Subtemporal Interdural Approach to Dumbbell-shaped trigeminal schwannomas: Cadaveric prosection

초록

Successful resection of dumbbell-shaped trigeminal schwannomas through subtemporal interdural approach requires understanding both of anatomy related to the bone dissection of the petrous apex and meningeal anatomy. We performed this study to detail the meningeal anatomy related to this approach and to present the dural incisions and mobilization in step-wise fashion. Meningeal anatomy around Meckel’s cave (MC) and porus trigeminus was examined during the subtemporal interdural anterior transpetrosal approach in 30 sides of 15 cadaveric heads. Histological study of MC region was performed in 2 cadaveric heads. The Gasserian ganglion and the trigeminal roots have two layers of dura propria on their dorsolateral surface: inner layer from the posterior fossa dura propria constituting the dorsolateral wall of MC; outer layer from the dura propria of the middle fossa. The cleavage plane between these two layers continues distally as the cleavage plane between the epineural sheaths of the trigeminal divisions and the dura propria of the middle fossa. This cleavage plane serves as the anatomical basis for the interdural exposure of the contents of MC. The superior petrosal sinus is sectioned at the medial aspect of Kawase’s triangle and refelected along with the roof of the porus trigeminus. Understanding of the critical meningeal architecture of and around the MC allows the experienced cranial neurosurgeon to develop a subtemporal interdural approach to dumbbell-shaped trigeminal schwannomas which effectively converts a multiple compartment tumor into a single compartment tumor. The method of dural incisions and mobilization complements previous description of the bony steps necessary to accomplish this surgical approach.