Pre- and postoperative changes in brain tissue surrounding a meningioma.

A retrospective study in 33 patients with intracranial meningioma demonstrates that two pathological mechanisms are involved in causing a hypodense area around the actual tumor: pressure-induced atrophy that persists after operation and true cerebral edema of unclear cause. The extent of the hypodense area is not related to tumor location or tumor size. A relationship between meningioma with a malignant tendency and the hemispheric spread of hypodensity can be observed.