A negative potential is occasionally recorded in humans and animals with profound deafness during\nbrainstem auditory evoked potential (BAER) tests if loud intensities are used. This acoustically evoked short latency\nnegative response (ASNR) is hypothesized to be of saccular origin. The sensitivity to sound of vestibular end organs\nis also used to produce vestibular evoked myogenic potentials (VEMP), a test that evaluates vestibular function. The\nsame saccular origin is accepted also for VEMP.\nCase presentation: A neutered male white domestic short hair cat presented with profound deafness and an\nASNR in the left ear during BAER test performed when he was 8 months old. BAER tracings were substantially\nunchanged at the age of 12 years, immediately before euthanasia that was requested by the owner for the\npresence of an unrelated neoplastic disorder. The cat underwent a complete post-mortem necropsy including\nhistopathology of the middle and inner ears. Histopathologic results confirmed the presence of a cochleosaccular\ndegeneration of the left ear while the cochlea and sacculus of the right ear and the utriculus and semicircular\ncanals of both ears were histologically normal.\nConclusions: This case report describes the auditory and histopathologic findings of a cat that showed an ASNR\nduring BAER test despite the presence of cochleosaccular deafness. These results confirm that a saccular origin for\nthe ASNR in this case, and in general in cats and dogs with congenital deafness associated with white\npigmentation, is improbable. The hypothesis that the sacculus is the vestibular end organ responsible for the\ngeneration of the ASNR and VEMP in humans comes mainly from animal studies. The findings in this report may\nchange the clinical interpretation of the results of BAER and VEMP not only in companion animals, but in humans\nas well.
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