Effect of dexamethasone treatment on peritumoral brain edema: evaluation by computed tomography.

In a prospective study, the effect of dexamethasone treatment on brain edema was evaluated by computed tomography (CT) in 14 patients with intracranial neoplasm. A CT study was made immediately prior to the beginning of the treatment and at various intervals for 8 to 19 days thereafter. The volume and attenuation of the edema were measured and related to the time after the start of treatment. In five cases of meningioma, only minor changes were shown; the edema volume either decreased or increased slightly or did not change at all. In four gliomas, a substantial decrease was noted in the edema volume in two cases and a smaller decrease was observed in two cases. In three metastases, a linear decrease in edema volume was noted during the entire follow-up, reducing it to one-fourth of the initial volume after 2 weeks of treatment. In one case of acoustic neuroma and in one undiagnosed lesion, a marked decrease in edema volume was also noted. The attenuation of the remaining edema was constant during the entire treatment time.