The neuronal control mechanisms of the middle ear pressure regulation

In recent years, two mechanisms have been brought to the fore which have been thought to play an effective role in regulating the middle ear pressure and controlled through neuronal reflex. These mechanisms are based on the principle that the baroreceptors located on the middle ear cavity and the mechanoreceptors on the tympanic membrane perceive the pressure changes in the middle ear cavity and control the Eustachian tube function through the brain stem. This study aims to define the role of the neuronal mechanisms mentioned above. With this objective, lidocaine has been administered to tympanic plexus and tympanic membrane, which are thought to form the afferent plexus of the reflex arc, in various patient groups. Then, the Eustachian tube functions forming the efferent plexus of the reflex arc with the blocked afferent plexus were evaluated. Three groups were created for this purpose: volunteers that had their tympanic membrane perforation observed during the autoscopic examination, and Eustachian tube dysfunctions were not observed, were classified as Group 1. Lidocaine was applied on the patients? promontorium and afterwards the Eustachian tube functions were re-evaluated. Adult volunteers that were observed for tinnitus complaints with natural autoscopic examinations and Eustachian tube dysfunctions were not observed were classified as Group 2. Intratympanic lidocaine was applied on the volunteers and after the administration the Eustachian tube functions were reassessed. Group 3 consisted of healthy, adult volunteers that had a natural autoscopic examination and an Eustachian tube dysfunction was not observed. A topical administration of lidocaine was applied on the volunteers? tympanic membranes and after the application the Eustachian tube functions were re-evaluated. The results of this study have shown that: 1. The Eustachian tube function is controlled neuronally. 2. In this neuronal control mechanism, it is highly possible that the baroreceptors established in the tympanic plexus and middle ear mucosa have an effective role. 3. In the neuronal control of the Eustachian tube function, the efficacy of the baroreceptors on the tympanic membrane seems to be minor. Since a method that would incorporate the anaesthesia of all tympanic membrane segments has not been employed in this research, definite results remain unattained.