Comparison of gentamicin distribution in the inner ear following administration via the endolymphatic sac or round window

Objective/Hypothesis: The distribution of gentamicin in the inner ear via the endolymphatic sac (ES) or round window (RW) routes was investigated. Study Design: Experimental study. Methods: A fluorescent gentamicin-Texas Red conjugate (GTTR) was adopted to visualize the gentamicin. Adult guinea pigs were treated with GTTR applied to the ES or RW, the animals were allowed to recover for 3 days, then confocal microscopy was used to observe and quantify GTTR distributions in cochlear and vestibular sensory epithelium. Results: When GTTR was applied via the ES, strong GTTR labeling was observed in the vestibule while little GTTR was detected in the cochlea (P < .0001). However, distinct GTTR fluorescence was observed in the cochlea and vestibule following RW application (P = .7967). There was less GTTR labeling in cochlea via ES application than through RW administration (P < .0001). Conclusions: ES drug application may be preferable for the treatment of intractable Meniere's disease.