Figure 9

Mean position errors (PE in mm) in Type A-, B1-, B2-, C1- and C2- interventions measured after completion of craniotomy and before dura opening, at three consecutive time points (M1, M2 and M3) during tumour resection and after dura closure or at the end of the intervention. ΔPEs (measured as difference in mm between the initial PE at the time of dura opening and the corresponding PE at the time of dura closure) were significantly higher in types C1 and C2 compared with control group (types A) (* p < 0,05, t test). There were no statistical differences between the two B-type procedures and control group (type A) (p > 0.05).