Auditory Neuropathy: Using OAEs and ABRs from Screening to Management

Abstract

Auditory neuropathy is operationally defined when one sees normal otoacoustic emissions (OAEs) with absent electrocochleograms and/or absent auditory brainstem responses (ABRs). The pathophysiology varies from patient to patient, sometimes encompassing systemic peripheral neuropathies, other times with symptoms suggesting a lack of inner hair cell or primary auditory neuron function. The natural course of the problem is different when the onset is noted at birth compared with later in life. Thus, in this meeting's context of early identification, we will focus mostly on infants.

Infants with auditory neuropathy show

• Normal otoacoustic emissions.

• Absent ABR with no wave I despite what may appear to be later as only modest pure tone audiometric loss

• A long-ringing cochlear microphonic that extends in to the 4- to 6-millisecond range, whether by ABR or transtympanic EcocG

• No synchronous ABR wave forms with phase-inverting MLS techniques

• Absent middle ear muscle reflexes

• No efferent suppression of otoacoustic emissions with binaural, ipsilateral, or contralateral noise

• Signs of genetic transmission

• Occasional remission: some infants sometimes outgrow the symptomatology; they are one who show a history of perinatal hyperbilirubinemia or blood dyscrasias

• Retrograde degeneration: some infants, instead of recovering, seem to go deeper into deafness and become cochlear implant candidates.

Some will “pass” single polarity ABR screenings as well as OAE screenings; therefore, we strongly recommend that both tools be used to fully evaluate the patients initially identified. Because some children appear to grow out of their deafness, we recommend keeping them in touch with their parents' native lan-guage by visual eavesdropping; cued speech is an ideal tool for positioning the child to learn and understand English (or whatever other language the family uses) and facilitates literacy. It is also compatible with American Sign Language should it be needed for socialization and cultural identity.

Key Words:

Auditory neuropathy - ABR - otoacoustic emissions - courses of recovery