Correlation of mastoid air cells with area of the entrance to the facial recess and location of the vertical segment of the facial nerve.

Objective: This study sought to analyze the correlational relationships between mastoid air cells, the area of the facial recess entrance, and the location of the vertical segment of the facial nerve.

Methods: CT scans of 60 ears from 30 patients were analysed. We used MIMICS to obtain inner ear coordinates in CT images. Mastoid air cells were analysed using CT value thresholds to classify them into three groups based on volume: Group A (< 5 mL), Group B (5-8 mL), and Group C (> 8 mL). The coordinates of the inner ear structures were entered into MATLAB to calculate the area of the entrance to the facial recess and the distance from the vertical segment of the facial nerve to the standard coronal and median sagittal planes.

Results: No significant differences in mastoid air cells volume between gender or side; the entrance area of the facial recess did not differ significantly among Groups A, B, and C; there was no significant relationship between the midpoint of the vertical segment of the facial nerve and the median sagittal plane (P > 0.05). However, the distance from the posterior point of the annulus to the midpoint pyramidal segment of the facial nerve and the distance between the midpoint of the vertical segment of the facial nerve and the standard coronal plane decreased progressively in Groups A, B, and C (P < 0.05).

Conclusion: The analyses showed no link between mastoid air cells volume and gender, side, or area of the facial recess entrance. Better mastoid pneumatisation correlates with a closer proximity of the annulus to the facial nerve and a more anterior position of the vertical segment of the facial nerve.