Cochlear implantation in a Chinese patient with a novel frameshift variant in POU3F4 gene and incomplete partition type III: a case report

Variations in the POU Class 3 Homeobox 4 ( POU3F4) gene are associated with X-linked mixed deafness. Here, the identification of a novel variant of POU3F4 in a male paediatric patient (the proband) with incomplete partition type III (IP-III) hearing impairment, is described. Clinical data were collected from the proband and his biological parents. Whole exome sequencing of the proband revealed a novel frameshift insertion mutation in POU3F4 (c.717_718ins GTGCCTTGCAG : p.Leu240Valfs*5) in a hemizygous state. This variant likely truncates the protein within the POU-specific domain, and the proband’s biological mother was found to be a carrier of this variant. After excluding all contraindications, the proband underwent cochlear implantation in the right ear in June 2020. Cerebrospinal fluid (CSF) gushing was observed during surgery, but there were no postoperative complications, such as CSF leak, meningitis, or facial nerve stimulation. A novel pathogenic frameshift variant of POU3F4 was identified, enriching the known mutation spectrum of POU3F4. Effective perioperative prevention and response measures should be taken to reduce the incidence of CSF gushing and meningitis in patients receiving IP-III cochlear implantation.

İnkomplet partisyon tip II bulunan unilateral ve bimodal koklear implant kullanıcılarının konuşma, uzaysal algı ve işitme kalitesinin değerlendirilmesi

Evaluation of the speech, spatial and qualities of hearing in unilateral and bimodal cochlear implant users with incomplete partition type II Objective: The aim of this study was to perform a scale-based assessment of the hearing abilities of cochlear implant users with IP type II malformation and normal cochlea, including discrimination, orientation, and positioning of speech and environmental sounds in their environment. Material and Methods: A total of 30 cochlear implant users, 15 participants with IP-II inner ear anomalies and 15 participants with normal cochlea, aged 18-55 years were included in this study. All participants included in the study are unilateral CI and bimodal users. Participants were assessed using the Speech, Spatial, and Hearing Qualities Scale (SSQ). Results: When cochlear implant users with IP-II malformations and cochlear implant users with normal cochlea individually scored auditory abilities, the results were similar. It was observed that bimodal listeners tended to have all subdomains and overall SSQ scores compared to use of unilateral CI. Conclusion: It is very important to benefit from the advantages of binaural hearing in hearing sounds. It is thought that the use of scales as well as routine audiological evaluation batteries in the follow-up processes of cochlear implant users will be beneficial for audiologists. Keywords: Cochlear implant, speech perception, spatial perception, hearing quality

Incomplete Partition type I: Radiological Evaluation of the Temporal Bone

Objective: Incomplete partition type I is an uncommon congenital anomaly of the inner ear, characterized by typical cystic cochleovestibular appearance. Incomplete partition type I was firstly defined as cystic cochlea and vestibule without large vestibular aqueduct; however, large vestibular aqueduct and/or enlarged endolymphatic duct could rarely be seen in incomplete partition type I anomaly. Correct diagnosis of the type of cochlear malformation and differentiation of incomplete partition type I is necessary for patient management and surgical approach. Our aim was to document the temporal bone imaging findings in a series of patients with incomplete partition type I. Materials and Methods: CT (n=85) and/or MRI (n=80) examinations of 99 ears in 59 incomplete partition type I patients were retrospectively evaluated. All structures of the otic capsule were retrospectively assessed. The appearances of cochlea and vestibule, vestibular aqueduct/endolymphatic duct, semicircular canals were qualitatively evaluated by an experienced neuroradiologist. The vertical dimension of vestibular aqueduct and/or endolymphatic duct (from the point where the duct arises from the vestibule) was measured on CT/MRI. Anterior-posterior diameter of the internal acoustic canal and the diameter of cochlear aperture were measured on CT. The cochleovestibular nerves were evaluated on sagittal-oblique high T2-weighted imaging. Results: All 99 ears had defective partition with unpartitioned cochlear basal turn and absent interscalar septae, separated but cystic cochlea. The vestibule was enlarged in all ears except one. Semicircular canals were usually dysplastic (92.9%). A total of 35 incomplete partition type I ears (35.3%) had large vestibular aqueduct and/or enlarged endolymphatic duct. Internal acoustic canal was wide in 21% of ears. Cochlear aperture was wide in 5.9% of ears. Cochlear nerve was either hypoplastic or aplastic in about a quarter of incomplete partition type I ears. Conclusion: In up to one-third of incomplete partition type I patients, an associated large vestibular aqueduct /endolymphatic duct could be seen accompanying typical inner ear findings. Although the cochlear nerves are normal in the majority of cases, auditory brainstem implantation may be necessary in certain cases of incomplete partition type I anomaly.

Role of Computed Tomography and Magnetic Resonance Imaging in detecting the Prevalence of inner ear anomalies among cochlear implant candidates

Background Hearing loss management using cochlear implants in patients with inner ear anomalies has long been discussed in the otology community. Magnetic resonances imaging (B,/IRI) and Computed tomography (CT) play important roles in the preoperative assessment of inner ear abnormalities such as cochlear nerve deficiency and variant anatomy as these abnormalities may not only affect the decision of the implantation procedure or the patient's prognosis regarding auditory improvement, but also the risk of complications. Objective To examine the prevalence of inner ear anomalies among cochlear implant recipients in patients with congenital sensorineural hearing loss among the pediatric age group in the Demerdash hospital, Ain Shams university using High resolution computed tomography (HRCT) and MRI imaging. Methods A retrospective descriptive study over the course of 9 months that included all patients that are candidates for cochlear implant referred to the Radiology department, Ain Shams University Hospitals for a preoperative imaging in the form of CT and VIRI scans. Results CT and MRI scans of 33 patients who had congenital hearing loss and were candidates for cochlear implantation with total 66 ears were reviewed. Inner ear anomalies were identified in 8 patients representing a prevalence (24.2%) with 14 ear diseased. Anomalies were seen bilaterally in 6 patients and unilaterally in 2 patients. Among the 14 diseased ear, 9 ears (64.3%) were seen with incomplete partition Il, 7 ears (50%) were seen with enlarged vestibular aqueduct, 4 ears (28.6%) were seen with cochlear hypoplasia, 3 ears (21.4%) were seen with semicircular canal aplasia, 2 ears (14.3%) were seen with incomplete partition type I, 2 ears (14.3%) were seen with cochlear nerve aplasia, 2 ears with cochlear aplasia (14.3%), I ear (7.1%) was seen with common cavity ear (7.1%) with complete labyrinthine aplasia. Conclusion Prevalence of inner ear anomalies among cochlear implant candidates was 24.2%. This result is consistent with results worldwide and the most common anomalies were Incomplete partition Il and large vestibular aqueduct. Abbreviations Computed tomography (CT), Magnetic resonance imaging (MRI), High resolution computed tomography (HRCT), Internal auditory canal (IAC), Cerebellopontine angle (CPA).

Cochlear Implantation in Inner Ear Malformations: Considerations Related to Surgical Complications and Communication Skills

<b><i>Introduction:</i></b> There are particular challenges in the implantation of malformed cochleae, such as in cases of facial nerve anomalies, cerebrospinal fluid (CSF) leaks, erroneous electrode insertion, or facial stimulation, and the outcomes may differ depending on the severity of the malformation. The aim of this study was to assess the impact of inner ear malformations (IEMs) on surgical complications and outcomes of cochlear implantation. <b><i>Methods:</i></b> In order to assess the impact of IEMs on cochlear implant (CI) outcomes, 2 groups of patients with similar epidemiological parameters were selected from among 863 patients. Both the study group (patients with an IEM) and control group (patients with a normal inner ear) included 25 patients who received a CI and completed at least 1 year of follow-up. Auditory performance, receptive and expressive language skills, and production and use of speech were evaluated preoperatively and at least 1 year after implantation. Types of surgical complications and rates of revision surgeries were determined in each group. <b><i>Results:</i></b> In the study group, the most common malformation was an isolated enlarged vestibular aqueduct (EVA) (44.8%). Overall, the patients with IEMs showed significant improvement in auditory-verbal skills. In general, the patients who had normal cochleae scored significantly better compared to patients with IEMs (<i>p</i> &#x3c; 0.05). The complication rate was significantly lower in the control group compared to the study group (<i>p</i> = 0.001), but the rate of revision surgeries did not differ significantly (<i>p</i> = 0.637). <b><i>Conclusion:</i></b> It is possible to improve communication skills with CIs in patients with IEMs despite the variations in postoperative performances. Patients with EVA, incomplete partition type 2, and cochlear hypoplasia type 2 were the best performers in terms of auditory-verbal skills. Patients with IEMs scored poorly compared to patients with normal cochleae. CSF leak (gusher or oozing) was the most common complication during surgery, which is highly likely in cases of incomplete partition type 3.

Incomplete Partition Type III: Computed Tomography Features and Cochlear Implantation Complications

In this case report, we review a male child who presented with severe bilateral hearing loss. Preoperative high-resolution computed tomography (HRCT) evaluation facilitated the initial diagnosis of the disease, which revealed typical findings of cochlear incomplete partition type III anomaly (IP-III), surgical planning, and cochlear implant selection to avoid possible complications. The child underwent cochlear implantation, which resulted in gushing and misplacement of the electrodes into the internal auditory canal (IAC) as postoperative complications. Postoperative imaging was used to determine the position of the implant and to assess the complications. The child’s postoperative X-ray revealed misplacement of the cochlear implant, the extent of which was further assessed by a HRCT scan for preplanning the revision surgery and electrode selection. Following the revision surgery, a further HRCT scan confirmed proper implantation and ruled out any further complications.

Potential implications of slim modiolar electrodes for severely malformed cochlea: A comparison with the straight array with circumferential electrodes

Objectives: Malformations of the inner ear account for approximately 20% of congenital deafness. In current practice, the straight arrays with circumferential electrodes (i.e., full-banded electrodes) are widely used in severely malformed cochlea. However, the unpredictability of the location of residual spiral ganglion neurons in such malformations argues against obligatorily pursuing the full-banded electrode in all cases. Here, we present an experience of electrically evoked compound action potential (ECAP) and radiography-based selection of an appropriate electrode for severely malformed cochlea. Methods: Three patients with the severely malformed cochlea, showing cochlear hypoplasia type II (CH-II), incomplete partition type I (IP-I), and cochlear aplasia with a dilated vestibule (CADV), were included, and the cochlear nerve deficiency (CND) was evaluated. Full-banded electrode (CI24RE(ST)) and slim modiolar electrode (CI632) were alternately inserted to compare ECAP responses and electrode position. Results: In patient 1 (CH-II with CND) who had initially undergone cochlear implantation (CI) using the lateral wall electrode (CI422), a revision CI was performed due to incomplete insertion of CI422 and resultant unsatisfactory performance, thus explanting the CI422 and re-inserting the CI24RE(ST) and CI632 sequentially. Although both electrodes elicited reliable ECAP responses with correct positioning, CI24RE(ST) showed overall lower ECAP thresholds compared to CI632; thus, CI24RE(ST) was selected. In patient 2 (IP-I with CND), CI632 elicited superior ECAP responses relative to CI24RE(ST), with correct positioning of the electrode; CI632 was chosen. In patient 3 (CADV), CI632 did not elicit an ECAP response while meaningful ECAP responses were obtained with the CI24RE(ST) array once correct positioning was achieved. All patients markedly improved auditory performance postoperatively. Conclusion: ECAP and radiography-based strategy for an appropriate electrode may be useful for severely malformed cochlea, leading to enhanced functional outcomes. Additionally, the practice of sticking to the full-banded straight electrode may not always be the best for IP-I and CH-II.

Postural Control in Subjects with Incomplete Partition Inner Ear Malformations: A Comparison of Incomplete Partition Types

<b><i>Introduction:</i></b> Children with inner ear malformation (IEM) are at risk of vestibular loss as well as hearing loss. Incomplete partition (IP) anomalies constitute about 41% of all IEMs. This study aimed to investigate the postural control in subjects with the same type of IP on both sides and to compare their results with cochlear implant (CI) users without IEM and healthy peers. <b><i>Methods:</i></b> The study group consists of 17 subjects with the same IP types on both sides and using auditory implants on at least one side, with the following 3 groups: 6 IP-I subjects (mean age 12.28 ± 6.25), 6 IP-II subjects (mean age 12.90 ± 3.23), and 5 IP-III subjects (mean age 6.98 ± 3.10). Six unilateral CI users (mean age 11.38 ± 3.57) with normal inner ear structures were included in the CI control group, and 6 healthy peers (10.20 ± 4.79) were included in the healthy control group. The postural control was measured using the Bruininks-Oseretsky Test of Motor Proficiency Second Edition (BOT-2) balance subtest. All devices were turned off during the balance test. <b><i>Results:</i></b> The BOT-2 balance scale scores were observed to be significantly different between the IP-I and healthy control group (medians of balance scores being 3.00 and 16.00, respectively, <i>p</i> &#x3c; 0.001) and the IP-III and healthy control group (medians of balance scores being 6.60 and 16.00, respectively, <i>p</i> = 0.04). The IP-II group had better balance scores (median = 8.00) than those of the other IP groups, although there were no significant differences between the IP-II and other groups (<i>p</i> &#x3e; 0.05). <b><i>Conclusion:</i></b> This study demonstrated that subjects with the same IP type on both sides and with early implantation may differ in terms of their postural control abilities depending on their IP type. Subjects with IP should be regularly followed up by the vestibular assessment and supported by their postural control ability by vestibular rehabilitation.