Reliability of Neuronavigation in Localizing the Internal Acoustic Canal during Middle Fossa Approach

Area of Science:

• Neurosurgery
• Anatomy
• Medical Imaging

Background:

• The middle fossa approach (MFA) is challenging due to imprecise landmarks and anatomical variations in the middle fossa floor.
• Accurate localization of the internal acoustic canal (IAC) is critical for surgical success during the MFA.

Purpose of the Study:

• To evaluate the reliability and utility of neuronavigation systems (NNS) during the MFA.
• To identify specific technical considerations for using NNS in the MFA.

Main Methods:

• Computed tomography (CT) scans (1mm thin-section) were performed on five human cadavers (10 sides).
• Structures including the IAC, vestibule, and cochlea were investigated under NNS guidance during simulated MFA.
• Superficial and deep landmarks were assessed for localization accuracy.

Main Results:

• NNS accurately localized superficial landmarks like the foramen spinosum and ovale.
• NNS could not directly localize deeper landmarks, such as the central IAC beneath the petrous apex.
• Orientation from the cochlea-vestibule junction guided precise bone removal over the IAC and medial-to-lateral drilling for IAC identification.

Conclusions:

• NNS is effective for the MFA, particularly for accurately localizing superficial landmarks on the middle fossa floor.
• Combining NNS with anatomical references like the cochlea-vestibule junction enhances IAC identification during the MFA.