The intra-operative incidence of Fallopian canal dehiscence during surgery for cholesteatoma: a prospective case–control study and review of the literature

Objective To investigate Fallopian canal dehiscence (FCD) during cholesteatoma surgery. Study design Prospective case–control study. Patients Four hundred and one patients with cholesteatoma and 172 with otosclerosis. Interventions Therapeutic. Setting District general hospital. Main outcome measures (i) Intra-operative incidence of FCD during (a) surgery for cholesteatoma versus a homogeneous control group (patients with otosclerosis); (b) revision surgery for cholesteatoma as compared to primary surgery. (ii) Intra-operative incidence of a fistula if FCD is present. Results Data were prospectively collected and analysed using chi-square tests. FCD was found in 19% of cases versus 5.2% of controls. Intra-operative incidence of (i) FCD during cholesteatoma surgery versus otosclerosis surgery was statistically very highly significant (P < 0.0001, OR = 5.43); (ii) FCD during revision versus primary cholesteatoma surgery was not statistically significant (P = 0.83); and (iii) encountering a fistula in the presence of FCD during cholesteatoma surgery was statistically very highly significant (P < 0.0001, OR = 6.71). Conclusions A surgeon is more likely to encounter FCD during cholesteatoma surgery than in stapes surgery. If during cholesteatoma surgery FCD is found, then a fistula is also more likely to be present, mainly of the semicircular canal. The incidence of FCD is not increased in revision surgery. These findings are very relevant for any otologist undertaking cholesteatoma surgery.