A model for quantitation of peritumoral brain edema.

A model system is described which is suitable for quantitation of peritumoral brain edema. The temporal development of peritumoral brain edema in dexamethasone-treated rabbits and untreated controls was evaluated following the implantation of VX2 carcinoma cells into the frontal lobe of New Zealand White rabbits. A colorimetric assay of Evans blue (EB) extravasation was used to quantitate edema. Animals receiving a sham tumor injection contained an equal amount of EB compared to control animals. Dexamethasone was found to significantly reduce the extravasation of EB in rabbits with VX2 brain tumors and to delay the onset of neurologic deficits. These results are consistent with events occurring in patients with brain tumors. Studies of new drugs or physiologic aspects of peritumoral edema can be conducted with this model system.