Related Experiment Video
Updated: Aug 22, 2026
Cochlear Implant Surgery and Electrically-evoked Auditory Brainstem Response Recordings in C57BL/6 Mice
Published on: January 9, 2019
Effects of gentamicin on sensorineural elements of the cochlea in human temporal bones
Takeshi Kusunoki1, Sebahattin Cureoglu, Patricia A Schachern
1International Hearing Foundation, Minneapolis, MN, USA.
Purpose:
Gentamicin is commonly prescribed for treatment of gram-negative bacterial infections. It has, however, been known to have vestibulotoxic and ototoxic effects in humans. Previous studies were confounded by the use of other types of ototoxic drugs, higher than therapeutic doses, and prolonged time periods between gentamicin administration and death. The purpose of this study is to observe the effects of parenteral gentamicin administration on the sensorineural elements of the cochlea in which the previously described factors did not exist.
Materials And Methods:
Temporal bone specimens were divided into 2 groups. Group 1 included 16 "normal" temporal bones with no history or histopathologic findings of otologic disease or ototoxic drug administration, and group 2 included 17 temporal bones that received gentamicin treatment within 6 months before death. Temporal bones were excluded from group 2 if patients had histopathologic findings or history of otologic disease and/or other ototoxic drugs. All temporal bones were examined under light microscopy.
Results:
The percentages of intact outer hair cells in the basal turn was significantly greater in group 1 compared with group 2. There was no significant difference in hair cell number between the groups in the other turns. There was no significant difference in the number of spiral ganglion cells between groups in any turn.
Conclusion:
Although gentamicin is primarily considered to be vestibulotoxic, this study showed that gentamicin can damage sensorineural elements of the cochlea, even in younger patients. During the administration of this drug, hearing of the patient should be carefully monitored.
Insights
Gentamicin can harm cochlear sensory cells, impacting hearing. This study confirms cochlear damage from gentamicin, even without confounding factors, necessitating careful hearing monitoring during treatment.
Area of Science:
- Ototoxicology
- Neuroscience
- Otolaryngology
Background:
- Gentamicin is a common antibiotic for gram-negative infections.
- Previous research on gentamicin's ototoxicity was limited by confounding factors.
- Gentamicin is known for potential vestibulotoxicity and ototoxicity.
Purpose of the Study:
- To investigate the ototoxic effects of parenteral gentamicin on cochlear sensorineural elements.
- To examine gentamicin's impact in the absence of confounding variables like other ototoxic drugs or prolonged administration periods.
Main Methods:
- Analysis of temporal bone specimens from two groups: control (no gentamicin) and gentamicin-treated.
- Exclusion of specimens with pre-existing otologic disease or exposure to other ototoxic drugs.
- Light microscopy examination of cochlear structures.
Main Results:
- A significant reduction in intact outer hair cells in the basal turn of gentamicin-treated temporal bones.
- No significant differences in hair cell numbers in other cochlear turns between groups.
- No significant difference in spiral ganglion cell counts between the control and gentamicin groups.
Conclusions:
- Gentamicin can cause cochlear damage, specifically affecting outer hair cells in the basal turn.
- This cochlear damage can occur even in younger patients and without confounding factors.
- Close audiological monitoring is recommended during gentamicin therapy to detect potential hearing loss.
Related Concept Videos
01:13The Cochlea
01:22Hair Cells