Peritumoral Brain Edema in Intracranial Meningiomas: Effects of Radiological and Histological Factors

OBJECTIVE: We examined the radiological and histological features influencing the development of peritumoral brain edema (PTBE) among patients with meningiomas. METHODS: Factors causing PTBE were retrospectively analyzed for 125 patients with primary intracranial meningiomas. These factors included tumor size, tumor location, brain-tumor interface, signal intensity on T2-weighted scans, contrast enhancement, and cyst formation (as observed on magnetic resonance imaging scans), as well as tumor vascularity and blood supply (as observed in digital subtraction angiography studies). We defined the edema/tumor volume ratio as the edema index, and we used this index to evaluate PTBE. RESULTS: A relationship between the tumor size and the volume of PTBE was observed. Convexity and middle fossa meningiomas demonstrated the greatest increases in mean edema indices. Meningothelial, anaplastic, microcystic, and angiomatous subtypes exhibited higher edema indices than did other types. Multivariate analysis demonstrated two significant radiological factors: cortical penetration (as defined by the disappearance of the arachnoid layer on magnetic resonance imaging scans) (relative risk, 2.067; P = 0.0148) and vascular supply from the pial-cortical arteries (as observed on angiograms) (relative risk, 2.087; P = 0.0082). CONCLUSION: Tumor infiltration into adjacent brain parenchyma and a pial-cortical blood supply are critical factors for the development of PTBE among patients with meningiomas.