Progression of Unilateral Hearing Loss in Children With and Without Ipsilateral Cochlear Nerve Canal Stenosis: A Hazard Analysis

Abstract

Objective: To investigate the risk of hearing loss progression in each ear among children with unilateral hearing loss associated with ipsilateral bony cochlear nerve canal (BCNC) stenosis.

Setting: Tertiary pediatric referral center.

Patients: Children diagnosed with unilateral hearing loss who had undergone temporal bone computed tomography imaging and had at least 6 months of follow-up audiometric testing were identified from a prospective audiological database.

Interventions: Two pediatric radiologists blinded to affected ear evaluated imaging for temporal bone anomalies and measured bony cochlear canal width independently. All available audiograms were reviewed, and air conduction thresholds were documented.

Main outcome measure: Progression of hearing loss was defined by a 10 dB increase in air conduction pure-tone average.

Results: One hundred twenty eight children met inclusion criteria. Of these, 54 (42%) had a temporal bone anomaly, and 22 (17%) had ipsilateral BCNC stenosis. At 12 months, rates of progression in the ipsilateral ear were as follows: 12% among those without a temporal bone anomaly, 13% among those with a temporal bone anomaly, and 17% among those with BCNC stenosis. Children with BCNC stenosis had a significantly greater risk of progression in their ipsilateral ear compared with children with no stenosis: hazard ratio (HR) 2.17, 95% confidence interval (CI) (1.01, 4.66), p value 0.046. When we compared children with BCNC stenosis to those with normal temporal bone imaging, we found that the children with stenosis had nearly two times greater risk estimate for progression, but this difference did not reach significance, HR 1.9, CI (0.8, 4.3), p = 0.1. No children with BCNC stenosis developed hearing loss in their contralateral year by 12 months of follow-up.

Conclusion: Children with bony cochlear nerve canal stenosis may be at increased risk for progression in their ipsilateral ear. Audiometric and medical follow-up for these children should be considered.

Figure 1

Flow diagram of imaging characteristics of children with unilateral sensorineural hearing loss

Figure 2. Comparison of proportion of children with hearing loss progression in their affected ears among children with and without BCNC stenosis

A greater proportion of children with BCNC stenosis demonstrated progression.

Figure 3. Comparison of hearing threshold stability over time in affected ears among children with and without BCNC stenosis

The estimated hazard rate for progression of hearing loss in the ipsilateral ear was 2.17 times greater for subjects with stenosis compared to those without stenosis, (95% CI: 1.01, 4.66)