From Profiles to Structure in Cochlear Nerve: A Clinical Study of Auditory Neuropathy

Area of Science:

• Neurology
• Otolaryngology
• Radiology

Background:

• Auditory neuropathy (AN) is a hearing disorder where the cochlear nerve (CN) has abnormal function.
• Magnetic Resonance Imaging (MRI) is crucial for visualizing the CN and identifying structural abnormalities like CN deficiency (CND).
• Understanding the correlation between AN clinical/audiological features and CN imaging is vital for diagnosis and management.

Purpose of the Study:

• To investigate the clinical and audiological characteristics of auditory neuropathy (AN) patients based on different cochlear nerve (CN) imaging findings on MRI.
• To analyze the prevalence and patterns of CN deficiency (CND) in AN patients.
• To explore the relationship between imaging features and clinical outcomes in AN.

Main Methods:

• A cohort of 132 AN patients from a multicenter study (2003-2023) were categorized into four groups based on CN size on MRI.
• Groups included bilateral AN with normal CN (BAN^cnn), bilateral AN with CN deficiency (BAN^cnd), unilateral AN with CN deficiency (UAN^cnd), and unilateral AN with normal CN (UAN^cnn).
• Clinical and audiological data were analyzed, with differential analysis using the Internal Auditory Meatus (IAM) grading system.

Main Results:

• The overall detection rate of CND was 35.6%, higher in unilateral AN patients (50.0%) compared to bilateral AN patients (32.7%).
• Patients with CND, particularly unilateral cases (UAN^cnd), showed more severe hearing loss.
• Bilateral AN patients with CND (BAN^cnd) had a later age of onset and diagnosis compared to those with normal CN (BAN^cnn).

Conclusions:

• CND is a significant finding in AN, predominantly observed in unilateral cases and associated with IAM grade IV.
• Clinical and audiological indicators correlate with CN imaging features, but these associations differ between bilateral and unilateral AN.
• Variations in CN imaging performance do not appear to negatively affect the prognosis or intervention rates in AN patients.