmic arteries in healthy nonpregnant, pre gnant, and postmenopausal women (before and after estrogen replacement therapy). STUDY DESIGN: Color flow Doppler ultrasonography was used t o determine systolic, diastolic, and mean velocity, as well as the res istance index in the central retinal and ophthalmic arteries in 10 non pregnant women, 10 third-trimester pregnant women, and 10 hypoestrogen ic postmenopausal women. The postmenopausal patients were again studie d 2 months after starting daily oral therapy with 2 mg of micronized 1 7 beta-estradiol. RESULTS: Pregnant women had a significantly (p < 0.0 5) higher diastolic blood velocity (4.2 +/- 0.8 cm/sec) and a lower re sistance index (0.56 +/- 0.05) in the central retinal artery, when com pared with nonpregnant women (diastolic velocity 2.8 +/- 0.8 cm/sec, r esistance index 0.68 +/- 0.1), and hypoestrogenic postmenopausal women (diastolic velocity 2.6 +/- 0.9 cm/sec, resistance index 0.73 +/- 0.0 8). Significant differences were not seen in the ophthalmic artery. In the postmenopausal patients estradiol therapy was associated with an increase in diastolic velocity (2.6 +/- 0.9 cm/sec vs 4.1 +/- 1.6 cm/s ec) and a decrease in the resistance index (0.73 +/- 0.08 vs 0.66 +/- 0.1) in the central retinal artery but not in the ophthalmic artery. C ONCLUSIONS: The blood velocity and vascular resistance in the cerebral microcirculation appear to change according to the phases of a woman' s reproductive life. This may be related, in part, to estrogen levels, because estradiol vasodilates small-diameter cerebral vessels in hypo estrogenic postmenopausal women.