Vestibular neurectomy in the guinea-pig: a retrosigmoid approach

The efferent cochlear system, composed of both ipsi- and contralateral bundles, runs along with the vestibular nerve and may serve as protection for the inner ear. Sectioning of the vestibular nerve could thus create an experimental model for further in-depth study of such a protective role. A personal surgical approach is described, involving a suboccipital (or retrosigmoid) route to the postero-medial aspect of the guinea-pig temporal bone, chosen because of its use for the induction of endolymphatic hydrops in the same species. The crucial step in this approach is the separation of the sigmoid sinus in its entirety, through an intra-dural access with a minimal removal/retraction of cerebellar tissue. This did not affect either the post-operative recovery of the animal or its hearing threshold level as assessed via auditory brainstem responses.