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Published on: February 29, 2020
Unilateral cochlear nerve deficiency in children
Clarice S Clemmens1, Jessica Guidi, Aviva Caroff
1Department of Otorhinolaryngology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Insights
Cochlear nerve deficiency (CND) is a common cause of unilateral sensorineural hearing loss (SNHL) in children. A narrow bony cochlear nerve canal effectively predicts CND, which is often associated with ophthalmologic abnormalities.
Area of Science:
- Pediatric Otolaryngology
- Neuroimaging
- Auditory Neuroscience
Background:
- Cochlear nerve deficiency (CND) is increasingly identified in pediatric sensorineural hearing loss (SNHL).
- Understanding CND prevalence and imaging features is crucial for diagnosis and management.
Purpose of the Study:
- To determine the prevalence of CND in children with unilateral SNHL.
- To characterize imaging findings of CND.
- To explore correlations between CND and audiologic phenotype.
Main Methods:
- Retrospective case series of 128 children with unilateral SNHL.
- High-resolution magnetic resonance imaging (MRI) was used to assess cochlear nerve (CN) size and signal intensity.
- Bony cochlear nerve canal (BCNC) width was measured and correlated with CN parameters and hearing loss characteristics.
Main Results:
- CND was present in 26% of children with unilateral SNHL, rising to 48% in severe-to-profound cases.
- A narrow BCNC (<1.7 mm) strongly predicted CND and correlated with CN size and area.
- Hearing loss severity showed a modest correlation with nerve size, and progression was rare without other inner ear malformations.
- Ophthalmologic abnormalities, particularly oculomotor disturbances, were common (67%) in children with CND.
Conclusions:
- CND is a frequent cause of unilateral SNHL, especially congenital deafness.
- BCNC width is a reliable predictor of CND, valuable even with CT imaging.
- Hearing in affected ears is expected to remain stable.
- CND diagnosis warrants ophthalmologic evaluation.
Objective:
Cochlear nerve deficiency (CND) is increasingly diagnosed in children with sensorineural hearing loss (SNHL). We sought to determine the prevalence of CND, its imaging characteristics, and correlations with audiologic phenotype in children with unilateral SNHL.
Design:
Case series with chart review.
Setting:
Tertiary pediatric hospital.
Subjects/Methods:
In 128 consecutive children with unilateral SNHL who underwent high-resolution magnetic resonance imaging, the diameters, area, and signal intensity of the cochlear nerve (CN) were measured and normalized to the ipsilateral facial nerve. Presence of CND was determined by comparison to normative data. Relationships among hearing loss severity, progression, and nerve size were investigated.
Results:
Cochlear nerve deficiency was present in 26% of children with unilateral SNHL. Its prevalence was higher (48%) in severe to profound SNHL, especially when in infants (100%). Width of the bony cochlear nerve canal (BCNC) correlated strongly with relative CN diameter, density, and area (R = 0.5); furthermore, a narrow BCNC (<1.7 mm) strongly predicted CND. Severity of hearing loss modestly correlated with nerve size, although significant variability was observed. Progression never occurred unless there were other inner ear malformations, whereas in the non-CND group, it occurred in 22%. Ophthalmologic abnormalities were very common (67%) in CND children, particularly oculomotor disturbances.
Conclusion:
Cochlear nerve deficiency is a common cause of unilateral SNHL, particularly in congenital unilateral deafness. Width of the BCNC effectively predicts CND, a finding useful when only computed tomography imaging is available. In an ear with CND, hearing can be expected to remain stable over time. Diagnosis should prompt evaluation by an ophthalmologist.
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