Przegląd badań ruchomości układu przewodzącego dźwięk w uchu środkowym za pomocą laserowej wibrometrii dopplerowskiej

Abstract

Summary Introduction The authors present the results of the work published between 1980–2011 affecting various aspects of sound conduction system measurements in the middle ear performed using Laser Doppler Vibrometry. Aim : The aim of this study was to analyze the methodology and results of measurements: the tympanic membrane, the ossicular chain, and its reconstruction, the round window in the published medical literature and their comparison with the results of experiments performed at Department of Otolaryngology, Medical University of Warsaw. Method and materials In the study were analyzed results of 30 publications related to the conductivity measurement in the middle ear using a Laser Doppler Vibrometry. In 20 of these research are described experiments on harvested human temporal bones, 10 – in vivo . The acoustic conductivity of the middle ear elements were measured on the eardrum, anterior and posterior branch of the stapes, incudo-stapedial joint, round window, different types of ossicular chain prosthetic. In each experiment, was used Laser Doppler Vibrometer. Results In most of publications authors have focused on determining the correct methodology of the study. In theoretical and experimental considerations, the authors showed that the results of measurements performed on fresh-frozen preparations of temporal bones are closest to the results obtained in vivo. Chien showed no significance influence of the laser beam angle on measurement in cases with approach with antromastoidectomy and posterior tympanotomy. Whittemore has proved that does not need to use a reflective element on the measuring point during surgery. In Asai, Heiland, Chien publications, authors noticed the biggest velocity of the back branch of the stapes at 1000 Hz, which was confirmed in research of the Department of Otolaryngology. Velocity of the tympanic membrane umbo differed considerably between publications. Conclusion Laser Doppler Vibrometry still needs to be clarified. Published results of measurements are often difficult to compare because of the lack standardization of experimental conditions. Changing the angle of the laser beam should not change significantly velocity amplitude obtained intraoperatively. For adequate sensitivity of a response, it is necessary to use reflective element. Anterior and posterior branch of the stapes, round window membrane are available for laser Doppler Vibrometry during surgery. Most preferred position of a measurement is posterior branch of the stapes. Reconstruction of ossicular chain changes the characteristics of the middle ear conduction system. These observations provide a starting point to develop an optimal procedure for air-bone gap closure. Based on the results of our research has been developed algorithm of intraoperative ossiculoplasty modification depending on the results of Laser Doppler Vibrometry measurements.