Immitance audiometry.
Immitance audiometry is a safe, simple, reliable, and relatively objective method of determining middle-ear function that provides advantages for examining the difficult patient because minimal cooperation is needed. Acoustic-immitance measurements obtain sophisticated data that give us valuable information about the middle ear mechanism as a whole. It can be used in a quiet office environment. Immitance audiometry can confirm a doubtful otoscopic diagnosis and screen for ear disease. There are limitations to observer reliability with otoscopy, which has good sensitivity but poor specificity, in contrast to immitance audiometry. The tympanogram can be classified into four different patterns on the basis of its characteristics. These patterns are diagnostic, distinguishing normal function from various types of middle ear pathology. Immitance audiometry has very high sensitivity and specificity. The acoustic reflex, a contraction of the stapedius muscle following an intense auditory stimulus, can be valuable in determining a conductive hearing loss and many other otologic diagnoses. As a screening tool, immitance audiometry is most valuable in populations at risk for middle ear effusion, primarily those aged 7 months to 5 years. Significant improvements in measurements of ear function also allow us to be more precise in the diagnoses of otosclerosis, perforation of the tympanic membrane, ossicular discontinuity, facial nerve dysfunction, and brain stem disorders.
Department of Family Practice, Southern Illinois University School of Medicine, Springfield.
J E
JE
Sutherland
K
K
Campbell
D000158:Acoustic Impedance Tests; D002648:Child; D004427:Ear Diseases / Q000175:diagnosis; D004432:Ear, Middle; D006801:Humans; D010033:Otitis Media / Q000175:diagnosis; D012022:Reflex, Acoustic