Prevention of experimental cerebral edema by corticosteroids: Biochemical and ultrastructural studies

Effect of an extract of Ginkgo biloba on triethyltin-induced cerebral edema

The effect of an extract of Ginkgo biloba was studied on cerebral edema in rats intoxicated with triethyltin chloride (TET). Brains of TET-treated rats showed elevated water and sodium levels and a significant increase in the sodium/potassium ratio. Animals treated with TET plus the extract did not show water and electrolyte changes. The course of intoxication and treatment was studied light- and electron-microscopically. A severe edema with extensive vacuolization was seen in the cerebral and cerebellar white matter. Morphometric measurements revealed a significant decrease in these manifestations of the cytotoxic edema when the animals were treated with an extract of Ginkgo biloba. Thus, we conclude that this extract has a protective effect on the development of a cytotoxic edema in the white matter of the brain.

A retrospective study on the effects of low and high doses of betamethasone on severe closed head injury

A retrospective analysis of 113 patients with severe head injuries (unconscious for six hours or more) showed no difference in the outcome for 59 patients treated with low doses of betamethasone compared to the outcome for 54 patients treated with high doses of betamethasone. There was no difference in the number of useful recoveries (low dose, 21/59; high dose, 20/54) and the mortality rates were about the same (low dose 29/59; high dose, 31/54). There were three deaths from infectious complications in the patients treated with high doses of betamethasone.

Effects of steroids on behavior, electrophysiology, water content and intracranial pressure in cerebral cytotoxic edema

The effect of therapy with methylprednisolone sodium succinate (5.33 mg/kg/day) and dexamethasone sodium phosphate (1 mg/kg/day) on grey matter of rabbits rendered edematous by a metabolic blocker, 6-aminonicotinamide, is presented. Methylprednisolone was observed to significantly reduce the water content of the grey matter (p less than 0.001), whereas dexamethasone had little effect. Both agents, however, were equally effective in reducing intracranial pressure (p less than 0.001) and improving intracranial elastance, when compared to untreated animals. However, in the dexamethasone-treated group, there was improved behavior and EEG findings in 50% of the animals when compared to the untreated controls, and similar improvement was present in less than 15% of the methylprednisolone group. The disparity between the effects on water content, behavior and EEG supports the thesis that in cerebral edema these agents have a metabolic effect out of proportion to their effect on tissue water.

Experimental allergic encephalomyelitis. Water, sodium and potassium concentration in spinal cord and hemispheres and their changes after dexamethasone treatment

Water content, Na+, K+ and Cl- concentration were measured in rats with experimentally produced allergic encephalomyelitis. Increase of water content by 10%, accumulation of Na+ by 13%, of Cl- by 20% and decrease of K+ by 10% was observed in the spinal cord, but no substantial changes were found in the brain tissue. The hydration of spinal cord is accompanied by perivascular infiltrates. Dexamethasone, administered from day 5, after injecting sensitising encephalitogenic basic protein, effects normal levels of water content and Na+, K+ and Cl- concentration.

Experimental allergic encephalomyelitis.-- The effect of dexamethasone on growth and proliferation in the draining lymph node

Dexamethasone, when administered from day 0 to day 9 following the sensitizing injection of encephalitogenic protein in complete Freund's adjuvant, suppressed both the characteristic enlargement of the paracortical area of the draining lymph node and the development of clinical and histopathological signs of experimental allergic encephalomyelitis. Division of cells within the node was not inhibited and therefore the effect of dexamethasone appeared to be a consequence of reduced migration of lymphocytes into the node.

Experimental effects of steroids and steroid withdrawal on cerebrospinal fluid absorption

The authors studied the effects on cerebrospinal fluid (CSF) absorption of chronic administration and acute withdrawal of steroids in dogs. CSF absorption was measured by determining the amount of isotope (indium 111DTPA) recovered over a 4-hour period after injection into the cisterna magna. Resistance to CSF absorption was estimated by determining rates of low of Ringer's lactate infusion into the cisterna magna over a range of pressure gradients between CSF and sagittal sinus. Steroid withdrawal was associated with a marked reduction in CSF absorption and an increase in resistance to CSF flow. Dogs on steroids also showed reduced CSF absorption although the reduction was not statistically significant when compared with controls. The results are discussed in terms of possible mechanisms of action of steroids on CSF absorption, the etiology of the benign intracranial hypertension syndrome and the use of steroids and in the control of intracranial hypertension.

Effect of drugs on experimental brain edema in mice

✓ Cold-induced hemorrhagic infarcts in mice caused a spreading decrease in tissue specific gravity around the lesion; the decrease in tissue density represents an increase in edema fluid. The maximum decrease in density in most brain areas had occurred by 6 hours. This time period was used to evaluate the effect of nine drugs on brain edema. Two agents increased edema formation: hexamethonium and meralluride. Metaraminol, cortisone, hydrocortisone, acetazolamide, and dextran did not significantly alter edema formation. Only in the phenoxybenzamine- and urea-treated mice was brain edema less than in the control mice.

The effect of dexamethasone phosphate on the production rate of cerebrospinal fluid in the spinal subarachnoid space of dogs

✓ The effect of intravenous dexamethasone on cerebrospinal fluid (CSF) production was studied in dogs by a method of caudocephalad perfusion of the spinal subarachnoid space with an inulin-containing buffer. The CSF production rate began to reduce immediately after the injection of 0.15 mg/kg and attained a maximal reduction of 50% in 50 minutes.

The effects of glucosteroids on experimental cold-induced brain edema. Gross morphological alterations and vascular permeability changes

✓ Although the beneficial effects of glucosteroids on brain edema are well documented and generally accepted clinically, investigations into their effects on experimental brain edema have been somewhat contradictory. In this study brain edema was produced by local cortical freezing in animals pretreated with glucosteroids and in untreated animals. Gross estimation of edema, wet weight-dry weight determination, and mechanical planimetry of areas of extravasated dye indicated a statistically significant reduction in edema of both white and gray matter at 24, 48, and 72 hours. Gross estimation of edema indicated a persisting effect with resolution of edema at 5 days in treated animals and from 7 to 12 days in untreated animals. These studies substantiate initial investigations and indicate a primary reduction in brain edema by glucosteroids. At least one of the effects of the glucosteroids appears to be reduction of the abnormal vascular permeability causing brain edema.

Effect of sexual maturity, adrenalectomy, and castration on experimental cerebral ischemia due to carotid ligation

✓ Experiments were carried out in young and mature rats to assess the effect of adrenalectomy and/or castration on cerebral ischemia due to carotid ligation, with particular reference to age and sexual maturity. The results indicate that gonadectomy after sexual maturity has no effect on the end result of brain ischemia, whereas resection of the gonads prior to sexual maturity results in a significant number of microscopic ischemic brain lesions. Adrenal resections in mature animals with or without removal of gonads is accompanied by a significant increase in mortality and morbidity, but the mortality is greater when adrenals are removed prior to sexual maturity, particularly when combined with gonadectomy. It appears that the impact of brain ischemia is significantly influenced by hormonal functions of the gonads and adrenals, presumably due to their effect on cerebral blood flow.