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Biomedical subjects

B Widder

Publications and source records attributed to B Widder.

At least 19 recordsLinked to original sources
PubMed1992

Course of carotid artery occlusions with impaired cerebrovascular reactivity.

BACKGROUND AND PURPOSE: Retrospective studies have found a close correlation between an impaired cerebrovascular reserve capacity and the incidence of hemodynamic stroke. The present study evaluates this relation prospectively. METHODS: We measured the CO2 reactivity in 85 patients with internal carotid artery occlusions by transcranial Doppler sonography (Doppler CO2 test). All patients were prospectively followed for 38 +/- 15 (mean +/- SD) months. RESULTS: In the group with sufficient CO2 reactivity, four of 48 (8%) developed ipsilateral transient symptoms, none a stroke. In cases with diminished or exhausted cerebrovascular reserve capacity, 12 of 37 (32%) suffered an ipsilateral event (four transient ischemic attacks, eight strokes) (p less than 0.01). CONCLUSIONS: The Doppler CO2 test seems to be a valuable method of estimating the risk of stroke in patients with carotid artery occlusions.

Adult↗
PubMed1991

Carbon dioxide reactivity and patterns of cerebral infarction in patients with carotid artery occlusion.

A total of 106 patients with 112 internal carotid artery occlusions were investigated by cranial computed tomography and transcranial Doppler ultrasonography (CO2 test), giving a measure of the cerebrovascular reserve capacity. The morphological patterns of the ischaemic lesions were classified into three categories: lacunar, thromboembolic and haemodynamic infarctions. Of 29 patients with an exhausted CO2 reactivity, 19 showed a haemodynamic type of infarction, whereas of 45 cases with a normal CO2 reactivity only 2, and of 38 patients with a diminished CO2 reactivity only 3 had haemodynamically caused infarctions (P less than 0.001). The correlation between an exhausted CO2 reactivity and the presence of haemodynamic infarctions could be of value for therapy in patients with carotid artery occlusions.

Arterial Occlusive Diseases↗
PubMed1991

Comparison of Doppler CO2 test, patterns of infarction in CCT, and clinical symptoms in carotid artery occlusions.

In patients with an internal carotid artery (ICA) occlusion the CO2 reactivity (autoregulatory reserve) is supposed to give information about the function of the collateral supply. To prove this hypothesis we compared the CO2 reactivity measured by transcranial Doppler sonography to the ipsilateral clinical symptoms and the patterns of infarction in cranial computed tomography (CCT). We studied 251 cases of ICA occlusion. Of the 141 cases with normal autoregulatory reserve, 37 (27%) had recently developed an ipsilateral neurological deficit. Of the 44 cases with exhausted CO2 reactivity, 28 (64%) had experienced an event. The difference is highly significant (p less than 0.0001). In 59 of the 75 patients for whom CCT images were available, we found signs of vascular-ischemic lesions. Of the 30 patients with hemodynamic infarctions, 13 showed an exhausted autoregulatory reserve, while of 19 cases with territorial infarctions only 1 and of 10 with lacunar infarctions none had an exhausted CO2 reactivity. The difference is significant (p less than 0.01).

Blood Flow Velocity↗
PubMed1991

[Terminology of ultrasound vascular diagnosis].

There is at present no accepted nomenclature regarding diagnostic vascular ultrasound. At two scientific meetings, the Study Group for Vascular Diagnosis of the German Society of Ultrasound in Medicine (DEGUM) developed a terminology for Doppler and duplex sonography of the arteries and veins supplying the brain and of peripheral vessels. The most important of these sonographic terms and their synonyms are presented. Recommendations as to which of the presently employed terms should be avoided, are given.

Blood Flow Velocity↗
PubMed1990

Morphological characterization of carotid artery stenoses by ultrasound duplex scanning.

Ulcerations and intraplaque hemorrhages are thought to play an important role in the development of neurological deficits in carotid artery stenoses. To assess the ability of duplex scanning to predict plaque morphology we compared different sonographic criteria (plaque border, plaque density, plaque structure) with the morphological findings in 169 consecutive carotid endarterectomies (144 cases with diameter reduction greater than 50%). Two percent of the sonograms were inadequate, and 20% showed poor image quality. Regular plaque borders revealed a smooth or at most minimally ulcerated surface in 92%. Grossly ulcerated stenoses, however, were only found in 27% of the irregular plaques. Moreover, the plaque border was nonvisible in 35% of all cases. Simple, fibro-atheromatous plaques were found to be echogenic in 72% and echolucency was present in 80% of the stenoses with relevant intraplaque hemorrhage. In conclusion, duplex scanning proved to be capable of detecting smooth, fibro-atheromatous stenoses with high accuracy. Ulcerations, however, cannot be predicted reliably, and intraplaque hemorrhage cannot be differentiated from atheromatous debris.

Carotid Arteries↗
PubMed1990

[Reproducibility of ultrasound criteria for characterizing carotid artery stenoses].

Comparisons with intraoperative findings suggest that Duplex scanning may be of value in predicting the morphology of carotid artery stenoses. Such studies, however, are based on the results obtained by experienced investigators. To clarify whether sonographic criteria can be standardized, 6 investigators from different hospitals each documented 30 carotid artery stenoses of greater than or equal to 40% diameter reduction which could be imaged in at least 2 planes. Three sonographic criteria (plaque surface, echo density, echo structure), each with 8 categories, were assessed from the image documentations by the 6 as well as by 2 independent further investigators. Depending on the experience and on the device used 29-81% of all stenoses greater than or equal to 40% examined in the different laboratories could be included in the study. The +/- 1 category concordance between the different investigators averaged 50-60% for all sonographic criteria independent from the degree of stenosis and from the image quality. Because of lack of sufficient reproducibility the subjective assessment of sonographic criteria is found to be not suitable for use in multicentre studies.

Brain Ischemia↗
PubMed1990

[Terminology of ultrasonic vascular diagnosis].

There is at present no accepted nomenclature regarding diagnostic vascular ultrasound. At two scientific meetings, the Study Group for Vascular Diagnosis of the German Society of Ultrasound in Medicine (DEGUM) developed a terminology for Doppler and duplex sonography of the arteries and veins supplying the brain and of peripheral vessels. The most important of these sonographic terms and their synonyms are presented. Recommendations as to which of the presently employed terms should be avoided, are given.

Brain↗
PubMed1989

Favourable effect of flunarizine on the recovery from hemiparesis in rats with intracerebral hematomas.

In 25 rats, an intracerebral hematoma was created in the foreleg area of the motor cortex by injection of 50 microliters blood. After the lesion, 13 were treated with flunarizine and 12 with the solvent. Neurological testing was performed by measuring the running time on a rotating platform. In animals with hemiparesis, the flunarizine group (n = 7) showed a significantly (P less than 0.05) better recovery than the control group (n = 8). No significant differences occurred in animals without neurological deficits (flunarizine: n = 6, control: n = 4). So the effect of the drug is not due to a non-specific activation; it may partially cure neurological deficits caused by intracerebral hematoma.

Animals↗
PubMed1989

The Doppler CO2 test to exclude patients not in need of extracranial/intracranial bypass surgery.

In patients with an internal carotid artery (ICA) occlusion who suffer from ipsilateral transient ischaemic attacks or minor stroke extra/intracranial (EC/IC) bypass surgery may be useful only where there is insufficient collateral supply. The transcranial Doppler CO2 test offers a simple method of investigating the residual autoregulatory capacity which gives quantitative information about the efficiency of the collaterals. In 155 patients with 162 ICA occlusions there was a significant correlation between a markedly decreased or exhausted autoregulatory capacity and a recent ipsilateral ischaemic event (p less than 0.001). The Doppler CO2 test may enable the exclusion of patients not in need of EC/IC bypass surgery. In the reported series this affected more than 80% of all ICA occlusions.

Adult↗
PubMed1988

[X-ray diagnosis of intimal ruptures of the internal carotid artery. A pathologico-anatomic controlled study].

In a prospective study to determine the accuracy of intravenous DSA in the diagnosis of ulcerative lesions of the internal carotid artery, preoperative findings obtained from DSA in patients with suspected cerebrovascular disease were reviewed and compared with thrombendarterectomy specimen (n = 74). The radiological parameters employed for the assessment of ulcerations were excavations of the vascular contour, ill defined vessel walls and steep plaque surfaces. Overall sensitivity of DSA was 66%, specificity 52%. The depth of excavations proved to be the most accurate sign in detecting ulcerative lesions (sensitivity 83%). However, in rare cases mural recesses with the angiographic appearance of ulceration corresponded to re-endothelialized cavities. Small intimal disruptions with a depth of 0.1 to 1 mm. could not be detected by intravenous DSA.

Arteriosclerosis↗
PubMed1987

[Determination of the degree of stenosis in carotid artery stenoses: ultrasound and i.v. DSA in comparison to surgical findings].

The specimens from 116 consecutive carotid thrombendarterectomies were taken as "gold standard" to evaluate the accuracy of ultrasound methods (duplex scanning + extra-/transcranial Doppler sonography) and intravenous digital subtraction angiography (i.v. DSA) in carotid artery stenoses. In 65 cases, in which the specimens could be gauged reliably, sonography estimated the degree of stenosis in 85% within a range of +/- 10%, in 97% within +/- 20% i.v. DSA was accurate in 52 respectively in 94%. High-grade stenoses were correctly assessed by ultrasound in 90%, by i.v. DSA in 64%. Sonography identified 4/10 kinkings and coilings of the carotid artery, i.v. DSA 9/10. Current available ultrasound methods enable estimation of the diameter reduction of carotid artery stenoses with low deviations. I.v. DSA seems to be less reliable, but can be used favourably as a complementary method to sonography.

Carotid Artery Diseases↗
PubMed1986

Transcranial Doppler CO2 test for the detection of hemodynamically critical carotid artery stenoses and occlusions.

Cerebral CO2-reactivity was tested by transcranial Doppler sonography (Doppler CO2 test) in 232 patients. Time averaged flow velocity in the middle cerebral artery at the 40 mm Hg blood pCO2 level was taken as a reference point, and the relative increase of flow in hypercapnia of 46.5 mm Hg pCO2 was defined as "Normalized Autoregulatory Response" (NAR). A total of 82 patients with no evidence of cerebrovascular disease gave "normal" values for NAR (23.2 +/- 5.2 SD). In 150 patients with 233 stenoses and occlusions of the internal carotid artery NAR was significantly decreased in higher-grade stenoses (P = 0.01 for 80% diameter reduction, P less than 10(-6) for 90% or more). In such stenoses, patients with NAR less than 14 had suffered more frequently (P less than 0.01) from ipsilateral transient ischemic attacks and/or stroke during the previous 6 months than patients with "normal" NAR. Preoperative NAR less than 14 always improved to "normal" values following carotid surgery, while preoperative NAR greater than 19 remained unchanged (60 cases). The transcranial Doppler CO2 test is thought to be a reliable noninvasive method to detect hemodynamically critical carotid stenoses and occlusions. This may be of interest in selecting patients for superficial temporal artery-middle cerebral artery bypass and carotid surgery. For practical use 4 categories of NAR are suggested.

Arterial Occlusive Diseases↗