PERITUMORAL EDEMA IN MENINGIOMAS - MICROSURGICAL OBSERVATIONS OF DIFFERENT BRAIN-TUMOR INTERFACES RELATED TO COMPUTED-TOMOGRAPHY

ALTHOUGH GENERALLY BENIGN tumors, meningiomas may be associated with e xtensive peritumoral brain edema as seen on computed tomographic scans . Fifty-two patients with intracranial meningiomas were studied, and t he hypodense areas on computed tomographic scans were related to the i ntraoperative microsurgical findings and to the sizes of the tumors. W e have identified three kinds of tumor-brain interfaces characterized by different difficulties in microsurgical dissection: smooth type, tr ansitional type, and invasive type. These different microsurgical inte rfaces seem to correlate very precisely with computed tomographic imag es of halo-like and finger-like hypodense areas, allowing prediction o f the microsurgical effort to be made in the surgery of meningiomas. T he size of the tumor seems to be important in our subjects in determin ing the amount of edema produced. Indeed, a positive correlation (P < 0.001) was found between the sizes of the tumors and the extent of per itumoral hypodensity. A positive correlation (P < 0.002) also has been found between grade of edema and cortical penetration. Cerebral corte x disruption was systematically observed by us in invasive-type mening iomas and in 3 of 21 cases (14.3%) in transitional-type meningiomas. N o penetration was observed in smooth-type meningiomas.