A comparative study of auditory and non-auditory characteristics of congenital, early, and late-onset auditory neuropathy spectrum disorder

The study explored the differences in audiological and non-audiological characteristics between congenital, early-onset, and late-onset auditory neuropathy spectrum disorder (ANSD). Ninety-five individuals diagnosed with ANSD were included in the study. They were divided into three groups congenital ANSD—children (30 individuals, 60 ears), adults with early-onset ANSD (30 individuals, 56 ears), and adults with late-onset ANSD (35 individuals, 62 ears). The non-audiological characteristics (gender, laterality, and risk factors) and audiological characteristics (behavioral and electrophysiological measures) were compared between the three groups.

Discriminant analyses showed that the pure tone average, audiogram configuration, and speech thresholds were the best auditory predictors of onset-based group differences in ANSD (congenital and early-onset versus late-onset ANSD). While the congenital and early-onset group showed poorer pure-tone and speech thresholds, along with flat configuration, the late-onset group demonstrated relatively better thresholds and other configurations (rising, tent-shaped, cookie-bite). In addition, long latency responses were delayed or absent in children with congenital ANSD, indicative of onset coding deficits at the cortical level.

The study highlights the audiological differences between congenital, early-, and late-onset ANSD groups. These differences could be because of variations in etiology, pathophysiology, site of lesion, or genetic variability between the groups, which needs to be explored further.