Search PubMed⌕ Search

Biomedical subjects

R von Kummer

Publications and source records attributed to R von Kummer.

At least 109 records · Page 6Linked to original sources
PubMed1988

Autoregulatory capacity and the effect of isovolemic hemodilution on local cerebral blood flow.

The effect of isovolemic hemodilution with dextran 40 on local cerebral blood flow was measured in eight cats by means of the hydrogen clearance technique. Under normotension the decrease of hematocrit from 35% to 25% causes a sudden increase of up to 30% in local cerebral blood flow. After lowering the mean arterial blood pressure from 140 to 80 mm Hg, hemodilution did not alter cerebral blood flow significantly. From this observation it is concluded that the increase of cerebral blood flow following hemodilution is caused by compensatory vasodilatation and not by reduction of blood viscosity. This could imply that hemodilution cannot improve blood flow in areas of impaired autoregulation.

Animals↗
PubMed1987

[Value of oligoclonal IgG fractions in the cerebrospinal fluid and blood in neurologic diseases].

CSF and serum from 700 patients were analysed by isoelectric focusing (IEF). Oligoclonal bands in the high alkaline range were detected in 156 cases. Ninety-five patients were diagnosed as having multiple sclerosis (MS), 38 various CNS inflammatory disorders, 18 vascular, neoplastic or degenerative and 5 patients other neurological diseases. IEF was positive in 98% of clinically definite and 85% of clinically probable MS cases and was found to be more sensitive as compared to intrathecal IgG production and evoked potentials. Neither the presence of oligoclonal IgG nor the banding distribution pattern is specific for any disease. Further characterization may be obtained by immunofixation if the antigen is known.

Blood-Brain Barrier↗
PubMed1986

Hydrogen clearance method for determining local cerebral blood flow. I. Spatial resolution.

To define the effective spatial resolution of the hydrogen clearance method, serial local CBF (LCBF) measurements were performed at different distances from the cortico-white matter junction of the cat brain. Twenty-five platinum-wire microelectrodes with a sensitive surface of 0.07 mm2 were inserted into the cerebral cortex of three cats through burr holes in the skull and advanced toward the ear-to-ear level in 1- or 0.1-mm steps. Most electrodes passed from high-perfusion regions into low-perfusion areas, indicating that the cortico-white matter junction had been traversed. Whereas within the gray and white matter the LCBF values were fairly constant, a striking decrease of CBF was registered at the cortico-white matter junction. Here the mean LCBF from 12 electrodes showed significant differences in flow between two locations 1 mm apart. On two occasions, a significant difference in CBF was found for locations only 0.1 mm apart. Despite this high spatial resolution, monoexponential clearance curves were detected only in the vicinity of the cortico-white matter junction. It is therefore assumed that factors other than flow might influence H2 clearance.

Animals↗
PubMed1986

Hydrogen clearance method for determining local cerebral blood flow. II. Effect of heterogeneity in cerebral blood flow.

The time course of hydrogen uptake and washout was followed simultaneously in extracranial arterial blood, cortex, subcortical white matter, and caudate nucleus of the cat brain to study intercompartmental hydrogen concentration differences. A clear delay of 1-2 min was seen between the onsets of concentration increase in arterial blood and low-flow brain tissues. Equilibration time was dependent on local CBF and varied between 3 and 34 min. Hydrogen was not cleared simultaneously from the regions under detection. This led to considerable concentration differences within the cerebral tissue during washin and washout phases. Analysis of the clearance curves revealed that secondary equilibration occurs during washout. Hydrogen concentration in the external carotid artery was not a reliable reflection of tracer input in the brain tissues. The consequences of these observations for other techniques of CBF measurement using less diffusive gases and external detection are discussed.

Animals↗
PubMed1986

Imaging of cerebral blood flow-to-volume distribution using SPECT.

The ratio between cerebral blood flow (CBF) and cerebral blood volume (CBV) has been proposed as an adequate parameter for the evaluation of cerebrovascular disease (CVD), but to date it has not been assessed with SPECT. We have chosen [123I]IMP for CBF and [99mTc] erythrocytes for CBV imaging. The distribution of both nuclides was investigated in succession using corrections for the contamination of the 99mTc tomograms by 123I. The ratio between 123I and 99mTc tomograms yielded the CBF/CBV distribution. Quantitation was obtained by side-to-side comparison of both hemispheres and of segments containing the territories affected by CVD. In 16 patients with CVD, CBF of the affected territories was 85 +/- 19% (s.d.) when related to the nonsymptomatic contralateral side (100%). When the regions of interest defined within one slice encompassed the entire affected hemisphere, the average CBF was 95 +/- 9%, again related to the nonsymptomatic side. The corresponding CBF/CBV data in 15 of these 16 patients were 60 +/- 32% and 81 +/- 16%. In unilateral internal carotid artery stenoses greater than 50% (N = 10), segmental CBF averaged 81.1 +/- 10.1% and CBF/CBV 49.6 +/- 15.5% relative to the contralateral side. The figures for the hemispheres were 92.8 +/- 5.8 and 75.8 +/- 12.6, respectively. These clinical findings mirror the characteristics of CBF autoregulation, namely the vasodilation of small vessels in decreased arterial perfusion pressure. They, therefore, substantiate SPECT imaging of CBF/CBV for the assessment of cerebral perfusion reserve in CVD.

Adult↗
PubMed1984

[Eye symptoms in hypophyseal adenomas, craniopharyngiomas and meningiomas of the anterior and middle cranial fossa].

Among 181 inpatients suffering from pituitary adenoma, craniopharyngioma, or meningioma of the anterior or middle cranial fossa, 112 had ocular symptoms initially or during the course of the disease. Patients' histories were analyzed with regard to ophthalmological, neurological, and radiological diagnostic procedures carried out, and the conclusions drawn from these. Initial symptoms and signs were often misinterpreted and appropriate investigations consequently delayed. The mean duration of the history was 2.67 years (0-13 years) for the pituitary adenomas, 1.44 years (3 months-6 years) for the craniopharyngiomas and 3.73 years (1 month-24 years) for the meningiomas. Typical initial eye symptoms were progressive loss of vision with or without optic nerve atrophy, visual field defects, extraocular nerve palsies, and exophthalmus, the last two occurring if parasellar extension of the tumor was present. Plain skull X-rays were abnormal in nearly all cases of pituitary adenomas, but the incidence of abnormalities was less frequent with cases of craniopharyngiomas and meningiomas. The tumor was demonstrated by computerized tomography in all cases of pituitary adenomas, in 5 out of 6 cases with craniopharyngiomas and, where the examination was performed before and after administration of contrast medium, in all cases of meningiomas. Introduction of CT, however, shortened the duration of the history only in the meningioma group; the mean dropped from 4.38 years to 3.04 years. The chance of achieving a cure by surgical intervention lessened with both increasing length of history and tumor size. Out of 90 patients (15.6%) operated on, 14 died in the postoperative period. Vision improved postoperatively in only 26 patients whereas it remained unchanged or decreased further in 40 patients. In 10 cases there were no postoperative data available. These results emphasize the necessity of making an early diagnosis. This can nearly always be achieved if a careful clinical examination and adequate additional diagnostic procedures are carried out.

Adenoma↗
PubMed1984

[Cerebral angiography in transitory global amnesia].

33 patients with transient global amnesia were examined by cerebral angiography. The presence of arterial lesions correlated with neurological symptoms, as well as with amnesia. In 55% of cases no pathological alterations were found, so that the pathogenesis of the transient global amnesia remained unclear. For clinical purposes, cerebral angiography is recommended only in those cases which show other neurological symptoms besides the transient global amnesia.

Adult↗
PubMed1982

Follow-up of spontaneous intracerebral haemorrhage by computed tomography.

The follow-up of 89 patients with spontaneous intracerebral haematomas was studied by computed tomography (CT). The aetiology of the haemorrhage was found to be hypertension in 52 cases, vascular malformation in 14 cases, and two haematomas were due to anticoagulant therapy. The lesion visible on CT consisted of an area of increased density surrounded by a rim of low attenuation. Most cases showed a progressive decrease in size of the total lesion. Exceptions to this pattern were observed, which may lead to the misdiagnosis of a tumour. The central area of increased density decreased in size much more quickly than the total lesion. Signs of a mass effect were observed up to the ninth week in the larger lesions. The resorption of blood, measured by the decrease in diameter of the central high attenuation area, was not dependent on the site or original size of the haematoma, but was slower in hypertensive haemorrhage than in haemorrhage due to vascular malformation. Contrast enhancement was observed up to the ninth week and was ring-like in most cases. Our data confirm the well-known finding that the bleeding cannot be demonstrated by examination of the CSF if the blood has not reached the ventricular system or the subarachnoid space.

Adolescent↗
PubMed1981

[Fibrinolytic treatment of severe thrombosis of the basilar artery (author's transl)].

Thrombosis of the basilar artery occurred in a 27-year-old woman after physical exercise (bowling). She became deeply unconscious without change so that four days after onset urokinase was administered. The neurological status than markedly improved, with partial regression of the paresis and the cranial nerve deficits, and she became responsive again. Angiography after four-day urokinase administration demonstrated complete recanalisation of the basilar artery. Subsequent rehabilitative measures led to almost complete disappearance of all symptoms. Later neurological tests revealed merely very discrete left hemiparesis, mainly of the arm.

Adult↗