Selective resection of the semicircular canals of rabbits with preservation of hearing.

The goal of this investigation was to develop a method of surgical removal of the semicircular canals of the rabbit without induction of auditory impairment. Four different surgical techniques were utilized: i) fenestration of the lateral semicircular canal; ii) fibrin glue perfusion of the canal following fenestration; iii) removal of the lateral semicircular canal by drilling after fenestration and fibrin glue perfusion, and iv) removal of all three canals after fenestration and fibrin gluing. Brainstem auditory potentials were recorded repeatedly for up to 3 months after operation and demonstrated preservation of hearing in all rabbits in the first group and in 78% of the second group. In the third group the potentials could be recorded in 67% of the animals and showed a 20 dB deterioration of hearing. After removal of all three semicircular canals residual hearing could be recorded in 50% of the rabbits. These animals regularly showed a 30-40 dB deterioration of hearing. A precise microsurgical technique using fibrin glue and bone chips for interruption of the peri- and endolymph flow proved crucial for hearing preservation.