Auditory neuropathy/dyssynchrony - Its diagnosis and management

Otoacoustic emissions, middle ear muscle reflexes, and auditory brain stem response (ABR) often are presented as "objective and infallible hearing screening tools." They are not. Although a normal ABR with a normal latency-intensity function usually accompanies normal peripheral hearing, an absent or grossly abnormal ABR is not always associated with deafness. In contrast, a hearing loss of 30 dB or more usually predicts absent otoacoustic emissions, but normal emissions can be seen in some patients whose behavioral audiograms imply total deafness. Under circumstances that may occur in at least 10% of children with language and hearing problems, ABR and middle ear muscle reflexes can be absent while emission results are normal. This combination seriously affects management guidelines and, therefore, should be part of the screening procedure for every new patient. This article reviews the underlying auditory physiology that makes these tests useful and potentially misleading, and recommends steps to be considered by primary care physicians and other professionals to compensate for the vulnerabilities of each of the procedures.