Prevalence of inner ear anomalies among cochlear implant candidates

Improving rehabilitation of deaf patients by advanced imaging before cochlear implantation

INTRODUCTION

Cochlear implants have advanced the management of severe to profound deafness. However, there is a strong disparity in hearing performance after implantation from one patient to another. Moreover, there are several advanced kinds of imaging assessment before cochlear implantation. Microstructural white fiber degeneration can be studied with Diffusion weighted MRI (DWI) or tractography of the central auditory pathways. Functional MRI (fMRI) allows us to evaluate brain function, and CT or MRI segmentation to better detect inner ear anomalies.

OBJECTIVE

This literature review aims to evaluate how helpful pre-implantation anatomic imaging can be to predict hearing rehabilitation outcomes in deaf patients. These techniques include DWI and fMRI of the central auditory pathways, and automated labyrinth segmentation by CT scan, cone beam CT and MRI.

DESIGN

This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were selected by searching in PubMed and by checking the reference lists of relevant articles. Inclusion criteria were adults over 18, with unilateral or bilateral hearing loss, who had DWI acquisition or fMRI or CT/ Cone Beam CT/ MRI image segmentation.

RESULTS

After reviewing 172 articles, we finally included 51. Studies on DWI showed changes in the central auditory pathways affecting the white matter, extending to the primary and non-primary auditory cortices, even in sudden and mild hearing impairment. Hearing loss patients show a reorganization of brain activity in various areas, such as the auditory and visual cortices, as well as regions involved in language and emotions, according to fMRI studies. Deep Learning's automatic segmentation produces the best CT segmentation in just a few seconds. MRI segmentation is mainly used to evaluate fluid space of the inner ear and determine the presence of an endolymphatic hydrops.

CONCLUSION

Before cochlear implantation, a DWI with tractography can evaluate the central auditory pathways up to the primary and non-primary auditory cortices. This data is then used to generate predictions on the auditory rehabilitation of patients. A CT segmentation with systematic 3D reconstruction allow a better evaluation of cochlear malformations and predictable difficulties during surgery.

Selection of speech processor in cochlear implant patients: experience in a tertiary hospital

BACKGROUND

There are two types of speech processors used in CI devices: behind-the-ear (BTE) and off-the-ear (OTE).

OBJECTIVES

This study aimed to investigate the characteristics of patients and revision cases in relation to the type of speech processors.

MATERIALS AND METHODS

A retrospective review of 452 ears that underwent CI was performed.

RESULTS

Children with severe inner ear anomalies (91.7%) more frequently preferred BTE speech processors than those without severe inner ear anomalies (p = .000). The magnet strength used in OTE speech processor users was significantly higher than in BTE speech processor users (p = .002). In cochlear implantees who underwent surgery before 12 months of age, the magnet strength in the revision group was greater than in the non-revision group (p = .025).

CONCLUSIONS AND SIGNIFICANCE

Overall, our findings suggest factors to consider when choosing the type of speech processor and modifying the magnet strength of the implant device. The choice between BTE and OTE speech processors led to different required magnet strengths, contributing to the occurrence of skin flap inflammation.

Prevalence of Temporal Bone Malformations in Prospective Cochlear Implant Candidates

Severe to profound Sensorineural Hearing Loss is a challenging medical problem, particularly if this condition is associated with an inner ear anomaly. This case series studies the prevalence of inner ear anomalies among 76 consecutive prospective cochlear implant candidates who presented to our tertiary care hospital over 2 years. Inner ear anomalies were identified in 11 cases with a prevalence rate of 14%. Narrow Internal Auditory Canal (IAC) is the most common inner ear anomaly (5) followed by Mondini (3) and Globular vestibule (3). Combined CT and MRI play an important role in the preoperative assessment of inner ear anomalies which may affect not only the decision to perform the Implant procedure and the prognosis but also the choice of implant and surgical technique.

Audiological and Speech Outcomes of Cochlear Implantation in Inner Ear Malformation Compared to the Normal Inner Ear

To compare the overall clinical outcomes of cochlear implantation in children with structural inner ear abnormalities, with results of implantation in children with radiologically 'normal' inner ears. To study the incidence and performance outcomes of cochlear implantation in children with inner ear malformations (IEMs). It is a retrospective case control study of 57 normal and 57 abnormal inner ear patients operated for cochlear implant between Jan 1, 2014 and Aug 1, 2017, by Veria technique. The age range was between 12 months and 15 years. The prevalence of IEMs was 13.8%. Of the 57 cases with IEMs, 33.3% were of enlarged vestibular acqueduct, 7% were of isolated Incomplete Partition type-2, 21.1% cases were of Mondini's dysplasia, 3.5% of Incomplete partition type-1 and 8.8% of cochlear nerve hypoplasia. Most commonly encountered malformation was EVA while IP-1 was the least common malformation. A CSF gusher was experienced in 11 cases. There was a statistically significant difference between the CAP and SIR scores of both IEM and control groups, both at 1 year and at 2 years (1 year CAP score p value < 0.001, 2 year CAP score p value 0.002 and 1 year SIR score, p value < 0.001, 2 year SIR score, p value 0.013). There was progressive improvement in the scores (of both groups) at the 2 year mark, compared to 1 year scores. Cochlear implantation is safe and surgically feasible in children with IEMs. However, the hearing outcome and speech perception outcomes are poor than those of patients with normal anatomy, with an exception seen in enlarged vestibular aqueduct.

Our Experience in 576 Cases of Cochlear Implant Surgery by Veria Technique

OBJECTIVE

To study and analyse the result obtained in cochlear implantation by Veria technique and evaluate the incidence of surgical complications and their management.

METHOD

Between Jan 1, 2014 to Jan 1, 2019, 602 cochlear implantations by Veria technique were done out of which 576 patients were analysed retrospectively for the study. The age range was between 18 months and 60 years.

RESULT

All 576 patients were operated by Veria technique. Out of 576 patients, 57 (9.9%) had abnormal cochlear malformation. Cytomegalovirus (CMV) being the most common non genetic cause of congenital hearing loss accounting to 60%. The overall complication rate of 5.5% was observed in 576 implanted patients.

CONCLUSION

The analysis of the results shows that this method has certain advantages, which are: it is simple and therefore the learning curve is fast; it is safe for the facial nerve, as the drilling is precisely controlled by the special perforator; it produces minimal bone trauma and due fast healing, it permits early fitting a few days after operation; it can be used for very small children where the mastoid may have not been yet sufficiently developed.

Cochlear implantation: Predicting the scala tympani volume of the pediatric recipients

OBJECTIVES

The main aim of this study was to estimate the volume of the Scala Tympani (ST) of our pediatric cochlear implant (CI) recipients from the computed tomography (CT) images. Then, to study the association between ST volume and both demographic characteristics and cochlear parameters.

METHODS

A retrospective study on the CT scans of pediatric CI patients at a tertiary referral CI center. Congenital or acquired cochlear defects were excluded. Two reviewers, with the same level of experience, blindly measured the main cochlear parameters and studied its anatomy. Then, the interrater reliability was tested to measure any differences between the two readings. After that, the ST volume of the included patients was calculated and analyzed. Furthermore, the correlations between the main cochlear parameters and ST volume were studied to propose a formula for estimating the ST volume from the cochlear duct length (CDL).

RESULTS

The mean predicted ST volume among our pediatric CI recipients was 38.51 ± 5.54 μl (range; 24.47-52.57 μl). The statistical analysis revealed that all cochlear parameters (A, B, H, and CDL values) could be significant predictors of the ST volume (p=<0.0001).

CONCLUSION

The main cochlear parameters along with the CDL are positively linked to the ST volume. There are considerable differences in cochlear size and scala tympani volume among our pediatric population. These findings confirm the importance of pre-operative planning for proper electrode array selection.

Cochlear Implant Induced Labyrinthine Ossificans in Mondini Malformation: A Case Series

Cochlear implantation is relatively a safe procedure with a favorable outcome. Labyrinthine ossification is one of the rare complications that has been observed in some occasions post-cochlear implantation. This paper report two cases of Mondini inner ear malformation cochlear implant failure associated with labyrinthine ossification, mandating revision surgery, and a literature review focusing on the reported cases, risk factors, surgical and non-surgical measures to mitigate this complication and to improve overall cochlear implant outcomes.

Molecular and genetic characterization of a large Brazilian cohort presenting hearing loss

Hearing loss is one of the most common sensory defects, affecting 5.5% of the worldwide population and significantly impacting health and social life. It is mainly attributed to genetic causes, but their relative contribution reflects the geographical region's socio-economic development. Extreme genetic heterogeneity with hundreds of deafness genes involved poses challenges for molecular diagnosis. Here we report the investigation of 542 hearing-impaired subjects from all Brazilian regions to search for genetic causes. Biallelic GJB2/GJB6 causative variants were identified in 12.9% (the lowest frequency was found in the Northern region, 7.7%), 0.4% carried GJB2 dominant variants, and 0.6% had the m.1555A > G variant (one aminoglycoside-related). In addition, other genetic screenings, employed in selected probands according to clinical presentation and presumptive inheritance patterns, identified causative variants in 2.4%. Ear malformations and auditory neuropathy were diagnosed in 10.8% and 3.5% of probands, respectively. In 3.8% of prelingual/perilingual cases, Waardenburg syndrome was clinically diagnosed, and in 71.4%, these diagnoses were confirmed with pathogenic variants revealed; seven out of them were novel, including one CNV. All these genetic screening strategies revealed causative variants in 16.2% of the cases. Based on causative variants in the molecular diagnosis and genealogy analyses, a probable genetic etiology was found in ~ 50% of the cases. The present study highlights the relevance of GJB2/GJB6 as a cause of hearing loss in all Brazilian regions and the importance of screening unselected samples for estimating frequencies. Moreover, when a comprehensive screening is not available, molecular diagnosis can be enhanced by selecting probands for specific screenings.

Prevalence & features of inner ear malformations among children with congenital sensorineural hearing loss: A Public Cochlear Implant Centre Experience

OBJECTIVE

To determine the prevalence and features of inner ear anomalies in children with congenital profound hearing loss who presented at our cochlear implant center based on imaging studies.

METHODS

This retrospective study reviewed charts of children with congenital SNHL, who presented to Department of Otolaryngology & Auditory Implant Centre, Capital Hospital Islamabad over a period of 2 years from 1^st May 2017 to 30^th April 2019. These included 481 cases of both genders aged between 1 to 12 years. After gathering demographic data, audiological data, computed tomography findings of the temporal bone were analyzed. Data was analyzed using SPSS 22.

RESULTS

The Inner Ear Malformations were identified in 48(10%) children including 28 (58.33%) males and 20 (41.67%) female. Most 20(41.67%) presented at >3-5 years of age followed by 19(39.58%) at 2-3 years. However, no significant association of gender (p=0.57, p=0.076) and age of presentation (p=0.344, p=0.697) for right and left ears was noted with inner ear malformations. The most common anomaly noted were CLA, CH-III and CH-II in decreasing order of frequency in both ears.

CONCLUSION

The prevalence of IEM's was found to be 48(10%). Commonest anomalies noted were CLA, CH-III and CH-II. No significant association of gender and age of presentation was noted with type of anomaly in both ears.

Diagnostic Value of 3D Segmentation in Understanding the Anatomy of Human Inner Ear Including Malformation Types

OBJECTIVE

To understand the anatomical and dimensional variations of the human inner ear using 3-dimensional (3D) segmentation within the Middle East population.

DESIGN

Retrospective study.

SETTING

King Abdullah Ear Specialist Center (KAESC) Riyadh, Saudi Arabia.

PARTICIPANT

Forty computed tomography (CT) images of patients with sensorineural hearing loss who underwent cochlear implant (CI) were taken for analysis.

MAIN OUTCOME MEASURES

Three-dimensional images showing the anatomical variations of the inner ear including various pathological conditions, cochlear parameters including basal turn diameter ("A" value), "B" value which is perpendicular to "A" value, cochlear height, length, and width of the internal auditory canal (IAC), intercochlear spacing, and electrode angular insertion depth (AID).

RESULTS

Out of 40 CT image data sets, 12 had normal inner-ear anatomy (NA), 4 with enlarged vestibular aqueduct syndrome (EVAS), 8 with only 2 turns of the cochlea (2TL), 7 with incomplete partition (IP) type II, 5 with cochlear hypoplasia, 1 with common cavity, and 3 with abnormal IAC. Taking the NA, EVAS, 2TL, and the IP type II cases altogether, age of the patient had no correlation with the "A" value; however, the "A" value had a linear correlation with the "B" value. The age of the patient had an increasing logarithmic correlation with the IAC length and the intercochlear spacing. The "A" value did not have any meaningful correlation with the cochlear height. Three data sets showed asymmetric inner-ear malformation types on either side of the ears. All these 40 cases were implanted with various CI electrode array variants and the corresponding postoperative plain film X-ray images showing the electrode AID are given separately in figures.

CONCLUSIONS

Three-dimensional segmentation of the inner ear from the temporal bone CT is a valuable clinical and training tool for surgeons and radiologists especially in difficult cases which will certainly help to understand the overall anatomical and dimensional variations.

Speech development in young children with Mondini dysplasia who had undergone cochlear implantation

OBJECTIVE

The purpose of this study was to investigate the development of speech skills in young children with Mondini dysplasia and age-matched deaf children with radiologically normal inner ears over a period of 5 years after cochlear implantation (CI).

METHODS

In total, 700 congenitally severely to profoundly deaf children (281 girls and 419 boys) participated in this study. All of the participants had undergone unilateral CI surgery before 36 months of age. The participants were categorized into two groups based on the absence or presence of Mondini dysplasia in the implanted ear, as assessed via high-resolution, thin-slice computerized tomography or magnetic resonance imaging: group A comprised 592 children with radiologically normal inner ears and group B comprised 108 children with Mondini dysplasia. The Meaningful Use of Speech Scale (MUSS) and Speech Intelligibility Rating (SIR) were used to evaluate the speech performance of all young children at various time points: pre-surgery and at 1, 3, 6, 12, 24, 36, 48, and 60 months after switch-on programming.

RESULTS

The mean scores of SIR and MUSS in children from both group A and group B showed significant improvements over time. No significant differences were found in the mean scores of SIR between the two groups at any time interval during the 5-year follow-up. The mean score of MUSS was significantly different between group A and group B at 12, 24, and 36 months after implantation, whereas no obvious differences were noted pre-surgery, and at 1, 3, 6, 48, and 60 months post-operation.

CONCLUSIONS

Young children with Mondini dysplasia develop their speech skills at a fast rate and achieve similar speech acquisition compared to age-matched children with radiologically normal inner ears 5 years post-operation. Therefore, CI is an effective intervention method for young children with Mondini dysplasia.

Key Genes and Pathways Associated With Inner Ear Malformation in SOX10 p.R109W Mutation Pigs

SRY-box 10 (SOX10) mutation may lead to inner ear deformities. However, its molecular mechanisms on inner ear development are not clear. In this work, the inner ear morphology was investigated at different embryonic stages of the SOX10 mutation miniature porcine model with sensorineural hearing loss, and high-throughput RNA-seq and bioinformatics analyses were applied. Our results indicated that the SOX10 mutation in the miniature pigs led to an incomplete partition (IP) of the cochlea, a cystic apex caused by fusion from middle and apical turns, cochlear modiolar defects and a shortened cochlear duct. The model demonstrated 173 differentially expressed genes (DEGs) and 185 differentially expressed long non-coding RNAs (lncRNAs). The down-regulated DEGs most significantly enriched the inflammatory mediator regulation of the TRP channels, arachidonic acid metabolism, and the salivary secretion pathways, while the up-regulated DEGs most significantly enriched the systemic lupus erythematosus and alcoholism pathways. Based on gene cluster analysis, we selected four gene groups: WNT1, KCNQ4, STRC and PAX6.