Auditory neuropathy spectrum disorder

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Auditory neuropathy spectrum disorder (ANSD) is a specific form of hearing loss defined by the presence of normal or near-normal otoacoustic emissions (OAEs) but the absence of normal middle ear reflexes and severely abnormal or completely absent auditory brainstem response (ABRs).

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Individuals presenting with this recently recognised hearing loss appear to display sporadic windows of hearing and not. Very few (1 in 14) will go on to develop normal speech and language but with poor speech perception in background noise and in others, no speech perception and therefore language development is possible.

The condition was originally termed auditory neuropathy (AN) [1] and in 2001 as Auditory Neuropathy / Auditory Dys-synchrony (AN/AD) [2] (to include those cases where no true neuropathy was apparent). In 2008 at a meeting convened at Lake Como in Italy (Guidelines Development Conference on the Identification and Management of Infants with Auditory Neuropathy, International Newborn Hearing Screening Conference, Como, Italy, June 19–21, 2008), a group of leading authorities on the condition reached a consensus and renamed it as auditory neuropathy spectrum disorder. [3]

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Amblyaudia is a term coined by Dr. Deborah Moncrieff to characterize a specific pattern of performance from dichotic listening tests. Dichotic listening tests are widely used to assess individuals for binaural integration, a type of auditory processing skill. During the tests, individuals are asked to identify different words presented simultaneously to the two ears. Normal listeners can identify the words fairly well and show a small difference between the two ears with one ear slightly dominant over the other. For the majority of listeners, this small difference is referred to as a "right-ear advantage" because their right ear performs slightly better than their left ear. But some normal individuals produce a "left-ear advantage" during dichotic tests and others perform at equal levels in the two ears. Amblyaudia is diagnosed when the scores from the two ears are significantly different with the individual's dominant ear score much higher than the score in the non-dominant ear Researchers interested in understanding the neurophysiological underpinnings of amblyaudia consider it to be a brain based hearing disorder that may be inherited or that may result from auditory deprivation during critical periods of brain development. Individuals with amblyaudia have normal hearing sensitivity but have difficulty hearing in noisy environments like restaurants or classrooms. Even in quiet environments, individuals with amblyaudia may fail to understand what they are hearing, especially if the information is new or complicated. Amblyaudia can be conceptualized as the auditory analog of the better known central visual disorder amblyopia. The term “lazy ear” has been used to describe amblyaudia although it is currently not known whether it stems from deficits in the auditory periphery or from other parts of the auditory system in the brain, or both. A characteristic of amblyaudia is suppression of activity in the non-dominant auditory pathway by activity in the dominant pathway which may be genetically determined and which could also be exacerbated by conditions throughout early development.

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Identification of a hearing loss is usually conducted by a general practitioner medical doctor, otolaryngologist, certified and licensed audiologist, school or industrial audiometrist, or other audiometric technician. Diagnosis of the cause of a hearing loss is carried out by a specialist physician or otorhinolaryngologist.

References

  1. Starr, A.; Picton, T.W.; Sininger, Y.; Hood, L.J.; Berlin, C.I. (1996). "Auditory neuropathy". Brain. 119 (3): 741–753. doi: 10.1093/brain/119.3.741 . PMID   8673487.
  2. Berlin, C.I.; Hood, L.J.; Rose, K. (2001). "On renaming auditory neuropathy as auditory dys-synchrony" (PDF). Audiology Today. 13: 15–17. Archived from the original (PDF) on 2020-11-24. Retrieved 2020-06-26.
  3. Berlin, C.I.; Morlet, T.; Hood, L.J. (2008). "Management of Individuals With Auditory Neuropathy Spectrum Disorder".{{cite journal}}: Cite journal requires |journal= (help)