抄録
Activation studies of cerebral circulation are important for evaluation of cerebrovascular reactivity (CVR) . In this study, CVR was investigated in 52 healthy subjects, 25 patients with chronic severe hypertension and 16 patients with hyperlipidemia. All the patients had normal findings of neurological studies, brain CT and neck vessel echo-Doppler. The CVR was assessed by TCD recording of blood flow velocity in the middle cerebral artery (MCAFV) under resting conditions and at 5, 10, 15 and 20 min after i.v. injection of 1g Acz. Additionally, we performed an Acz-activated 133Xe-CT study in 8 healthy patients (16 hemispheres) who had mild carotid stenosis on MR-angiography. The regional cerebral blood flow (rCBF) in the MCA territory was measured and the CVR was also analyzed. MCAFV and CVR determined by TCD study showed a non-significant tendency to be reduced in the group aged over 60 yr. The MCAFV under resting conditions was nearly the same in the normal controls and in the patients with hypertension, but the CVR was decreased in patients even without stroke. The normal value of CVR seemed to be 40-50% in this study. When planning surgical treatment for asymptomatic patients (e.g.; those with occlusive cerebrovascular disease and unruptured cerebral aneurysm) with decreased CVR, they should be treated carefully using prophylaxis for ischemic complications.
