Vestibulo-ocular reflex (VOR) in guinea pigs. Impairment induced by aminoglycoside antibiotics.

The vestibulo-ocular reflexes (VORs) were studied in guinea pigs receiving daily administration of aminoglycoside antibiotics. The vestibular epithelia were also examined by scanning electron microscope technique (SEM). The treatment with aminoglycosides led to varying degrees of VORs according to (i) the type of aminoglycoside drug; (ii) the duration of the treatment and, (iii) the sensitivity of the various vestibular receptors. Gentamicin caused an earlier and severe reduction of the VOR gain. Dibekacin also caused evident damage, but the onset of its action was delayed. Both drugs affected mainly the vertical responses. Tobramycin and netilmicin altered the VORs slightly. Histological examination revealed damage to the sensory epithelia corresponding to the observed VOR impairments.