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Biomedical subjects

R von Kummer

Publications and source records attributed to R von Kummer.

At least 91 records · Page 5Linked to original sources
PubMed1994

Sensitivity and prognostic value of early CT in occlusion of the middle cerebral artery trunk.

PURPOSE: To investigate the incidence and prognostic value of local brain swelling, the extent of parenchymal hypodensity, and the hyperdense middle cerebral artery sign as shown by CT within the first 5 hours after the onset of symptoms in patients with angiographically proved middle cerebral artery trunk occlusions. METHODS: Fifty-three patients were studied prospectively with CT 46 to 292 minutes (median, 120; mean, 134 +/- 59) after symptom onset and scored clinically at admission and 4 weeks later. All patients were treated with recombinant tissue plasminogen activator (30 to 100 mg). RESULTS: Early CT showed parenchymal hypodensity in 43 patients (81%), local brain swelling in 20 patients (38%), and hyperdensity of the middle cerebral artery trunk in 25 patients (47%). Hypodensity covering more than 50% of the middle cerebral artery territory had an 85%, local brain swelling a 70%, and the hyperdense middle cerebral artery sign a 32% positive predictive value for fatal clinical outcome. Specificity of these findings for fatal outcome was 94%, 83%, and 51%, respectively, and sensitivity was 61%, 78% and 44%, respectively. CONCLUSIONS: Early CT in acute middle cerebral artery trunk occlusion is highly predictive for fatal clinical outcome if there is extended hypodensity or local brain swelling despite aggressive therapeutic attempts such as thrombolysis or decompressive surgery.

Adult↗
PubMed1993

Use of the hydrogen clearance technique for measurements of pancreatic blood flow.

The hydrogen clearance technique (HCT) was employed for measurements of local pancreatic blood flow (PBF) in dogs, opossums, and rats under normal conditions and in opossums during biliary pancreatitis. Local PBF (ml/min/100 g) in dogs was 57.6 +/- 10.4, in opossums 60.6 +/- 9.5, and in rats 144.7 +/- 23.4, under resting conditions. Regional distribution of local PBF in dogs showed no statistical differences. Technical aspects of the HCT were described in detail. Under physiological conditions parenchymal trauma following electrode implantation was negligible in nearly all cases. More than 95% of registered clearance curves were monoexponential and showed excellent reproducibility of PBF values in repeated measurements (percentage deviation < or = 6.7). Five days after initiating biliary pancreatitis by common channel ligation in opossums local PBF was 72.1 +/- 14.7 after implantation of new electrodes. Chronically implanted electrodes, however, recorded only 39.7 +/- 15.8, due to massive fibro-proliferative alterations around the implanted electrode tips. We therefore conclude that the HCT as described is a useful tool for measuring local PBF in acute experimental settings only. Biliary pancreatitis in our model causes no significant alterations of PBF after 5 days.

Animals↗
PubMed1993

[Balloon occlusion test of the internal carotid artery for evaluating resectability of blood vessel infiltrating cervical metastasis of advanced head and neck cancers--Heidelberg experience].

During the last two years 17 patients of the ENT-Department of the University of Heidelberg suffering from squamous-cell carcinomas of the head and neck underwent a balloon occlusion test of the internal carotid artery (ICA). The investigation was performed because of tumorous infiltration of the large cervical vessels. The balloon occlusion of the ICA was accomplished at the Department of Neuroradiology of the University of Heidelberg. While stopping bloodflow in the ICA of one side for 15-20 min, clinical, electrophysiological and Doppler sonographic monitoring was performed, to detect severe cerebral complications. The specific electrophysiological monitoring contained the detection of MSSEP's (median nerve stimulated somatosensorial evoked potentials) and TCMEP's (transcortical motor evoked potentials) during test occlusion. Balloon occlusion was not possible in three patients because of severe arteriosclerosis. Test occlusion had to be discontinued in three patients because of clinical complications (temporary amaurosis, orthostatic complications). Finally, seven patients showed contraindications during test occlusion for permanent occlusion of the ICA. Four patients had a permanent occlusion of the ICA after tumour resection. In two patients the ICA was removed without problems in test occlusion. The third patient underwent a permanent carotid occlusion because of bleeding complications (in spite of poor clinical tolerance of the test occlusion). In the fourth patient, only intraoperative neuromonitoring with MSSEP's was conducted before permanent carotid occlusion. All four patients did not show any neurological deficits after resection of the ICA. Neurophysiological monitoring played an important role in predicting cerebral complications after permanent occlusion of the ICA.

Adult↗
PubMed1993

Is the hydrogen clearance technique a useful tool for measurements of pancreatic blood flow during acute experimental pancreatitis?

Changes of pancreatic blood flow (PBF) during acute pancreatitis (AP) have been under investigation by means of electromagnetic flowmeters, radioactive microspheres, isotope fractionation, radioactive gas clearance, and venous outflow techniques. All methods, however, have certain drawbacks, which make the application of other techniques desirable. In this study, the hydrogen clearance technique (HCT) was tested for the first time in a well-established foxhound model of AP. PBF, systemic blood pressure, and heart rate were monitored over 90 min after the onset of AP and 60 min after therapeutic infusion of Dextran-40 (10 ml/kg body wt). Our results fully agree with the data found by other techniques in this experimental model. Sixty-five of 73 electrodes implanted into the pancreas of eight foxhounds were found working. From 1,024 registered clearance curves, 876 were identified as monoexponential. In the other cases, and only then, we found either dislocation of the electrode tips (n = 6) or perielectrodal hemorrhage during histological examination (n = 4). We believe that the HCT is a feasible and reliable tool for measuring PBF in experimental settings like AP.

Acute Disease↗
PubMed1993

[Thrombolysis in acute cerebral ischemia].

During the last years some medical centers have performed emergency treatment for intracranial thromboembolic occlusions by thrombolysis using streptokinase, urokinase, and recombinant tissue plasminogen activator intraarterially or intravenously. So far, it appears that the risk of intracranial hemorrhage with clinical deterioration is not increased by thrombolysis if thrombolysis is performed during the first 8 hours after symptom onset. Successful recanalization of occlusions in the anterior or posterior circulation is associated with a decrease of mortality and morbidity. Intraarterial application of the thrombolytic agent seems to be more effective than intravenous application. However, there is still a lack of controlled studies that could exclusively prove which thrombolytic agent and which mode of application is the most effective with regard to arterial recanalization and clinical outcome.

Acute Disease↗
PubMed1993

[Radiology of stroke].

Today radiologic methods play an important role in the diagnosis of cerebral stroke. The aim of the radiologist, however, should not only be to classify the stroke into the four main categories (ischemic stroke, intracerebral bleeding, subarachnoid hemorrhage, sinovenous thrombosis), but also to interpret the findings with regard to the etiology of the disease. The pattern of lesions gives information about the etiology of ischemic stroke; the correct interpretation of these lesion patterns allows one to optimize therapeutic decisions. This paper additionally focuses on the differential diagnosis of intracerebral hemorrhage and the CT and MR signs of sinovenous thrombosis. New developed concepts in the field of stroke therapy and prophylaxis call for authority and continuous education of the radiologist on this topic. Pure descriptions of radiologic findings without an understanding of the pathogenesis of the disease will be ignored by the clinician. On the other hand, the radiologist can turn the therapeutic decisions in the right direction by combining morphological descriptions with pathogenetic orientated interpretations. In this way, the radiologist can contribute to the reduction of costs in the public health system.

Cerebrovascular Disorders↗
PubMed1992

Safety and efficacy of intravenous tissue plasminogen activator and heparin in acute middle cerebral artery stroke.

BACKGROUND AND PURPOSE: There is little reported of the safety and efficacy of high-dose intravenous recombinant tissue plasminogen activator (alteplase) in combination with heparin anticoagulation in patients presenting with acute ischemic stroke. METHODS: Thirty-two patients with severe hemispheric stroke syndrome caused by angiographically proven middle cerebral artery and/or intracranial internal carotid artery occlusion were treated with 100 mg alteplase by intravenous infusion over 90 minutes within a mean +/- SD of 226 +/- 68 minutes after symptom onset. Recanalization was assessed by digital subtraction angiography in all patients immediately after treatment and by transcranial Doppler monitoring (n = 30) and/or a third angiogram (n = 5) 12-24 hours later. RESULTS: Complete or partial reperfusion was observed in 11 patients (34%) 90 minutes after the initiation of alteplase infusion and in 17 patients (53%) within 12-24 hours. Hemorrhagic infarction without clinical deterioration was detected by follow-up computed tomography in nine patients (28%). Fatal parenchymal hemorrhage occurred in three patients (9%) with huge middle cerebral artery infarcts. Serious hemorrhage from the puncture site occurred in two patients (6%). Good clinical outcome correlated with reperfusion (p less than 0.05) and the presence of grade 2 collateral blood flow (p less than 0.01). CONCLUSIONS: When 100 mg of recombinant tissue plasminogen activator was given within the first 6 hours of acute stroke together with heparin the incidence of deleterious hemorrhage was less than 10%. Reperfusion and effective collateral blood flow seem to be two important factors associated with a small infarct volume and good clinical outcome.

Adult↗
PubMed1992

Advantages and disadvantages of using the hydrogen clearance technique to measure pancreatic blood flow.

This study was undertaken to identify the advantages and disadvantages of using the hydrogen clearance technique (HCT) to measure pancreatic blood flow (PBF) in the opossum over short and long periods. An open study was performed on 8 opossums. A total of 72 platinum electrodes were implanted into the pancreas. On the fifth day 41 additional electrodes were implanted. All implantation sites were examined histologically after five days. Measurements of pancreatic blood flow were taken every other day for five days. Three measurements were taken from each electrode and the mean of the three was used for analysis. In the anaesthetized animal mean PBF (SD) was 63.5 (12.8) ml min-1 100 g-1 immediately after electrode implantation and 34.3 (11.4) ml min-1 100 g-1 on the 5th postoperative day. Of the implanted electrodes, 35% failed during the experimental course, mainly as the result of proliferation of scar tissue around the electrodes. Mild to moderate fibroproliferation had taken place around the platinum tips of the remaining 65%. Primary electrode implantation caused no or negligible trauma to the pancreas. We recommend the HCT only for short-term measurements of PBF. Implantation of electrodes for any length of time leads to inflammatory changes around the platinum tips that cause proliferation of scar tissue and lead to failure of the electrodes, misleadingly low PBF recordings, and fewer monoexponential clearance curves.

Animals↗
PubMed1991

Cerebrovascular CO2 reactivity in migraine: assessment by transcranial Doppler ultrasound.

Cerebrovascular reactivity to CO2 inhalation was studied by transcranial Doppler sonography in 30 patients with classic or common migraine and 39 healthy controls without clinical or ultrasonic signs of arteriosclerosis. Systolic and diastolic Doppler frequencies of the middle cerebral artery were plotted against end-tidal CO2 partial pressure; the reactivity index (I x R) was defined as relative frequency change during a PCO2 increase of 5 mmHg. In the normal subjects, I x R was 20.0 +/- 6.3 for systolic velocities, and 26.0 +/- 8.2 for diastolic values. Migraineurs during their headache-free interval had significantly higher I x R values on the affected side (mean: 41.6 systolic, 61.2 diastolic), compared with either controls (P less than 0.01) or the contralateral side (mean: 28.3 systolic, 30.8 diastolic; P less than 0.01). During the headache attack, CO2 reactivity was significantly lower than normal only for systolic velocities (mean: 8.3; P less than 0.05). Increased CO2 reactivity is thought to be one phenomenon of migraine. Transcranial Doppler CO2 testing of cerebrovascular reactivity is a reliable method that may be of interest for the diagnostic evaluation and management of migraine patients.

Adult↗
PubMed1990

Controlled-release levodopa/benserazide (Madopar HBS): clinical observations and levodopa and dopamine plasma concentrations in fluctuating parkinsonian patients.

In five levodopa (L-dopa)-treated patients with Parkinson's disease with severe fluctuations of motor performance, plasma L-dopa as well as dopamine levels were measured during 2 days, first under optimal standard L-dopa with peripheral decarboxylase inhibitor (PDI) and then after a dose adjustment period using slow-release L-dopa/benserazide (Madopar HBS) in an open inpatient trial. Three patients benefited from the slow-release preparation; two patients deteriorated with a tendency to have an unpredictable response, a delay to turn "on" with the first dose in the morning, as well as an increase in dyskinesia corresponding to L-dopa cumulation during the day. These problems were subsequently also seen during the follow-up period of 1 year in those patients who benefited from Madopar HBS as inpatients. This might indicate that patient compliance is more difficult with the new formulation. After 1 year all patients had returned to their previous standard L-dopa/PDI treatment. L-Dopa levels continued to fluctuate, but to a lesser degree with Madopar HBS. The equivalent L-dopa dosage had to be increased by 56% (29-100%) with Madopar HBS while mean dopamine levels increased in four patients (by 47-257%) without the occurrence of peripheral side-effects. This implies that with the new formulation more L-dopa is metabolized to dopamine and explains the necessity to increase the equivalent L-dopa dosage.

Aged↗
PubMed1990

[Intracranial MR flow signal changes in extracranial occlusions of the internal carotid artery].

Spin-echo sequences allow an identification of the basal brain vessels because of their typical signal void. The increasing use of MRI also in clarification of cerebrovascular disease requires a good knowledge of intracranial flow alterations. We saw characteristic signal pattern in the carotid siphon in 22 prospective examined patients with occlusion of the internal carotid artery confirmed by ultrasound. The lower siphon showed a loss of flow void and a brain isointense signal. The signal in the upper siphon was identical or showed a flow void with significant calibre reduction, probably because of collateral filling. This diagnostic potential of MRI is a remarkable advantage in comparison to CT and should be routinely considered in patients with cerebrovascular disease.

Arterial Occlusive Diseases↗
PubMed1989

Haemodilution with dextran 40 and hydroxyethyl starch and its effect on cerebral microcirculation.

The effect of haemodilution with Ringer's solution, hydroxyethyl starch (HAES) 200/0.5 10% and dextran 40 on cerebral blood flow (CBF) was measured in ten cats by means of the hydrogen clearance technique. As expected from theoretical considerations the haemodilution effect was short and not significant with Ringer's solution, but was 25% with HAES and 35% with dextrane 40. The corresponding rise in CBF was significant in both the latter but not with Ringer's solution. CBF was similarly highly correlated with diminution of haematocrit (Hct). The different effects of the substances on CBF could all be explained by their different effects on the Hct. Data analysis, together with recent literature, suggests that the dominating factor determining CBF was the O2-transport capacity, which in these experiments was in close relation to Hct. The results support the assumption that the increase of CBF by haemodilution is caused by a regulatory mechanism and not by a change of rheological parameters.

Animals↗