Abstract
The authors studied the characteristics of low density area accompanied by intracranial meningiomas on computer-assisted cranial tomography (CT). In 1977 8 cases were experienced; 2 had no low density area, 3 had grade I edema and another 3 had grade III edema, according to the classification of brain edema proposed by Kazner et al. The conclusions are as follows :
1) Grade I edema on CT may not represent pathological edema in intracranial meningiomas, but may show dilated subarachnoid space around the tumors. The entrapped CSF space can be well defined, crescentic in shape and narrow.
2) Grade II and III edema on CT may represent pathological edema. The difference between grade II and III simply is one of spread and extent of edema, which would be influenced by the size and location of the tumor, tissue pressure gradient, compromising of cerebrovascular bed and function of the falx and/or tentorium as a barrier or buffer.
3) It would be reasonable to assume that if the edema on CT disappears completely soon after surgery for meningiomas, it may chiefly consist of increase in water content in the white matter, and if it persists and delays its disappearance after surgery, it may be associated with breakdown of myelin in the edematous brain.
