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Biomedical subjects

M Hennerici

Publications and source records attributed to M Hennerici.

At least 109 records · Page 6Linked to original sources
PubMed1996

Urinary retention and space-occupying lesions of the frontal cortex.

The authors present 2 cases in which urinary retention was related to supratentorial cortical lesions. These cases support the presence and function of a supratentorial center involved in control of the voiding reflex loop and indicate that lesions affecting this center can result in urinary retention rather than the syndrome of incontinence, urgency, and increased urinary frequency that is generally attributed to dysfunction of this system. In such cases, a clinical presentation of urinary retention in the absence of associated remarkable neurological deficits renders clinical evidence as a localizing sign.

Aged↗
PubMed1996

Ischemia-induced migraine from paradoxical cardioembolic stroke.

Although little is known on the pathophysiologic mechanism of migraine-related stroke, the prevailing attitude is that vasoconstriction and activation of clotting factors play a primary role. In 2 female patients presenting with migraine and stroke, risk profiles and history were consistent with this pathophysiologic mechanism. Cerebro- and cardiovascular workup, however, led to a diagnosis of paradoxical cardioembolic stroke through a patent foramen ovale. Since there is hardly any evidence in the literature that migraine acts as a risk factor for stroke on its own, these case reports emphasize the importance of complete cardiovascular evaluation in patients with suspected migrainous stroke.

Adolescent↗
PubMed1996

Lubeluzole in acute ischemic stroke. A double-blind, placebo-controlled phase II trial. Lubeluzole International Study Group.

BACKGROUND AND PURPOSE: We aimed to assess the safety and efficacy of lubeluzole in patients with a clinical diagnosis of acute (< 6 hours) ischemic stroke in the carotid artery territory. METHODS: A randomized, double-blind, placebo-controlled multicenter trial was conducted in 232 patients. Because treatment was administered within 6 hours and a CT scan was not mandatory before the start of treatment, 39 patients with either an intracerebral hemorrhage or ischemic stroke in the vertebrobasilar circulation were excluded from the primary efficacy analysis as prespecified in the protocol. Of the 193 patients with acute ischemic stroke in the carotid artery territory (target population), 61 received placebo, 66 lubeluzole 7.5 mg over 1 hour followed by 10 mg/d for 5 days, and 66 lubeluzole 15 mg over 1 hour followed by 20 mg/d for 5 days. RESULTS: The trial, initially aimed at a patient inclusion of 270, was terminated prematurely according to the advice of the Safety Committee because of an imbalance in mortality between the treatment groups. Mortality rates at the final follow-up of 28 days for placebo, lubeluzole 10 mg/d, and lubeluzole 20 mg/d were, respectively, 18%, 6%, and 35% in the target population, results that were confirmed in the intent-to-treat population. Multivariate logistic regression analysis showed that the lower mortality in the lubeluzole 10 mg/d group was significantly in favor of the 10 mg/d treatment (P = .019). The higher mortality rate in the 20 mg/d group could be explained, at least in part, by an imbalance at randomization that led to a higher number of patients in that group with severe ischemic stroke. A total of 26 of 66 patients (39%) who received lubeluzole 10 mg/d had a score on the Barthel Index of > 70 at day 28, indicating no or mild disability, compared with 21 of 61 (34%) in the placebo group and 19 of 66 (29%) in the lubeluzole 20 mg/d group (P = NS). CONCLUSIONS: In patients with acute ischemic stroke, the dosage regimen of 7.5 mg over 1 hour followed by 10 mg/d of intravenous lubeluzole is safe and statistically significantly reduced mortality. Further clinical trials in a larger number of patients are ongoing to confirm efficacy.

Acute Disease↗
PubMed1996

Sonographic assessment of carotid artery stenosis. Comparison of power Doppler imaging and color Doppler flow imaging.

BACKGROUND AND PURPOSE: Power Doppler imaging (PDI) is a new ultrasound technique that, in contrast to color Doppler flow imaging (CDFI), generates intravascular color signals from the reflected echo amplitude depending mainly on the density of red blood cells. We evaluated the diagnostic significance of PDI compared with CDFI for the measurement of carotid stenosis and characterization of plaque surface. METHODS: In 25 internal carotid artery stenoses, reduction of the intrastenotic lumen contrasted by blood density signals and color Doppler signals on longitudinal and transverse views was assessed for correlative evaluation. In addition, the peak systolic flow velocity of the Doppler spectrum was correlated with PDI and CDFI measurements. RESULTS: PDI provided good visualization of the residual lumen in all stenoses, whereas displays on CDFI were inadequate in two calcified plaques. PDI revealed two ulcerative stenoses classified as smooth on CDFI. The correlation between PDI and CDFI was high for measurement of area stenosis (r = .93) and moderate for diameter stenosis (r = .73). Similarly, cross-sectional reduction on both imaging methods correlated more significantly with peak systolic flow velocity than diameter reduction. CONCLUSIONS: This pilot study suggests that PDI provides additional information for luminal measurement and characterization of plaque surface in complicated high-grade carotid stenosis. Because of the absent visualization of hemodynamics, PDI should be used in combination with CDFI.

Aged↗
PubMed1996

High-intensity transient signals in patients with cerebral ischemia.

BACKGROUND AND PURPOSE: This study investigated the diagnostic relevance of transcranial Doppler monitoring for the detection of high-intensity transient signals (HITS) in patients with recent cerebral ischemic events of various origins. METHODS: We prospectively performed bilateral transcranial Doppler monitoring (mean, 48 +/- 8 minutes) from both middle cerebral arteries in 280 patients with an acute (< 4 weeks) cerebral ischemic event in the middle cerebral artery territory and in 118 asymptomatic control subjects. HITS were analyzed according to a standardized protocol. RESULTS: Symptomatic patients had a significantly (P < .001) higher rate (9.3%) of HITS than asymptomatic control subjects (1.7%). Patients with reversible ischemia (4.2%) and patients with suspected small-vessel syndromes (4.5%) had lower rates of HITS (P < .05) than those with large-vessel territory strokes (14.2%). Brain imaging (CT/MRI) results corresponded with this observation: the occurrence of HITS was significantly higher (P < .001) in patients with a pattern of large-vessel territorial brain infarction (19.0%) than in those with lacunar lesions (0%) or unidentified ischemic lesions (3.4%). Patients with identified sources of potential embolism (12.9%) had HITS (P < .001) more frequently than those without (0%). Patients with cardiac sources of embolism (excluding artificial heart valves) showed fewer HITS (6.2%) than patients with vascular sources (17.1%). CONCLUSIONS: The results indicate that HITS occur predominantly in patients with large-vessel territory stroke patterns and persisting deficits that are most likely due to artery-to-artery or cardiogenic embolism. In contrast, patients with small-vessel disease and rapid recovery only occasionally present with HITS. Thus, the detection of HITS may substantially support the classification of the individual pathogenesis of cerebral ischemia, particularly when multiple risk constellations for stroke coexist.

Adult↗
PubMed1996

Assessment of regional cerebral blood volume in acute human stroke by use of single-slice dynamic susceptibility contrast-enhanced magnetic resonance imaging.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the clinical usefulness of dynamic susceptibility contrast-enhanced MRI (DSC-MRI) in acute cerebral ischemia. METHODS: During bolus injection of gadolinium-diethylenetriamine pentaacetic acid, a series of rapid T2*-weighted images was recorded from one slice. Concentration-time curves and images of regional cerebral blood volume (rCBV) were calculated from this data set. DSC-MRI, MR angiography, conventional spin-echo MRI (SE-MRI), and CT were performed in 11 patients within 6 hours after stroke onset and before thrombolytic or anticoagulant treatment was begun. A follow-up MRI examination was performed 24 to 48 hours after stroke onset. RESULTS: In 7 of 11 patients (group 1) with territorial infarcts of the middle (n = 6) or posterior cerebral artery (n = 1), DSC-MRI showed reduced rCBV in the affected territory before conventional SE-MRI displayed ischemic lesions. DSC-MRI was helpful to differentiate severely ischemic tissue from peri-infarct parenchyma. Partial reperfusion (n = 3), unchanged reduction of rCBV (n = 2), and progressive reduction of rCBV (n = 2) were observed in the follow-up study. Normal DSC-MRI findings were present in 4 of 11 patients (group 2) with lacunar infarcts. CONCLUSIONS: DSC-MRI accomplished the detection of the ischemic territory in the very early stage (< 6 hours) before SE-MRI delivered unequivocal results. DSC-MRI might be helpful to discriminate completely ischemic tissue from potentially salvageable ischemic parenchyma at risk and may play an important role in stroke therapy and evaluation.

Aged↗
PubMed1995

Cerebrovascular regulation and vasoneuronal coupling.

Maintenance of cerebral perfusion pressure is a prerequisite for the prevention of cerebral ischemia. Physiological fluctuations in systemic perfusion pressure are compensated by cerebrovascular autoregulation. Cerebral hypoperfusion could result from (1) systemic hemodynamic failure (eg, distal to severe arterial stenosis), overcharging the vasoregulatory capacity; (2) dysfunction and exhaustion of cerebrovascular autoregulation; or (3) both. Ultrasound offers an excellent temporal resolution, is noninvasive, and is easily applicable for follow-up investigations. Despite its poor spatial resolution, transcranial Doppler sonography has been used for determination of cerebral perfusion reserve studies measuring cerebral blood flow velocity (CBFV) during hypercapnia or application of vasoactive agents (eg, acetazolamide). This approach evaluates vasomotor regulation in patients with hemodynamic compromise distal to severe stenosis or occlusion of the brain supplying arteries. Monitoring CBFV during tilt table examinations directly measures cerebral autoregulation. In patients with systemic orthostatic hypotension, maintainance or failure of cerebrovascular compensation and, even more importantly, cerebrovascular dysautoregulation, despite normal systemic blood pressure regulation, may be demonstrated. Vasoneuronal coupling is reflected by CBFV variations during appropriate neuronal stimulation. Neuronal dysfunction is associated with CBFV abnormalities as exemplified by preconditions of focal cerebral dysfunction in the posterior cerebral artery (PCA) in migraineurs with aura, where massive alteration of vasoneuronal coupling and ischemia is threatening during spreading depression. A highly significant asymmetric gain of vasoneuronal coupling in the interictal state may act as a trigger mechanism in these patients. Testing for vasoneuronal coupling within the middle cerebral artery (MCA) territory is more difficult due to the poor spatial resolution with various neuronal stimuli (eg, motorsensory or cognitive paradigms), only eliciting local neuronal areas underrepresented in the MCA CBFV global changes. However, motor stimulation evoked CBFV may be used to indicate dysintegration of vasoneuronal coupling in the course of acute cerebral ischemia with sensorimotor hemiparesis and, moreover, seems to be of prognostic value regarding the motor deficit.

Blood Flow Velocity↗
PubMed1995

New and future developments in cerebrovascular ultrasound, magnetic resonance angiography, and related techniques.

Four-dimensional (4D) analysis of atherosclerotic plaque and wall motion, the application of 4D ultrasound to the study of atherogenesis, and the incorporation of ultrasound data into flow models for simulation of cerebrovascular hemodynamics are new frontiers in diagnostic ultrasound that use computer vision and optical flow techniques to exploit the full potential of real-time imaging and Doppler studies. New approaches to improve blood vessel delineation with ultrasound include application of contrast agents, harmonic imaging, and red blood cell density imaging. An assessment of the potential clinical utility of these new developments in cerebrovascular ultrasound requires an analysis of comparable trends in magnetic resonance (MR) technology, eg, rapid advances in the fields of MR angiography, dynamic contrast-enhanced MR, and MR diffusion imaging. Likewise, the value of ultrasound techniques for the measurement of blood flow to evaluate cerebrovascular hemodynamics must be compared to related methods in magnetic resonance, such as dynamic MR inflow tracking. This article addresses several new and future developments in cerebrovascular ultrasound and discusses their relative merits in terms of ongoing research in the field of magnetic resonance angiography, imaging, and related techniques.

Blood Flow Velocity↗
PubMed1995

Magnetic resonance angiography of spontaneous vertebral artery dissection suspected on Doppler ultrasonography.

Spontaneous vertebral artery dissection (VAD) is a rare but well-known cause of cerebrovascular disease and is often difficult to diagnose even using conventional arteriography. While noninvasive tests such as Doppler ultrasonography and magnetic resonance imaging (MRI) have failed to provide reliable criteria for the diagnosis of VAD, the diagnostic value of magnetic resonance angiography (MRA) has not yet been undetermined. To establish the reliability of a combined noninvasive approach, 11 patients were prospectively examined for VAD by means of colour-coded duplex studies, MRI and three-dimensional time-of-flight MRA prior to conventional angiography. Among 11 patients with VAD suspected clinically as well as on Doppler ultrasonography, angiography confirmed the diagnosis in seven patients but found a vertebral artery occlusion in three and a vertebral artery stenosis in one. The combination of MRI and MRA findings led to the correct diagnosis of dissection in three patients, of vertebral artery occlusion in three patients, and of vertebral artery stenosis in one. VAD was misinterpreted as vertebral artery occlusion in four patients. Doppler ultrasonography is a valuable screening method for the detection of vertebral artery pathologies. The diagnosis of VAD can only be established if a typical intramural vessel wall haematoma is seen on T1-weighted MRI in combination with MRA findings of irregular artery stenosis or occlusion.

Adult↗
PubMed1995

Epileptic seizures in subcortical vascular encephalopathy.

Cerebrovascular disease is one of the most common causes of epilepsy in the elderly. Most of the studies published relate to cortical infarction, subarachnoid, and intracranial hemorrhage, whereas the incidence of epilepsy from subcortical ischemia, i.e. deep lacunar infarctions and diffuse white matter lesions, is obscure. Therefore, we prospectively examined 18 patients with the precisely defined diagnosis of subcortical vascular encephalopathy (SVE), who were admitted to our hospital due to epileptic seizures (group A), and compared them to a similarly selected group matched for age, sex, risk factors, and neurological deficits with an equivalent severity of SVE but without seizures (group B). Subcortical lacunar infarctions were significantly more frequent in group A than group B (15/18 versus 4/18, p < 0.001), whereas neither the extension, degree, distribution of periventricular white matter changes, nor the presence of internal hydrocephalus, focal or diffuse cortical atrophy showed any statistical significance. However, a temporal constant theta or delta EEG focus was present in 10/18 patients in group A but only in 1/18 patients from group B (p < 0.005). 10/18 patients developed epilepsy with further seizures during follow-up. The association of SVE, multiple subcortical lacunas, and temporal EEG abnormalities are suggestive for an increased risk for epileptic seizures, which is particularly important for the treatment of patients with SVE if uncertain paroxysmal episodes occur, e.g. transient ischemic attacks, seizures, or cardiac syncope.

Adult↗
PubMed1995

Variability of vascular territory in stroke. Pitfalls and failure of stroke pattern interpretation.

BACKGROUND AND PURPOSE: We investigated the efficacy and feasibility of determining infarction mechanisms and underlying embolic or hemodynamic pathologies from topographical patterns of ischemic damage seen on computed tomography or magnetic resonance imaging. METHODS: Infarction patterns from 22 patients with ipsilateral severe, hemodynamically relevant carotid stenosis (n = 6) or occlusions (n = 16) were superimposed, using two matching algorithms, onto maps showing the variability of the cerebral vascular territories as determined from recent cadaver studies. These images were used to classify the infarctions as border-zone or territorial for the two conditions of minimal and maximal middle cerebral artery distribution. RESULTS: Classification of infarction patterns resulting from carotid stenosis was independent of the territorial extension map chosen: 83% were classified as territorial. Classification of patterns due to carotid occlusion, however, varied highly; 81% of infarctions were considered territorial when the maximal middle cerebral artery distribution map was used, whereas only 19% were when the minimal territorial extension map was used. CONCLUSIONS: The current concept that stroke mechanisms can be inferred from the interpretation of stroke patterns seen on computed tomography scans or magnetic resonance imaging is significantly confounded by the demonstrated variability in intracranial vascular distributions. Stroke pattern interpretation appears to be highly dependent on the in vivo vascular tree of the individual, which is unknown to the examiner. This calls into question the reliability of classifying infarction patterns as border-zone or territorial. Determination of true underlying stroke mechanisms requires a comprehensive approach and cannot be based solely on stroke pattern interpretation.

Brain↗
PubMed1995

Circulating selectin- and immunoglobulin-type adhesion molecules in acute ischemic stroke.

BACKGROUND AND PURPOSE: Cellular adhesion molecules mediate adhesion between endothelial cells and leukocytes as a precondition for extravasation of leukocytes at sites of tissue injury. The pattern of release of circulating adhesion molecules has been characterized in patients with acute ischemic stroke. METHODS: Serum concentrations of soluble selectin-type adhesion molecules (solube endothelial leukocyte adhesion molecule-1 [sELAM-1], soluble lymph node homing receptor [sL-selectin]) and immunoglobulin-type adhesion molecules (soluble vascular cell adhesion molecule-1 [sVCAM-1], soluble intercellular adhesion molecule-1 [sICAM-1]) were serially determined (at hours 4, 8, and 10 and at days 1, 3, and 5) in 22 patients with acute ischemic stroke. As control subjects, age- and sex-matched individuals with (n = 40) and without (n = 22) vascular risk factors were studied. RESULTS: We observed increased concentrations of sICAM-1 and decreased levels of sL-selectin in patients with risk factors even in the absence of stroke. Patients with acute stroke had, in addition, an initial transient increase of sELAM-1 and a persistent increase of sVCAM-1. CONCLUSIONS: The results suggest a chronic alteration of expression of adhesion molecules sICAM-1 and sL-selectin in subjects with risk factors for atherosclerosis; they also indicate acute changes of levels of sELAM-1 and sVCAM-1 in response to acute ischemic stroke. Determination of soluble adhesion molecules could allow in vivo monitoring of the initial steps of leukocyte-mediated brain damage in acute ischemic stroke.

Aged↗
PubMed1995

Vascular dementia: a changing concept.

The traditional concept of vascular dementia implied the thickening of arteries of the brain as a source of diffuse reduction of cerebral blood flow leading to neuronal death, cerebral atrophy, and finally dementia. Although this concept has been recently revived, with the increasing use of brain imaging technologies, new concepts of vascular dementia came into view. Present classification tends to separate various pathomechanisms (large- and small-vessel disease), to define different brain territories involved (strategic infarctions, cortico-subcortical and subcortical lacunes, borderzone/junctional zone infarctions, and white matter lesions) and most recently even genetics dispositions to vascular dementia of nonatherosclerotic etiology (CADASIL). Dementia caused by other mechanisms are separated from the aforementioned.

Dementia, Vascular↗
PubMed1994

[Prognosis and therapy of carotid stenoses--a review of results of current studies].

Carotid stenoses as either a source of artery-to-artery emboli or a hemodynamic process of reduced brain perfusion can lead to transient ischemic attacks and brain infarcts. Although the prognosis of both symptomatic and asymptomatic patients correlates with the degree of the lumen narrowing and the progression of the atherosclerotic vessel process, the risk of a new cerebral ischemia is 5 to 15 times greater in symptomatic patients than in those whose vessel process has remained silent. Correspondingly, multicenter studies have shown that surgical treatment of high degree carotid stenosis under certain conditions as secondary prevention is warranted while until now no indication for carotid endarterectomy in the asymptomatic stage can be verified. An exact analysis of the studies' protocols and the results of multicenter examinations show that detailed patient selection is a prerequisite for both conservative and surgical treatment of a patient at risk.

Carotid Arteries↗