Auditory neuropathy: unexpectedly common in a screened newborn population

Abstract

Auditory neuropathy, or dyssynchrony, is defined by an abnormal or absent auditory brainstem response but intact otoacoustic emissions or cochlear microphonics. It is associated with impaired hearing on behavioural pure‐tone audiometry, absent acoustic reflexes, and poor speech perception, particularly in noisy environments. These results suggest a disorder of inner hair‐cell and or eighth‐nerve function. We describe a case‐note survey of patients with and without auditory neuropathy, using data from the local newborn hearing screening programme collected prospectively from 2002 to 2007. During this period, 45 050 infants were screened with otoacoustic emissions, 30 patients were diagnosed with suspected severe to profound hearing loss (16 males, 14 females), and 12 of those 30 had auditory neuropathy (six males, six females). Mean gestational age was 33 weeks 1 day in the auditory neuropathy group and 35 weeks in the non‐auditory neuropathy group. The most significant risk factors for auditory neuropathy were hyperbilirubinaemia (p=0.018), sepsis (p=0.024), and gentamicin exposure (p=0.024). Children with auditory neuropathy comprise a subgroup of patients with hearing impairment involving different pathologies most commonly associated with the risk factors related to admission to neonatal intensive care units. Improvement is possible with maturity, at least in a minority.

The Medial Olivocochlear System Attenuates the Developmental Impact of Early Noise Exposure

“…The increased refinement of newborn screening procedures indicates that auditory neuropathy is unexpectedly prevalent, particularly among young children with hearing loss (Dowley et al 2009). Commonly cited risk factors include bilirubin toxicity (Shapiro 2003), low birth weight (Xoinis et al 2007), and ototoxic exposure (Dowley et al 2009).…”

“…Commonly cited risk factors include bilirubin toxicity (Shapiro 2003), low birth weight (Xoinis et al 2007), and ototoxic exposure (Dowley et al 2009). Because these medical conditions are often associated with long-term hospitalization in a relatively loud neonatal intensive care unit (NICU) (Benini et al 1996), many of these children have experienced the type of early noise exposure that was an important environmental risk factor in α9KO mice.…”

The genetic basis of auditory neuropathy spectrum disorder (ANSD)

“…Patients with the characteristics of auditory neuropathy were initially reported as early as the 1970s by Hinchcliffe et al [2]. However, subsequent suspicions were raised in the 1980s when the patients with normal pure-tone audiograms and absent auditory brainstem responses (ABR) who reported to have difficulty in understanding speech especially in the presence of background noise were seen in the clinics [3][4][5][6][7][8]. For example, a pioneering work by Soliman in 1987 reported a total of 11 patients with low frequency sensorineural hearing loss with similar pattern, which he subsequently defined as 'low frequency syndrome' [8].…”

Auditory neuropathy spectrum disorder in the wider health context: Experiences of parents whose infants have been identified through newborn hearing screening programme

“…However there is some evidence to imply that babies identifi ed with ' typical ' SNHL through the SCBU protocol are born on average at a higher gestational age and higher birth weight, have lower bilirubin levels, and are administered smaller doses of aminoglycosides (e.g. Dowley et al, 2009). So it is perhaps reasonable to suggest that parents of ANSD babies do in general experience a more traumatic perinatal period and more anxiety and worry about the child ' s survival and long-term health and developmental sequelae than parents of children with ' typical ' SNHL identifi ed through the SCBU protocol.…”