Auditory Brain-stem Response and Acoustic Reflex Test: Results for Patients With and Without Tumor Matched for Hearing Loss

Abstract

\s=b\Auditory brain-stem response (ABR) and acoustic reflex test (ART) results were reviewed for 30 patients with cerebellopontile angle tumors and for 30 patients without tumor. Patients included in the nontumor group were selected to match the audiometric configurations for individual patients in the tumor group. The ABR waveforms were abnormal for all but one of the patients with tumor and for seven of the patients without tumor. The ART results were abnormal for 25 of the patients with tumor and two of the patients without tumor. Patients without tumor yielding abnormal ABR results usually had more severe hearing losses than the patients without tumor who demonstrated normal ABR waveforms. The ABR and ART merit continued use in the audiologic examination of patients suspected of having retrocochlear lesions, but obviously, degree of hearing loss and other medical information must be considered also when retrocochlear lesions are suspected. (Arch Otolaryngol 1983;109:522-525) Audiologic tests are useful in the examination of patients sus¬ pected of having retrocochlear lesions. Two test procedures that seem to be particularly sensitive are the acoustic reflex and decay test (ART) and the Rochester, MN 55905 (Dr Bauch). auditory brain-stem response (ABR) test.Acoustic reflex responses are con¬ sidered abnormal when acoustic reflex thresholds for 500-, 1,000-, or 2,000-Hz tones are elevated or totally absent at high intensities. Acoustic reflex decay is considered abnormal if the amplitude of the reflex response diminishes to one half or less in 5 s when a continuous 500-or 1,000-Hz tone is presented at 10 dB above the acoustic reflex threshold. When applying these criteria for abnormali¬ ty, the sensitivity of the ART to retro¬ cochlear lesions has been reported to range as high as 94% to 100%.'6 Other studies have indicated ART to be less sensitive, but still quite accurate (77% to 87%) in indicating retrocochlear involvement.714 Absence of acoustic reflexes and/or acoustic-reflex decay for patients having cochlear lesions has ranged from as low as 1% to 16%'-9I2M to as high as 22% to 49V.7.9.I5 (Table 1).Most ABR studies agree that more than 90% of surgically confirmed re¬ trocochlear lesions will yield abnor¬ mal ABR results, ie, no observable response or delayed wave V latency.14·20 Disagreement exists, however, on the frequency of occurrence of abnormal ABR findings for patients having cochlear hearing losses, varying from less than 10%141S21 to as much as 25% to 33%16·22·23 (Table 1).The differences in results noted in Table 1 can be attributed to many possible sources. One of the major variables is the degree of hearing loss. For example, it is difficult to interpret the absence of an acoustic reflex when the hearing loss exceeds the 65-dB hearing level (HL) or 80-dB HL, depending on the test unit's maximum output levels. It is also reported that hearing loss exceeding the 75-dB HL at higher frequencies has the poten¬ tial to distort ABR waveform resolu¬ tion and/or prolong latency of the various comp...

Cost‐Effective Initial Screening for Vestibular Schwannoma: Auditory Brainstem Response or Magnetic Resonance Imaging?

“…ABR testing is the most useful audiologic test for the diagnosis of VS. 2 Selters and Brackmann 3 were one of the earliest to describe abnormal ABR findings in 94% of a group of 46 patients with eighth nerve tumors. The high sensitivity of the test in detecting eighth nerve lesions was further corroborated by Glasscock et al 4 and Bauch et al 5 Comparison of ABR with other site-of-lesion audiologic tests like acoustic reflex tests, tone decay test, and speech tests has shown that ABR has a higher hit rate than all of these procedures either singly or in combination. 2 This quality has given ABR an edge over other tests as a cost-effective screening test for the diagnosis of VS.…”

Sensitivity and Specificity of Brain Stem Potentials as a Means of Differentiating Cochlear and Retrocochlear Disorders (Acoustic Neuromas)

“…The audiologist's armamentar ium has since been enlarged by two addi tional test procedures: in the early 1950s by Metz's [1952] procedure of measuring the stapedius reflex, and in the late 1960s and early 1970s by the procedure of registering brain stem potentials [Sohmer and Fein-mcsser, 1967;Jewett et al, 1970;Sohmer and Feinmcsser, 1973]. The stapedius reflex test is reported pretty uniformly to have a true positive rate of better than 80% [Josey et al, 1980;Bauch et al, 1983;Thomsen et al, 1983]. Recent studies (table 1) on the use of brain stem potentials to detect acoustic neuromas report true positive rates of be tween 93 and 100%, and a mean true posi tive rate of 97%.…”