Prediction of trigeminal nerve position based on the main feeding artery in petroclival meningioma

The trigeminal nerve is often displaced by petroclival meningioma (PCM) compression, making it difficult to locate during PCM surgery. This study investigated whether the deviated position of the trigeminal nerve could be easily predicted using the main tumor feeding artery. We retrospectively examined 32 patients who underwent surgery for primary PCM. The deviation of the trigeminal nerve was classified as either Type 1 (displacement toward the back of the cerebellar tentorium), Type 2 (toward the back of the superior petrosal sinus), Type 3 (toward the back of the petrous apex dura), Type 4 (toward the inferior aspect of the tumor), or Type 5 (toward the surface of the brain stem). The main feeding artery was determined by preoperative angiography. The trigeminal nerve was classified as Type 2 in 60% of cases where the proximal tentorial artery (TA) was the main feeding vessel. The nerve was Type 5 where the distal portion of the TA was the main feeding vessel (60% of the cases). The nerves were Type 3 and Type 4 where the proximal inferior lateral trunk (ILT) (60%) and distal ILT (75%), respectively, were the main feeding vessels. In 66.7% of the cases where the dorsal meningeal artery was the main feeding vessel, the nerve was Type 3. Type 1 classification applied in all cases where the ascending pharyngeal artery was the main feeding artery. The main feeding artery can be used to predict trigeminal nerve transposition during PCM surgery.