STUDY POPULATION/SAMPLE SIZE: Patients with presumed low-grade glioma or meningioma, who are scheduled for resective surgery, will be included in the study. Fifteen patients will be invited in feasibility study. Based on the yearly numbers of meningioma and low-grade glioma patients that are operated in the Elisabeth-TweeSteden Hospital Tilburg, it is expected that 60 patients will be randomized in the RCT per year for 2.5 years. With a maximum attrition rate of 33%, a minimum of 100 patients (50 per group) will be evaluated.