Pineal tumor surgery-the choice of the approach related to tumor characteristics and posterior fossa anatomy

Objective This research aimed to determine whether an adequate surgical approach can be chosen based on clearly defined values of anatomical landmarks (tentorial angle), and tumor size and extension. Methods We conducted a retrospective analysis of patients operated on because of pineal tumors. The cohort was divided depending on the surgical approach. On preoperative magnetic resonance imaging, we measured maximal diameters, tumor volume, and tumor propagation. In the group of patients operated with the supracerebellar infratentorial approach, we also tested the correlation of tentorial angle with residual tumor. Differences among groups in resection, complications rate, and outcome were tested by the Chi-square test. Finally, in both groups, the correlation of residual tumor with tumor volume, propagation, and diameters was tested using the receiver operating characteristic curve. Results In group operated with supracerebellar approach total resection was achieved in 78% of the patients. The critical value of cranio-caudal diameter correlated with tumor residue was 31mm, for lateral-lateral diameter 25mm, for the lateral extension 14mm, and tumor volume 12cm3. Tentorial angle did not influence the extent of the resection. In group operated with occipital transtentorial approach the critical tumor volume related to tumor residue was 9mm3, anterior-posterior diameter 29mm, and cranio-caudal diameter 28mm. The extent of the resection was significantly higher in the supracerebellar group. Conclusions In both approaches, tumors larger than 3cm show increased risk of subtotal resection. Except when most tumor volume is localized above the venous system, we advocate a supracerebellar corridor as an effective approach that is not limited by tentorial angle.