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Background: The clinical implication of the tortuosity of white matter medullary arterioles has never been clarified precisely. We quantitatively investigated the relationship between such vascular tortuosity and the severity of hypertension (HT), which was graded according to the WHO classification. Methods: Forty-seven autopsied brains with age-adjusted stages of HT were evaluated. The largest tortuosity diameter and the largest vascular diameter in the same tortuous lesion were measured by light microscopic observation at the level of the corona radiata and centrum semiovale. A maximum ratio of these diameters was calculated for each patient. Results: Maximum ratios were found in almost all arterioles and were significantly increased according to the HT stages. Conclusions: Arteriolar tortuosity in the hemispheric white matter may reflect the severity of HT and be an indicator of hypertensive small vessel disease of the brain.

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In patients with severe hypertension, chronic heart failure or a history of stroke, the lower limit of autoregulation of cerebral blood flow (CBF) is shifted to higher levels of blood pressure (BP) than those observed in healthy subjects. The aim of pharmacotherapy for hypertensive patients with an impaired autoregulation of CBF should be to reduce BP while preserving an appropriate CBF. In the present study, 16 hypertensive patients who had had an episode of stroke more than 4 weeks previously were administered the angiotensin II (AT 1 ) receptor antagonist losartan at daily doses of 25-100 mg for 4 weeks. Systolic and diastolic blood pressures were recorded for 24 h using an ambulatory BP monitoring system. CBF in both hemispheres of the cerebrum and cerebellum was quantified using single photon emission tomography with N-isopropyl-p-[ 123 I]iodoamphetamine. At baseline, CBF was 29.776.7 ml/min/100 g in the cerebrum and 31.577.5 ml/min/100 g in the cerebellum. At the end of treatment, BP was lower, while CBF increased by 7.7% in the cerebrum, and remained at the baseline level in the cerebellum. Thus, CBF was preserved despite the reduction in BP. We consider the use of losartan is advantageous for hypertensive patients with a history of stroke in whom autoregulation of CBF is potentially impaired.

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