Diagnosis and Tests of Function

In this chapter, I describe the available diagnostic procedures and tests of the structure and function of the Eustachian tube system. In other chapters in this text, I briefly refer to many of these procedures in describing certain aspects of the anatomy, physiology, and pathophysiology of Eustachian tube function and dysfunction and the tubal system’s role in pathogenesis of otitis media and related diseases and disorders. In the following two chapters, I discuss the role of the Eustachian tube in management in which some of these tests have also been alluded to but not described in detail. The reader is advised to use this chapter as a reference for a more comprehensive description of the available diagnostic tests and procedures when reviewing these other chapters. As I discuss in this chapter, several of these tests are fairly accurate in distinguishing between normal and abnormal structure and function of the Eustachian tube system, but none are truly physiologic because most only measure a short period in an individual’s life and some are invasive. The most physiologic assessment of the function of the tubal system is to observe the status of the individual patient and his or her ears, when the tympanic membranes are intact, over a relatively prolonged period of time. The best test is how is the patient doing? But because some middle-ear diseases and disorders are relatively asymptomatic (silent), periodic evaluation of the patient is prudent. The methods described are presented related to the access to the middle ear (intact vs nonintact tympanic membrane) because the testing will not be the same. Also, assessment of the nasopharyngeal end of the tube is dependent on the age and cooperation of the patient. Methods to assess the ventilatory function of the system are readily available to the clinician and should be performed when indicated (described later). Also, function tests available for clinical and laboratory studies are presented. The ventilatory function is the most important of the three functions because adequate hearing depends on relatively equal air or gas pressure on both sides of the tympanic membrane being maintained. In addition, impairment of the pressure regulation function can result not only in middle-ear underpressures and symptoms of Eustachian tube dysfunction but also otitis media and certain related diseases (such as perforation of the tympanic membrane) and disorders (atelectasis or retraction pocket). Tests to assess the protective and clearance functions are also addressed.