Steroid and hyperosmotic diuretic effects on the early phase of experimental vasogenic oedema.

The effects of either dexamethasone or mannitol on the early phase of vasogenic oedema were studied by evaluating proton relaxation behaviour with in vitro NMR spectroscopy. Vasogenic cerebral oedema was induced by cold injury in cats. Significant (p less than 0.05) decreases in both longitudinal relaxation rate (R1 = 1/T1) and transverse relaxation rate (R2 = 1/T2) and increases in water content were observed in the white matter beneath the cold lesions four hours after injury. In the dexamethasone treated group, the decrease in R2 in the oedematous white matter was significantly (p less than 0.05) less than that in the non-treated control group and the mannitol group. The R2 in the oedematous white matter exhibited a two-component decay. The slow component of R2 in the dexamethasone-treated group was significantly (p less than 0.05) smaller than that in the control group. Our results indicated that dexamethasone has a prophylactic effect on the early phase of vasogenic oedema by preventing the accumulation of fluid in the extracellular space and that mannitol had no prophylactic effect on oedema formation.