Cochlear Nerve Deficiency in Pediatric Unilateral Hearing Loss and Asymmetric Hearing Loss.

INTRODUCTION: The rates of cochlear nerve abnormalities and cochlear malformations in pediatric unilateral hearing loss (UHL) are conflicting in the literature, with important implications on management. The aim of this study was to investigate the incidence of cochlear nerve deficiency (CND) in pediatric subjects with UHL or asymmetric hearing loss (AHL). METHODS: A retrospective chart review of pediatric subjects <18 years of age evaluated for UHL or AHL with fine-cut heavily T2-weighted magnetic resonance imaging (MRI) between January 2014 and October 2019 (n = 291) at a tertiary referral center was conducted. MRI brain and computed tomography temporal bone were reviewed for the presence of inner ear malformations and/or CND. Status of the ipsilateral cochlear nerve and inner ear was evaluated. Pure tone average (PTA) at 500, 1,000 and 2,000 Hz was assessed. RESULTS: 204 subjects with UHL and 87 subjects with AHL were included. CND (aplasia or hypoplasia) was demonstrated in 61 pediatric subjects with UHL (29.9%) and 10 with AHL (11.5%). Ipsilateral cochlear malformations were noted in 25 subjects with UHL (12.3%) and 11 with AHL (12.6%), and ipsilateral vestibular malformations in 23 (11.3%) and 12 (13.8%) ears, respectively. Median PTA was statistically significantly higher in ears with CND (98.33) than ears with normal nerves (90.84). DISCUSSION/CONCLUSION: Imaging demonstrated a high incidence of inner ear malformations, particularly CND, in pediatric subjects with UHL. Auditory findings indicated CND cannot be ruled out by thresholds alone as some CND ears did demonstrate measurable hearing. Radiologic evaluation by MRI should be performed in all patients within this population to guide counseling and management of hearing loss based on etiology, with implications on candidacy for cochlear implantation.

Comparison of test methods to assess the implanted ear alone for pediatric cochlear implant recipients with single-sided deafness.

OBJECTIVES: The purpose of this investigation was to compare three test methods for isolating the test ear for children with single-sided deafness (SSD) who use a cochlear implant (CI). METHODS: Word recognition was assessed for five CI recipients with SSD and six bilateral CI recipients with no acoustic hearing. For the SSD subjects, performance was compared: 1) in the sound field with masking in the normal-hearing ear, 2) in the sound field with an earplug and earmuff ("plug-and-muff"), and 3) via direct connect (DC). For the bilateral CI subjects, performance was compared: 1) in the sound field and 2) via DC. RESULTS: For the bilateral CI subjects, word recognition was similar when assessed in the sound field versus via DC. For the SSD subjects, performance was similar when assessed with the plug-and-muff and DC methods but was significantly poorer with masking presented to the normal-hearing ear. DISCUSSION: Masking the normal-hearing ear to isolate the CI for word recognition is problematic in this population. The plug-and-muff and DC test methods may provide a more accurate assessment. CONCLUSION: DC or plug-and-muff methods are recommended to isolate the CI-ear for word recognition testing in children with SSD. Patient specific variables should be considered.