Middle ear gentamicin-soaked pledgets in the treatment of Ménière's disease

Perilymph pharmacokinetics of locally-applied gentamicin in the guinea pig

Intratympanic gentamicin therapy is widely used clinically to suppress the vestibular symptoms of Meniere's disease. Dosing in humans was empirically established and we still know remarkably little about where gentamicin enters the inner ear, where it reaches in the inner ear and what time course it follows after local applications. In this study, gentamicin was applied to the round window niche as a 20 μL bolus of 40 mg/ml solution. Ten 2 μL samples of perilymph were collected sequentially from the lateral semi-circular canal (LSCC) at times from 1 to 4 h after application. Gentamicin concentration was typically highest in samples originating from the vestibule and was lower in samples originating from scala tympani. To interpret these results, perilymph elimination kinetics for gentamicin was quantified by loading the entire perilymph space by injection at the LSCC with a 500 μg/ml gentamicin solution followed by sequential perilymph sampling from the LSCC after different delay times. This allowed concentration decline in perilymph to be followed with time. Gentamicin was retained well in scala vestibuli and the vestibule but declined rapidly at the base of scala tympani, dominated by interactions of perilymph with CSF, as reported for other substances. Quantitative analysis, taking into account perilymph kinetics for gentamicin, showed that more gentamicin entered at the round window membrane (57%) than at the stapes (35%) but the lower concentrations found in scala tympani were due to greater losses there. The gentamicin levels found in perilymph of the vestibule, which are higher than would be expected from round window entry alone, undoubtedly contribute to the vestibulotoxic effects of the drug. Furthermore, calculations of gentamicin distribution following targeted applications to the RW or stapes are more consistent with cochleotoxicity depending on the gentamicin concentration in scala vestibuli rather than that in scala tympani.

Simultaneous Labyrinthectomy With Cochlear Implantation in Patients With Bilateral Ménière’s Disease

Objective:

The development of second-side Ménière’s disease in the only remaining serviceable ear is difficult to treat. We describe an intervention to control disabling disease combining a labyrinthectomy and cochlear implant to restore hearing.

Methods:

Following a thorough preoperative assessment and consenting process, 2 patients underwent labyrinthectomy of the affected ear with simultaneous cochlear implantation.

Results:

Both patients achieved control of Ménière’s attacks with improved hearing rehabilitation. Oscillopsia was noted by both patients. Both patients were pleased to have undergone the treatment.

Conclusion:

Severe symptomatic second-side Ménière’s disease in the only hearing ear is uncommon. We report the successful treatment of 2 patients in this difficult management scenario, by simultaneous surgical labyrinthectomy and cochlear implantation. We propose this as a potential management strategy in this rare but complex group of patients in whom all less destructive measures have failed.