Medidas de imitância acústica de banda larga em indivíduos com otosclerose / Wideband acoustic immittance measurements in subjects with otosclerosis

Na prática clínica, nota-se uma dificuldade em identificar a rigidez do sistema tímpano-ossicular decorrente da Otosclerose por meio dos métodos de avaliação rotineiramente empregados. Assim, as medidas de imitância acústica de banda larga podem fornecer mais informações sobre a condição do sistema tímpano-ossicular por avaliarem uma ampla faixa de frequência. O objetivo do estudo foi caracterizar as medidas de imitância acústica de banda larga com os estímulos tom puro e chirp em indivíduos com diagnóstico de Otosclerose submetidos à estapedectomia ou estapedotomia. Foram avaliados 40 indivíduos na faixa etária de 33 a 80 anos, totalizando 54 orelhas operadas e 22 orelhas não operadas. A avaliação audiológica foi realizada por meio da otoscopia, audiometria tonal liminar, logoaudiometria e imitanciometria. As medidas de imitância acústica de banda larga foram obtidas por meio do sistema de medidas Middle-Ear Power Analyzer MEPA3, versão 5.0 (Mimosa Acoustics), utilizando os estímulos tom puro e chirp. Os dados obtidos foram submetidos à análise estatística descritiva e inferencial, com nível de significância de 0,05. As orelhas com Otosclerose apresentaram maior absorvância em 750 Hz, uma tênue diminuição até 3000 Hz, acentuando-se a partir desta frequência. A magnitude da admitância foi maior na faixa de frequência de 1992 a 4008 Hz, assim como a magnitude da impedância foi maior nas frequências baixas com diminuição até 4008 Hz e aumento em 6000 Hz. Estas orelhas foram dominadas pela rigidez nos sons graves e médios, por resistência entre 3000 e 4008 Hz e a partir desta frequência pela massa. A fase da impedância foi maior em 258 Hz e o delay da reflectância (slope) apresentou uma variação de comportamento entre as frequências, não sendo possível caracterizar um padrão de resposta. Conclui-se que há diferenças nas medidas obtidas nas orelhas com Otosclerose submetidas à cirurgia, quando analisadas as frequências baixas e médias, o que demonstra o impacto positivo da intervenção cirúrgica na funcionalidade do sistema tímpano-ossicular.(AU)

In clinical practice, there is a difficulty in identifying the rigidity of the tympano-ossicular system resulting from Otosclerosis through the routinely employed evaluation methods. Thus, wideband acoustic immitance measurements can provide more information on the condition of the tympanic-ossicle system by evaluating a wide frequency range. This study aimed at characterizing the wideband acoustic immitance measurements with the pure tone and chirp stimuli in individuals diagnosed with Otosclerosis submitted to stapedectomy or stapedotomy. Forty individuals aged 33 to 80 years were evaluated, totaling 54 operated and 22 non-operated ears. Audiology assessment was performed through otoscopy, pure-tone audiometry, logoaudiometry and imitanciometry. Wideband acoustic immitance measurements were obtained using the Middle-Ear Power Analyzer (MEPA3), version 5.0 (Mimosa Acoustics), by means of pure tone and chirp stimuli. Data were submitted to descriptive and inferential statistical analysis, with a significance level of 0.05. The ears with Otosclerosis presented a greater absorbance in 750 Hz, a slight diminution until 3000 Hz, being accentuated from this frequency. The admittance magnitude was higher in the frequency range from 1992 to 4008 Hz, as well as the impedance magnitude was higher in the low frequencies with a decrease up to 4008 Hz and an increase in 6000 Hz. These ears were dominated by rigidity in the low and medium sounds, by resistance between 3000 and 4008 Hz, and from this frequency, by the mass. The impedance phase was higher at 258 Hz and the reflectance delay (slope) showed a behavioral variation between the frequencies, a response not being characterized. It can be concluded that there are differences in the measurements obtained in Otosclerosis ears submitted to surgery, when the low and medium frequencies were analyzed, which demonstrates the positive impact of the surgical intervention on the tympano-ossicle system.(AU)

Early and late hearing outcomes after CO2 laser stapedotomy.

BACKGROUND: Carbon dioxide (CO) laser stapedotomy is now one of the standard surgical treatments for otosclerosis. However, there are little normative data of the course of postoperative hearing acuity and the course of postsurgical depression of cochlear function of this technique. OBJECTIVE: To compare the hearing outcomes between early (between 1 to 3 months) and late (more than 1 year) postoperative periods in otosclerotic patients who underwent CO2 laser stapedotomy. MATERIAL AND METHOD: The charts of 73 primary CO2 laser stapedotomy procedures performed at Bangkok Metropolitan Administration Medical College and Vajira Hospital between 1997 and 2005 were reviewed. Only patients with early postoperative audiometric data between 1 to 3 months and with long-term postoperative audiometric data more than 1 year were selected for inclusion in the present study. Any patients who underwent CO2 laser stapedotomy for diseases other than otosclerosis and those who had revision surgery were excluded from the present study. The early and the late postoperative hearing outcomes were compared using postoperative closure of air-bone gaps and postoperative sensorineural hearing loss at pure-tone average and different frequencies. RESULTS: A group of 26 patients who underwent 30 CO2 laser stapedotomies met the criteria for analysis. The hearing outcomes were followed at the early and the late postoperative periods for an average of 1.8 and 36.2 months, respectively. The present study indicated that closure of air-bone gaps at pure-tone average and individual frequencies began in the early postoperative period and continued to improve through the late postoperative period. Bone conduction hearing thresholds were stable even in the early postoperative follow-up and the improvement in bone conduction hearing thresholds at 1 and 2 kHz and worsening at 4 kHz were seen. CONCLUSION: After CO2 laser stapedotomy, the stability of cochlear function begins in the early postoperative period and remains stable through the late postoperative period. The conductive component of hearing thresholds continues to improve through the late postoperative period. Thus, the early postoperative hearing outcomes reflect a side effect of postsurgical sensorineural hearing loss and the long-term postoperative hearing outcomes determine the efficacy of this procedure.

Otosclerose clínica: estudo comparativo dos limiares de via ossea pré e pós-estapedectomia e do valor diagnóstico da timpanometria

Com o objetivo de estudar a variaçäo das curvas timpanométricas e dos limiares pós-otosclerose, foram selecionados 78 pacientes estapedectomizados. Verficou-se que na otosclerose clínica as curvas timpanométricas apresentam distribuiçäo homogênea, porém com maior fato de rigidez quando comparadas com as de indivíduos näo portadores de otosclerose. Nenhuma variaçäo significativa ocorreu entre os limiares de via óssea e pós-cirurgicos, assim como também näo houve ocorrência significativa de lesäo cirúrgica do ouvido interno causando perda auditiva sensorioneural