ROLE OF PIA MATER VASCULARIZATION OF THE TUMOR IN THE SURGICAL OUTCOME OF INTRACRANIAL MENINGIOMAS

The authors reviewed a personal series of 150 consecutive cases of int racranial meningiomas operated on between 1974 and 1988 with the aim o f finding out the main prognostic factors determining surgical outcome . Severity of pre-operative clinical status and size of the tumour wer e found to be significant adverse factors, p < 0.001 and p < 0.01, res pectively. In this article the authors stress on the role played in pr ognosis by pia mater vascularization of the tumour. When the tumour va scular supply predominated from pial-cortical arteries, in most cases cleavage could not be found in the arachnoid plane, but only in the su bpial plane (because of incorporation of pia mater into the tumour ''c apsule''). Clinical consequences were that in the most eloquent areas (for example in the central region) a bad outcome - with transient or permanent deficit - frequently occurred when cleaving could not be per formed in the arachnoid plane (p < 0.001). The neurological disorders were due to cortical and underlying sub-cortical ischaemia and haemorr hagic infarction. Participation of the pia mater in the tumour vascula r supply can be predicted pre-operatively, directly on selective inter nal/external carotid angiograms, indirectly by the presence of an impo rtant peritumoural hypodensity on CT scan (which - according to our fi ndings - is an indication of predominant pial-cortical vascular supply to the tumour). The positive correlation between cortical-pial supply (and its consequences) and tumour size (p < 0.001), pleads for surger y of meningioma at the earliest possible stage provided there are no c ontra-indications.