Risk assessment of brain retraction injury based on quantitative evaluation of brain retraction distance during skull-base meningioma surgery.

OBJECTIVE

In skull-base surgery, excessive brain retraction may cause brain retraction injury (BRI), yet the brain retraction distance (BRD) that contributes to BRI and the potential of skull-base approaches to reduce BRD remain unclear. This study used a virtual reality (VR)-based method to quantify BRD related to BRI and to assess the impact of skull-base approaches on reducing BRD.

METHODS

We retrospectively analyzed 18 patients who underwent frontotemporal craniotomy for anterior skull-base tumors. Three-dimensional models were generated from perioperative imaging, and the frontal lobe was virtually elevated on the 3D model to reproduce the surgical exposure. BRD was estimated by comparing pre- and post-retraction configurations, and its association with BRI was assessed. Additionally, a virtual orbitotomy was performed to evaluate how much BRD could be reduced with this approach.

RESULTS

Four patients developed BRI. The median BRD was 6.2 mm in the non-BRI group, whereas it was 12.2 mm in the BRI group, demonstrating a significant difference. Receiver operating characteristic curve analysis identified 10.1 mm as the optimal cutoff value for predicting BRI, yielding a sensitivity of 100% and a specificity of 92.9%. The median BRD decreased from 8.3 mm to 5.8 mm after adding an orbitotomy on the 3D model, with the greatest reduction observed in cases requiring larger BRD.

CONCLUSION

VR-based preoperative measurement of BRD may help assess both the risk of BRI and the potential benefit of skull-base approaches. This technique could support selecting an optimal surgical strategy by considering the anticipated BRD for each patient.