rCBF was measured by 133Xenon inhalation at rest and during pCO2 manipulation in 19 patients prior to and at various times after STA-MCA bypass surgery. The resting flow increased gradually postoperatively, seemingly more due to progressive clinical recovery from the original neurologic disability than due to the surgical intervention. CO2 reactivity increased in some patients, more in those who preoperatively had the poorest reactivity. The negative relationship between preoperative reactivity and postoperative change in reactivity was highly significant. These observations are consistent with the interpretation that the surgery did not significantly affect the resting flow level but did augment the collateral reserve in those cases in which it had been most severely impaired by the arterial lesion.
Blood velocity in the middle cerebral artery was measured by transcranial Doppler ultrasonography in 15 patients suffering complete hemiplegia of <12 hours' duration, presumed due to cerebral ischemia. Among seven patients in whom blood velocity was > 30 cm/sec, five made complete or partial useful recovery of the involved hand and arm. Among eight patients in whom blood velocity was <30 cm/sec, one recovered completely while the other seven retained permanent total paralysis of the hand and arm. (Stroke 1988; 19:648-649) A cute hemiplegia is often due to ischemia in the territory supplied by the middle cerebral artery (MCA). There is a consensus that if this ischemia persists for longer than a few hours, permanent tissue damage will result. This short time period greatly constrains the opportunity for treatment by emergency revascularization surgery or thrombolysis.Transcranial Doppler ultrasonography (TCD) offers the possibility in some cases for rapid noninvasive diagnosis of the arterial lesion. Although there is controversy about the quantitative accuracy and significance of the measurement of blood velocity in the accessible intracranial vessels, there can be little doubt that the demonstration of measurable blood velocity in the MCA means that the artery is not occluded. This qualitative fact, relatively easily and quickly demonstrable by TCD, may have practical importance in facilitating some of the decisions that would be necessary for emergency medical or surgical revascularization. The purpose of my report is to present preliminary experience with TCD evaluation in cases of acute hemiplegia. Subjects and MethodsFifteen consecutive patients with complete hemiplegia had initial clinical neurologic and TCD examinations within 12 hours of onset of the hemiplegia (early cases) and were then followed daily in the hospital and subsequently up to 6 months as outpatients. An initial noncontrast computed tomogram and lumbar puncture were normal in all 15 patients; arteriography was not done in any. Using an EME TC 2-64 TCD recorder (Uberlingen, F.R.G.) operating with pulsed ultrasound at 2 MHz, 1 -2 mean blood velocity was measured in the horizontal portion of the MCA on each side at 5-mm intervals between the depths of 60 and 40 mm from the temporal scalp. The average of these five measurements in each artery was then calculated and used for comparing the two sides
This paper introduces a new index for the assessment of regional cerebral blood flow. The index is proportional to total flow, and is obtained from the ratio of regional count rate to arterial indicator input to a region. This index is a more sensitive indicator of impaired perfusion than the traditional flow rate indices which express flow per unit mass of tissue per minute. It accounts for brain tissue partly or totally deprived of its blood supply. Examples of clinical application are reported. A good correlation with the findings of computer-assisted tomography has been found.
SUMMARY An initial assessment of the differential sensitivity of total versus partial curve analysis in estimating task related focal changes in cortical blood flow measured by the 133 Xe inhalation technique was accomplished by comparing the patterns during the performance of two sensorimotor tasks by normal subjects. The validity of these patterns was evaluated by comparing them to the activation patterns expected from activation studies with the intra-arterial technique and the patterns expected from neuropsychological research literature. Subjects were 10 young adult nonsmoking healthy male volunteers. They were administered two tasks having identical sensory and cognitive components but different response requirements (oral versus manual). The regional activation patterns produced by the tasks varied with the method of curve analysis. The activation produced by the two tasks was very similar to that predicted from the research literature only for total curve analysis. To the extent that the predictions are correct, these data suggest that the 133 Xe inhalation technique is more sensitive to regional flow changes when flow parameters are estimated from the total head curve. The utility of the total head curve analysis will be strengthened if similar sensitivity is demonstrated in future studies assessing normal subjects and patients with neurological and psychiatric disorders.Stroke Xe in the mouth, sinuses and pharynx is one of the more serious of these methodological problems. Obrist et al 2 3 tried to reduce the influence of these artifacts by fitting a model to the subset of data collected after the concentration of xenon in end-expired air has fallen below 20 percent of its maximum value. However, their simulation studies showed that, in the absence of scattered radiation, estimates for K, (gray matter clearance) match the true value when model fitting is started near time zero and decline as the start fit time is increased. Thus, although the effects of scattered radiation are minimized, data corresponding to the inhalation phase (during which most of the relevant information on gray matter flow occurs) are discarded. Hazelrig et al. 4 have recently proposed a time domain correction method to adjust for the presence of these artifacts, thereby allowing utilization of the entire head curve in the estimation of the blood flow parameters.One of our long term goals is to determine whether analysis of the total head curve can improve the sensitivity of the l33 Xe inhalation technique in demonstrating focal activation of cortical flow relative to focal changes in flow estimated by the partial curve method. The purpose of this study was to make an initial assessFrom the
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