Stereotaxic lesion as a model of brain edema.

Repeated computed tomographic (CT) examinations after thalamotomy showed a lesion vrying in size over time. This variation was interpreted as indicating presence of an edema. The effect of steroid treatment upon such an edema was tested in a pilot study of 28 patients, 16 of whom were given betamethasone. The diameter of the lesion as observed on CT was used as a measure of the amount of edema. The mean diameter was significantly lower in the steroid-treated group as compared with controls (p less than 0.01, Mann-Whitney U test). The groups were comparable with respect to other variables that might influence lesion size. It is concluded that steroid treatment has an edema-preventing effect.