[Severe stenoses and persistent occlusions of the middle cerebral artery: hemodynamic and metabolic consequences studied by positron tomography].
Using positron emission tomography and the 15O continuous inhalation technique, we have measured the regional cerebral blood flow (rCBF) oxygen extraction fraction (rOEF) and oxygen consumption (rCMRO2) of non-infarcted tissue in six patients with either tight stenosis (N = 3) or occlusion (N = 3) of the trunk of the middle cerebral artery (MCA); these arterial lesions were shown to be persistent on late and/or repeated angiograms. The patients were studied 1 to 6 months after their last cerebral ischemic event. The data were analyzed in 4 cm2 regions of interest (fig. 1) and were compared to age-matched control values. Regional right/left ratios were tested for significance individually by comparison to 95 p. 100 confidence limits found in control subjects. We found a significant reduction in mean rCBF in the affected MCA territory; concomitantly, there was a lesser decrease in rCMRO2 significant only in the peri-sylvian area; this was associated with a moderate but significant increase in rOEF in the same areas (Table II, fig. 2 and 3). Individually, the reduction in rCBF and the increased rOEF were significant in 5/6 and 2/6 patients, respectively (Table III). These data indicate that rCBF is decreased distal to persistent hemodynamic MCA obstruction in most patients. This hypoperfusion appears due in part to a mild degree of cerebral ischemia (as demonstrated by the occurrence of "misery perfusion"), indicating inadequate perfusion pressure distal to the MCA obstruction. This was associated with a metabolic depression of the cortex possibly resulting from either neuronal loss, or deactivation (diaschisis), or long-standing hemodynamic local failure or any combination of the three.(ABSTRACT TRUNCATED AT 250 WORDS)
D000328:Adult; D000368:Aged; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D002539:Cerebral Arterial Diseases / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D014055:Tomography, Emission-Computed
Sténoses serrées et occlusions persistantes de l'artère cérébrale moyenne: conséquences hémodynamiques et métaboliques étudiées par tomographie à positons.