Audiological Features in 63 Patients With Cochlear Nerve Deficiency.

Area of Science:

• Pediatric audiology
• Neuroimaging
• Genetics of hearing loss

Background:

• Cochlear nerve deficiency (CND) is a significant cause of congenital hearing loss.
• Accurate diagnosis and understanding of CND's clinical features are essential for effective management.
• Previous studies have been limited in scope, necessitating larger investigations.

Purpose of the Study:

• To investigate the clinical features of cochlear nerve deficiency (CND) in children.
• To analyze the long-term hearing disability and audiogram patterns in pediatric CND cases.
• To evaluate the diagnostic utility of MRI and CT in conjunction with audiometric assessments for CND.

Main Methods:

• Retrospective observational study of 63 children diagnosed with CND via MRI.
• Analysis of imaging data (MRI and CT) and audiometric assessments (pure-tone audiometry, distortion product otoacoustic emissions).
• Classification of CND based on cochlear nerve morphology (aplasia/hypoplasia) and audiometric patterns.

Main Results:

• The majority of CND cases (90.2%) presented with cochlear nerve aplasia, leading to severe-to-profound hearing loss (mean 92.2 dB HL).
• Common audiometric patterns included flat (78.7%), cookie-bite (9.8%), and high-frequency (9.8%).
• A small percentage of CND cases showed distortion product otoacoustic emission (DPOAE) responses, suggesting overlap with auditory neuropathy spectrum disorder (ANSD).

Conclusions:

• Accurate CND diagnosis requires both MRI and CT imaging.
• While hearing loss in CND is typically severe-to-profound, diverse audiometric patterns exist.
• Differentiating CND from other ANSDs is possible with sustained DPOAE responses, and MRI is recommended for congenital deafness cases passing newborn hearing screening.