The intra-aural muscle reflex in retrocochlear pathology: a model study in the rabbit.

An animal model for the evaluation of the acoustic stapedius reflex is described. The intra-aural muscle reflex in the rabbit can be recorded with a technique identical to that used in man. The validity and reproducibility of the measurements are good. Lesions in the reflex pathway were shown to be followed by changes in reflex properties. The type of alteration depended on the location of the damage. Lesions in the dorsal cochlear nucleus were not followed by reflex changes. Lesions in the ventral cochlear nucleus and/or the eighth nerve were followed by a rise of reflex threshold and often, but not always, by reflex decay. Lesions in the midline of the trapezoid body were followed by specific changes in the crossed reflex, whereas the ipsilateral reflex was unaffected. The advantage of making simultaneous ipsilateral and contraleral reflex recordings was pointed out.