RESUMEN
OBJECTIVES: One of the risks in middle ear surgery is high frequency hearing loss. It is believed that manipulations on the middle ear ossicles with the instruments may cause overstimulation of the inner ear and damage of the hear cells. Controversy arises whether temporary separation of the ossicles has any impact on middle ear transfer function and hearing threshold after surgery. The aim of the study is to evaluate the influence of incudostapedial joint (ISJ) separation on middle ear function in an experimental model. METHODS: With the use of single point laser Doppler vibrometer (LDV) stapes velocity in the intact chain and after ISJ separation was measured in 5 fresh human cadaver temporal bones. RESULTS: In all cases there was a decrease in stapes velocity after ISJ separation. Mead stapes velocity was reduced for 1 dB in 800 Hz to 9 dB in frequencies above 1,000 Hz. The decrease of velocity was greater in higher frequencies. CONCLUSION: Separation of the ISJ does not reduce significantly the middle ear function.
Asunto(s)
Humanos , Cadáver , Oído Interno , Oído Medio , Audición , Pérdida Auditiva , Articulaciones , Flujometría por Láser-Doppler , Modelos Teóricos , Estribo , Hueso TemporalRESUMEN
It is desirable to use more safe, objective, non-invasive method than visual scoring for the evaluation of irritation reaction and determine the optimum eoncentration of sodium lauryl sulfate(SLS) as a positive irritant control in routine patch test. In this study, SLS was applied to the volar forearm of ll non-atopic, healthy volunteers in concentrations of 0.5, 1.0, 2.0, and 5.0% under occlusion for 24h. The blood flow in test sites exposed to SLS was tecorded by laser Doppler velocimetry (LDV). The test sites were scored visually and the skin blood flow was measured at 24h, 48h, and 72h after the application of FiLS. We obtained the following results,' 1. There was a good correlation between visual scoring and skin blood flow using LDV(p = 0.4547). 2. 5.0% SLS could be used as a positive irritant control in routine patch test (p<0,05).