[Prognostic factors in the surgery for intracranial meningioma. Role of the tumoral size and arterial vascularization originating from the pia mater. Study of 150 cases]

Abstract

The authors report a series of 150 consecutive patients operated on for an intracranial meningioma over a period of 14 years (1974-1988). The patients were aged from 15 to 85 years (mean: 58 y; 49 were over 60 y) and severely disabled preoperatively in 42 cases (Karnofsky score 10 to 60). Tumors were located in the convexity in 22% the parasagittal region and falx in 24%, the skull base in 14% and the posterior fossa in 13%. In 21 cases the diameter of the tumor was less than 3 cm, in 86 it ranged from 3 to 6 cm, and in 43 cases it was more than 6 cm (29%). Tumor was hypervascularized in 51% of cases. Peritumoral edema was present in 73 of the 106 patients studied (69%). The tumor was removed completely (grade I and II of Simpson classification) in 136 cases (91%). Post-operative mortality was 10%. 88.5% of the surviving patients had a normal life with a score of 80 to 100 according to Karnofsky scale. Recurrence rate amounted at 3.3%. Mortality and severe morbidity (poor outcome) were assessed and correlated with sex, age, tumor, size, location, vascularization, peritumoral edema and histology. From this retrospective study the only predictives of a poor outcome, statistically significant, were: severe preoperative neurological conditions (p < 0.001) and tumor size (p < 0.01). There was no statistically significant correlation with the other parameters. Cortical arteries participation to tumor vascularization, in a equal part of more than the dural arteries, led to subpial dissection for achieving complete tumor removal. This was a source of hemorrhagic infarction through ischemia, with patent neurological deficits for rolandic meningiomas (p = 0.001). The importance of pial supply of the tumor was correlated with its size (p < 0.001). Pial supply of the tumour and consequently subpial dissection were foreseeable in the preoperative study: on selective angiography (p < 0.001) and the presence of peritumoral edema on CT scan (p < 0.001). The authors conclude that besides the "classic" pronostic factors (preoperative neurological conditions, tumor size), the mode of vascularization of the tumor (pial supply) plays an important role in the possibility or not to find an extra pial plan of dissection from the adjacent parenchyma, and consequently in the neurological outcome of the patients.