Objectives

There are significant variations across centers on how to acquire and interpret imaging of children with congenital sensorineural hearing loss and cochleovestibular abnormalities. This study assesses the quality of imaging, sequences included, and accuracy of official radiology reports, to determine if these children are being assessed appropriately.

Methods

This study is retrospective review of CTs and MRIs from 40 pediatric patients diagnosed with profound sensorineural hearing loss and cochleovestibular structure/nerve abnormalities presenting to a tertiary referral academic center. Images were reviewed by two experienced neuroradiologists and a neurotologist. Findings were compared to official reports, when available.

Results

Twelve (30%) patients had an MRI only, while 28 (70%) had both an MRI and a CT. There were 3 (10.7%) CTs and 7 (17.5%) MRIs noted to be of poor quality. Children received an average of 6.8 (±2.7) CT acquisitions and 10.9 (±5.7) MRI acquisitions. There was non-concordance between the official report and expert review for 27 (71.1%) ears on CT and 27 (56.3%) ears on MRI.

Conclusions

These data demonstrate high variability in protocols and quality of medical imaging of children with sensorineural hearing loss. Interpretation of images is highly discordant between official reports and tertiary review. Given these results, we recommend that these children be imaged and evaluated at centers with neuroradiologists who are experienced in interpreting congenital abnormalities of the cochleovestibular system.

Background

Childhood hearing impairment affects language and cognitive development. Profound congenital sensorineural hearing impairment can be due to an abnormal cochleovestibular nerve (CVN) and cochleovestibular malformations, however, the etiology of these conditions remains unclear.

Methods

We used a trio-based exome sequencing approach to unravel the underlying molecular etiology of a child with a rare nonsyndromic CVN abnormality and cochlear hypoplasia. Clinical and imaging data were also reviewed.

Results

We identified a de novo missense variant [p(Asn174Tyr)] in the DNA-binding Homeodomain of SIX1, a gene which previously has been associated with autosomal dominant hearing loss (ADHL) and branchio-oto-renal or Branchio-otic syndrome, a condition not seen in this patient.

Conclusions

SIX1 has an important function in otic vesicle patterning during embryogenesis, and mice show several abnormalities to their inner ear including loss of inner ear innervation. Previous reports on patients with SIX1 variants lack imaging data and nonsyndromic AD cases were reported to have no inner ear malformations. In conclusion, we show that a de novo variant in SIX1 in a patient with sensorineural hearing loss leads to cochleovestibular malformations and abnormalities of the CVN, without any other abnormalities. Without proper interventions, severe to profound hearing loss is devastating to both education and social integration. Choosing the correct intervention can be challenging and a molecular diagnosis may adjust intervention and improve outcomes, especially for rare cases.