Abstract
We investigated cerebral blood flow (CBF) and metabolism in patients with hemodynamic ischemia by positron emission tomography (PET) and thermal diffusion flow meter. We also studied neuropsychological functions to evaluate the effects of surgical revascuralization.
Bypass surgery of the superficial temporal artery to the proximal middle cerebral artery was performed on 26 patients satisfying the following categories: 1) stenosis or occlusive lesion in main cerebral arteries; 2) no marked focus of infarction on CT or MRI. PET was performed before and 1 month after the operation, and CBF, the cerebral metabolic rate of oxygen (CMRO2) and oxygen extraction fraction (OEF) were analyzed. Cerebrovascular reserve capacity (CVRC) was also calculated after acetazolamide challenge. CBF during the operation was continuously measured with a thermal diffusion flow meter. CO2 response of CBF was analyzed before and after anastomosis. Neuropsychological functions were evaluated by Hasegawa dementia scale revised (HDS-R), minimental state examination (MMSE) and Wechsler adult intelligence scale revised (WAIS-R).
Before the operation, increase in OEF accorded with the decrease in CBF, and a significant relationship between both CBF and CVRC, and OEF and CVRC was found. A decrease in CVRC was noted prior to a decrease in CBF and elevation of OEF. CVRC caused by acetazolamide might reflect CO2 reactivity. Significant improvement of CBF and CVRC, and normalization of OEF were observed after the operation. Also, significant improvement of neuropsychological function was observed by HDS-R and WAIS-R. Disturbance in neuropsychological function might reflect elevation of OEF.
