Objective Although brainstem dys-synchrony is a hallmark of children with auditory neuropathy spectrum disorder (ANSD), little is known about how the lack of neural synchrony manifests at more central levels. We used time-frequency single-trial EEG analyses (i.e., inter-trial coherence; ITC), to examine cortical phase synchrony in children with normal hearing (NH), sensorineural hearing loss (SNHL) and ANSD. Methods Single trial time-frequency analyses were performed on cortical auditory evoked responses from 41 NH children, 91 children with ANSD and 50 children with SNHL. The latter two groups included children who received intervention via hearing aids and cochlear implants. ITC measures were compared between groups as a function of hearing loss, intervention type, and cortical maturational status. Results In children with SNHL, ITC decreased as severity of hearing loss increased. Children with ANSD revealed lower levels of ITC relative to children with NH or SNHL, regardless of intervention. Children with ANSD who received cochlear implants showed significant improvements in ITC with increasing experience with their implants. Conclusions Cortical phase coherence is significantly reduced as a result of both severe-to-profound SNHL and ANSD. Significance ITC provides a window into the brain oscillations underlying the averaged cortical auditory evoked response. Our results provide a first description of deficits in cortical phase synchrony in children with SNHL and ANSD.

Objective: We examined 1) auditory cortical organization and functioning, and 2) variability in cortical responses in a paediatric patient with unilateral auditory neuropathy spectrum disorder (ANSD). Study design: Measures of high-density EEG (including cortical auditory evoked potentials (CAEPs)), dipole and current-density analyses, independent component analyses-stacked trials (ICA), inter-trial coherence, and the patient's performance on measures of speech perception were compared for the ear with normal hearing (NH) and the ear with ANSD. Results: Differences were observed between the NH ear and the ear with ANSD for all test measures. Conclusions: Our results suggest that for some patients, 1) congenital ANSD may result in abnormal auditory cortical organization, and 2) neural dys-synchrony in the central auditory system, which characterizes ANSD, may result in a high degree of variability in cortical responses. In this study, cortical auditory activation in ANSD was examined using high-density EEG. Our study also demonstrates use of single-trial and time- frequency EEG analyses in evaluating the effect of neural dys-synchrony on cortical variability in patients with ANSD.