Ventral approach to rat inner ear preserves cochlear function.

Conclusion: This technique enabled us to visualize the cochlea without causing damage.

Objective: The mammalian inner ear is difficult to approach surgically. This is particularly true in the cases of the rat and mouse, which both have small cochleae. Rat and mouse research is particularly important because their genomes are well characterized, and significantly similar to that of the human. The aim of the present study was to develop a method of accessing the rat cochlea without affecting its function.

Materials And Methods: In the ventral approach, a small hole was made for access to the scala tympani. Cochlear function was assessed through auditory brainstem response (ABR) threshold measurements.

Results: The ventral approach enabled the direct visualization of the tympanic bulla. Thus, the tympanic bulla could be easily opened in a manner that was benign to cochlear function. There was no significant difference in ABR threshold before and after surgery.