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Biomedical subjects

M Hennerici

Publications and source records attributed to M Hennerici.

At least 127 records · Page 7Linked to original sources
PubMed1994

Proinflammatory cytokines in serum of patients with acute cerebral ischemia: kinetics of secretion and relation to the extent of brain damage and outcome of disease.

The release of the proinflammatory cytokines IL-1 beta, IL-6, TNF-alpha and soluble TNF-receptors p55 and p75 in peripheral blood was serially determined in 19 patients with acute cerebral ischemia. Only patients admitted within 4 h following onset of symptoms were studied. In contrast to serum levels of IL-1 beta, TNF-alpha and TNF-receptors, which did not exhibit a significant response, IL-6 showed a significant increase of serum levels already within the first hours following onset of disease and reached a plateau at 10 h until day 3 and returned to baseline by day 7. The increase of levels of this cytokine was significantly (P < 0.05) correlated with increasing volumes of brain lesion and was also significantly (P < 0.005) associated with poor functional and neurological outcome. The increase of levels of IL-6 despite a considerable dilution in peripheral blood shown in this preliminary study suggests an early inflammatory response in ischemic brain lesion.

Activities of Daily Living↗
PubMed1994

Pathophysiologic assessment of data from a stroke data bank.

Stroke data banks have been instrumental in helping us to clarify stroke etiology and in the investigation of clinical-topographic correlations. For these purposes they have relied upon results from noninvasive vascular and cardiac methods, including extra- and transcranial Doppler sonography and echocardiography, as well as from procedures such as cranial computed tomography and magnetic resonance imaging. Conventional database concepts have also been used to assess pathophysiologic aspects of stroke. Although such applications have made important contributions in this multidiscipline area of investigation, they are limited by a lack of explicit representation of pathophysiologic knowledge for data interpretation. Recent results from artificial intelligence research suggest exciting new frontiers for medical database design with concepts stemming from second generation expert systems. We propose an extended concept for stroke data banks to include a knowledge-based system which incorporates current patient data, heuristic knowledge relating clinical features to functional impairment, and pathophysiologic models of neurological disease.

Cerebrovascular Disorders↗
PubMed1994

Compensatory carotid artery dilatation in early atherosclerosis.

BACKGROUND: From pathological studies of coronary arteries, it has been recognized that progressive plaque development may be compensated for by an increase of the arterial diameter. However, the dynamics of this process have not been investigated, and it is not known whether compensatory dilatation is a general pathomechanism in human arteries. METHODS AND RESULTS: Using a high-resolution duplex scanner and subsequent three-dimensional plaque reconstruction, we prospectively studied the effect of carotid plaque development on the vascular geometry in 32 patients at 6- to 12-month intervals. Plaque progression in 41% (n = 26) of studies was associated with an increase of the vessel diameter between 0.4 and 1.2 mm in 76% (n = 20). Among 36 unchanged plaque developments, enlargement of the arterial diameter was assessed in only 28% (n = 10) (P < .001). CONCLUSIONS: Our data suggest that increasing plaque volume is significantly associated with enlargement of carotid artery segments, which compensates for arterial narrowing in early stages of the disease.

Aged↗
PubMed1994

Noninvasive monitoring of internal carotid artery dissection.

BACKGROUND AND PURPOSE: Internal carotid artery dissection has increasingly been reported as a cause of transient ischemic attack or stroke. However, scarce data exist on the natural history of the arterial lesions and the temporal profile of recanalization. METHODS: We followed 48 patients with 50 angiographically confirmed internal carotid artery dissections by sequential duplex Doppler studies in 2- to 4-day intervals during the first weeks after the onset of symptoms and after 4 weeks in 1- to 2-month intervals for up to 2 years. We assessed sonographic features as well as the frequency and time course of resolution. RESULTS: Initial Doppler findings were abnormal in all patients, most of whom (68%) presented with a characteristic bidirectional high-resistance Doppler signal in the internal carotid artery. Gradual recanalization was found in 68% of the dissections after an average interval of 51 days. Changes of Doppler flow patterns in follow-up studies and features of intra-arterial angiography correlated with the development of internal carotid artery dissection and mirrored the recanalization process. CONCLUSIONS: Our findings suggest that Doppler sonography provides early recognition of internal carotid artery dissection and monitoring of its resolution. Thus, ultrasound studies may guide clinical decisions according to the development of the dissection.

Adolescent↗
PubMed1994

Pattern of activation of the hypothalamic-pituitary-adrenal axis in acute stroke. Relation to acute confusional state, extent of brain damage, and clinical outcome.

BACKGROUND AND PURPOSE: The aim of this study was to characterize the response of the hypothalamic-pituitary-adrenal system in the first hours of ischemic stroke and to relate its extent to the occurrence of acute confusional state, volume of brain damage, and clinical outcome. METHODS: The secretion of corticotropin (adrenocorticotropic hormone [ACTH]) and cortisol was studied in 23 patients by determinations at hours 4, 6, 8, 10, and 14 and days 1, 3, 5, and 7 after onset of symptoms. Acute confusional state (DSM-III-R criteria), extent of lesion (volumetry of computed tomographic scans), and neurological and functional outcome (Scandinavian Stroke Scale, Barthel Index scores) were assessed. RESULTS: The massive neuroendocrine response observed consisted of an initial phase with concomitantly increased levels of ACTH and cortisol and a second phase with decreased levels of ACTH while high concentrations of cortisol persisted. Initial levels of ACTH but not cortisol were significantly increased in patients with acute confusional state and significantly correlated with volume of brain lesion and neurological and functional outcome. CONCLUSIONS: An early and persisting activation of the hypothalamic-pituitary-adrenal axis was observed in relation to severity of disease. Its characteristic biphasic pattern suggests an initial central stimulation of release of ACTH followed by feedback suppression concomitant with an increased susceptibility of the adrenal gland. Because these hormones are known to exacerbate hypoxic injury to neurons, their massive release in hyperacute stroke may increase the extent of brain damage.

Acute Disease↗
PubMed1993

The influence of image resolution on the positron emission tomographic measurement of caudate glucose consumption.

The aim of this study was to investigate the influence of image resolution on (a) relative and absolute values of caudate glucose consumption (rCMRGlc) determined by positron emission tomography (PET), and (b) the detection of significant differences in these metabolic values between groups of subjects. For this purpose, raw data of cerebral accumulation of fluorine-18 fluorodeoxyglucose (FDG) obtained in 11 normal subjects and in nine patients with unilateral thalamic infarction were reconstructed using filtered backprojection with four different cut-off frequencies (CFs), yielding images with a transaxial resolution of 5.7, 7.1, 8.9 and 11 mm (full-width at half-maximum; FWHM). Absolute values of caudate rCMRGlc decreased significantly by more than 30% over the range of image resolutions studied. Bilateral ratios of caudate rCMRGlc were insensitive to variations in image resolution. Levels of significance assessing the differences in mean metabolic values between patients and controls were all below 0.01. They were, however, slightly better at image resolutions of 7.1 and 8.9 mm than at a resolution of 5.7 mm. These data indicate (a) that relative values of rCMRGlc are better suited to compare quantitative results from different PET cameras than are absolute values, and (b) that the CF used for the filtered back-projection exerts a small but not negligible influence on levels of significance assessing differences in metabolic values between groups of subjects.

Adult↗
PubMed1993

Magnetic resonance angiography in vertebrobasilar ischemia.

BACKGROUND AND PURPOSE: Magnetic resonance angiography is a new, noninvasive technique whose diagnostic value in vertebrobasilar artery disease has not yet been determined. METHODS: Forty-one patients with acute cerebellar and/or brain-stem ischemia were examined by routine magnetic resonance imaging, extracranial and transcranial Doppler ultrasound, and selective intra-arterial arteriography. Results were correlated with magnetic resonance angiography. Magnetic resonance angiography was accomplished using a three-dimensional time-of-flight gradient-echo technique. RESULTS: Magnetic resonance angiography correctly identified all occlusions, stenoses, and an aneurysm within the distal vertebrobasilar system as revealed by conventional intra-arterial arteriography but missed the diagnosis of vertebral artery dissection in one case. This results in a sensitivity of magnetic resonance angiography of 97% and a specificity of 98.9%. However, the degree of stenoses was difficult to evaluate by magnetic resonance angiography. At least for severe obstructive lesions, this drawback can be eliminated by application of presaturation pulses, which allow the analysis of flow direction and collateral blood flow. Doppler ultrasound studies add useful hemodynamic information for less severe degrees of stenoses. CONCLUSIONS: The combined use of magnetic resonance angiography and Doppler ultrasound findings may replace the invasive intra-arterial arteriography examination in many patients with suspected macroangiopathy of the vertebrobasilar arteries.

Adult↗
PubMed1992

On the influence of spatial resolution and of the size and form of regions of interest on the measurement of regional cerebral metabolic rates by positron emission tomography.

Factors that affect the accuracy of the positron emission tomographic (PET) quantification of cerebral metabolic rates include the spatial resolution of the employed imaging device and the method used for extraction of regional metabolic values from the PET data set. The present article reviews (i) how and to what extent these two factors are presumed to influence the measurement of absolute values of cerebral metabolic rates and their ratios, and (ii) whether and how these factors may affect comparisons of regional metabolic rates between groups of subjects.

Brain↗
PubMed1992

Regional cerebral glucose consumption measured by positron emission tomography in patients with Wilson's disease.

Using positron emission tomography (PET), the regional cerebral metabolic rate of glucose consumption (rCMRGlc) was measured in 14 patients with Wilson's disease (WD) and 23 normal subjects. In WD patients, cerebellar, striatal and--to a lesser extent--cortical and thalamic rCMRGlc were significantly decreased compared with controls. Striatal rCMRGlc was significantly reduced in those 4 patients who had recently started decoppering therapy as compared with striatal rCMRGlc measured in those 10 patients with longer duration of medication. Caudate rCMRGlc correlated significantly with various signs of extrapyramidal dysfunction. Cerebellar, thalamic and cortical rCMRGlc correlated significantly with the severity of pyramidal signs. These data indicate that the PET measurement of rCMRGlc may be a useful tool to evaluate cerebral involvement in WD and to monitor the response to treatment.

Adult↗
PubMed1992

Magnetic resonance imaging follow-up in Creutzfeldt-Jakob disease.

The history of a 67-year-old woman with histologically proven Creutzfeldt-Jakob disease (CJD) is presented. Before typical clinical and neurophysiological signs of CJD developed, magnetic resonance imaging (MRI) showed slightly enhanced signal intensity of the caudate nuclei and putamina in T2-weighted and proton density images, corresponding to spongiform degeneration in neuropathological examination. Five weeks later characteristical progressive cortical atrophy was demonstrated by follow-up MRI.

Aged↗
PubMed1992

Comparison of flow disturbances in small carotid atheroma using a multi-gate pulsed Doppler system and Doppler color flow imaging.

The capacity of a multi-gate pulsed Doppler (MPD) system and Doppler color flow imaging (DCFI) for the evaluation of flow patterns was studied in 14 patients with 17 nonstenotic carotid plaques (luminal narrowing less than 40%). Plaque morphology was assessed by means of a high-resolution B-mode system with subsequent three-dimensional reconstruction of the lesion surface. MPD velocity profiles obtained proximally, centrally and distally to the plaque (51 analyses) were normal in 31 sites corresponding to 28 undisturbed and 3 turbulent flow patterns assessed by Doppler color flow imaging (90% specificity). Of the 10 irregular MPD flow profiles, DCFI detected turbulence in 7 (70% sensitivity). 10 asymmetric MPD waveforms without irregularities were normal in 7 and turbulent in 3 DCFI studies. These results suggest, that MPD is superior to DCFI for the detection of nonturbulent flow asymmetry nearby small carotid plaques. However, DCFI displays turbulence with a high specificity and reasonable sensitivity and visualizes the morphologic-hemodynamic interaction in carotid atherosclerosis simultaneously.

Aged↗
PubMed1992

Stroke and dolichoectatic intracranial arteries.

During a 6-year-period, in 45 patients the diagnosis of dolichoectatic intracranial arteries was established. Dolichoectasia of the vertebrobasilar system was the most frequent finding (n = 39). Twenty-two patients presented with brain stem ischaemia, and 10 patients had ischaemic hemispheric events. Six patients had symptoms due to compression of cranial nerves. Hydrocephalus was observed once. Peak and mean flow velocities in 39 patients with dolichoectatic basilar arteries as revealed by transcranial Doppler ultrasound were significantly reduced (p less than 0.00001) when compared with an age-adjusted control group of 20 patients without evidence of vertebrobasilar dolichoectasia on angiogram. Non-invasive MR-angiography offered an excellent imaging of the vascular abnormality. The combined use of CT, TCD, MRI and MR-angiography allows reliable non-invasive diagnosis of dolichoectatic intracranial arteries. This condition seems to play an underestimated role in stroke patients, in particular with respect to the vertebrobasilar circulation.

Brain Ischemia↗
PubMed1992

Hypoglycemia presenting as basilar artery thrombosis.

BACKGROUND AND PURPOSE: Following our treatment of a patient with hypoglycemia-induced brain stem symptoms, we examined the possible mechanisms for hypoglycemia presenting as basilar artery disease. CASE DESCRIPTION: We describe a patient who had progressive brain stem symptoms due to a diet-induced hypoglycemia initially diagnosed as basilar artery thrombosis. Symptoms ceased immediately after intravenous glucose. CONCLUSIONS: Before invasive diagnostic and thrombolytic strategies are considered, hypoglycemia as a rare but important cause of acute brain stem dysfunction must be considered in patients suspected to suffer from basilar artery thrombosis.

Adult↗
PubMed1992

Spontaneous vertebral artery dissection initially mimicking myocardial infarction.

BACKGROUND AND PURPOSE: Vertebral and carotid artery dissections may present with very different signs and symptoms, making early recognition difficult. However, diagnosis should be established as soon as possible to prevent unnecessary diagnostic investigations and to institute adequate treatment. CASE DESCRIPTION: A 46-year-old man presented with severe intermittent pain of his left upper arm and general discomfort. During extensive cardiological evaluation for suspected myocardial infarction, a severe brain stem syndrome occurred. Ultrasound Doppler studies detected vertebral artery dissection, which was confirmed by angiography. CONCLUSIONS: The unusual initial presentation of vertebral artery dissection delayed an early diagnosis and adequate treatment. Because noninvasive methods are available today, their applications are recommended in similarly uncharacteristic circumstances.

Aortic Dissection↗
PubMed1992

Symptomatic and asymptomatic high-grade carotid stenoses in Doppler color-flow imaging.

We examined 63 patients with 31 symptomatic and 44 asymptomatic carotid stenoses with Doppler color-flow imaging (DCFI); conventional Doppler duplex had shown a hemodynamic obstruction (greater than or equal to 80% stenosis) in all patients. Analysis of plaque surface morphology demonstrated more ulcerated plaques in symptomatic (43%) than asymptomatic (23%) stenoses. Although the frequency of homogeneous and heterogeneous plaques was not different, calcific lesions were more frequent in asymptomatic (46% versus 29%), and echolucent plaques, probably indicating mural thrombi, were more frequent in symptomatic (29% versus 11%) stenosis. Color-coded hemodynamic patterns, such as jet flow, poststenotic turbulence, or reversed flow, were not different in symptomatic and asymptomatic stenoses. Comparison of DCFI with 30 angiograms showed agreement in plaque surface analysis in 70%. DCFI measurements of area reduction in cross sections correlated with angiography in 85%, while DCFI tended to underestimate the degree of stenosis from diameter reduction in longitudinal cuts. The advanced DCFI technique identified distinct morphologic features but no hemodynamic patterns, separating symptomatic from asymptomatic high-grade carotid stenoses.

Carotid Arteries↗