[Evaluation of hearing in patients with otospongiosis based on direct measurement of bone conduction].

The conventional bone conduction audiometry does not allow an objective assessment of hearing in patients with otospongiosis. We evaluated a new method of direct bone conduction audiometry with the stimulator applied to the promontory intraoperatively. A comparison of conventional and direct bone conduction audiometry thresholds was made in 100 patients in various stages of otospongiosis before stapedectomy. A significant correlation between hearing thresholds obtained by both methods was observed for all frequencies tested (500, 1000, 2000 and 4000 Hz). The direct bone conduction method was at least 30 dB more sensitive for all frequencies. Interestingly, the average direct bone conduction threshold curve did not exhibit a Carhart notch at 2000 Hz compared to the conventional method. We concluded that our bone conduction technique enabled a better assessment of cochlear reserve in patients with otospongiosis.