The Natural History of Petroclival Meningiomas: A Volumetric Study.

OBJECTIVES: This study characterizes primary petroclival meningioma growth rates, before intervention, using volumetric analysis. In addition, predictors of growth are analyzed.

METHODS: Patients with previously untreated petroclival meningiomas were retrospectively reviewed (1999-2015). Image analysis software was used to perform volumetric analyses of tumor size and growth. Three-dimensional segmentation volumetric analyses were compared with volumes estimated utilizing three orthogonal dimensions. Tumor growth was defined as a 15% increase in volume.

RESULTS: Thirty-four patients who underwent at least two magnetic resonance imaging (MRI) studies before intervention were included. The mean age was 55.2 years, and 65.7% were women. The mean tumor volume at presentation was 5.6 cm (range, 0.1-25.8 cm) as determined from segmentation volumetric analysis. At a mean follow-up of 44.5 months (range, 3.7-125.1 mo), 88.2% of tumors grew. The mean annual volumetric growth rate was 2.38 cm/yr (-0.63 to 25.9 cm/yr). Tumor volume, T2 hyperintensity within the tumor, peritumoral edema, and ataxia and/or cerebellar symptoms at presentation were all significantly associated with greater rates of tumor growth. Ultimately, 10 (29.4%) patients underwent treatment during the follow-up period.

CONCLUSION: Our experience demonstrates that the vast majority (88%) of untreated petroclival meningiomas grow; the mean volumetric growth rate was noted to be 2.38 cm/yr. We found a significant association between increased growth rate and larger tumor size at diagnosis, T2 hyperintensity within the tumor, peritumoral edema, and the presence of ataxia and/or cerebellar symptoms.