Histological effects of intratympanic gentamicin on the vestibular organ of guinea pigs.

BACKGROUND: Transtympanic administration of gentamicin may be suitable to achieve unilateral vestibular ablation, in order to control unilateral Ménière's disease. In low doses, gentamicin appears to affect selectively the vestibular system, with relative sparing of the cochlea. An experimental study on guinea pigs was conducted to determine what single dose of gentamicin would produce a unilateral vestibular organ lesion when applied to the middle ear. STUDY DESIGN: Experimental and prospective. METHODS: Four groups of guinea pigs received different gentamicin doses (1, 5, 10 and 25 mg) administered to the middle ear. The animals' vestibular organs were then assessed by scanning electron microscopy, in order to quantify the level of vestibular damage. RESULTS: Study of the utricular macula and the ampullar crista of the lateral semicircular canal revealed vestibular neuroepithelial lesions in all infused ears. CONCLUSIONS: The severity of the vestibular neuroepithelial lesions was dose-dependent. Lower gentamicin doses were observed to damage vestibular structures more than cochlear structures.

Hair cell loss and regeneration in the chick cochlea after treatment with gentamicin.

Hair cells can be damaged by countless agents, among them aminoglycoside antibiotics. In the chick cochlea, the hair cell loss can be recovered by regeneration. The objectives of the present investigation were to study the time progression of injury caused by gentamicin and the regeneration process in chick hair cells. Gentamicin was administered in a single subcutaneous dose of 125 or 250 mg/kg to two groups of 3-day old chicks. The cochleae were processed for analysis by scanning electron microscopy on the 1st, 3rd, 5th and 20th day after injection. The cellular sequence of degeneration and regeneration was studied. On the 20th day, most it he damaged cochlear area showed regenerated hair and support cells. Stereocilia and microvilli were observed on the apical surface of the regenerated hair cells.

Hair cell loss and regeneration in the chick cochlea after treatment with gentamicin.

Hair cells can be damaged by countless agents, among them aminoglycoside antibiotics. In the chick cochlea, the hair cell loss can be recovered by regeneration. The objectives of the present investigation were to study the time progression of injury caused by gentamicin and the regeneration process in chick hair cells. Gentamicin was administered in a single subcutaneous dose of 125 or 250 mg/kg to two groups of 3-day old chicks. The cochleae were processed for analysis by scanning electron microscopy on the 1st, 3rd, 5th and 20th day after injection. The cellular sequence of degeneration and regeneration was studied. On the 20th day, most it he damaged cochlear area showed regenerated hair and support cells. Stereocilia and microvilli were observed on the apical surface of the regenerated hair cells.