It is less commonly used in this role today because of reduced sensitivity in patients with small vestibular schwannomas-tumors readily detected with the high accuracy offered by magnetic resonance imaging (MRI). In the past, the ABR was believed to be a highly sensitive test for the presence of a retrocochlear lesion. Other cranial nerve findings, asymmetric tinnitus, or vestibular complaints-even if mild-should increase the level of suspicion.Īuditory brainstem response (ABR) testing is useful in evaluating the possibility of a retrocochlear etiology and for establishing thresholds in difficult-to-test patients (young children or patients with nonorganic hearing loss). The examiner should have a high degree of suspicion for retrocochlear etiologies when loss is asymmetric, speech discrimination is abnormally reduced or asymmetric, performance-intensity relationships (“rollover”) on speech discrimination testing are abnormal, or abnormalities in acoustic reflex are apparent. By retrocochlear, we mean a lesion proximal to the cochlea, the most common retrocochlear lesion being vestibular schwannoma. Tympanometry can be especially helpful in excluding the possibility of a conductive component in patients with profound losses or bilateral losses in the presence of a masking dilemma.īasic audiologic tests also can provide essential diagnostic clues as to whether SNHL is cochlear or retrocochlear in origin. Tympanometry with acoustic reflex testing verifies the conductive or sensorineural nature of the hearing loss and provides additional clues regarding etiology. retrocochlear) and provides essential prognostic information regarding the potential benefits of amplification. Speech discrimination testing with assessment of the performance-intensity function helps to define further the nature of the SNHL (cochlear vs. Speech audiometry verifies the pure tone audiometric results. Bone-conduction and air-conduction pure tone audiometry helps to determine the type of hearing loss: conductive, sensorineural, or mixed. Air conduction, bone conduction, and speech audiometry and tympanometry measurements constitute the minimum test battery in patients with suspected SNHL. Conventional audiometric and electrophysiologic testing are discussed more thoroughly in Chapter 134.Īudiometric testing serves to verify and quantify the degree of hearing loss. Only a brief discussion of audiometric testing is presented here. Flint MD, FACS, in Cummings Otolaryngology: Head and Neck Surgery, 2021 Audiometric Testing
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