Pneumatisation patterns surrounding the internal acoustic meatus

Area of Science:

• Otorhinolaryngology
• Neurosurgery
• Radiology

Background:

• Temporal bone pneumatization is a common anatomical variation.
• Understanding pneumatization patterns around the internal acoustic meatus (IAM) is vital for skull base surgery.
• Previous studies have not comprehensively detailed IAM-adjacent pneumatization across its distinct regions.

Purpose of the Study:

• To determine the prevalence and anatomical distribution of temporal bone pneumatization surrounding the internal acoustic meatus (IAM).
• To assess pneumatization in the porus acusticus internus, proper IAM, and fundus.
• To investigate the relationship between IAM-adjacent pneumatization and overlying tegmen thickness.

Main Methods:

• Cone-beam computed tomography (CBCT) analysis of 160 internal acoustic meatuses (IAMs) from 80 patients.
• Subdivision of the IAM into medial (porus), mid (proper IAM), and lateral (fundus) portions.
• Assessment of pneumatization on superior, inferior, anterior, and posterior walls, with tegmen thickness measurements.

Main Results:

• Superior wall pneumatization was observed in approximately 23% of sides.
• Inferior wall pneumatization was absent in over 50% of cases; posterior wall pneumatization was largely absent.
• Pneumatized regions exhibited significantly greater tegmen thickness (p < 0.001).

Conclusions:

• Temporal bone pneumatization adjacent to the IAM predominantly involves the superior wall.
• Increased tegmen thickness is associated with IAM-adjacent pneumatization.
• Findings enhance understanding for safer skull base surgical approaches and neurotological procedures.