Changes in electrovestibular brainstem responses after aminoglycoside intoxication in guinea pigs.
OBJECTIVE
To verify the usefulness of short-latency vestibular responses evoked by a combination of round window electrical stimulation and sinusoidal rotation (electrovestibular brainstem responses; EVBRs) as a new monitoring tool of the vestibular function in animal experiments.


METHODS
EVBRs were obtained before, during, and after treatment with aminoglycosides, along with compound action potential (CAP) audiograms. The changes in EVBRs were compared with morphological changes observed by scanning electron microscopy.


RESULTS
EVBR amplitudes did not change in the group of guinea pigs treated with amikacin, but markedly decreased in the streptomycin and gentamicin- treated groups. CAP audiograms indicated a significant threshold elevation in the amikacin group, a moderate elevation in the gentamicin group, and no change in the streptomycin group. Under scanning electron microscopy, the loss of the sensory hair cells observed in the cristae ampullares was slight to moderate in the amikacin group, moderate to severe in the streptomycin group, and severe in the gentamicin group.


CONCLUSIONS
EVBRs reflect overall pathological changes undergone by vestibular hair cells, and support the vestibular specificity of EVBRs.
Sugasawa
K
K
Department of Otolaryngology, Faculty of Medicine, Tokyo University, 1-6-7 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. keisuga-tky@umin.ac.jp
Charlet de Sauvage
R
R
Lima da Costa
D M
DM
Erre
J P
JP
Sugasawa
M
M
Aran
J M
JM
D000200:Action Potentials / Q000502:physiology; D000617:Aminoglycosides; D000818:Animals; D000900:Anti-Bacterial Agents / Q000633:toxicity*; D001933:Brain Stem / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D003051:Cochlea / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006168:Guinea Pigs; D008855:Microscopy, Electron, Scanning; D010812:Physical Stimulation; D012399:Rotation; D014722:Vestibule, Labyrinth / Q000187:drug effects* / Q000473:pathology / Q000502:physiology
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents