Abstract
BACKGROUND: Accurate middle cranial fossa (MCF) morphometry is crucial for the safe application of middle fossa approaches such as the Dolenc and Kawase approaches, which expand exposure to the cavernous sinus and petroclival region. These parameters vary widely among individuals and populations, making population-specific data important. We therefore collected MCF measurements in Mexican adults using both CT scans and dry skulls to establish normative values and assess the accuracy of CT scans. METHODS: Two cohorts (97/107 subjects each) were analyzed: head CT scans (in vivo) and dry skulls (ex vivo) of adult Mexicans. Key distances (Foramen ovale (FO) - Foramen spinosum (FS), FO - arcuate eminence (AE), FS - AE) and innominate pillar thickness were measured bilaterally (each in duplicate). CT versus skull differences were tested (α = 0.05) using side-to-side symmetry analysis, and the 5th/95th percentiles were used as anatomical limits. RESULTS: CT and osteology showed close concordance for FO-FS, supporting CT-based extradural orientation for the middle fossa approach. In contrast, FO-AE and FS-AE were larger on dry skulls by a few millimeters, indicating that routine CT slightly underestimates the drillable petroclival window relevant to Kawase. The innominate pillar was consistently present and appeared slightly thicker on CT (partial-volume effect), remaining a practical landmark to localize CN V3 (mandibular division of the trigeminal nerve) between FO and FS. Left-right asymmetry was not evident on CT; osteology showed only small AE-related leftward tendencies. Percentile guardrails (P5, P50, P95) provide pragmatic bounds for preoperative planning. CONCLUSIONS: This study provides the first MCF morphometric norms for Mexican adults to support safer, individualized Dolenc, Kawase, and middle fossa approach planning. CT-based measurements are largely reliable for surgical planning, although they slightly underestimate the Kawase approach reference points.