Quantitative Anatomical Comparison of Anterior, Antero-Lateral and Lateral, Microsurgical and Endoscopic Approaches to the Middle Cranial Fossa

OBJECT: To quantitatively compare different microsurgical and endoscopic approaches to the middle cranial fossa in a preclinical setting with a novel, computer-based research method. METHODS: Different approaches were performed bilaterally in 5 head and neck specimens that underwent high-resolution computed tomography scans: five transcranial anterolateral (supraorbital, mini-pterional, pterional, pterional-transzygomatic, fronto-temporal-orbito-zygomatic) without and with anterior clinoidectomy; two transcranial lateral (subtemporal and subtemporal-transzygomatic); two endoscopic transnasal (transpterygoid, transpterygoid to infratemporal fossa); two endoscopic transorbital (superior eyelid and inferolateral) and endoscopic transmaxillary. A dedicated navigation system was used to quantify surgical working volumes and exposure of different areas of the middle cranial fossa (ApproachViewer, part of GTx-Eyes II, University Health Network, Toronto, Canada). Statistical analysis was performed using a mixed linear model with bootstrap re-sampling. RESULTS: Endoscopic transnasal and fronto-temporal-orbito-zygomatic approaches with anterior clinoidectomy showed the largest surgical volumes. Endoscopic approaches allowed a wider exposure of medial anatomical surfaces (e.g. the petrous apex) compared to transcranial ones. Transcranial approaches with larger craniotomies allowed the widest exposure of supero-medial anatomical structures (e.g. roof of cavernous sinus). The resection of the zygomatic arch allowed exposure of more medial surfaces with an inferior to superior trajectory. CONCLUSIONS: This study implemented a novel neuronavigation-based research method to quantitatively compare different approaches to the middle cranial fossa; its results might guide, after consideration of clinical implications, the choice of the neurosurgical approach to different areas of this complex skull base region.