[Incidence of facial nerve dehiscence in mastoidectomy]

To describe the incidence and location of the facial nerve dehiscence (FND) in chronic suppurative otitis media patients with and without cholesteatoma.

360 patients (370 ears) who received canal wall down tympanomastoidectomy due to otitis media(145 ears without cholesteatoma and 225 ears with cholesteatoma) were analyzed retrospectively, in which the incidence and locations of FND was studied, and the relevance for FND, clinical features (age, disease duration, preoperative facial paralysis) and intraoperative findings (state of FND and lateral semicircular canal fistula), were analyzed.

The presence of FND was 31.6% of total surgical procedures and the locations of FND were the tympanic segment. The dehiscence was detected 28.4% (94/334) in adults, but 61.1% (22/36) in the patients 18 years and younger, the differences were statistical significance (P < 0.05). The dehiscence rate was 37.1% (104/280) and 14.4% (13/90) respectively, in the cases of disease duration more than and less than 5 years, with significant difference (P < 0.05). Facial nerve dehiscence was detected in 29 patients (20.0%) and 89(39.1%) in cases without and with cholesteatoma respectively (P < 0.05). Facial nerve prolapse over the oval window was 11.4% (42/370), with FND of 83.3% (35/42). The incidence of lateral semicircular canal fistula was 7.8% (29/370), with FND of 65.5% (19/29). The presence of preoperative facial paralysis with FND was 75.0% (18/24), and that without FND was 28.6% (99/346), the differences were statistical significance (P < 0.05).

The incidence of FND most commonly located at the tympanic segment. The facial nerves should be taken much care in mastoidectomy for patients with cholesteatoma, preoperative facial paralysis and lateral semicircular canal fistula, as well as long disease duration.