To evaluate mastoid pneumatisation and facial canal dimensions.

In this retrospective study, 169 multidetector computed tomography scans of temporal bone were reviewed. Facial canal dimensions were evaluated at the labyrinthine, tympanic and mastoid segments using axial and coronal multidetector computed tomography scans of temporal bone. Mastoid pneumatisation and facial canal dehiscence were evaluated. Facial canal dehiscence was measured if it was found to be present.

This study showed that facial canal dimensions decreased in pneumatised mastoids. Facial canal dimensions in females were smaller than in males. Facial canal dehiscence was detected in 5.9 per cent and 6.5 per cent of the patients on the right and left sides, respectively. No correlations were found between facial canal dehiscence and mastoid pneumatisation. The length of dehiscence was 1.92 ± 0.44 mm (range, 0.86–2.51 mm) on the left side. In older subjects, left facial canal dehiscence was detected more, and the length of the dehiscence increased.

This study concluded that during surgery, facial canal dehiscence should be kept in mind in order to avoid complications.