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Arterial oxygen saturation and posture in acute stroke.

Patients with acute stroke are at risk of hypoxaemia and the degree of oxygen desaturation may depend on posture. Using a fingertip pulse oximeter, we studied the effects of different nursing positions on arterial oxygen saturation (SaO2) in ten elderly patients within 48 hours of a hemiplegic stroke and 10 age-matched controls admitted to hospital with other acute illnesses. Mean SaO2 was consistently higher in the controls than the stroke patients in all recumbent positions, but when patients were propped up the difference between the groups was statistically insignificant. The difference between semirecumbent and lying SaO2 values was then tested in a further nine stroke patients. Overall the mean SaO2 was significantly higher and, in at least four cases, the duration of episodes of desaturation (SaO2 < 90%) was substantially less when the patients were propped up. We suggest that, wherever possible, acute stroke patients should be nursed sitting up to minimize the risk of oxygen desaturation and possible aggravation of ischaemic brain damage.

Acute Disease↗

Loss of circadian rhythm of blood pressure following acute stroke.

BACKGROUND: Epidemiology of acute stroke in developing countries differs from that in the developed world, for example, the age at stroke, risk factors, subtypes of stroke and prognosis. Hypertension remains a dominant risk factor and prognostic indicator in patients with stroke in all communities. The risk of stroke is directly related to elevations of blood pressure. A number of clinical studies have shown that the control of hypertension leads to a reduction in the incidence of stroke in a community. However there is still considerable controversy surrounds the changes in blood pressure in various subtypes of strokes and problem of management of elevated BP after stroke. We studied the circadian rhythm of blood pressure in patients following acute stroke. METHODS: To study the circadian rhythm of blood pressure, fifty consecutive patients with an acute stroke who were admitted to medical emergency within 120 hours of onset were included in the study. After a detailed history and clinical examination, a continuous blood pressure monitor (Spacelab 90207) was attached on the side ipsilateral to intracranial lesion (unaffected arm). The blood pressure was recorded for 24 hours at 15 minutes interval during daytime (6.00 am-6.00 pm) and 20 minutes interval overnight (6 pm to 6 am). RESULTS: Risk factors for stroke in 50 patients included hypertension in 31(62%), diabetes mellitus in 4 (8%), smoking in 13 (26%) and previous history of transient ischemic attack in 7 (14%) patients. Mean systolic pressure and diastolic pressure at admission were higher in patients with hemorrhagic stroke -29 patients (177 +/- 24 mmHg and 105 +/- 19 mmHg respectively) compared to patients with ischemic strokes-21 patients (150 +/- 36 mm Hg and 89 +/- 18 mm Hg respectively, p value <0.01 in both comparisons). The normal diurnal variation in blood pressure (night time dipping of more than 10%) was abolished in 44 (88%) of patients. Out of 44 nondippers, 29 patients showed reverse dipping i.e. rise of BP during night time compared to day time levels. None of the risk factors, clinical or laboratory variables, type of stroke or blood pressure changes differed significantly between these two groups. CONCLUSIONS: Therefore, we showed a pathologically reduced or abolished circadian BP variation after stroke. Absence of normal dipping results in a higher 24 hour blood pressure load and may have more target organ damage than those with normal diurnal variation of blood pressure.

Adult↗

Stroke severity determines body temperature in acute stroke.

BACKGROUND AND PURPOSE: Several studies have claimed that temperature on admission is of prognostic significance in acute stroke. Experimental studies showing that hyperthermia increases infarct size have lent credibility to this assumption. The aim of the present study was to test the hypothesis that initial body temperature is of importance for stroke outcome. METHODS: This prospective study included 725 consecutive patients, 584 with cerebral infarcts and 141 with intracerebral hemorrhages, admitted to an acute stroke unit within 6 hours of stroke onset. Time of stroke onset and time of admission were recorded. Body temperature was measured on admission and every 2 hours during the first 24 hours. Patients were divided into 2 groups on the basis of stroke severity on admission: Scandinavian Stroke Scale Score (SSS) </=25 was defined as major stroke, and SSS >25 was defined as mild to moderate stroke. RESULTS: On admission, mean body temperature was normal. In the major stroke patients, body temperature started to rise 4 to 6 hours after stroke onset. At 10 to 12 hours after stroke onset, increased body temperature was found to be related to poor outcome. In mild to moderate stroke, there was no significant rise in temperature. Initial temperature >37.5 degrees C was not related to stroke severity or stroke outcome. CONCLUSIONS: In major stroke, a significant rise in temperature occurred hours after stroke onset. Severe infarcts and intracerebral hemorrhages caused temperature to rise, whereas initially increased temperature had no influence on stroke severity. Elevated body temperature on admission within 6 hours of stroke onset had no prognostic influence on stroke outcome at 3 months.

Acetaminophen↗

Prediction of long-term outcome in the early hours following acute ischemic stroke. Italian Acute Stroke Study Group.

OBJECTIVE: To develop a model for predicting outcome in the first few hours after the onset of an ischemic stroke on the basis of the clinical findings obtained during a rapid bedside examination. DESIGN: Clinical records were retrieved from the data bank of a randomized multicenter trial. The resulting case series was split into two subgroups that served as a "training set" and a "test set." Logistic regression was applied to the training set to select the prognostic predictors among baseline clinical findings. The performances of the model based on independent prognostic predictors were then validated in the test set. SETTING: Eleven primary care institutions (either hospitals or university clinics) participating in the Italian Acute Stroke Study on the efficacy of hemodilution and monosialoganglioside in acute ischemic stroke. PATIENTS: Consecutive noncomatose patients (N = 300) observed within the first 6 hours after the onset of a first supratentorial ischemic stroke. MAIN OUTCOME MEASURE: Death or disablement 4 months after the index stroke. Disablement was defined as a score of 3 or higher on the Rankin Scale. RESULTS: Age and CNS score defined six risk groups with a predicted 4-month poor outcome rate ranging from 10% (patients aged 70 years or younger and with an initial CNS score of 7 or higher) to 89% (patients older than 70 years and with a CNS score of 4.5 or lower). When a risk of poor outcome of 60% was taken as a cutoff, the accuracy of the prediction was 78% +/- 6% in the training set and 72% +/- 9% in the test set. CONCLUSION: Long-term outcome can be predicted in the first few hours following an acute ischemic stroke by means of a simple model based on age and CNS score.

Acute Disease↗

Cardiopulmonary and arterial baroreflex-mediated control of forearm vasomotor tone is impaired after acute stroke.

BACKGROUND AND PURPOSE: Elevated blood pressure (BP) levels are well recognized after acute stroke and are associated with increased BP variability. The underlying mechanisms producing such changes are unclear but may include abnormalities of baroreceptor-mediated control of heart rate and vasomotor tone. Lower body negative pressure (LBNP) can be used to assess the integrity of "low-pressure" cardiopulmonary and "high-pressure" arterial baroreceptor-derived responses by inducing nonhypotensive and hypotensive stimuli. METHODS: Cardiovascular responses, including BP, heart rate, forearm blood flow, and forearm vascular resistance, to nonhypotensive and hypotensive LBNP were assessed in 13 consecutive stroke patients. Patients were studied within 72 hours of stroke (acute) and again at 10 to 14 days (subacute) and were compared with 13 control subjects individually matched for age, sex, and BP. RESULTS: At an LBNP of -10 mm Hg, BP was unchanged in all groups, but a significant increase in forearm vascular resistance occurred only in the control group (11 U [interquartile range, 7 to 15]; P < .05) compared with stroke patients in the acute (9 U [3 to 14]; P = NS) or subacute phases (7 U [2 to 12]; P = NS). After LBNP at -40 mm Hg, the reductions in systolic BP levels were similar in all groups (control: -9 mm Hg [-16 to -3]; acute stroke: -9 mm Hg [-22 to 3]; subacute stroke: -7 mm Hg [-35 to 20]), as was the associated increase in heart rate (control: 8 bpm ([4 to 11]; acute stroke: 6 bpm ([1 to 12]; subacute stroke: 9 bpm [2 to 19]). However, forearm vascular resistance increased significantly only in control subjects (20 U [9 to 30]; P < .01). CONCLUSIONS: The present study has identified abnormal vasomotor responses to LBNP after acute stroke, with an increase in FVR only being observed in control subjects in response to nonhypotensive and similar hypotensive levels of LBNP. In acute stroke patients, the stimulus of hypotensive LBNP appears to be compensated by an increase in cardiac output since there appears to be no increase in peripheral vascular resistance, unlike the changes seen in control subjects. However, the exact mechanisms for these changes are still unclear and are the subject of further study.

Acute Disease↗

The emerging role of induced hypothermia in the management of acute stroke.

Current treatment of acute stroke remains unsatisfactory. This review presents experimental and clinical data which suggest that mild induced hypothermia could be a potent and practicable neuroprotective treatment of acute ischaemic stroke and intracerebral haemorrhage. Hypothermia, if proven to be safe, effective and widely practicable in patients with acute stroke, could have an enormous positive impact on reducing the burden of stroke worldwide. Critical issues that will need to be considered in a well designed randomised controlled trial of induced hypothermia in acute stroke patients are discussed.

Acute Disease↗

The value of diffusion-weighted imaging for prediction of lasting deficit in acute stroke: an analysis of 134 patients with acute neurologic deficits.

Acute stroke is one of the three major causes of death and disability in the United States. Now that new, and possibly effective therapy is becoming available, accurate, rapid diagnosis is important to provide timely treatment, while avoiding the risk of complications from unnecessary intervention. Our objective was to test the hypothesis that use of echo-planar (EPI) diffusion-weighted imaging (DWI) is more accurate than conventional T2 weighted MRI in predicting progression to stroke in patients with acute ischemic neurologic deficits. We studied 134 patients presenting with acute neurologic deficits to a community hospital emergency room with both conventional MRI and DWI within 72 h of the onset of the acute deficit. We found DWI significantly more sensitive to permanent neurologic deficit at discharge (sensitivity 0.81) than conventional MRI (sensitivity 0.41). When available, DWI should be considered for routine use in patients being imaged for acute stroke.

Adult↗

Is use of mechanical ventilation a reasonable proxy indicator for coma among Medicare patients hospitalized for acute stroke?

OBJECTIVE: To ascertain whether use of mechanical ventilation on admission to the hospital is a proxy indicator of coma (i.e., very severe stroke) among acute stroke patients. METHODS: A secondary analysis of data from a medical record review on a nationally representative sample of 2,824 Medicare patients, ages 65 years or older, who were hospitalized for stroke in 1982-1983 or 1985-1986 in 297 acute care hospitals in 30 areas within five geographically dispersed states. RESULTS: Use of mechanical ventilation on the first day of hospitalization was significantly associated with level of consciousness on admission: < 2 percent of noncomatose patients versus 17.5 percent of comatose (p < .001). With a high specificity and high likelihood ratio for a positive test, use of mechanical ventilation on the first day of hospitalization ruled-in coma. It was also significantly associated with severity of illness, prognostic indicators (i.e., admission through the emergency room, admission to intensive care, and having a "do-not-resuscitate" order written during the hospital stay), and with in-hospital death. Adjusting for patient demographics, stroke type, comorbidity, and process of care, early initiation of mechanical ventilation remained significantly associated with both coma and in-hospital death. CONCLUSIONS: A stroke patient's use of mechanical ventilation on the first day of hospitalization is a valid proxy indicator of level of consciousness.

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Advantages of adding diffusion-weighted magnetic resonance imaging to conventional magnetic resonance imaging for evaluating acute stroke.

BACKGROUND: Accurate localization of acute ischemic lesions in patients with an acute stroke may aid in understanding the etiology of their stroke and may improve the management of these patients. OBJECTIVE: To determine the yield of adding diffusion-weighted magnetic resonance imaging (DWI) to a conventional magnetic resonance imaging (MRI) protocol for acute stroke. DESIGN: A prospective cohort study. SETTING: A referral center. PATIENTS AND METHODS: Fifty-two patients with a clinical diagnosis of acute stroke who presented within 48 hours after symptom onset were included. An MRI scan was obtained within 48 hours after symptom onset. A neuroradiologist (A.M.N.) and a stroke neurologist (G.W.A.) independently identified suspected acute ischemic lesions on MRI sequences in the following order: (1) T2-weighted and proton density-weighted images, (2) fluid-attenuated inversion recovery images, and (3) diffusion-weighted images and apparent diffusion coefficient maps. MAIN OUTCOME MEASURES: Diagnostic yield and interrater reliability for the identification of acute lesions, and confidence and conspicuity ratings of acute lesions for different MRI sequences. RESULTS: Conventional MRI correctly identified at least one acute lesion in 71% (34/48) to 80% (39/49) of patients who had an acute stroke; with the addition of DWI, this percentage increased to 94% (46/49) (P<.001). Conventional MRI showed only moderate sensitivity (50%-60%) and specificity (49%-69%) compared with a "criterion standard." Based on the diffusion-weighted sequence, interrater reliability for identifying acute lesions was moderate for conventional MRI (kappa = 0.5-0.6) and good for DWI (kappa = 0.8). The observers' confidence with which lesions were rated as acute and the lesion conspicuity was significantly (P<.01) higher for DWI than for conventional MRI. CONCLUSION: During the first 48 hours after symptom onset, the addition of DWI to conventional MRI improves the accuracy of identifying acute ischemic brain lesions in patients who experienced a stroke.

Acute Disease↗

[Learning capacity of acute stroke patients. A pilot study].

INTRODUCTION: Acute stroke patients find themselves in a new and totally altered health situation. Several factors add to its complexity. In order to master the health situation as independently as possible, patients must possess the appropriate knowledge. In turn, they must be able to learn. The aim of this study was to answer the question, to which extent will acute stroke patients be able to attain and recall health related and rehabilitation related information. The hypotheses were, that acute stroke patients do possess the ability but that their performance differs, depending on the localization of the lesion and from the performance of non-stroke patients. METHOD: A convenience sample resulted in 12 participants with hemispheric infarct, eight participants with lacunar infarct and nine participants in a comparison group. By means of structured interview the level of knowledge of all participants was asked, followed by structured teaching and the same structured interview. Five days later the structured interview was carried out again. RESULTS: The results show that acute stroke patients are able to attain and recall the information offered. Different performance related to the region of lesion and to non-stroke patients could not be proved. CONCLUSIONS: The ability of acute stroke patients as demonstrated here represents a resource for their rehabilitation during the acute phase. The method and content of structured teaching prevents occasional and inconsistent knowledge transfer. The specific information needs of these patients may not be left disregarded. The information needs of significant others must be taken into account as well. Further research is needed, to lighten up the learning behavior of acute stroke patients and to prove the effect of structured teaching for this group of patients.

Acute Disease↗

New perspectives on developing acute stroke therapy.

The development of additional acute stroke therapies to complement and supplement intravenous recombinant tissue-type plasminogen activator within the first 3 hours after stroke onset remains an important and pressing need. Much has been learned about the presumed target of acute stroke therapy, the ischemic penumbra, and clinically available imaging modalities such as magnetic resonance imaging and computed tomography hold great promise for at least partially identifying this region of potentially salvageable ischemic tissue. Understanding the biology of ischemia-related cell injury has also evolved rapidly. New treatment approaches to improve outcome after focal brain ischemia will likely be derived by looking at naturally occurring adaptive mechanisms such as those related to ischemic preconditioning and hibernation. Many clinical trials previously performed with a variety of neuroprotective and thrombolytic drugs provide many lessons that will help to guide future acute stroke therapy trials and enhance the likelihood of success in future trials. Combining knowledge from these three areas provides optimism that additional acute stroke therapies can be developed to maximize beneficial functional outcome in the greatest proportion of acute stroke patients possible.

Acute Disease↗

Cardiac sequelae of acute stroke.

The possibility that acute stroke produces an increase in sympathetic tone with resultant cardiac abnormalities was examined in 100 stroke patients admitted to a stroke ICU and in 50 controls found to have diagnoses other than stroke or TIA after admission to the Unit. Continuous 24 hour Holter ECG tapings were performed and serum cardiac enzymes and plasma norepinephrine concentrations were measured within 48 hours after admission. Significantly, (p less than .001) more serious arrhythmias were observed during 24 hour Holter ECG monitoring in stroke patients compared with controls and the difference remained (p less than .01) after matching for age and co-existing heart disease. Arrhythmias were more common in older stroke (p less than .001) and older control (p = .05) patients and with infarction of the cerebral hemispheres (p less than .05) as compared to brainstem lesions. Arrhythmia occurrence was independent of the presence of co-existing heart disease and the level of sympathetic activity. However, the 15 stroke patients with abnormally high CK values (mean 34.3 units) had a higher (p less than .02) mean plasma norepinephrine concentration (650.4 pg/ml) than stroke patients with normal CK (427.7 pg/ml). Acute stroke may cause cardiac arrhythmias and myocardial cell damage, the latter through stroke induced increases in sympathetic tone.

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Randomised controlled trial of streptokinase, aspirin, and combination of both in treatment of acute ischaemic stroke. Multicentre Acute Stroke Trial--Italy (MAST-I) Group.

In ischaemic stroke, thrombolytic drugs speed the recanalisation of intracerebral arteries. The effects of aspirin are not known. A trial was conducted to determine whether, separately or together, streptokinase and aspirin have clinical benefits in acute ischaemic stroke similar to those in acute myocardial infarction. 622 patients with acute ischaemic stroke within 6 hours of symptom onset were randomised with a 2 x 2 factorial design to (i) a 1-hour intravenous infusion of 1.5 MU streptokinase, (ii) 300 mg/day buffered aspirin for 10 days, (iii) both active treatments, or (iv) neither. Early results raised a question whether the trial should be continued. Streptokinase (alone or with aspirin) was associated with an excess of 10-day case fatality (odds ratio 2.7; 95% confidence interval 1.7-4.3; 2p < 0.00001). Of the four groups randomised, only patients allocated to streptokinase plus aspirin had a significantly higher risk of early death than those given neither streptokinase nor aspirin (odds ratio 3.5; 95% CI 1.9-6.5; 2p < 0.00001). Streptokinase (alone or with aspirin) and aspirin (alone or with streptokinase) reduced, albeit not significantly, the incidence of combined six-month case fatality and severe disability: odds ratio for streptokinase 0.9 (95% CI 0.7-1.3) and odds ratio for aspirin 0.9 (95% CI 0.6-1.3). The risk of early death with thrombolytic treatments should be weighed against the potential benefit of a marginal reduction of severe disability after the first six months.

Acute Disease↗

Virtual TeleStroke support for the emergency department evaluation of acute stroke.

OBJECTIVES: Telemedicine-enabled acute stroke consultation (TeleStroke) may be useful to determine eligibility for treatment with tissue plasminogen activator (tPA) and provide support to emergency departments without on-site stroke expertise. METHODS: Emergency physicians consulted with stroke neurologists via two-way videoconferencing in the evaluation of patients with possible acute stroke. History, neurologic examination, and computed tomography of the head were reviewed to determine eligibility for treatment with tPA. Interpretations of computed tomography were compared for inter-rater reliability between the neurologist and the neuroradiologist using a conventional workstation. Videotape and written records were analyzed to determine time intervals, patient management, and user satisfaction. RESULTS: The authors reviewed data from 24 patients evaluated over 27 months at an island-based hospital. The mean National Institutes of Health Stroke Scale score was 5.7 (range, 0-22). Fifteen patients arrived at the emergency department less than three hours after symptom onset; 12 were presented for TeleStroke consultation within three hours after symptom onset. Eight of these 12 (75%) had acute ischemic stroke, and six of these eight potentially eligible patients (75%) received intravenous tPA. There was very good agreement among all remote readers for detecting the one case of imaging exclusion (subdural hemorrhage). There were no protocol violations, and a mean (+/- SD) consult-to-needle time of 36 (+/- 15) minutes and door-to-needle time of 106 (+/- 22) minutes was achieved. Transfer was avoided in 11 patients. Physicians believed that TeleStroke consultation improved care in >95% of the cases. CONCLUSIONS: TeleStroke videoconferencing can support emergency department-based evaluation of acute stroke and may facilitate tPA delivery in neurologically underserved facilities. A prospective, randomized trial is needed to determine if these systems are superior to traditional telephone consultation.

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Acute stroke treatment in Europe: a questionnaire-based survey on behalf of the EFNS Task Force on acute neurological stroke care.

In 1997 the EFNS Task Force on Acute Neurological Stroke Care published its recommendations for acute stroke care (Brainin et al., 1997), which, in 1999, was followed by a stroke care inventory (Brainin et al., 2000) assessing the development of acute stroke care. In 2000 all 33 members of the EFNS Stroke Scientist Panel were asked to complete a questionnaire on the treatment of acute stroke in their country as of 2000. Data were based either on national surveys or a personal estimate of national practice, together with data from the personal practice of the panel member. Data from 22 countries were received. One of the principal findings is the lack of systematic evidence about practice in a significant number of European countries. Results illustrate that neurologists have a leading role in implementing acute stroke treatment guidelines and in adopting new therapeutic methods in most countries, but there is a wide variation in the application of different therapeutic procedures.

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A population-based study of acute stroke and TIA diagnosis.

BACKGROUND: Acute stroke therapy is heavily dependent on the diagnostic acumen of the physician in the emergency department (ED). OBJECTIVE: To determine this diagnostic accuracy in a population-based multiethnic stroke study. METHODS: The Brain Attack Surveillance in Corpus Christi (BASIC) Project prospectively ascertained all acute stroke or TIA cases in an urban Texas county of 313,645 residents without an academic medical center. Cases were validated by board-certified neurologists using source documentation. Case validation was used as the gold standard to compare the diagnosis given by the ED physician. RESULTS: From January 2000 to August 2002, a total of 13,015 patients were screened. Of these, 1,800 were validated as stroke/TIA. Overall sensitivity of the emergency physician for the BASIC-validated diagnosis was 92%, and positive predictive value was 89%. Of the cases that the emergency physician thought were stroke, 11% were validated as no stroke. In multivariable modeling, motor symptoms was an independent predictor of protection from false-negative ED diagnosis of stroke/TIA (odds ratio [OR] = 0.61; 95% CI 0.41 to 0.89). Protection from false-positive stroke/TIA diagnosis was predicted by sensory symptoms (OR = 0.43; 95% CI 0.28 to 0.66), motor symptoms (OR = 0.44; 95% CI 0.32 to 0.62), and severe neurologic deficit (OR = 0.33; 95% CI 0.14 to 0.78). History of stroke/TIA predicted false-positive stroke diagnosis (OR = 1.72; 95% CI 1.23 to 2.40). The majority of disagreements occurred in patients with generalized neurologic or acute medical, nonneurologic syndromes. CONCLUSIONS: Physicians practicing in the ED are sensitive for stroke/TIA diagnosis. The modest positive predictive value argues for a systems approach with neurology support so that proper decisions regarding acute stroke therapy can be made.

Acute Disease↗

Hyperglycaemia and mortality from acute stroke.

Hyperglycaemia has been observed after acute stroke, and is associated with a poor prognosis. It is not known whether this is due to the stress response of the acute illness or whether hyperglycaemia is, in itself, harmful to ischaemic nervous tissue. Seventy-one patients admitted to hospital with acute stroke and no history of diabetes or other acute illness were recruited, and fasting blood sampling was carried out within 24 h of symptom onset, for plasma glucose and stress hormones and levels of haemoglobin A1c (HbA1c). Computerized tomography of the brain was carried out on 77% of the subjects. The subjects were followed up for 3 months or until death. Glucose levels were higher in subjects who died during the course of the study (p = 0.025), but this relationship became non-significant after age (p < 0.001) and cortisol (p = 0.001) levels were taken into account with multivariate analysis. The correlation between serum cortisol and the volume of the lesion on CT scan was also stronger than the relation of glucose with volume. Haemoglobin A1c had no relationship with either mortality or lesion volume. These findings suggest that the hyperglycaemia seen after an acute stroke is secondary to a stress response and they do not support the theory of hyperglycaemia being harmful to ischaemic nervous tissue. These findings have implications for the treatment of acute stroke with hypoglycaemic agents.

Acute Disease↗

Radiologic manifestations of focal cerebral hyperemia in acute stroke.

In 16 acute stroke patients with focal cerebral hyperemia angiography and regional cerebral blood flow (rCBF) were studied 1 to 4 days post stroke. CT was performed twice with and without contrast enhancement 3 +/- 1 days and 16 +/- 4 days post stroke. Angiographic evidence of focal cerebral hyperemia was seen in 8 patients in the form of early filling veins. In 5 of these the hyperemic areas were located within infarcted areas and in 3 patients in areas which appeared normal on CT. In the remaining 8 patients the hyperemias were located perifocally around ischemic infarcts. Early filling veins were not seen in this type of hyperemia. The blood flow was higher and the transit time of the contrast medium was faster in the former type of hyperemia probably because of arteriovenous shunting. Contrast enhancement was not observed on the early CT but was typically seen in the infarcts on the late CT at a time when the hyperemic state is known to have vanished. It is concluded that focal cerebral hyperemia is not responsible for contrast enhancement on CT.

Acute Disease↗