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1.
BMC Urol ; 21(1): 47, 2021 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-33773592

RESUMO

BACKGROUND: Existing evidence suggests that there is an association between body size and prevalent Benign Prostatic Hyperplasia (BPH)-related outcomes and nocturia. However, there is limited evidence on the association between body size throughout the life-course and incident BPH-related outcomes. METHODS: Our study population consisted of men without histories of prostate cancer, BPH-related outcomes, or nocturia in the intervention arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) (n = 4710). Associations for body size in early- (age 20), mid- (age 50) and late-life (age ≥ 55, mean age 60.7 years) and weight change with incident BPH-related outcomes (including self-reported nocturia and physician diagnosis of BPH, digital rectal examination-estimated prostate volume ≥ 30 cc, and prostate-specific antigen [PSA] concentration > 1.4 ng/mL) were examined using Poisson regression with robust variance estimation. RESULTS: Men who were obese in late-life were 25% more likely to report nocturia (Relative Risk (RR): 1.25, 95% Confidence Interval (CI): 1.11-1.40; p-trendfor continuous BMI < 0.0001) and men who were either overweight or obese in late-life were more likely to report a prostate volume ≥ 30 cc (RRoverweight: 1.13, 95% CI 1.07-1.21; RRobese: 1.10, 95% CI 1.02-1.19; p-trendfor continuous BMI = 0.017) as compared to normal weight men. Obesity at ages 20 and 50 was similarly associated with both nocturia and prostate volume ≥ 30 cc. Considering trajectories of body size, men who were normal weight at age 20 and became overweight or obese by later-life had increased risks of nocturia (RRnormal to overweight: 1.09, 95% CI 0.98-1.22; RRnormal to obese: 1.28, 95% CI 1.10-1.47) and a prostate volume ≥ 30 cc (RRnormal to overweight: 1.12, 95% CI 1.05-1.20). Too few men were obese early in life to examine the independent effect of early-life body size. Later-life body size modified the association between physical activity and nocturia. CONCLUSIONS: We found that later-life body size, independent of early-life body size, was associated with adverse BPH outcomes, suggesting that interventions to reduce body size even late in life can potentially reduce the burden of BPH-related outcomes and nocturia.


Assuntos
Tamanho Corporal , Noctúria/epidemiologia , Hiperplasia Prostática/epidemiologia , Fatores Etários , Humanos , Masculino , Pessoa de Meia-Idade
2.
Neurology ; 78(4): 250-5, 2012 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-22238418

RESUMO

OBJECTIVE: To determine whether unihemispheral hemodynamic failure is independently associated with cognitive impairment among participants in the National Institute of Neurological Disorders and Stroke-sponsored, multicenter, randomized clinical trial, Randomized Evaluation of Carotid Occlusion and Neurocognition (RECON). METHODS: Forty-three patients were randomized into RECON after recent symptomatic carotid artery occlusion and asymmetrically increased oxygen extraction fraction (OEF) by PET (OEF ratio >1.13), indicating stage II hemodynamic failure on the side of occlusion. The PET-positive patients were compared with 28 RECON-enrolled patients who met all clinical and radiographic inclusion/exclusion criteria but had no OEF asymmetry. A multivariable regression compared patients with PET OEF >1.13 or ≤1.13, stratifying by TIA vs. stroke as the qualifying event. The dependent variable was a composite neurocognitive score derived from averaging age-normalized z scores on a test battery that included global and internal carotid artery (ICA) side-relevant hemisphere-specific tests. RESULTS: There were no differences in demographic, clinical, or radiologic characteristics between the PET-positive and PET-negative patients except for PET OEF asymmetry. The unadjusted average neurocognitive z score was -1.45 for the PET-positive and -1.25 for the PET-negative patients, indicating cognitive impairment in both groups but no difference between them (p = 0.641). After adjustment for age, education, side of occlusion, depression, and previous stroke, there was a significant difference between PET-positive and PET-negative patients among those with TIA as a qualifying event (average z score = -1.41 vs. -0.76, p = 0.040). Older age and right ICA side were also significant in this model. CONCLUSION: Hemodynamic failure is independently associated with cognitive impairment in patients with carotid occlusion. This finding establishes the physiologic parameter upon which the extracranial-intracranial bypass will be tested.


Assuntos
Circulação Cerebrovascular , Transtornos Cognitivos/fisiopatologia , Transtornos Cognitivos/psicologia , Idoso , Doenças das Artérias Carótidas/complicações , Doenças das Artérias Carótidas/fisiopatologia , Doenças das Artérias Carótidas/psicologia , Transtornos Cognitivos/diagnóstico por imagem , Estudos de Coortes , Escolaridade , Feminino , Lateralidade Funcional , Humanos , Ataque Isquêmico Transitório/diagnóstico por imagem , Ataque Isquêmico Transitório/fisiopatologia , Ataque Isquêmico Transitório/psicologia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Destreza Motora , Testes Neuropsicológicos , Tomografia por Emissão de Pósitrons , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/psicologia , Teste de Sequência Alfanumérica , Percepção Visual , Testes de Associação de Palavras
4.
J Nucl Med ; 42(8): 1195-7, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11483680

RESUMO

UNLABELLED: PET measurement of increased oxygen extraction fraction (OEF) identifies patients at high risk for subsequent stroke. OEF methodology remains controversial. In this study we compare the sensitivity and specificity of absolute OEF measurements with ipsilateral-to-contralateral ratios of absolute OEF and count-based OEF estimates. METHODS: Multivariate analyses of OEF methods were performed using data from patients with symptomatic carotid artery occlusion (n = 68). Outcome and receiver operating characteristic (ROC) curve analyses were performed. RESULTS: All 3 methods were predictive of stroke risk in univariate analysis. Only the count-based method remained significant in multivariate analysis. The area under the ROC curve was greatest for the count-based ratio: 0.815 versus 0.769 (absolute) and 0.737 (ratios of absolute). CONCLUSION: All 3 methods are predictive of stroke risk in patients with unilateral carotid artery occlusion. ROC curve analysis is useful for selecting optimal thresholds for maximal sensitivity and specificity.


Assuntos
Consumo de Oxigênio/fisiologia , Acidente Vascular Cerebral/diagnóstico por imagem , Tomografia Computadorizada de Emissão/métodos , Arteriosclerose/complicações , Arteriosclerose/diagnóstico por imagem , Química Encefálica , Estenose das Carótidas/diagnóstico por imagem , Estenose das Carótidas/mortalidade , Humanos , Valor Preditivo dos Testes , Estudos Retrospectivos , Medição de Risco , Acidente Vascular Cerebral/etiologia , Resultado do Tratamento
5.
Neurology ; 57(1): 18-24, 2001 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-11445622

RESUMO

BACKGROUND: Arterial hypertension is common in the first 24 hours after acute intracerebral hemorrhage (ICH). Although increased blood pressure usually declines to baseline values within several days, the appropriate treatment during the acute period has remained controversial. Arguments against treatment of hypertension in patients with acute ICH are based primarily on the concern that reducing arterial blood pressure will reduce cerebral blood flow (CBF). The authors undertook this study to provide further information on the changes in whole-brain and periclot regional CBF that occur with pharmacologic reductions in mean arterial pressure (MAP) in patients with acute ICH. METHODS: Fourteen patients with acute supratentorial ICH 1 to 45 mL in size were studied 6 to 22 hours after onset. CBF was measured with PET and (15)O-water. After completion of the first CBF measurement, patients were randomized to receive either nicardipine or labetalol to reduce MAP by 15%, and the CBF study was repeated. RESULTS: MAP was lowered by -16.7 +/- 5.4% from 143 +/- 10 to 119 +/- 11 mm Hg. There was no significant change in either global CBF or periclot CBF. Calculation of the 95% CI demonstrated that there is less than a 5% chance that global or periclot CBF fell by more than -2.7 mL x 100 g(-1) x min(-1). CONCLUSION: In patients with small- to medium-sized acute ICH, autoregulation of CBF was preserved with arterial blood pressure reductions in the range studied.


Assuntos
Anti-Hipertensivos/uso terapêutico , Hemorragia Cerebral/tratamento farmacológico , Hemorragia Cerebral/fisiopatologia , Circulação Cerebrovascular/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Labetalol/uso terapêutico , Nicardipino/uso terapêutico , Doença Aguda , Adulto , Idoso , Pressão Sanguínea/efeitos dos fármacos , Hemorragia Cerebral/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X
6.
J Cereb Blood Flow Metab ; 21(7): 804-10, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11435792

RESUMO

A zone of hypoperfusion surrounding acute intracerebral hemorrhage (ICH) has been interpreted as regional ischemia. To determine if ischemia is present in the periclot area, the authors measured cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and oxygen extraction fraction (OEF) with positron emission tomography (PET) in 19 patients 5 to 22 hours after hemorrhage onset. Periclot CBF, CMRO2, and OEF were determined in a 1-cm-wide area around the clot. In the 16 patients without midline shift, periclot data were compared with mirror contralateral regions. All PET images were masked to exclude noncerebral structures, and all PET measurements were corrected for partial volume effect due to clot and ventricles. Both periclot CBF and CMRO2 were significantly reduced compared with contralateral values (CBF: 20.9 +/- 7.6 vs. 37.0 +/- 13.9 mL 100 g(-1) min(-1), P = 0.0004; CMRO2: 1.4 +/- 0.5 vs. 2.9 +/- 0.9 mL 100 g(-1) min(-1), P = 0.00001). Periclot OEF was less than both hemispheric OEF (0.42 +/- 0.15 vs. 0.47 +/- 0.13, P = 0.05; n = 19) and contralateral regional OEF (0.44 +/- 0.16 vs. 0.51 +/- 0.13, P = 0.05; n = 16). In conclusion, CMRO2 was reduced to a greater degree than CBF in the periclot region in acute ICH, resulting in reduced OEF rather than the increased OEF that occurs in ischemia. Thus, the authors found no evidence for ischemia in the periclot zone of hypoperfusion in acute ICH patients studied 5 to 22 hours after hemorrhage onset.


Assuntos
Isquemia Encefálica/fisiopatologia , Encéfalo/irrigação sanguínea , Hemorragia Cerebral/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Anti-Hipertensivos/administração & dosagem , Velocidade do Fluxo Sanguíneo , Pressão Sanguínea , Feminino , Humanos , Labetalol/administração & dosagem , Masculino , Manitol/administração & dosagem , Pessoa de Meia-Idade , Consumo de Oxigênio , Fatores de Tempo , Tomografia Computadorizada de Emissão , Tomografia Computadorizada por Raios X
7.
Radiology ; 220(1): 195-201, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11425997

RESUMO

PURPOSE: To investigate the relationship between the patterns of cerebral infarction that have been associated with hemodynamic impairment and the presence of severe chronic hemodynamic compromise (increased oxygen extraction fraction) in a large prospectively enrolled group of patients with carotid artery occlusion. MATERIALS AND METHODS: At enrollment in a prospective study of cerebral hemodynamics, 110 patients with carotid occlusion underwent (a) positron emission tomography for the measurement of cerebral oxygen extraction fraction and (b) computed tomographic (CT) or magnetic resonance (MR) examinations of the brain. Infarcts were categorized retrospectively by vascular territory, location, and pattern. The association of these findings with hemodynamic impairment (increased oxygen extraction fraction) was investigated. RESULTS: No border zone-region infarctions were found in 35 asymptomatic patients. In 75 symptomatic patients, cortical border zone-region infarction was found in seven of 36 patients with increased oxygen extraction fraction, and in two of 39 with normal oxygen extraction fraction (P =.08, difference not significant). The pattern of multiple white matter lesions arranged parallel to the lateral ventricle was observed only in symptomatic patients with increased oxygen extraction fraction (eight of 36 patients; P =.002; sensitivity, 22%; specificity, 100%). This finding was more frequent with MR imaging (seven of 14 patients) than with CT (one of 22 patients). CONCLUSION: Multiple white matter infarctions, arranged parallel to the lateral ventricle, are associated with severe hemodynamic impairment. This pattern of infarction is likely due to a hemodynamic mechanism.


Assuntos
Estenose das Carótidas/complicações , Estenose das Carótidas/diagnóstico , Infarto Cerebral/diagnóstico , Infarto Cerebral/etiologia , Imageamento por Ressonância Magnética/métodos , Tomografia Computadorizada de Emissão/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Circulação Cerebrovascular , Diagnóstico por Imagem/métodos , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Probabilidade , Estudos Prospectivos , Valores de Referência , Estudos Retrospectivos , Medição de Risco , Sensibilidade e Especificidade , Índice de Gravidade de Doença
8.
Neurosurg Clin N Am ; 12(3): 473-87, vii, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11390308

RESUMO

Preventing further stroke in patients with complete carotid artery occlusion remains a difficult challenge because there is no therapy proven effective for this prevention. These patients comprise approximately 15% of patients with carotid artery territory transient ischemic attacks or infarction. Patients with symptomatic carotid artery occlusion have an overall risk of subsequent stroke of 7% per year and a risk of stroke ipsilateral to the occluded carotid artery of 5.9% per year. The presence of severe hemodynamic failure demonstrated by increased oxygen extraction fraction (OEF) of the brain, in a cerebral hemisphere distal to a symptomatic occluded carotid artery, is an independent predictor of subsequent ischemic stroke with a risk comparable to that seen in medically treated patients with symptomatic severe carotid artery stenosis.


Assuntos
Encéfalo/irrigação sanguínea , Encéfalo/cirurgia , Estenose das Carótidas/complicações , Revascularização Cerebral/métodos , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/cirurgia , Circulação Cerebrovascular/fisiologia , Hemodinâmica/fisiologia , Humanos , Fatores de Risco , Acidente Vascular Cerebral/prevenção & controle
9.
Neurosurg Clin N Am ; 12(3): 613-24, ix-x, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11390318

RESUMO

In 1985, the International Study of Extracranial-to-Intracranial Arterial Anastomosis demonstrated no benefit from extracranial-to-intracranial arterial bypass operations in treatment of patients with extensive cerebrovascular disease including those with occlusions of the internal carotid artery. Interest in the potential use of extracranial-to-intracranial arterial bypass operations, however, has been rekindled by evidence that some patients with occlusion of the internal carotid artery have a poor collateral circulation and a high risk for recurrent ischemic events. Other patients with adequate perfusion after occlusion have a low likelihood for recurrent stroke. Restricting surgical treatment to only those patients judged to have a high risk for recurrent stroke might improve the usefulness of the bypass operation. A new clinical trial is proposed, testing the potential usefulness of extracranial-to-intracranial arterial bypass operations for treatment of carefully selected patients with occlusion of the internal carotid artery. Several issues that are being addressed in this new trial are described in this article.


Assuntos
Encéfalo/irrigação sanguínea , Estenose das Carótidas/cirurgia , Revascularização Cerebral/métodos , Ensaios Clínicos como Assunto , Anastomose Arteriovenosa , Artéria Carótida Interna/cirurgia , Circulação Cerebrovascular/fisiologia , Humanos , Seleção de Pacientes
11.
J Nucl Med ; 41(5): 800-7, 2000 May.
Artigo em Inglês | MEDLINE | ID: mdl-10809195

RESUMO

UNLABELLED: The St. Louis Carotid Occlusion Study (STLCOS) demonstrated that increased cerebral oxygen extraction fraction (OEF) detected by PET scanning predicted stroke in patients with symptomatic carotid occlusion. Consequently, a trial of extracranial-to-intracranial (EC/IC) arterial bypass for these patients was proposed. The purpose of this study was to examine the cost-effectiveness of using PET in identifying candidates for EC/IC bypass. METHODS: A Markov model was created to estimate the cost-effectiveness of PET screening and treating a cohort of 45 symptomatic patients with carotid occlusion. The primary outcome was incremental cost for PET screening and EC/IC bypass (if OEF was elevated) per incremental quality-adjusted life year (QALY) saved. Rates of stroke and death with surgical and medical treatment were obtained from EC/IC Bypass Trial and STLCOS data. Costs were estimated from the literature. Sensitivity analyses were performed for all assumed variables, including the PET OEF threshold used to select patients for surgery. RESULTS: In the base case, PET screening of the cohort followed by EC/IC bypass on 36 of the 45 patients yielded 23.2 additional QALYs at a cost of $20,000 per QALY, compared with medical therapy alone. A more specific PET threshold, which identified 18 surgical candidates, gained 22.6 QALYs at less cost than medical therapy alone. The results were sensitive to the perioperative stroke rate and the stroke risk reduction conferred by EC/IC bypass surgery. CONCLUSION: If postoperative stroke rates are similar to stroke rates observed in the EC/IC Bypass Trial, EC/IC bypass will be cost-effective in patients with symptomatic carotid occlusion who have increased OEF. A clinical trial of medical therapy versus PET followed by EC/IC bypass (if OEF is elevated) is warranted.


Assuntos
Estenose das Carótidas/diagnóstico por imagem , Estenose das Carótidas/economia , Revascularização Cerebral , Tomografia Computadorizada de Emissão/economia , Estenose das Carótidas/terapia , Revascularização Cerebral/economia , Análise Custo-Benefício , Humanos , Cadeias de Markov , Anos de Vida Ajustados por Qualidade de Vida , Fatores de Risco , Acidente Vascular Cerebral/economia , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/prevenção & controle , Resultado do Tratamento
12.
AJNR Am J Neuroradiol ; 21(4): 631-8, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10782770

RESUMO

BACKGROUND AND PURPOSE: Deep white matter may be the location of an internal arterial border zone. The purpose of this study was to determine whether the deep white matter was subject to a greater degree of ischemia than was the cortex among patients with chronic carotid occlusion. METHODS: Thirty-six patients with carotid occlusion and structurally normal deep white matter were studied with positron emission tomography. Measurements of oxygen extraction fraction were made in superficial (cortical and subcortical) regions in the middle cerebral artery territory and in deep white matter (internal border zone) regions. The presence of selective ischemia of the deep white matter was assessed by the ratio of deep white matter:superficial oxygen extraction fraction. Ipsilateral hemispheric ratios among patients were assessed as a group as compared with contralateral hemispheric ratios and as compared with normal hemispheric ratios from 15 control volunteers. RESULTS: Mean deep white matter to superficial oxygen extraction fraction ratios (+/-95% confidence limits) were 0.99 (+/-0.07), 1.01 (+/-0.06), and 1.02 (+/-0.08) for ipsilateral, contralateral, and normal hemispheres, respectively. No statistically significant difference was found between ipsilateral and contralateral (P = .691) or normal hemispheres (P = .68), nor was any statistically significant difference found when the analysis was limited to patients with increased superficial oxygen extraction fraction (n = 9). Individual deep white matter:superficial ratios were within the normal range for all patients. CONCLUSION: Normal deep white matter among patients with carotid occlusion is not subject to a greater degree of ischemia than is the overlying cortex. It is unlikely that deep white matter infarctions observed among patients with carotid occlusion are owing to chronic selective hemodynamic compromise occurring at an internal arterial border zone.


Assuntos
Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/metabolismo , Estenose das Carótidas/complicações , Oxigênio/metabolismo , Tomografia Computadorizada de Emissão , Idoso , Idoso de 80 Anos ou mais , Isquemia Encefálica/etiologia , Circulação Cerebrovascular , Doença Crônica , Feminino , Hemodinâmica , Humanos , Masculino , Pessoa de Meia-Idade
13.
Neurology ; 54(4): 878-82, 2000 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-10690980

RESUMO

OBJECTIVE: To determine the prognosis of asymptomatic carotid artery occlusion. BACKGROUND: As opposed to symptomatic carotid occlusion, little information is available on the prognosis of asymptomatic carotid occlusion. METHOD: Thirty never-symptomatic and 81 symptomatic patients with carotid occlusion underwent baseline assessment of 15 risk factors together with PET measurements of oxygen extraction fraction (OEF). Every 6-month telephone contact recorded interval medical treatment and subsequent stroke occurrence during an average follow-up of 32 months. Patients, treating physicians, and an end point adjudicator were blinded to PET results. RESULTS: Ischemic stroke occurred in 1 of 30 of never-symptomatic patients (3.3%) and 15 of 81 of symptomatic patients (18.5%; p = 0.03). No strokes in the carotid territory distal to the occluded vessel occurred in the never-symptomatic patients. Multivariate analysis of baseline risk factors for all 111 patients revealed that age, plasma fibrinogen level, and PET findings of high OEF distal to the occluded carotid artery were the only independent predictors of subsequent stroke (p < 0.05). Previous ipsilateral hemispheric or retinal symptoms was not a significant predictive variable. The lower risk of stroke in never-symptomatic patients was associated with a lower incidence of high OEF (4 of 30) as opposed to symptomatic patients (39 of 81; p = 0.002), but there was no significant difference in age or fibrinogen level. CONCLUSIONS: Never-symptomatic carotid occlusion carries a very low risk of subsequent ischemic stroke. This benign prognosis is associated with a low incidence of cerebral hemodynamic compromise in these patients. These data support further the importance of hemodynamic factors in the pathogenesis of ischemic stroke in patients with carotid occlusion.


Assuntos
Arteriopatias Oclusivas/fisiopatologia , Doenças das Artérias Carótidas/fisiopatologia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico
14.
J Neurosurg ; 92(1): 7-13, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10616076

RESUMO

OBJECT: Hyperventilation has been used for many years in the management of patients with traumatic brain injury (TBI). Concern has been raised that hyperventilation could lead to cerebral ischemia; these concerns have been magnified by reports of reduced cerebral blood flow (CBF) early after severe TBI. The authors tested the hypothesis that moderate hyperventilation induced early after TBI would not produce a reduction in CBF severe enough to cause cerebral energy failure (CBF that is insufficient to meet metabolic needs). METHODS: Nine patients were studied a mean of 11.2+/-1.6 hours (range 8-14 hours) after TBI occurred. The patients' mean Glasgow Coma Scale score was 5.6+/-1.8 and their mean age 27+/-9 years; eight of the patients were male. Intracranial pressure (ICP), mean arterial blood pressure, and jugular venous oxygen content were monitored and cerebral perfusion pressure was maintained at a level higher than 70 mm Hg by using vasopressors when needed. Measurements of CBF, cerebral blood volume (CBV), cerebral metabolic rate for oxygen (CMRO2), oxygen extraction fraction (OEF), and cerebral venous oxygen content (CvO2) were made before and after 30 minutes of hyperventilation to a PaCO2 of 30+/-2 mm Hg. Ten age-matched healthy volunteers were used as normocapnic controls. Global CBF, CBV, and CvO2 did not differ between the two groups, but in the TBI patients CMRO2 and OEF were reduced (1.59+/-0.44 ml/100 g/minute [p < 0.01] and 0.31+/-0.06 [p < 0.0001], respectively). During hyperventilation, global CBF decreased to 25.5+/-8.7 ml/100 g/minute (p < 0.0009), CBV fell to 2.8+/-0.56 ml/100 g (p < 0.001), OEF rose to 0.45+/-0.13 (p < 0.02), and CvO2 fell to 8.3+/-3 vol% (p < 0.02); CMRO2 remained unchanged. CONCLUSIONS: The authors conclude that early, brief, moderate hyperventilation does not impair global cerebral metabolism in patients with severe TBI and, thus, is unlikely to cause further neurological injury. Additional studies are needed to assess focal changes, the effects of more severe hyperventilation, and the effects of hyperventilation in the setting of increased ICP.


Assuntos
Lesões Encefálicas/metabolismo , Lesões Encefálicas/terapia , Isquemia Encefálica/metabolismo , Encéfalo/metabolismo , Circulação Cerebrovascular , Hiperventilação/metabolismo , Pressão Intracraniana , Oxigênio/metabolismo , Adulto , Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Lesões Encefálicas/complicações , Lesões Encefálicas/diagnóstico por imagem , Lesões Encefálicas/fisiopatologia , Isquemia Encefálica/etiologia , Isquemia Encefálica/prevenção & controle , Estudos de Casos e Controles , Feminino , Escala de Coma de Glasgow , Humanos , Hiperventilação/fisiopatologia , Masculino , Seleção de Pacientes , Fatores de Tempo , Tomografia Computadorizada de Emissão
15.
Neurology ; 53(2): 251-9, 1999 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-10430410

RESUMO

Stenosis or occlusion of the major arteries of the head and neck may cause hemodynamic impairment of the distal cerebral circulation. Hemodynamic factors may play an important role in the pathogenesis of ischemic stroke for patients with cerebrovascular disease. Several neuroimaging methods are currently available for the indirect assessment of the hemodynamic effect of atherosclerotic stenosis or occlusion on the distal cerebrovasculature. Because these methods rely on different underlying physiologic mechanisms, they are not interchangeable. Two basic categories of hemodynamic impairment can be assessed with these techniques: Stage 1, in which autoregulatory vasodilation secondary to reduced perfusion pressure is inferred by the measurement of either increased blood volume or an impaired blood flow response to a vasodilatory stimulus; and Stage 2, in which increased oxygen extraction fraction (OEF) is noninvasively but directly measured. The correlation of different Stage 1 methods with each other and with Stage 2 techniques is quite variable. Clinical studies associating different manifestations of hemodynamic impairment with stroke risk often suffer from methodologic problems. The best evidence to date for such an association is for increased OEF measured in patients with symptomatic carotid occlusion. In the absence of data demonstrating improvement in patient outcome, there is currently no role for the routine use of these tools to guide clinical management in patients with cerebrovascular disease.


Assuntos
Circulação Cerebrovascular , Transtornos Cerebrovasculares/etiologia , Transtornos Cerebrovasculares/fisiopatologia , Hemodinâmica , Humanos , Fatores de Risco
16.
Radiology ; 212(2): 499-506, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10429709

RESUMO

PURPOSE: To test the ability of a count-based positron emission tomographic (PET) method, without arterial sampling, for the measurement of regional cerebral oxygen extraction fraction (OEF) to predict ischemic stroke in patients with symptomatic carotid arterial occlusion. MATERIALS AND METHODS: The outcome analysis of a blinded prospective study designed to determine if increased OEF was an independent predictor of stroke in patients with symptoms and with carotid occlusion was repeated by substituting a count-based method of OEF measurement for the original quantitative technique. The performance of the quantitative and count-based methods was assessed by using Kaplan-Meier cumulative survival functions (log-rank, [p < .05]). Receiver operating characteristic (ROC) curves for both methods were generated. RESULTS: Thirteen ipsilateral strokes occurred during a mean follow-up of 3.1 years for 81 patients. All ipsilateral strokes occurred in 50 patients with increased count-based OEF (P = .002, sensitivity 100%, specificity 46%). Sixty-eight patients underwent complete quantitative studies, which allowed comparison of OEF methods. Both the count-based and the quantitative methods were predictive of stroke in this subgroup (P = .005 and .025, respectively). ROC analysis demonstrated a greater area under the curve for the count-based OEF method. CONCLUSION: Count-based PET measurement of OEF without arterial sampling accurately predicts stroke in patients with carotid occlusion.


Assuntos
Arteriopatias Oclusivas/complicações , Arteriopatias Oclusivas/diagnóstico por imagem , Isquemia Encefálica/etiologia , Encéfalo/diagnóstico por imagem , Doenças das Artérias Carótidas/complicações , Doenças das Artérias Carótidas/diagnóstico por imagem , Tomografia Computadorizada de Emissão , Isquemia Encefálica/epidemiologia , Feminino , Seguimentos , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Valor Preditivo dos Testes , Curva ROC , Estudos Retrospectivos , Sensibilidade e Especificidade , Fatores de Tempo
17.
Stroke ; 30(5): 1019-24, 1999 May.
Artigo em Inglês | MEDLINE | ID: mdl-10229738

RESUMO

BACKGROUND AND PURPOSE: The purpose of this experiment was to assess long-term cerebral hemodynamic and metabolic changes in patients with increased oxygen extraction fraction (OEF) in the hemisphere distal to an occluded carotid artery who remain free of stroke. Methods--Ten patients with increased OEF and no interval stroke underwent repeated positron emission tomography examinations 12 to 59 months after the initial examination. Quantitative regional measurements of cerebral blood flow, cerebral blood volume, cerebral rate of oxygen metabolism (CMRO2), and OEF were obtained. Regional measurements of the cerebral rate of glucose metabolism (CMRGlc) were made on follow-up in 5 patients. Statistical significance (P<0.05) was measured with t tests and linear regression analysis. RESULTS: The ipsilateral/contralateral OEF ratio declined from a mean of 1.16 to 1.08 (P=0.022). Greater reductions were seen with longer duration of follow-up (P=0.023, r=0.707). The cerebral blood flow ratio improved from 0.81 to 0.85 (P=0.021). No change in cerebral blood volume or CMRO2 was observed. CMRGlc was reduced in the ipsilateral hemisphere (P=0.001 compared with normal), but the CMRO2/CMRGlc ratio was normal. CONCLUSIONS: Increased OEF improves in patients with carotid occlusion and no interval stroke. This improvement in OEF is due to an improvement in collateral blood flow.


Assuntos
Arteriopatias Oclusivas/fisiopatologia , Isquemia Encefálica/fisiopatologia , Doenças das Artérias Carótidas/fisiopatologia , Circulação Cerebrovascular/fisiologia , Idoso , Arteriopatias Oclusivas/diagnóstico por imagem , Arteriopatias Oclusivas/metabolismo , Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/metabolismo , Doenças das Artérias Carótidas/diagnóstico por imagem , Doenças das Artérias Carótidas/metabolismo , Córtex Cerebral/irrigação sanguínea , Córtex Cerebral/diagnóstico por imagem , Córtex Cerebral/metabolismo , Doença Crônica , Feminino , Seguimentos , Glucose/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio , Tomografia Computadorizada de Emissão
18.
Stroke ; 30(5): 1025-32, 1999 May.
Artigo em Inglês | MEDLINE | ID: mdl-10229739

RESUMO

BACKGROUND AND PURPOSE: Misery perfusion, identified by increased oxygen extraction fraction (OEF), predicts subsequent stroke in patients with carotid occlusion. The purpose of this investigation was to determine the relationship of angiographic findings to increased OEF in these patients. METHODS: Forty-seven patients with carotid occlusion were studied with cerebral angiography and positron emission tomography (PET). The following angiographic data were collected blind to PET results: (1) pial collateralization, defined as retrograde filling of the MCA branches to the level of the insula; (2) presence of border zone shift; (3) presence of delayed venous phase; and (4) measurement of posterior communicating artery size. Patients were divided into 2 groups based on the PET measurement of normal or increased OEF. RESULTS: Seventeen of 47 patients had increased OEF distal to the occluded carotid artery. No significant relationship between increased OEF and any angiographic finding was found. Pial collateralization was present in only 2 patients, both with increased OEF (P=0.105). Border zone shift was equally distributed between the 2 groups (12 of 30 with normal OEF and 6 of 15 with increased OEF). Delayed venous phase was present in 4 patients, 3 of whom had increased OEF (P=0.073). The relationship between the size of the posterior communicating artery and OEF was not significant by linear regression analysis (P=0.242). CONCLUSIONS: With the possible but infrequent exceptions of delayed venous phase and pial collateralization, anatomic findings made on routine angiographic studies of patients with carotid occlusion do not correlate with increased OEF.


Assuntos
Arteriopatias Oclusivas/fisiopatologia , Doenças das Artérias Carótidas/fisiopatologia , Circulação Cerebrovascular , Circulação Colateral , Adulto , Idoso , Arteriopatias Oclusivas/diagnóstico por imagem , Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/fisiopatologia , Doenças das Artérias Carótidas/diagnóstico por imagem , Angiografia Cerebral , Transtornos Cerebrovasculares/diagnóstico por imagem , Transtornos Cerebrovasculares/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oxigênio/sangue , Tomografia Computadorizada de Emissão , Resultado do Tratamento
20.
Otolaryngol Head Neck Surg ; 120(1): 17-24, 1999 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9914544

RESUMO

Technical advances in accessing the lateral cranial base have permitted disease in this area previously deemed inoperable to be resected. The procedures required to effect an oncologically adequate resection are often long and accompanied by the potential for serious, even life-threatening, complications. Although it has been demonstrated that such disease can be extirpated, the question of whether such heroic surgery improves long-term survival remains unanswered. We retrospectively reviewed the records of 25 patients who underwent a combination of frontotemporal craniotomy with other, more conventional, anterolateral procedures (eg, infratemporal fossa approach, maxillectomy, orbitectomy, mandibulopharyngectomy) to resect stage IV malignant disease of the lateral to midcranial base between 1983 and 1990. Perioperative deaths occurred in 2 patients, 1 patient died of unrelated causes free of disease, and 2 patients were lost to follow-up, leaving 20 patients with a minimum 5-year evaluation. Five (25%) of the 20 patients we monitored were free of disease. Of those patients in whom recurrent disease developed, local control was achieved in about 50%; however in 80% of those with recurrence, metastatic disease developed. Surgical treatment of selected stage IV malignant disease of the lateral to midcranial base appears to have provided long-term disease-free survival to 25% of patients in this series who would otherwise have had little hope of survival.


Assuntos
Procedimentos Neurocirúrgicos , Neoplasias da Base do Crânio/cirurgia , Adulto , Idoso , Craniotomia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias , Estudos Retrospectivos , Neoplasias da Base do Crânio/mortalidade , Neoplasias da Base do Crânio/patologia , Análise de Sobrevida , Resultado do Tratamento
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