Aplasia of the cochlea: radiologic assessment and options for hearing rehabilitation

Comprehensive Etiologic Analyses in Pediatric Cochlear Implantees and the Clinical Implications

Cochlear implantation is the treatment of choice for children with profound sensorineural hearing impairment (SNHI), yet the outcomes of cochlear implants (CI) vary significantly across individuals. To investigate the CI outcomes in pediatric patients with SNHI due to various etiologies, we prospectively recruited children who underwent CI surgery at two tertiary referral CI centers from 2010 to 2021. All patients underwent comprehensive history taking, next generation sequencing (NGS)-based genetic examinations, and imaging studies. The CI outcomes were evaluated using Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scores. Of the 160 pediatric cochlear implantees (76 females and 84 males) included in this study, comprehensive etiological work-up helped achieve clinical diagnoses in 83.1% (133/160) of the patients, with genetic factors being the leading cause (61.3%). Imaging studies identified certain findings in 31 additional patients (19.3%). Four patients (2.5%) were identified with congenital cytomegalovirus infection (cCMV), and 27 patients (16.9%) remained with unknown etiologies. Pathogenic variants in the four predominant non-syndromic SNHI genes (i.e., SLC26A4, GJB2, MYO15A, and OTOF) were associated with favorable CI outcomes (Chi-square test, p = 0.023), whereas cochlear nerve deficiency (CND) on imaging studies was associated with unfavorable CI outcomes (Chi-square test, p < 0.001). Our results demonstrated a clear correlation between the etiologies and CI outcomes, underscoring the importance of thorough etiological work-up preoperatively in pediatric CI candidates.

A novel method of identifying inner ear malformation types by pattern recognition in the mid modiolar section

Identification of the inner ear malformation types from radiographs is a complex process. We hypothesize that each inner ear anatomical type has a uniqueness in its appearance in radiographs. The outer contour of the inner ear was captured from the mid-modiolar section, perpendicular to the oblique-coronal plane, from which the A-value was determined from CT scans with different inner ear anatomical types. The mean A-value of normal anatomy (NA) and enlarged vestibular aqueduct syndrome (EVAS) anatomical types was greater than for Incomplete Partition (IP) type I, II, III and cochlear hypoplasia. The outer contour of the cochlear portion within the mid-modiolar section of NA and EVAS resembles the side view of Aladdin’s lamp; IP type I resembles the side-view of the Sphinx pyramid and type II a Pomeranian dog’s face. The steep spiraling cochlear turns of IP type III resemble an Auger screw tip. Drawing a line parallel to the posterior margin of internal auditory canal (IAC) in axial-view, bisecting the cavity into cochlear and vestibular portions, identifies common-cavity; whereas a cavity that falls under the straight-line leaving no cochlear portion identifies cochlear aplasia. An atlas of the outer contour of seventy-eight inner ears was created for the identification of the inner malformation types precisely.

Audiological and Speech Performance After Cochlear Implantation in Cochlear Aplasia Deformity

Inner ear malformation is a congenital anomaly associated with prelingual sensory neural hearing loss in the pediatric population. This is a case report of bilateral radiologically diagnosed cochlear aplasia in a child who underwent unilateral left cochlear implantation with audiological results at one-year follow-up after surgery. Sixteen months after the cochlear implantation surgery, the child could produce 200 words and say a sentence with two words. In certain cases of inner ear malformation, the subgrouping of cystic cavity can be difficult and should not delay the trial of cochlear implant provided an acceptable anatomical appearance of the inner ear with cochleovestibular nerve existence and a proper electrode used for implantation.

Embryology, Malformations, and Rare Diseases of the Cochlea

Despite the low overall prevalence of individual rare diseases, cochlear dysfunction leading to hearing loss represents a symptom in a large proportion. The aim of this work was to provide a clear overview of rare cochlear diseases, taking into account the embryonic development of the cochlea and the systematic presentation of the different disorders. Although rapid biotechnological and bioinformatic advances may facilitate the diagnosis of a rare disease, an interdisciplinary exchange is often required to raise the suspicion of a rare disease. It is important to recognize that the phenotype of rare inner ear diseases can vary greatly not only in non-syndromic but also in syndromic hearing disorders. Finally, it becomes clear that the phenotype of the individual rare diseases cannot be determined exclusively by classical genetics even in monogenetic disorders.

Evaluating Common Cavity Cochlear Deformities Using CT Images and 3D Reconstruction

OBJECTIVES

The aim of this study is to compare the common cavity (CC) with the normal anatomy inner ear in order to evaluate whether the cavity is representing both the cochlear and the vestibular parts of the inner ear and to revisit CC deformity from a three-dimensional (3D) perspective.

METHODS

High-resolution computed tomography image datasets of 17 temporal bones initially identified as CC were evaluated with 3D reconstruction and multiplanar image analysis using a free available software for 3D segmentation of the inner ear. All 3D images of CC were compared to a normal inner ear. Maximum and minimum diameter of the CC were correlated with the circumference of the CC in an axial plane.

RESULTS

In 13 cases (76%), CC represented only the vestibular part of the inner ear and did not represent CC as defined here and by Sennaroglu, Kontorinis, and Khan. True CC was correctly diagnosed in only one case (6%). In three cases (18%), a rudimentary part of the cochlear portion could be identified. The axes' length of the elliptical cavity showed a strong positive linear relation to the circumference of the cavity (long axis: r = 0.94; P < .0001; short axis: r = 0.68; P = .0029).

CONCLUSION

This study supports the assumption that many reported CC cases only represent the vestibular part of the inner ear and are therefore cases of cochlear aplasia. 3D segmentation and systematic analysis of CT-imaging add clinical value to the comprehension of the morphology of the anatomical structures of the inner ear.

LEVEL OF EVIDENCE

2C Laryngoscope, 131:386-391, 2021.

Assessing the Benefit-Risk Profile for Pediatric Implantable Auditory Prostheses

BACKGROUND/AIMS

Children with congenital cochleovestibular abnormalities associated with profound hearing loss have few treatment options if cochlear implantation does not yield benefit. An alternative is the auditory brainstem implant (ABI). Regulatory authority device approvals currently include a structured benefit-risk assessment. Such an assessment, for regulatory purposes or to guide clinical decision making, has not been published, to our knowledge, for the ABI and may lead to the design of a research program that incorporates regulatory authority, family, and professional input.

METHODS

Much structured benefit-risk research has been conducted in the context of drug trials; here we apply this approach to device studies. A qualitative framework organized benefit (speech recognition, parent self-report measures) and risk (surgery- and device-related) information to guide the selection of candidates thought to have potential benefit from ABI.

RESULTS

Children with cochleovestibular anatomical abnormalities are challenging for appropriate assessment of candidacy for a cochlear implant or an ABI. While the research is still preliminary, children with an ABI appear to slowly obtain benefit over time. A team of professionals, including audiological, occupational, and educational therapy, affords maximum opportunity for benefit.

CONCLUSIONS

Pediatric patients who have abnormal anatomy and are candidates for an implantable auditory prosthetic require an individualized, multisystems review. The qualitative benefit-risk assessment used here to characterize the condition, the medical need, potential benefits, risks, and risk management strategies has revealed the complex factors involved. After implantation, continued team support for the family during extensive postimplant therapy is needed to develop maximum auditory skill benefit.