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Biomedical subjects

E B Ringelstein

Publications and source records attributed to E B Ringelstein.

At least 163 records · Page 9Linked to original sources
PubMed1996

[Cerebrovascular ultrasound diagnosis].

Introduction of color-coded duplex sonography has further increased diagnostic confidence of neurovascular ultrasound. Thus, reliable and noninvasive preoperative assessment of patients with carotid artery stenoses becomes feasible, preventing potential adverse effects of cerebral angiography. Moreover, reliable diagnosis of subtotal stenoses and occlusions of the carotid arteries is possible. Transcranial ultrasonography provides reliable assessment of cross-flow through the circle of Willis, and stenoses, occlusions and vasospasm of the major basal cerebral arteries. Transcranial color-coded duplex sonography identifies intracranial hemorrhage, cerebrovascular malformations and hydrocephalus but is inferior to neuroradiological techniques. It is likely that power Doppler sonography and transpulmonary contrast agents will provide an additional increase in diagnostic confidence of neurovascular ultrasonography. In the future, cerebral microemboli may become a marker for embolic activity of occlusive carotid artery and cardiac disease.

Carotid Stenosis↗
PubMed1996

[Therapy and prevention of cerebral ischemia].

Two large randomized studies - NINDS and ECASS - have shown that fibrinolytics, when given early enough, reduce morbidity and mortality in acute stroke. The treatment has to be initiated within three hours after onset of symptoms. In middle cerebral artery stroke, fibrinolysis can be performed within six hours from onset, guided by computed tomography criteria. Thereafter, s.c. low-molecular-weight heparin can still improve the fate of the patient. Currently, the potential benefit or harm of unfractionated heparin and aspirin is not yet known. However, large-scale studies using standard heparin, aspirin of low-molecular-weight heparin are in progress with results expected soon. After the acute stage of stroke, risk factors have to be eliminated or modified, and anticoagulants, platelet inhibitors and, in selected cases, carotid endarterectomy are useful in preventing recurrent stroke or other vascular events.

Angioplasty, Balloon↗
PubMed1995

Cerebral hemodynamics in pre-eclampsia/eclampsia syndrome.

Pre-eclampsia and eclampsia represent a syndrome with progressive pregnancy-induced hypertension. They are associated with considerable morbidity and mortality. The pre-eclampsia/eclampsia syndrome has been hypothesized to reflect a subtype of hypertensive encephalopathy. Additionally, an endothelial dysfunction with impaired cerebral autoregulation has been proposed. Neurological symptoms in hypertensive encephalopathy have been attributed to marked vasospasm or forced vasodilatation. This study was undertaken to evaluate the changes in cerebral hemodynamics due to this syndrome. Twelve patients with pre-eclampsia/eclampsia syndrome, five of them with a concomitant syndrome involving hemolysis, elevated liver enzymes and low platelets (HELLP syndrome), were investigated. Mean blood flow velocities of the middle, anterior and posterior cerebral arteries were assessed bilaterally by means of a 2-MHz, pulsed Doppler ultrasound device. After the initial diagnosis, follow-up examinations were performed twice a week until delivery, and then weekly over a 4-week period postpartum. Intracranial arterial blood flow velocities were elevated in ten out of 12 patients. Values of up to twice the normal flow velocities were observed in individual cases. Flow velocities correlated with the systemic arterial blood pressure (r = 0.75, p = 0.008). Eight patients showed pathologically increased flow velocities despite a mean arterial blood pressure below 150 mmHg. Our preliminary findings suggest that a forced vasodilatation, probably due to passive overdistension of cerebral arterioles and vasogenic edema rather than vasospasm, is responsible for the observed high cerebral flow velocities. We hypothesize that endothelial dysfunction plays a crucial role in the altered cerebral hemodynamics in the pre-eclampsia/eclampsia syndrome.

Adult↗
PubMed1995

[Effect of morphological changes on perfusion and metabolism in cerebral microangiopathy. A comparison of PET, SPECT, and magnetic resonance imaging findings].

51 patients with cerebral microangiopathy were studied with MRI, 18FDG-PET, and 99mTc-HMPAO-SPECT. Exact morphological correlation of MRI-findings to functional data from PET and SPECT was obtained by a special head holder system applied to the patient's head. Patients with less than four lacunar infarctions (LI) and without or only slight deep white matter lesions (DWML) in MRI showed no significantly changed parameters (rMRGlu, rCBF) compared to patients with four or more LI and severe DWML. Patients with medium to severe outer and inner brain atrophy showed significantly lower rMRGlu and rCBF values in both cortex and white matter than patients with no to only slight atrophy. Thus, in patients with cerebral microangiopathy only atrophy and not the presence of LI and DWML is associated with a significant reduction of rCBF and rMRGlu.

Brain↗
PubMed1995

[The idiopathic QT syndrome as the cause of epileptic and nonepileptic seizures].

The long QT syndrome (LQTS) is characterized by a pathological lengthening of the corrected QT interval on the surface ECG and the occurrence of syncopal attacks, sometimes presenting as a seizure disorder. They are caused by ventricular tachycardia of the torsade de pointes type, an arrhythmia that is also responsible for the high incidence of sudden death among these patients. Besides the acquired forms of LQTS which are transient (e.g. therapy with QT-prolonging drugs), congenital variants (Romano-Ward syndrome, Jervell/Lange-Nielsen syndrome, sporadic form) can occur as well. The latter mostly become manifest during childhood or adolescence. Because the syndrome is rare, it is often not included in the primary differential diagnosis of syncope. Thus, misinterpretation as epilepsy may occur. Especially if siblings are affected, a genetic epilepsy may be diagnosed. However, the correct diagnosis can be made by standard ECG methods. Early recognition of the syndrome is very importance because of prognostic and therapeutic consequences. In this article, two cases of idiopathic LQTS are presented. Problems regarding differential diagnosis and therapy are discussed.

Adolescent↗
PubMed1995

Variability of Doppler microembolic signal counts in patients with prosthetic cardiac valves.

BACKGROUND AND PURPOSE: The purpose of this study was the evaluation of intraobserver, interobserver, and intrasubject variability in the Doppler detection of microembolic signals in patients with mechanical prosthetic valves. Simultaneously, the feasibility of automated embolus detection by means of a neuronal network was investigated. METHODS: From 25 patients with mechanical prosthetic heart valves, single transcranial Doppler monitoring sessions of 30 minutes' duration were recorded on videotape, randomized, and subsequently analyzed by eight independent trained observers from three centers. Three observers evaluated these tapes on three separate occasions, blinded to their previous results. An additional 48 patients with prosthetic heart valves were repetitively monitored with transcranial Doppler ultrasonography for 30 minutes three times within 1 year to examine the long-term variability in the occurrence of microembolic signals. Finally, in an effort to assess the short-term intrasubject variability, 20 patients were examined for 90 minutes, and the results of the three 30-minute periods were compared. The interobserver, intraobserver, and intrasubject (both short- and long-term) variability was evaluated. RESULTS: No significant differences in microembolic signal counts were found among the different observers, between the human observers and the neuronal network, or among the three separate evaluations of stored data by the same observer. The same was true for repeat examinations of the same patient (P > .05, Student's two-paired t test and Friedman's test). CONCLUSIONS: The detection of microembolic signals in patients with prosthetic cardiac valves is a reproducible technique. The reliable performance of the neuronal network argues for a broader use of this device. The intrasubject stability of the microembolic rate over 1 year supports the concept that the underlying emboligenic process is associated with intrinsic mechanical properties of the valve implant and not due to a thromboembolic process in the heart.

Cerebral Arteries↗
PubMed1994

Comparison of transcranial contrast Doppler sonography and transesophageal contrast echocardiography for the detection of patent foramen ovale in young stroke patients.

The prevalence of a patent foramen ovale was assessed by simultaneously performing transesophageal contrast echocardiography and transcranial contrast Doppler sonography (TCD) in 137 subjects (mean age 36 years) with stroke of unclarified etiology (n = 41), clarified etiology (n = 33), and in normal subjects (n = 63; mean age 32 years). Patent foramen ovale was found significantly more often in patients with unclarified than clarified strokes or in normal subjects (66% vs 33%, or 43%). Massive paradoxical embolism through a patent foramen ovale, identified by TCD, occurred significantly (p < 0.01) more often in patients with unclarified (64%) than clarified (27%) strokes or in normal subjects (3%). However, minimal shunts were typical in normal subjects (79%). Patent foramen ovale was detected indirectly by TCD when calculated on the basis of transesophageal contrast echocardiographic findings (sensitivity 89%, specificity 92%). Thus, TCD reliably detects paradoxical cerebral embolism through a patent foramen ovale, and provides important additional information for evaluating its clinical relevance by semi-quantification of embolic contrast material.

Adult↗
PubMed1994

Cerebral vasomotor reactivity is significantly reduced in low-flow as compared to thromboembolic infarctions: the key role of the circle of Willis.

To test the hypothesis that cerebral vasomotor reactivity (CVMR) is significantly more reduced in patients with hemispheric low-flow infarctions than in brain infarctions due to arterio-arterial embolism, a series of 64 consecutive patients with internal carotid artery occlusions were studied. CVMR was calculated from relative changes of blood flow velocity within the middle cerebral artery (MCA) measured by transcranial Doppler ultrasonography (TCD) during hypo- and hypercapnia. The configuration of the circle of Willis (COW) was also determined by TCD using common carotid artery compression tests. Anterior, posterior or ophthalmic artery collateral flow, and absence or combinations of these, were differentiated. CT scans were categorized as showing either no infarction (group I; n = 20) or territorial (group II; n = 28), or low-flow infarctions (group III; n = 16). As compared to normal, CVMR was significantly reduced but equal in groups I and II, however, even more reduced in group III. CVMR was lowest, and low-flow infarctions were most frequent in patients whose collateral hemispheric blood supply was from the ophthalmic artery as opposed to patients with a complete or nearly complete COW. Our findings indicate that low-flow infarctions in extracranial ICA occlusions represent brain damage due to a critical reduction in cerebral perfusion pressure, as opposed to thromboembolically induced lesions. The configuration of the COW seems to play the key role. Our findings also support the view that the pattern of hemispheric infarction seen on CT indicates the pathogenesis of stroke.

Aged↗
PubMed1994

Transcranial Doppler ultrasonic assessment of middle cerebral artery blood flow velocity changes during verbal and visuospatial cognitive tasks.

Hemisphere specific changes of blood flow velocity in the right and left middle cerebral artery (MCA) induced by cognitive demands of verbal and nonverbal tasks were examined by means of a newly developed technique of simultaneous bilateral transcranial ultrasonic Doppler sonography (TCD). Thirty-one right-handed healthy volunteers served as subjects. Identical stimulus and response procedures were used with all tasks to avoid possible differential effects of these conditions on blood flow velocity. Compared to the preceding resting phase, the increase in flow velocity induced by each of the verbal tasks (sentence completion, similar or contrasting word meaning, similarities) proved to be significantly higher in the left than in the right MCA. Among the non-verbal visuospatial tasks only the "identical pictures" (perceptual speed) task led to a complementary higher increase in right MCA blood flow velocity. No such asymmetry in blood flow acceleration was observed, however, with the tasks "figure assembly" and "cube comparison" which require visualization and mental rotation of figures. The findings underline the recently emerging uncertainty in neuropsychological research with regard to the functional specialization of the right hemisphere.

Adult↗
PubMed1994

Adult Toxocara canis encephalitis.

A 48-year-old patient with Toxocara canis infection developed severe ataxia, rigor and neuropsychological disturbances. An aetiology was proven by an indirect immunofluorescence test. CT and MRI revealed both diffuse and circumscribed white matter lesions. Angiography showed multiple occlusion of branches of the middle cerebral artery. Anthelminthic treatment was beneficial in the initial stage of the disease, but had no effect on progression of CNS symptoms. Immunosuppressive therapy with prednisolone and azathioprine yielded partial recovery and stabilisation of the patient.

Animals↗
PubMed1993

The case of aphasia or neglect after striatocapsular infarction.

The occurrence of aphasia or neglect was related to anatomo-structural (CT/MRI), functional [regional cerebral blood flow (rCBF)] and pathogenetic features [duration of middle cerebral artery (MCA) occlusion and degree of cortical leptomeningeal anastomoses] in 57 cases (26 with and 31 without aphasia or neglect) with strictly subcortical infarcts of one defined type, i.e. striatocapsular infarcts. No distinct pattern of language disturbances was found. Aphasic syndromes did not differ in the amount of involvement of the putamen, pallidum, head of caudate nucleus and white matter. Patients with aphasia or neglect had larger infarcts than those without. However, there was no specific involvement of the basal ganglia, the internal capsule or the deep white matter in patients with aphasia or neglect. Patients with aphasia or neglect had a significantly longer duration of MCA occlusion and mostly poor leptomeningeal collaterals. The cortical rCBF was significantly decreased in the cortical MCA territory in the patients with aphasia or neglect only. The rCBF remained low at follow-up after 1 year and corresponded to focal cortical atrophy on MRI, although neglect had subsided completely in all patients and aphasia had improved considerably in almost 75% of the cases. Aphasia or neglect after striatocapsular infarcts are most likely due to selective neuronal loss of the cerebral cortex due to prolonged MCA occlusion and insufficient collateral blood flow. Individual differences in recovery from aphasia after striatocapsular infarction can be explained in terms of the number of surviving cortical neurons.

Adolescent↗