Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0085584 (encephalopathy)
 18,178 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

One hypothesis on the pathogenesis of post-ischemic-anoxic encephalopathy is impaired cerebral perfusion or the no-reflow phenomenon. Therapies aimed at preventing the development of this phenomenon are increased cerebral perfusion pressure (CPP) and hyperventilation or hypercapnia. Using a dog model in which we have described the progressive development of post-ischemic (PI) cerebral hypoperfusion after 15 minutes of global ischemia induced by aortic and vena cavae clamping, our aims in this study were to determine during the PI cerebral hypoperfusion period: (1) cerebrovascular reactivity to CO2, and (2) cerebral blood (CBF) autoregulation. Post-ischemic cerebral hypoperfusion to about 50% of normal was not accompanied by raised intracranial pressure (ICP) but cerebrovascular CO2 reactivity was markedly attenuated while maintaining some kind of autoregulatory phenomenon. Cerebral uptake of oxygen was not significantly affected by changing PACO2 from 20 to 60 torr at constant CPP or by changing CPP from 64 to 104 torr at constant PaCO2. These results suggest that increasing both CPP and hypocapnia/hypercapnia would not significantly attenuate PI neurological deficit after global cerebral ischemia. However, in two dogs inadvertently hemodiluted in the PI period, increasing CPP from 50 to 200 torr increased CBF by 200%, suggesting that hemodilution plus increased CPP may be effective therapy for amelioration of post-ischemic-anoxic encephalopathy. The significance of our findings on cerebrovascular CO2 reactivity and autoregulation with respect to the mechanism of the no-reflow phenomenon is discussed.
 ...
PMID:Global ischemia in dogs: cerebrovascular CO2 reactivity and autoregulation. 115 79

Continuous monitoring of the cerebral blood flow, oxyhemoglobin, deoxyhemoglobin, total hemoglobin, oxidized cytochrome a, a3, and tissue pH during prolonged CO2 or N2 loading in 2-week-old rabbits was performed by near-infrared spectroscopy, the thermocouple method, and a tissue pH meter. Near-infrared spectroscopy demonstrated decreases in oxyhemoglobin and oxidized cytochrome a, a3 and increases in deoxyhemoglobin and total hemoglobin in the early stage within 5 min, which gradually lessened with time on both 10% concentration of inspired O2 with CO2 and N2. CBF increased with venous retention in the early stage and then slowly decreased in parallel with blood pressure and oxidized cytochrome a, a3 on abolition of autoregulation. These changes were more remarkable during the 10% concentration of inspired O2 with CO2 than N2 which may be caused by marked acidosis and hypotension associated with hypercarbia. Oxidized cytochrome a, a3, however, demonstrated a gradual decrease in 10% concentration of inspired O2 with N2 rather than CO2; therefore, the continuous monitorings demonstrated hemodynamic and oxygenation changes despite the same extent of prolonged hypoxic loading. These changes in prolonged hypoxic conditions may occur in human intrapartum asphyxia which develops into postnatal hypoxic-ischemic encephalopathy.
 ...
PMID:Monitoring of immature rabbit brain during hypoxia with near-infrared spectroscopy. 155 75

We measured CBF and the CMRglc in normal controls and in patients with severe liver disease and evidence for minimal hepatic encephalopathy using positron emission tomography. Regions were defined in frontal, temporal, parietal, and visual cortex; the thalamus; the caudate; the cerebellum; and the white matter along with a whole-slice value obtained at the level of the thalamus. There was no difference in whole-slice CBF and CMRglc values. Individual regional values were normalized to the whole-slice value and subjected to a two-way repeated measures analysis of variance. When normalized CBF and CMRglc values for regions were compared between groups, significant differences were demonstrated (F = 5.650, p = 0.00014 and F = 4.58, p = 0.0073, respectively). These pattern differences were due to higher CBF and CMRglc in the cerebellum, thalamus, and caudate in patients and lower values in the cortex. Standardized coefficients extracted from a discriminant function analysis permitted correct group assignment for 95.5% of the CBF studies and for 92.9% of the CMRglc studies. The similarity of the altered pattern of cerebral metabolism and flow in our patients to that seen in rats subjected to portacaval shunts or ammonia infusions suggests that this toxin may alter flow and metabolism and that this, in turn, causes the clinical expression of encephalopathy.
 ...
PMID:Altered cerebral blood flow and glucose metabolism in patients with liver disease and minimal encephalopathy. 199 5

Orthostatic test with passive tilting of the upper body was performed in 28 patients with VVI pacemaker. The changes in BP (Riva-Rocci method), CVR and CBF (impedance technique, REG II) as well as in EEG (automatic spectral analysis) observed after tilting, were compared to those in 20 age-matched controls. While in healthy subjects the autoregulation of the CBF was accomplished through a decrease in CVR and resulted in a moderate but significant increase in CBF, in patients the CVR did not change. This event was estimated as a sign of impaired autoregulation, the CBF remained unchanged most probably on account of the increased diastolic and mean BP. Alpha and beta power spectra in the EEG rose significantly after tilting, the shifts being more pronounced in the controls. In the patients there was an increase in theta activity. Cerebral angiopathy due to "subclinical" brain ischaemia during cardiac rhythm disorders preceding pacemaker implantation was accepted as a mechanism underlying the disturbed autoregulation of the cerebral blood flow. For the occurrence of alterations in orthostatic EEG reactivity, a dyscirculatory encephalopathy has been suspected.
 ...
PMID:Cerebral blood flow autoregulation during orthostatic manoeuvre in patients with permanent cardiac pacemaker. 368 47

Reported evaluations of CBF with Xe/CT were performed in 11 patients during the lucid interval following CO intoxication. Results were compared with clinical and SPECT data. Two patients developed neuropsychiatric behavior (delayed encephalopathy) one month following the initial recovery. The symptoms persisted in one of them 15 months later. Their CBF values as well as those in most of the other patients, monitored at the basal ganglia and white matter areas, were in relation with the clinical outcome, However, further studies with a larger number of patients, are needed to confirm the predictive significance of Xe/CT measurements for the long term sequelae of CO poisoning.
 ...
PMID:Regional cerebral blood flow measurements with Xenon-CT in the prediction of delayed encephalopathy after carbon monoxide intoxication. 868 36

Cerebral blood flow of 10 asphyxiated term newborns was continuously measured during the first 7 days of life and compared with that of 10 normal term infants by CDI. Frequency spectrum and blood flow variables in the anterior, middle and posterior cerebral arteries were studied. The results showed evidently lower systolic amplitude in patients than that in normal subjects. End diastolic amplitude was zero in part of vessels, and values of blood flow variables were all lower in day 1 of the life as compared with the control groups. Frequency spectrum recovered to normal patterns in 9 survived infants in day 2, but blood flow variables recovered to normal by day 7. Values of resistance index (RI) rose to 1 in some vessels of moderate hypoxic ischemic encephalopathy (HIE) infants and stayed at 1 in the severe HIE infants. It is concluded that low CBF plays a key role in brain damage of post-asphyxiated newborns and RI may be an important parameter in the evaluation prognosis.
 ...
PMID:Measurements of cerebral blood flow in post-asphyxiated newborns by color Doppler imaging (CDI). 938 93

Sepsis is often complicated by encephalopathy, neuroendocrine dysfunction and cardiovascular autonomic failure. The cause of septic brain dysfunction is not fully understood. The aim of the present study is to explore whether septic brain dysfunction in a common septic model in the rat correlates with abnormalities either of local cerebral blood flow (LCBF) of defined brain areas or of whole brain blood flow (CBF). 45 male Wistar rats (320+/-13 g) were randomly assigned to a sepsis group (31 rats, cecal ligature and puncture, CLP) or a control group (14 rats, sham operation). Of these 45 rats, 16 rats were used for blood analysis; the remaining 29 rats were used for CBF/LCBF measurements. LCBF measurements were performed 24h after initial surgery using quantitative autoradiography with 4-iodo[N-methyl-(14)C]antipyrine, which allows to analyze CBF on a regional/local and global basis. In 42 different brain regions bilateral optical density measurements were performed. Septic rats (vs. control) presented tachycardia (507+/-37 vs. 452+/-44 min(-1), P<0.05), leukocytopenia (2.96+/-2.37 vs. 8.83+/-2.9710(9) x L(-1), P<0.05), hypocapnia (29.3+/-4.6 vs. 36.4+/-3.9 mmHg, P<0.05), and higher serum lactate concentrations (5.7+/-3.9 vs. 2.2+/-2.0 mmol x L(-1), P<0.05). LCBF of all 42 areas, as well as, CBF (116+/-59 vs. 115+/-52 m x 100 g(-1)min(-1), n.s.) did not differ. The results showed that severe sepsis (mortality rate of 43 %) did not induce alterations in mean CBF and LCBF. It is concluded that brain dysfunction is not reflected in changes of CBF during severe sepsis.
 ...
PMID:Local cerebral blood flow is preserved in sepsis. 1731 43

Hypoxic-ischemic encephalopathy carries an uncertain prognosis. We sought to retrospectively assess the prognostic value of arterial spin-labeling MR imaging in 22 adult patients diagnosed with hypoxic-ischemic encephalopathy. Quantitative CBF maps were generated from the M0 map, and arterial spin-labeling data on a per-voxel basis were regionally interrogated via visual inspection and ROI placement. Hyperperfusion was defined as regional increases in CBF of >20% (relative to global CBF) and/or >100 mL/100 g/min. Eleven of 22 patients had prominent bilateral medial occipital lobe hyperperfusion, all of whom died before hospital discharge. One patient who had nondistinct arterial spin-labeling hyperperfusion and restricted diffusion survived. Medial occipital lobe hyperperfusion is a distinctive pattern that merits prospective investigation in a cohort of patients with moderate hypoxic-ischemic encephalopathy to determine its predictive ability in patients with a higher likelihood of survival.
...
PMID:Medial Occipital Lobe Hyperperfusion Identified by Arterial Spin-Labeling: A Poor Prognostic Sign in Patients with Hypoxic-Ischemic Encephalopathy. 2633 17

We report a case of posterior reversible encephalopathy syndrome (PRES) in which followed-up MRI demonstrated a transient reduction in venous signal on initial SWAN images. The progressive normalization of venous signal on D10 and D40 imaging paralleled the progressive decrease of hyperperfusion on CBF images. Decreased venous susceptibility has never been reported in PRES; it relates most likely to a transient BOLD effect induced by brain hyperperfusion.
...
PMID:Transient reduction in venous susceptibility during posterior reversible encephalopathy syndrome. 2643 16