Cervical Vestibular Evoked Myogenic Potential in Children with Auditory Neuropathy Spectrum Disorder of prelingual onset

Objectives: Aims of the current work were to describe cervical vestibular evoked myogenic potential (c-VEMP) in children with ANSD of pre-lingual onset, and to compare c-VEMP findings to those in children with non- ANSD sensorineural (non -ANSD SNHL) of pre-lingual onset. Methods: The study included 35 children with bilateral ANSD, and 32 children with bilateral non-ANSD SNHL of severe, severe to profound, or profound degree. Both groups of children had the onset SNHL pre-lingually. The study also included 15 control children. Mean age and SD were 6.9 years ± 2.9 for the control children, 7.8 years ± 3.1 for the ANSD children, and 8.8 years ± 3.4 for the non-ANSD children. All participant children were subjected to full history taking, otological examination, hearing assessment, recording for auditory brainstem response and cochlear microphonics, Distortion product otoacoustic emission recording, and c-VEMP recording. Results: Results showed that the vast majority of ANSD children (88% of ears) had intact c-VEMP response. Moreover, there was no statistically significant difference between the ANSD children and control children as regards the VEMP parameters (P1-N1 amplitude, asymmetric ratio, P1 latency, N1 latency, and inter-aural latency differences of P1 and N1). There was no statistically significant difference between ANSD with risk factors and those without risk factors as regards VEMP parameters. Results indicate that the vast majority of ANSD children with pre-lingual onset, even those with risk factors, have normal saccular function along with intact and normally functioning inferior vestibular nerve, and the other central connections responsible for the VEMP response. On the other hand, 53.1% of ears children with non-ANSD SNHL had an absent c-VEMP response, and 46.9% of ears had intact and normal c-VEMP response. The overall results indicate that while the pathology of non-ANSD SNHL involves the saccule in more than half of children, the underlying pathology ANSD spares the saccule and its central connection. Conclusions: Results suggest that the site of lesion in ANSD children of pre-lingual onset is restricted to the auditory system with sparing the vestibular system in the majority of children. These findings support the choice of cochlear implantation as the best line of management in children with ANSD, even in the presence of risk factors. So cochlear implantation in children with ANSD is safer than children with SNHL as there will be no fear of bilateral saccular dysfunction in the case saccular damage occurred in the surgery side as a result of the surgical procedure.