Incidence of fallopian canal dehiscence at surgery for chronic otitis media.

The objectives of this study were to determine the incidence and locations of dehiscence of the fallopian canal (FC) in patients undergoing surgery for different middle ear pathologies and to describe the findings that will aid in pre-operative prediction of dehiscence. Charts and operative details of the 118 ears managed with canal wall-down and 147 ears managed with canal wall-up tympanomastoidectomy performed by a single surgeon were retrospectively reviewed. The distribution of the diagnoses for ears that were operated was as follows: 118 ears cholesteatoma, 42 ears adhesive otitis, 23 ears tympanosclerosis, and 82 ears chronic otitis media. The presence and the location of facial nerve dehiscence after exenteration of the disease as well as the presence of any coexisting inner ear fistula and dural defect were noted. FC dehiscence was observed in 56 of the cases. The incidence of dehiscence was highest among ears with cholesteatoma (n = 44, P < 0.05). Adults and also male patients in the study had significantly higher incidence of dehiscence compared to pediatric (P < 0.05) and female (P < 0.01) patients. The most common location for dehiscence was the tympanic segment which was significantly higher than the other locations (P < 0.01). Among the ears with FC dehiscence, labyrinthine fistula presence was seen in ten ears which was also significant (P < 0.001). Patients with dural exposure were 12.06 times more likely to have FC dehiscence than those without dural exposure. The incidence of FC dehiscence was 1.26 times higher in revision operations, but the difference was not significant (P > 0.05). An otologic surgeon should be more careful while performing operation for cholesteatoma in an adult and male patient because of the high incidence of dehiscence observed in these ears. Presence of lateral semicircular canal fistula and erosion of the bony tegmen should also be considered as a clue for the presence of dehiscence before surgery. Operation of these ears should be performed by experienced surgeons in otology.