To measure the outcomes of laser treatment of cholesteatoma covering cochlear and vestibular fistulas.

Cholesteatoma matrix over the fistula was denatured; the power density was sufficient only to gradually heat, but not vaporise, the keratin-forming matrix. The denaturing speed was controlled so that the integrity of the fistula cover was maintained. The change in bone conduction threshold and the residual rate of cholesteatoma at the fistula were measured.

Thirty-six fistulas were assessed. There were seven cochlear fistulas. All were 5 mm or less in maximum length. For the entire group, the average change in bone conduction threshold was −0.3 dB. For cochlear fistulas, the average change in bone conduction was + 0.2 dB. The distribution of hearing results for the entire group was Gaussian; the apparent changes in hearing could be attributed to errors associated with testing. All patients underwent second-stage surgery. In all cases, the cholesteatoma was completely cleared from the fistula site. There were no facial palsies.

Laser denaturing of cholesteatoma matrix over fistulas measuring 5 mm or less of vestibular apparatus and the cochlea is effective at eliminating cholesteatoma, and is not associated with cochlear hearing loss or facial palsy.