Clues for facial canal dehiscence in chronic otitis media.

Introduction And Objectives: The goal of this study was to determine the impact of external and middle ear findings in the incidence of facial canal dehiscence (FCD) during mastoidectomy for chronic otitis media.

Material And Methods: We examined the operative details of 186 patients who underwent primary tympanomastoidectomy for chronic otitis media between January 2015 and January 2020 retrospectively. In this study we only evaluated the second portion of the facial nerve canal.

Results: The global prevalence of FCD was 22.6% (42/186 patients) with a higher incidence, of 38.7% (36/93), in patients with chronic otitis media with cholesteatoma (C-COM). Associations were found between facial canal dehiscence, labyrinthine fistula (p˂ .001) and facial nerve paralysis (p˂ .001). Ossicular erosions were observed at a significant level in patients with facial canal dehiscence, the incidence of FCD was significantly higher (p=.005, Odds ratio 5.489) when malleus and incus were eroded, incus plus stapes were eroded (p=.014; OR 4.059) and malleus, incus, and stapes together were eroded (p=.002; OR 4.929).

Conclusions: This study revealed an incidence of facial canal dehiscence of 22.6%. It also revealed that the presence of lateral semicircular canal fistula is associated with a higher prevalence of facial canal dehiscence. The same was noted in the case of some ossicular erosions, especially the combinations of eroded malleus and incus, incus and stapes, and all 3 ossicles. These findings raise awareness about the usefulness of middle ear findings in predicting FCD, thus providing valuable information for the otological surgeon to avoid iatrogenic injuries.