Prediction of facial nerve displacement in extralarge vestibular schwannoma

The primary objective in the surgery of extra large vestibular schwannoma i s the total removal of the tumour mass while preserving the facial nerve. P reservation of the facial nerve in extra large tumours is reported as being notoriously difficult in the majority of cases. This study was undertaken to evaluate the accuracy in predicting displaceme nt of the facial nerve by preoperative radiological imaging studies in 19 c ases of extra large vestibular schwannoma. The direction of displacement of the facial nerve was predicted with preoperative axial and coronal MRI sca ns and verified intraoperatively. We achieved total removal of rumours in 84.2%, facial nerve displacement wa s predicted in 80% and we accomplished anatomical preservation in 80%. Pred iction of displacement was difficult in tumours with little or no intracana licular components or with severe bony destruction of the internal acoustic meatus. The preoperative prediction of facial nerve displacement in extra large rum ours allows safe internal decompression of the tumour and careful dissectio n near the predicted area of the facial nerve during the operation. Consequ ently, a high rate of anatomical preservation of the facial nerve can be ac hieved.