Formation and resolution of white matter oedema in various types of brain tumours.
ABSTRACT Following infusion of 200 ml of Iopamidol for 1 hour the propagation of extravasated contrast medium around different types of 12 brain tumours was examined and imaged via CT. Increasing volume of expanding peritumoural contrast enhanced brain tissue was measured by integrating volumes of planimetrically measured enhanced area on CT slice of 0.5 cm in thickness. So far our data failed to demonstrate differences in the peritumoural contrast expansion between the different types of tumours. Formation and resolution as well as the speed of oedema propagation were determined by calculation of the increasing volume of the enhanced peritumoural brain tissue. Average formation rate of oedema fluid from 1 cm3 of tumour was 0.06 ml/hr, and was lower in larger tumours, while formation rate of oedema fluid from whole tumour was higher in larger tumours. Average resolution rate of oedema fluid during the passage through 1 cm3 of the peritumoural white matter was 0.03 ml/hr, and was not affected by tumour size. Average speed of oedema propagation was 0.59 mm/hr, and was higher in larger tumours. The main therapeutic effect of steroid in peritumoural oedema was a reduction in formation rate of oedema fluid.
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ABSTRACT: Among glucocorticoids, dexamethasone is most widely used for treatment of cerebral edema because of its long biological half-life and its low mineralocorticoid activity (sodium retaining). A systematic review of the literature on the effects of dexamethasone on the brain from in vivo studies in humans. A MEDLINE database search (via the PubMed interface) and an EMBASE database search (via the Dialog interface) of the past 35 years was performed. Every article relating to human use reported in English was included. In addition, references of all eligible articles were searched to identify other possible sources. Twenty-four articles matched the eligibility criteria. There were disparate methodologies and conflicting results, although they tended to indicate a decrease in blood-tumor barrier permeability, decreased tumoral perfusion, decreased tumoral diffusivity, and the possibility of decreased perfusion in contralateral normal-appearing brain tissue. Treatment with dexamethasone may alter imaging parameters from cerebral perfusion studies used in the management of brain tumors. In adequately powered studies, it may be possible to assess the longer term effects of dexamethasone on normal brain tissue to help optimize use with longer term survivors that are emerging as improvements in glioma treatment are made.Neurosurgery 12/2010; 67(6):1799-815; discussion 1815. · 3.03 Impact Factor
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ABSTRACT: Peritumoural brain oedema is a prominent feature of malignant brain tumours. Glucocorticoids diminish the neurological symptoms and signs caused by the oedema and reduce the abnormally high cerebral water content. The exact mechanisms of action of the glucocorticoids are unknown. The present study investigates the influence of dexamethasone on NMR relaxation time T1 in peritumoural oedema in 13 patients with gliomas. It is shown that NMR T1 images can be used as a potent monitor of brain oedema, and that dexamethasone significantly reduces mean T1 after 1, 3, and 7 days of treatment by 2%, 6%, and 13% respectively. Using an image histogram analysis technique the term "super-oedema" was defined as the 50% of the total oedema area with the highest T1, corresponding to the highest water content. It is shown, that with this technique the treatment effect of steroids on super-oedema was a reduction of 13%, 33%, and 57% after 1, 3, and 7 days of treatment respectively. The mean change after 24 hours of treatment was statistically significant (p < 0.01). The method can be used in all situations where the anti-oedematous effect of a given treatment is to be monitored.Acta Neurochirurgica 02/1993; 122(3-4):218-24. · 1.79 Impact Factor