Photochemically induced double lateral wall lesions in the guinea pig cochlea.
OBJECTIVE
Multiple patches of atrophy have been reported in the stria vascularis (SV) in elderly persons with presbycusis The aim of this study was to investigate the correlation between sensorineural hearing loss and this strial condition.


METHODS
We established a new animal model comprising two small lesions in the SV in the second turn of the cochlea by means of photochemical reaction. Using this model, we investigated morphological and physiological changes in the cochlea at 3, 7 and 14 days after SV damage.


RESULTS
Scanning electron microscopy studies revealed that the strial cells between the two damaged areas of the SV remained intact, although the outer hair cells (OHCs) facing the intact SV area were damaged. Furthermore, damage to the first and second rows of OHCs gradually progressed throughout the 14-day observation period. The endocochlear potential (EP) measured at a point midway between the 2 lesions at 3 and 7 days was found to be significantly lower compared with control values, but had returned to a normal level at 14 days


CONCLUSIONS
The reversible EP change and localized OHC loss seen in the present investigation may help to understand acute idiopathic or progressive sensorineural hearing loss.
Department of Otolaryngology, Hamamatsu University School of Medicine, Hamamatsu, Japan. tamotsu@smz.ja-shizuoka.or.jp
Tamotsu
T
Takeshita
Satoshi
S
Iwasaki
Mitsuyoshi
M
Nagura
Takahiro
T
Watanabe
Kazuo
K
Umemura
Tomoyuki
T
Hoshino
D000818:Animals; D015834:Cochlear Diseases / Q000139:chemically induced / Q000473:pathology* / Q000503:physiopathology*; D003055:Cochlear Microphonic Potentials / Q000187:drug effects; D005456:Fluorescent Dyes / Q000008:administration & dosage; D006168:Guinea Pigs; D006199:Hair Cells, Auditory, Inner / Q000187:drug effects; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects; D008297:Male; D008855:Microscopy, Electron, Scanning; D023421:Models, Animal; D010777:Photochemistry; D012395:Rose Bengal / Q000008:administration & dosage; D013316:Stria Vascularis / Q000187:drug effects / Q000473:pathology*; D013997:Time Factors
D005456:Fluorescent Dyes; D012395:Rose Bengal