Changes in the Tullio phenomenon and the fistula sign in the course of endolymphatic hydrops.

We performed electronystagmography with caloric stimulation and studied vestibular evoked myogenic potentials (VEMPs) associated with changes in the Tullio phenomenon and the fistula sign during the clinical course of a patient with endolymphatic hydrops. The Tullio phenomenon and the fistula sign disappeared in association with a reduction in the caloric response, which implicates the ampullary function of the lateral semicircular canal. Even when no VEMP could be detected for the affected ear, the Tullio phenomenon and fistula signs were observed; thus, either these phenomena had a lower response threshold than the VEMPs, or saccular receptors were not involved in the Tullio phenomenon.