RESUMO
CONCLUSION: This technique enabled us to visualize the cochlea without causing damage. OBJECTIVE: The mammalian inner ear is difficult to approach surgically. This is particularly true in the cases of the rat and mouse, which both have small cochleae. Rat and mouse research is particularly important because their genomes are well characterized, and significantly similar to that of the human. The aim of the present study was to develop a method of accessing the rat cochlea without affecting its function. MATERIALS AND METHODS: In the ventral approach, a small hole was made for access to the scala tympani. Cochlear function was assessed through auditory brainstem response (ABR) threshold measurements. RESULTS: The ventral approach enabled the direct visualization of the tympanic bulla. Thus, the tympanic bulla could be easily opened in a manner that was benign to cochlear function. There was no significant difference in ABR threshold before and after surgery.
Assuntos
Cóclea/fisiopatologia , Cóclea/cirurgia , Complicações Pós-Operatórias/fisiopatologia , Animais , Limiar Auditivo/fisiologia , Tronco Encefálico/fisiopatologia , Nervo Coclear/fisiopatologia , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Feminino , Células Ciliadas Auditivas/fisiopatologia , Masculino , Ratos , Rampa do Tímpano/fisiopatologia , Rampa do Tímpano/cirurgiaRESUMO
OBJECTIVE: To study sensitivity to impulse noise in guinea pig, rat and mice. METHODS: Six groups were divided. Group I: Guinea pigs (n = 5) were exposed to 50 impulses of 160 dB SPL; Group II: Guinea pigs (n = 5) were exposed to 100 impulses of 160 dB SPL; Group III: Guinea pigs (n = 5) were exposed to 200 impulses of 160 dB SPL; Group IV: Guinea pigs (n = 6) were exposed 400 impulses of 160 dB SPL; Group V: Rats (n = 10) were exposed to 50 impulses of 160 dB SPL; Group VI: Mice (n = 10) were exposed to 50 impulses of 160 dB SPL. ABR thresholds were determined prior to, immediately, one day, one week, two weeks and four weeks after impulse noise exposure. RESULTS: The rat and mice were shown temporary threshold shift (TTS) and permanent threshold shift (PTS) after 50 times impulse noise (160), while no TTS and PTS in the guinea pigs but it was shown TTS and PTS after 400 times impulse noise (160). CONCLUSIONS: Sensitivity to impulse noise is different among guinea pig, rat and mouse. Guinea pig has less sensitivity to impulse noise while rat and mouse have higher sensitivity to impulse noise. In addition, rat has higher sensitivity to impulse noise than mouse.