Ultrastructural and Electrophysiologic Changes of Rat Cochlea after Irradiation
Version of Record online: 3 JAN 2009
Copyright © 2004 The Triological Society
Volume 114, Issue 7, pages 1276–1280, July 2004
How to Cite
Akmansu, H., Eryilmaz, A., Korkmaz, H., Sennaroğlu, G., Akmansu, M., Göçer, C. and Tatar, İ. (2004), Ultrastructural and Electrophysiologic Changes of Rat Cochlea after Irradiation. The Laryngoscope, 114: 1276–1280. doi: 10.1097/00005537-200407000-00025
- Issue online: 3 JAN 2009
- Version of Record online: 3 JAN 2009
- Manuscript Accepted: 23 JAN 2004
- otoacoustic emissions;
- electron microscopy
Objective/Hypothesis: To determine the acute and subacute cochlear effects of sublethal total body irradiation.
Study Design: The study was designed prospectively as a Sprague-Dawley (SD) rat model with otoacoustic emission measurement.
Methods and Materials: Ten rats and 20 ears were included in the study. Distortion product otoacoustic emission (DPOAE) measurements were performed under ketamine anesthesia before and 1 to 8 weeks after sublethal dose total body irradiation. Eight and six rats survived at the first and eighth week measurements, respectively. The frequency bandwidth was set to 1,067 Hz (referenced to f1) – 9,512 Hz (referenced to f2) (2f1 − f2 = 832 − 6,076 Hz) and eight points were sampled per octave, but low-frequency (<2,549 Hz [referenced to 2f1 − f2]) results were not included in the analysis. Averages were obtained at each frequency, and statistical analysis was performed to compare the pre-and postradiation values. Then, three of the rats were killed for transient electron microscopy (TEM) of the temporal bones.
Results: The posttreatment DPOAEs at almost all frequencies showed a trend toward decline at both the first and eighth weeks, but significant reduction was only detected at 3,600 and 3,961 Hz (referenced to 2f1 − f2) in the first week. TEM of the cochlea revealed ultrastructural changes in the outer hair cells (OHCs) and stria vascularis of the basal turn. The cochlear ganglion nuclei and cochlear nerve axons were unaffected.
Conclusion: Radiation can affect the cochlea in the acute phase at the mid to high frequencies; further prediction for long-term effects requires longer follow-ups.