Absent or Elevated Middle Ear Muscle Reflexes in the Presence of Normal Otoacoustic Emissions: A Universal Finding in 136 Cases of Auditory Neuropathy/Dys-synchrony

We extracted a subpopulation of 136 patients (from our database of 257 AN/AD subjects) in whom middle ear muscle reflexes had been measured. None showed normal reflexes at all frequencies tested. Only three subjects showed any reflexes at 95 dB HL or below, but never at both 1 and 2 kHz in both ears whether ipsilaterally or contralaterally elicited. All the other reflex measures in these remaining 133 patients were either absent or observed above 100 dB HL, which is incongruous with their normal otoacoustic emissions throughout the frequency bands.Therefore, we urge colleagues to test ipsilateral middle ear muscle reflex at least at 1 kHz and 2 kHz in any perinatal hearing screening that depends solely on otoacoustic emissions. If the emissions are present and the reflexes are absent or elevated, an ABR may be required to properly intervene, because the management of AN/AD patients often differs drastically from what the behavioral audiogram or the ABR suggest.

Hearing Threshold Estimation in Infants Using Auditory Steady-State Responses

Successful early intervention in children with permanent hearing loss requires assessment techniques that can accurately reflect the behavioral audiogram in infancy. This retrospective study compared auditory steady-state response (ASSR) findings from subjects tested in the first three months of life with subsequently obtained behavioral hearing levels. ASSR audiograms were established using amplitude and frequency modulated tones at octave frequencies (500 Hz to 4 kHz). Results obtained from 575 subjects including 285 with normal hearing, 271 with sensorineural hearing loss, and 19 with auditory neuropathy-type hearing loss are presented. ASSR and behavioral hearing thresholds for subjects in the normal and sensorineural groups were highly correlated, with Pearson r values exceeding 0.95 at each of the test frequencies. In contrast, ASSR thresholds in children with AN-type hearing loss did not accurately reflect the behavioral audiogram. Overall, the findings indicate that ASSR testing can offer useful insights into the hearing acuity of children tested in infancy.