Cerebral edema and fluid-filled
cysts are common accompaniments of
brain tumors. They contribute to the mass effect imposed by the primary
tumor and are often responsible for a patient's signs and symptoms.
Cerebral edema significantly increases the morbidity associated with
tumor biopsy, excision,
radiation therapy, and
chemotherapy. Both
edema and
cyst formation are thought to result from a deficiency in the blood-brain barrier, with consequent extravasation of water,
electrolytes, and
plasma proteins from altered
tumor microvessels. The resultant expansion of the cerebral interstitial space contributes to the
elevated intracranial pressure observed with
brain tumors. Departure from the typical blood-brain barrier microvascular architecture may only partially explain the occurrence of
edema and
tumor cyst formation. Biochemical mediators have also been implicated in vascular extravasation.
Vascular permeability factor or
vascular endothelial growth factor (VPF/
VEGF) is a
protein that has recently been isolated from a variety of
tumors including human
brain tumors. VPFb is an extraordinarily potent inducer of both microvascular extravasation (edemagenesis) and the formation of new blood vessels (angiogenesis). Its role in
tumor growth and progression would therefore appear pivotal. Herein, the author presents an updated account of the investigation of VPF. Historical and clinical perspectives of the study and treatment of
tumor associated
edema are provided. The efficacy of high-dose
dexamethasone in the treatment of neoplastic
brain edema is discussed. A hypothetical role for VPF in edemagenesis is presented and discussed. It is hoped that an expanded understanding of the mechanisms responsible for the genesis of
edema will ultimately facilitate therapeutic intervention.