Cerebral blood flow findings in moyamoya disease in adults

Three adult patients with moyamoya disease are described. They presented with intracerebral hematoma, cerebral infarction and subarachnoid hemorrhage, respectively. Subarachnoid hemorrhage is rare in moyamoya and is usually the result of aneurysm rupture. No aneurysm was found in our patient. Regional cerebral blood flow (rCBF) and the cerebral perfusion reserve assessed by the acetazolamide test, were significantly reduced in all three patients. The areas with most reduced baseline rCBF and most impaired vasoreactivity did not always correspond to the site of the vascular accident, indicating that these CBF changes were at least in part due to the moyamoya disease and/or its underlying causes, and not solely to the vascular accidents.     

Cerebral blood flow in infants: comparison of carotid blood flow and cerebral blood velocity

Carotid blood was measured with a ultrasonic volume flow meter in 38 infants. The carotid blood flow was 1.50 +/- 0.55 ml/sec. At the same time peak systolic flow velocity, mean blood velocity, end diastolic velocity, pulsatility index (PI) and resistance index (RI) in the middle and anterior cerebral arteries were measured by duplex Doppler scanning. There was a correlation between the carotid blood flow and the mean blood velocity in middle and anterior cerebral arteries. However, PI and RI were not well correlated with carotid blood flow.     

Cerebral blood flow is an earlier indicator of perfusion abnormalities than cerebral blood volume in Alzheimer's disease

The purpose of this study was to elucidate whether cerebral blood flow (CBF) can better characterize perfusion abnormalities in predementia stages of Alzheimer''s disease (AD) than cerebral blood volume (CBV) and whether cortical atrophy is more associated with decreased CBV or with decreased CBF. We compared measurements of CBV, CBF, and mean cortical thickness obtained from magnetic resonance images in a group of healthy controls, patients with mild cognitive impairment (MCI) who converted to AD after 2 years of clinical follow-up (MCI-c), and patients with mild AD. A significant decrease in perfusion was detected in the parietal lobes of the MCI-c patients with CBF parametric maps but not with CBV maps. In the MCI-c group, a negative correlation between CBF values and cortical thickness in the right parahippocampal gyrus suggests an increase in CBF that depends on cortical atrophy in predementia stages of AD. Our study also suggests that CBF deficits appear before CBV deficits in the progression of AD, as CBV abnormalities were only detected at the AD stage, whereas CBF changes were already detected in the MCI stage. These results confirm the hypothesis that CBF is a more sensitive parameter than CBV for perfusion abnormalities in MCI-c patients.     

Cerebral blood flow and brain stem lesion

Summary In 11 necropsy cases with prolonged states of unresponsiveness (apallic syndrome) of various origin (8 cases following closed head injuries, one patient with postmeningitic phlebothrombosis and 2 postanoxic encephalopathies) the decrease of cerebral blood flow (CBF) was correlated to the extent and pattern of the anatomical lesions. Arranging the patients according to the severity and pattern of brain stem damage and according to the CBF values a Spearman rank correlation resulted in a highly significant relationship between these two parameters. By contrast, the extent of damage to the telencephalon and basal ganglia did not correlate to the CBF reduction in these cases. One patient with extensive neocortical destruction without damage to the brain stem had moderately decreased CBF.The data indicate that CBF reduction may result from both extensive destruction of the cerebral pallium and from states in which the cerebral cortex is out of function due to damage at lower levels. The importance of the reticular formation in the brain stem for the function and perfusion of the cerebral cortex is stressed.

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Zusammenfassung An 11 Autopsiefällen mit protrahierten Bewußtseinsstörungen (apallisches Syndrom) verschiedener Genese (8 Zustände nach gedecktem Schädel-Hirn-Trauma, 1 Patient mit postmeningitischer Sinusthrombose und 2 post-anoxische Encephalopathien) wurde die Reduktion der Hirndurchblutung (HDB) mit der Ausdehnung und Lokalisation der anatomischen Hirnschäden korreliert. Unter Anordnung der Patienten jeweils nach der Schwere und Ausdehnung der Hirnstammläsionen sowie nach den HDB-Werten wurde eine Rang-Korrelation nach Spearman durchgeführt, die eine hochsignifikante Korrelation zwischen diesen beiden Parametern ergab. Hingegen zeigten diese Fälle keine Beziehungen zwischen Schwere bzw. Ausdehnung der Läsionen in Telencephalon und Stammganglien und der HDB-Reduktion. Ein Patient mit ausgedehnter postanoxischer Zerstörung des Neocortex ohne Hirnstammläsionen bot eine mäßiggradige HDB-Reduktion.Die erhobenen Befunde weisen darauf hin, daß eine Reduktion der Hirndurchblutung sowohl durch ausgedehnte Schädigung des Hirnmantels als auch durch Funktionsausfall der Großhirnrinde infolge von Schädigungen auf tieferen Ebenen bedingt sein kann. Die Bedeutung der Formatio reticularis des Hirnstammes für die Funktion und Durchblutung der Hirnrinde wird hervorgehoben.

     

Cerebral blood flow and oxygen metabolism in infants with hydrocephalus

In this study, regional cerebral blood flow (rCBF) and the cerebral metabolic rate of oxygen (rCMRO₂) were measured using positron emission tomography (PET) with oxygen-15 radiopharmaceuticals to clarify the pathophysiology of ventriculomegaly in the developing brain. Four hydrocephalic infants without severe neurological deficit were studied. Hypoperfusion was observed in the frontal, parietal, and visual association cortices which surrounded dilated anterior or posterior horns of the lateral ventricle. Lower rCMRO₂ values than adult rates were observed in all cases. In the infants with markedly enlarged anterior or posterior horns, the surrounding cortices showed relatively lower rCMRO₂ values with the fall of rCBF. Postoperative studies were performed in two infants. rCMRO₂ increased in every region after ventriculoperitoneal shunting, but little change was observed in rCBF. These results indicate that metabolic deterioration occurs in the developing brain with hydrocephalus.     

Cerebral blood flow abnormalities in adults with infantile autism.

Structural brain abnormalities have recently been discovered using magnetic resonance imaging in infantile autism, a neurodevelopmental disorder of unknown etiology. However, functional neuroimaging studies in autism using positron emission tomography have had conflicting results and have not explained how the known structural brain abnormalities in autism act in a functioning brain to produce autistic behavior. Using a new technology, high-resolution brain single photon emission tomography, we studied and scanned four young adults with infantile autism and four age-matched controls using the labeled ligand 99mTc-D,L-hexamethyl-propylene amine oxime (99mTc-HMPAO). Total brain perfusion was significantly decreased in autism subjects (range, 58% to 72% of controls, p less than or equal to .02). In addition to the globally decreased perfusion, the autism group also had regionally decreased flow in the right lateral temporal and right, left, and midfrontal lobes compared with controls (p less than or equal to .02, Mann-Whitney t-test).     

Cerebral blood flow velocity in term infants treated with phototherapy.

The relationship between phototherapy and changes in the cerebral circulation was studied in 50 jaundiced newborn infants. The aim of the study was to determine whether important alterations in cerebral hemodynamic occur under blue light therapy. Blood flow velocity, i.e., the pulsatility index (PI) and the area under the velocity curve (AUVC), was measured in the anterior cerebral arteries (ACA) using a Duplex scan technique. No prominent changes compromise flow in the ACA. PI and AUVC values were similar during and after phototherapy (p greater than 0.5) suggesting effective cerebral autoregulation in term infants undergoing light treatment for hyperbilirubinemia.     

Cerebral blood flow in chronic symptomatic mild traumatic brain injury

Patients with mild traumatic brain injury (MTBI) challenge physicians' skills and test their patience. Their manifold symptomatology is often not supported by objective neurological findings. We sought to compare regional cerebral blood flow (rCBF) between symptomatic subjects with longstanding MTBI and healthy controls, and to examine the correspondence between neuropsychological deficit and rCBF compromise. Twenty-eight clinically symptomatic male subjects with MTBI and twenty matched controls underwent neuropsychological testing and Tc-99m-HMPAO brain SPECT imaging. Neuropsychological test data were used to categorize subjects into sub-groups according to the presumed location of lesions based on their neurobehavioral deficits. Image subtraction comparisons were made between controls, all MTBI subjects and sub-groups. MTBI patients demonstrated regions of hypoperfusion in frontal, pre-frontal and temporal cortices, and sub-cortical structures. Hypoperfusion in 'frontal', 'left posterior' and to a lesser extent 'sub-cortical' sub-groups was concordant with neuropsychological localization. This was not the case for the 'right posterior' group, where no concordance was found. The rCBF is reduced in symptomatic patients with longstanding MTBI and unremarkable structural brain imaging. Although group analysis is appropriate for the generation of statistically significant differences, the clinical application of brain SPECT imaging in MTBI calls for a capability to associate clinical examination, neuropsychological assessment and cerebral perfusion at the individual subject level. Such competence is still to be attained.     

The effect of hematocrit and systolic blood pressure on cerebral blood flow in newborn infants

The effects of hematocrit and systolic blood pressure on cerebral blood flow were measured in 15 stable, low birth weight babies. CBF was measured with a modification of the xenon-133 (133Xe) clearance technique, which uses an intravenous bolus of 133Xe, an external chest detector to estimate arterial 133Xe concentration, eight external cranial detectors to measure cephalic 133Xe clearance curves, and a two-compartmental analysis of the cephalic 133Xe clearance curves to estimate CBF. There was a significant inverse correlation between hematocrit and CBF, presumably due to alterations in arterial oxygen content and blood viscosity. Newborn CBF varied independently of systolic blood pressure between 60 and 84 mm Hg, suggesting an intact cerebrovascular autoregulatory mechanism. These results indicate that at least two of the factors that affect newborn animal CBF are operational in human newborns and may have important clinical implications.     

Intravenous morphine attenuates pain induced changes in skin blood flow in newborn infants

Abstract

In a previous study we found that pain and discomfort caused a marked increase in skin blood flow, in newborn infants, and that skin blood flow decreased after morphine. In this study we tested morphine effect on the skin blood flow response to pain more systematically. Skin blood flow was measured using a laser Doppler technique during 19 percutaneous central venous catheter placements in 18 infants, 10 of whom received intravenous morphine premedication. The mean ± SD baseline skin blood flow was similar between the two groups: 22.5±9.5 ml 100 g-7 m/n-7 in the morphine group, and 23.7± 8.0 ml TOO g~1 min~1 in the no-morphine group, respectively (p = n.s.). During PCVC placement in the morphine treated group, skin blood flow remained low with minimal variability. The mean value was 22.6 ±7.7 ml 100 g~1 min(p = n.s. compared to baseline). In 7/9 infants not treated with morphine skin blood flow increased dramatically during PCVC placement; while in two it did not. But the mean skin blood flow in this group of 9 infants during PCVC placement was 45.3 ±34 ml 100 g~1 min~ \ an overall change of 97% increase from the baseline. This was statistically significant compared with the baseline and the morphine group value during PCVC insertion (p< 0.04). During the 45 min time period after PCVC placement, skin blood flow values between groups again were similar. We conclude that morphine pretreatment for PCVC placement minimizes pain-associated increases in skin blood flow. The issue of whether skin blood flow changes could serve as measures of adequate analgesia needs to be evaluated with further studies. [Neurol Res 1996; 18: 440-444]     

Cerebral blood flow correlates of higher brain dysfunctions in corticobasal degeneration

To investigate clinicoanatomic correlations of higher brain dysfunctions in corticobasal degeneration, regional cerebral blood flow (rCBF) was semiquantitatively measured with single-photon emission computed tomography in 9 patients with corticobasal degeneration and 12 age-matched control subjects. The patients showed significant reductions of relative tracer uptake in widespread cortical areas, as well as the basal ganglia and thalamus. Interhemispheric difference of hypoperfusion was significant in the sensorimotor and posterior parietal cortices. Asymmetric limb apraxia and cortical sensory disturbance corresponded to either sensorimotor cortical or posterior parietal cortical hypoperfusion or both. Compared with the patients without dementia, those with dementia showed significant reductions of relative rCBF in the inferior prefrontal region in the more affected hemisphere. The unique correlation of cortical signs with regional hypoperfusion may be useful in distinguishing between corticobasal degeneration and other neurodegenerative diseases.     

Cerebral blood flow and cerebral metabolic rate of oxygen requirements for cerebral function and viability in humans

This study was undertaken to determine the minimum CBF and CMRO2 required by the human brain to maintain normal function and viability for more than a few hours. Positron emission tomography (PET) was used to perform regional measurements in 50 subjects with varying degrees of cerebral ischemia but no evidence of infarction. There were 24 normal subjects, 24 subjects with arteriographic evidence of vascular disease of the carotid system, and two subjects with reversible ischemic neurological deficits due to cerebral vasospasm. Minimum values found in the 48 subjects with normal neurological function were 19 ml/100 g-min for regional cerebral blood flow (rCBF) and 1.3 ml/100 g-min for regional cerebral metabolic rate of oxygen (rCMRO2). Minimum values for all 50 subjects with viable cerebral tissue were 15 ml/100 g-min for rCBF and 1.3 ml/100 g-min for rCMRO2. Comparison of these measurements with values from 20 areas of established cerebral infarction in 10 subjects demonstrated that 80% (16/20) of infarcted regions had rCMRO2 values below the lower normal limit of 1.3 ml/100 g-min. Measurements of rCBF, regional cerebral blood volume, and oxygen extraction fraction were less useful for distinguishing viable from infarcted tissue. These data indicate that quantitative regional measurements of rCMRO2 with PET accurately distinguish viable from nonviable cerebral tissue and may be useful in the prospective identification of patients with reversible ischemia.     

Cerebral blood flow and autoregulation after pediatric traumatic brain injury

Traumatic brain injury is a global health concern and is the leading cause of traumatic morbidity and mortality in children. Despite a lower overall mortality than in adult traumatic brain injury, the cost to society from the sequelae of pediatric traumatic brain injury is very high. Predictors of poor outcome after traumatic brain injury include altered systemic and cerebral physiology, including altered cerebral hemodynamics. Cerebral autoregulation is often impaired after traumatic brain injury and may adversely impact the outcome. Although altered cerebrovascular hemodynamics early after traumatic brain injury may contribute to disability in children, there is little information regarding changes in cerebral blood flow and cerebral autoregulation after pediatric traumatic brain injury. This review addresses normal pediatric cerebral physiology and cerebrovascular pathophysiology after pediatric traumatic brain injury.     

Reversal of diastolic cerebral blood flow in infants without brain death

The reversal of diastolic cerebral blood flow has been regarded as a characteristic waveform of brain death and a useful confirming sign. We report 2 patients who had diastolic flow reversal but survived. One, a 1-month-old boy with status epilepticus, had reversal of diastolic cerebral blood flow detected by Doppler ultrasound soon after admission. Reversal disappeared after medical management for increased intracranial pressure and seizure control. He recovered without sequelae. The other, a 6-month-old girl with choroid plexus papilloma, had reversal of diastolic flow during abrupt clinical deterioration. Emergent surgical removal of the tumor was performed and she survived with hemiparesis and psychomotor retardation. Our patients demonstrated that even in the presence of diastolic reversal of cerebral blood flow, prompt and effective treatment can avoid a fatal outcome.     

Cerebral blood flow is regulated by changes in blood pressure and in blood viscosity alike

There is still considerable controversy regarding the influence of blood viscosity upon CBF. We have measured CBF with microspheres in 23 cats. Autoregulation was disturbed in the left caudate nucleus by microsurgical occlusion of the left middle cerebral artery. Induced hypertension or hypotension was used and i.v. mannitol (1 g/kg) administered. In all cats blood viscosity decreased an average of 16% at 15 minutes and, in 16 cats, increased 10% at 75 minutes post-mannitol. CBF in the right caudate was 79 +/- 6 ml/100g/min, in the left 38 +/- 6 (p less than 0.001). Only minor changes of CBF occurred in areas with presumed normal autoregulation, including the right caudate, in conjunction with pressure or viscosity changes. In the left caudate CBF decreased 21% with hypotension and 18% with higher viscosity, more than on the right (p less than 0.01 and p less than 0.2, respectively). CBF increased in the left caudate 56% with hypertension and 47% with lower viscosity, again much more than on the right (p less than 0.001 and p less than 0.01, respectively). In the other area which is (nearly) exclusively supplied by the middle cerebral artery of the cat, i.e., the ectosylvian cortex, results were similar to those in the caudate nucleus. These results show that viscosity changes must result in compensatory readjustments of vessel diameter, but that these adjustments do not occur where autoregulation to pressure changes is known to be defective. The adjustments to viscosity changes might be called blood viscosity autoregulation of CBF. We hypothesize that pressure autoregulation and blood viscosity autoregulation share the same mechanism.