Cochlear nerve dysplasia in unilateral severe to profound congenital sensorineural hearing loss - Prevalence in Australian children and the impact of socioeconomic disadvantage on its management.

INTRODUCTION: Congenital unilateral sensorineural hearing loss (cuSNHL) carries potentially significant social, educational, and developmental consequences. Early diagnosis enables investigation, and consideration of options for management and early intervention, helping to mitigate the effects of hearing loss. Cochlear nerve dysplasia (CND) is a prominent cause of cuSNHL and may affect candidacy for cochlear implantation. Socioeconomic disadvantage may impact on a patient's family's capacity to participate in necessary intervention and follow-up. METHODS: Infants with severe-profound cuSNHL referred to a large Australian quaternary pediatric center between October 2004 and December 2020 were retrospectively included. Audiometric and clinical data, and the presence of hearing loss risk factors were obtained from a prospectively collated database. In Australia MRI scans are provided free-of-charge to citizens and residents. MRI scans were reviewed to determine the status of the nerves within the internal acoustic meatus (IAM grade) along with attendance rates. Travel distance to the hospital was also calculated. Reasons for non-attendance at MRI were obtained from patient medical records and correspondence. Socioeconomic, educational, and occupational indices, and travel distances were obtained using patient residential postcodes with reference to Australian Bureau of Statistics data. RESULTS: A total of 98 patients were reviewed, 64.3% (n = 63) of whom underwent MRI. The median age at diagnosis was 40 days (IQR 27). The prevalence of CND was 75% (n = 47). Importantly, there was no significant difference in the degree of hearing loss between IAM grades (F(4,57) = 1.029, p = 0.405). Socioeconomic indices were significantly lower in patients not attending MRI investigations compared with patients who did attend. Travel distance was not significantly different between the two groups. CONCLUSION: CND is a prominent cause of cuSNHL in Australian infants. MRI at a young age allows parent education regarding management options and timely intervention where indicated. Socioeconomic disadvantage significantly impacts on participation in further routine assessment of cuSNHL, potentially limiting management options for these children long term.

Frequency and natural course of congenital cytomegalovirus-associated hearing loss in children.

BACKGROUND: Congenital cytomegalovirus-associated hearing loss (cCMV-associated HL) is a common cause of congenital or early-onset deafness. Although cCMV infection has been reported to lead to various types of HL, the natural course of cCMV-associated HL over a long period is not yet known. OBJECTIVES: To investigate the clinical phenotype of cCMV-associated HL in the largest study to date. METHODS: Thirty-one CMV-positive children, diagnosed by examining CMV DNA extracted from their dried umbilical cords retrospectively, were divided into unilateral and bilateral HL groups, and their hearing ability was evaluated using pure-tone audiometry and auditory steady-state response over time. RESULTS: Thirteen patients (41.9%) had unilateral HL and 18 (58.1%) had bilateral HL. In most cases of unilateral cCMV-associated HL, the ear with better hearing maintained a normal hearing threshold. Notably, in most cases of both unilateral and bilateral HL, the ear with worse hearing ultimately showed severe to profound HL. CONCLUSION: Our findings revealed that the natural course of cCMV-associated HL was different between the cases of unilateral and bilateral HL, as well as between the ears with better or worse hearing in all cases. These findings indicate that accurate diagnosis could enable proper follow-up and management of cCMV-associated HL in children.

Isolated Incudostapedial Cholesteatomas: Unique Radiologic and Surgical Features.

OBJECTIVES: Congenital cholesteatomas originate from epithelial tissue present within the middle ear in patients with an intact tympanic membrane, no history of otologic surgery, otorrhea, or tympanic membrane perforation. They are diagnosed by a pearl-like lesion on otoscopy and computed tomography (CT) scan showing an expansile soft-tissue mass. We describe a series of patients with no prior otologic history presenting with progressive unilateral conductive hearing loss and normal otoscopy. The CT scans showed ossicular erosion without obvious soft-tissue mass. Surgery confirmed incudostapedial erosion found to be cholesteatoma. In this study, we characterize the clinical course of patients diagnosed with isolated incudostapedial cholesteatoma (IIC) and review possible pathologic mechanisms. METHODS: Retrospective review of IIC cases treated by the Department of Pediatric Otolaryngology, Rady Children's Hospital, San Diego, 2014 to 2020. Data included patient demographics, clinical features, imaging, surgical findings, and audiologic data. RESULTS: Five patients were diagnosed with IIC (3 [60%] female; mean age at presentation 10.7 years [range 5.5-16.0]). All patients presented with postlingual unilateral conductive hearing loss and normal otoscopy without any past otologic history; delay in diagnosis ranged from 4 months to several years. The CT scans showed ossicular chain erosion with an absent long process of the incus and/or stapes superstructure. All patients underwent middle ear exploration, revealing a thin layer of cholesteatoma in the incudostapedial region, confirmed by histopathology. Mean preoperative speech reception threshold was 55 dB and improved to a mean of 31 dB in the 4 patients who underwent ossicular chain reconstruction. CONCLUSION: Isolated incudostapedial cholesteatoma should be included as a possible etiology in pediatric patients with insidious onset of unilateral conductive hearing loss with normal otoscopy, unremarkable otologic history, and a CT scan showing ossicular abnormality/disruption without notable middle ear mass. These patients should be counseled preoperatively regarding the possibility of cholesteatoma and should undergo middle ear exploration with possible ossiculoplasty.

Therapeutic challenges and clinical characteristics of single-sided deafness in children.

INTRODUCTION: The clinical implications of single-sided deafness (SSD) in children has historically been underappreciated by patients and providers alike, despite a large body of literature on the wide-ranging neurocognitive, language, scholastic, and functional impairments that occur. Conventional amplification options are marked by variable results and frequent loss of follow-up. METHODS: Retrospective case series for pediatric SSD from 2008 to 2018. RESULTS: 88 children with congenital SSD were identified. Seventeen (N = 17/88, 23.9%) passed their newborn hearing screen. Median age at first otolaryngology evaluation was 0.65 years (range 0.1-16.9 years). Most common etiologies included cochlear nerve deficiency (N = 39, CND, 44.3%), unknown (N = 30, 35.2%), inner ear malformation (N = 7, 8.0%), and congenital cytomegalovirus (N = 6, 6.8%). 32.5% of patients elected for continued observation only, followed by bone conduction hearing aid (27.7%), contralateral routing of sound aid (20.5%), conventional hearing aid (13.3%), or cochlear implant (6%). Lack of follow-up at ≥1 year was common (39.8%). Of those with device use data (N = 39), 84.7% reported either discontinued or <6 h of daily use. CONCLUSIONS: Despite early diagnosis and evaluation, the pediatric SSD cohort is characterized by high rates of loss of follow-up and amplification discontinuation. Cochlear nerve deficiency is commonly seen in congenital SSD. Early specialist referral is critical for habilitation evaluation. Patients and caregivers should be educated on the significant implications of unilateral hearing loss.

Outcomes of regional-based newborn hearing screening for 35,461 newborns for 5 years in Akita, Japan.

OBJECTIVES: Newborn hearing screening (NHS) has been actively performed since 2001 in Akita, Japan. The NHS coverage rate has increased yearly, and performance has been consistently >90% since 2012. The purpose of this study was to summarize NHS outcomes in the Akita prefecture of Japan and to obtain new insights for from our summarized data for the future. METHODS: A total of 35,461 newborns in hospitals and clinics where hearing screening was performed in Akita from 2012 to 2016 were included. The outcome data of NHS were collected for analysis. RESULTS: The overall screening coverage rate for hearing loss was 94.7%. Of the screened infants, 0.53% received a referral on the 2-stage automated auditory brainstem response (ABR), and 80.4% of referred infants had a check-up at the hospital to receive a diagnostic hearing examination. Finally, the prevalence of bilateral congenital hearing loss was 0.14%, that of bilateral moderate to profound hearing loss was 0.12%, and that of unilateral congenital hearing loss was 0.10%. Furthermore, the average consultation period in infants with risk factors was significantly later than that in infants without risk factors (p = 0.0015). Follow-up for infants diagnosed with normal hearing after diagnostic hearing examination revealed that 4.7% suffered bilateral moderate to profound hearing loss later. This percentage is significantly higher than that of the general group (p < 0.001). CONCLUSION: The prevalence of bilateral congenital hearing loss was 0.14% in Akita and 0.12% of infants were diagnosed with bilateral moderate to severe hearing loss. Medical personnel should be enlightened regarding the importance of performing hearing diagnostic examinations until 3 months of age. Even if infants were diagnosed with normal hearing after a diagnostic examination, we strongly suggest continuing follow-up until they are able to perform pure tone audiometry with accuracy.

Comparison of the prevalence and features of inner ear malformations in congenital unilateral and bilateral hearing loss.

OBJECTIVES: The aim of the study was to clarify differences in the prevalence and features of bony malformations in inner ear between congenital unilateral sensorineural hearing loss (USNHL) and congenital bilateral sensorineural hearing loss (BSNHL). METHODS: We conducted a retrospective study of 378 consecutive infants referred from routine newborn hearing screening in the past 18 years. Clinical background, audiological data, and temporal bone computed tomography (CT) findings were analyzed. The prevalence of malformations between USNHL and BSNHL groups were compared using the Chi-square test. RESULTS: The proportion of family history of hearing loss was significantly higher in infants with BSNHL than in those with USNHL (26/107 [24.3%] vs. 4/105 [3.7%]; p = 0.0001). Temporal bone CT scanning revealed significantly a higher prevalence of inner ear malformations in infants with USNHL than in those with BSNHL (93/109 [85.3%] vs. 4/107 [3.7%]; p < 0.0001). The most frequent anomaly in USNHL was cochlear nerve canal stenosis (69.7%), followed by cochlear malformations (20.2%), and narrow internal auditory canal (17.4%). Four infants with BSNHL accompanied by inner ear anomaly had complications such as Down's syndrome, developmental delay, or epilepsy. CONCLUSIONS: The prevalence of bony malformations in inner ear and/or IAC was markedly higher in infants with congenital USNHL than in infants with BSNHL. Temporal bone CT scanning may help to clarify the etiology of congenital hearing loss, especially in USNHL.

An Analysis of Risk Factors in Unilateral Versus Bilateral Hearing Loss.

A retrospective review of children with confirmed hearing loss identified through universal newborn hearing screening (UNHS) in Virginia from 2010 to 2014 was conducted in order to compare the incidence of Joint Committee on Infant Hearing (JCIH) risk factors in children with unilateral hearing loss (UHL) to bilateral hearing loss (BHL). Over the 5-year study period, 1004 children (0.20% of all births) developed a confirmed hearing loss, with 544 (51%) children having at least one JCIH risk factor. Overall, 18% of children with confirmed hearing loss initially passed UNHS. Of all children with risk factors, 226 (42%) demonstrated UHL and 318 (58%) had BHL. The most common risk factors for UHL were neonatal indicators (69%), craniofacial anomalies (30%), stigmata of HL syndromes (14%), and family history (14%). The most common risk factors in BHL were neonatal indicators (49%), family history (27%), stigmata of HL syndromes (19%), and craniofacial anomalies (16%). Children with the risk factor for positive family history were more likely to have BHL, while those with craniofacial anomalies were more likely to have UHL (P < .001). Neonatal indicators were the most commonly identified risk factor in both UHL and BHL populations. Children with UHL were significantly more likely to have craniofacial anomalies, while children with BHL were more likely to have a family history of hearing loss. Further studies assessing the etiology underlying the hearing loss and risk factor associations are warranted.

The impact of permanent early-onset unilateral hearing impairment in children - A systematic review.

BACKGROUND: Decision-making on treatment and (re)habilitation needs to be based on clinical expertise and scientific evidence. Research evidence for the impact of permanent unilateral hearing impairment (UHI) on children's development has been mixed and, in some of the reports, based on fairly small, heterogeneous samples. Additionally, treatment provided has been highly variable, ranging from no action taken or watchful waiting up to single-sided cochlear implantation. Published information about the effects of treatment has also been heterogeneous. Moreover, earlier reviews and meta-analyses published on the impact of UHI on children's development have generally focused on select areas of development. OBJECTIVES: This systematic review aimed to summarize the impact of children's congenital or early onset unilateral hearing impairment on listening and auditory skills, communication, speech and language development, cognitive development, educational achievements, psycho-social development, and quality of life. METHODS: Literature searches were performed to identify reports published from inception to February 16th, 2018 with the main electronic bibliographic databases in medicine, psychology, education, and speech and hearing sciences as the data sources. PubMed, CINALH, ERIC, LLBA, PsychINFO, and ISI Web of Science were searched for unilateral hearing impairment with its synonyms and consequences of congenital or early onset unilateral hearing impairment. Eligible were articles written in English, German, or Swedish on permanent unilateral hearing impairments that are congenital or with onset before three years of age. Hearing impairment had to be of at least a moderate degree with PTA ≥40 dB averaged over frequencies 0.5 to 2 or 0.5-4 kHz, hearing in the contralateral ear had to have PTA0.5-2 kHz or PTA0.5-4 kHz ≤ 20 dB, and consequences of unilateral hearing impairment needed to be reported in an unanimously defined population in at least one of the areas the review focused on. Four researchers independently screened 1618 abstracts and 566 full-text articles for evaluation of study eligibility. Eligible full-text articles were then reviewed to summarize the results and assess the quality of evidence. Additionally, data from 13 eligible case and multi-case studies, each having less than 10 participants, were extracted to summarize their results. Quality assessment of evidence was made adapting the Grades of Recommendations, Assessment, Development, and Evaluation (GRADE) process, and reporting of the results adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards. RESULTS: Three articles with the quality of evidence graded as very-low to low, fulfilled the eligibility criteria set. Due to the heterogeneity of the articles, only a descriptive summary could be generated from the results. Unilateral hearing impairment was reported to have a negative impact on preverbal vocalization of infants and on sound localization and speech perception both in quiet and in noise. CONCLUSIONS: No high-quality studies of consequences of early-onset UHI in children were found. Inconsistency in assessing and reporting outcomes, the relatively small number of participants, low directness of evidence, and the potential risk of confounding factors in the reviewed studies prevented any definite conclusions. Further well-designed prospective research using larger samples is warranted on this topic.

Persistent stapedial artery in PHACE syndrome.

INTRODUCTION: PHACE syndrome is characterized by posterior fossa malformations, haemangioma, arterial anomalies, coarctation of the aorta, and eye abnormalities. CASE REPORT: We present the case of a 6-year-old girl followed since birth for PHACE syndrome and left hemifacial haemangioma, who presented with left hearing loss. Computed tomography scan showed left persistent stapedial artery (PSA). DISCUSSION: Two types of arterial anomalies may be observed in PHACE syndrome: persistence of embryonic arteries and anomalies of cerebral arteries. PSA can be observed in the context of PHACE syndrome. Children with PHACE syndrome require regular audiometric follow-up to detect hearing loss and avoid its consequences on speech and language development.

Unilateral congenital hearing loss in children: Challenges and potentials.

The estimated incidence of sensorineural hearing impairment (>40 dB HL) at birth is 1.86 per 1000 newborns in developed countries and 30-40% of these are unilateral. Profound sensorineural unilateral hearing impairment or single sided deafness (SSD) can be treated with a cochlear implant. However, this treatment is costly and invasive and unnecessary in the eyes of many. Very young children with SSD often do not exhibit language and cognitive delays and it is hard to imagine that neurocognitive skills will present difficulties with one good ear. In the current paper we review the most recent evidence on the consequences of unilateral hearing impairment for auditory and neurocognitive factors. While data of both adults and children are discussed, we focus on developmental factors, congenital deafness and a window of opportunity for intervention. We discuss which etiologies qualify for a cochlear implant and present our multi-center prospective study on cochlear implants in infants with one deaf ear. The large, state-of-the art body of research allows for evidence-based decisions regarding management of unilateral hearing loss in children.

Improved directional hearing of children with congenital unilateral conductive hearing loss implanted with an active bone-conduction implant or an active middle ear implant.

Different amplification options are available for listeners with congenital unilateral conductive hearing loss (UCHL). For example, bone-conduction devices (BCDs) and middle ear implants. The present study investigated whether intervention with an active BCD, the Bonebridge, or a middle ear implant, the Vibrant Soundbridge (VSB), affected sound-localization performance of listeners with congenital UCHL. Listening with a Bonebridge or VSB might provide access to binaural cues. However, when fitted with the Bonebridge, but not with a VSB, binaural processing might be affected through cross stimulation of the contralateral normal hearing ear, and could interfere with processing of binaural cues. In the present study twenty-three listeners with congenital UCHL were included. To assess processing of binaural cues, we investigated localization abilities of broadband (BB, 0.5-20 kHz) filtered noise presented at varying sound levels. Sound localization abilities were analyzed separately for stimuli presented at the side of the normal-hearing ear, and for stimuli presented at the side of the hearing-impaired ear. Twenty-six normal hearing children and young adults were tested as control listeners. Sound localization abilities were measured under open-loop conditions by recording head-movement responses. We demonstrate improved sound localization abilities of children with congenital UCHL, when listening with a Bonebridge or VSB, predominantly for stimuli presented at the impaired (aided) side. Our results suggest that the improvement is not related to accurate processing of binaural cues. When listening with the Bonebridge, despite cross stimulation of the contralateral cochlea, localization performance was not deteriorated compared to listening with a VSB.

Duplicated internal auditory canal with inner ear malformation: Case report and literature review.

Internal auditory canal anomalies are rare. Narrow internal auditory canal is believed to occur as a result of aplasia or hypoplasia of the vestibulocochlear nerve. Narrow duplication of the internal auditory canal is considered to be very rare. Narrow duplication of the internal auditory canal with inner ear malformation has been reported in only 3 cases. We present 2 cases of narrow duplication of the internal auditory canal with inner ear malformation. The first case had inner ear malformation on only one side and the second case had inner ear malformation on both sides. The embryogenesis may be different between internal auditory canal and inner ear.

Cochlear Implantation in Children With Congenital Unilateral Deafness: A Case Series.

OBJECTIVES: Cochlear implant is regarded as a treatment option for hearing rehabilitation of adults with unilateral sensorineural hearing loss. A clear benefit has been experienced in regard to speech comprehension in noise, localization, and quality of life. The aim of this study was to investigate the benefit of cochlear implantation for children with congenital unilateral hearing loss. STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center; cochlear implant program. PATIENTS: Ten children with congenital unilateral hearing loss. INTERVENTION: After extensive consultation with the families and intensive counseling, the children received a cochlear implant. MAIN OUTCOME MEASURES: Categories of auditory performance, speech discrimination in open set, subjective assessment by Speech, Spatial and Qualities scale questionnaire. CONCLUSION: Eight of ten children use their cochlear implant consistently on a daily basis. Two children who were equipped with an implanted device at a later age tend to nonuse of the device. The evaluation of binaural hearing in small children is still difficult and methods have to be developed to allow objective assessment.

No auditory experience, no tinnitus: Lessons from subjects with congenital- and acquired single-sided deafness.

Recent studies have adopted the Bayesian brain model to explain the generation of tinnitus in subjects with auditory deafferentation. That is, as the human brain works in a Bayesian manner to reduce environmental uncertainty, missing auditory information due to hearing loss may cause auditory phantom percepts, i.e., tinnitus. This type of deafferentation-induced auditory phantom percept should be preceded by auditory experience because the fill-in phenomenon, namely tinnitus, is based upon auditory prediction and the resultant prediction error. For example, a recent animal study observed the absence of tinnitus in cats with congenital single-sided deafness (SSD; Eggermont and Kral, Hear Res 2016). However, no human studies have investigated the presence and characteristics of tinnitus in subjects with congenital SSD. Thus, the present study sought to reveal differences in the generation of tinnitus between subjects with congenital SSD and those with acquired SSD to evaluate the replicability of previous animal studies. This study enrolled 20 subjects with congenital SSD and 44 subjects with acquired SSD and examined the presence and characteristics of tinnitus in the groups. None of the 20 subjects with congenital SSD perceived tinnitus on the affected side, whereas 30 of 44 subjects with acquired SSD experienced tinnitus on the affected side. Additionally, there were significant positive correlations between tinnitus characteristics and the audiometric characteristics of the SSD. In accordance with the findings of the recent animal study, tinnitus was absent in subjects with congenital SSD, but relatively frequent in subjects with acquired SSD, which suggests that the development of tinnitus should be preceded by auditory experience. In other words, subjects with profound congenital peripheral deafferentation do not develop auditory phantom percepts because no auditory predictions are available from the Bayesian brain.

Cochlear Implantation in Children With Congenital Single-Sided Deafness.

OBJECTIVE: To determine audiological and clinical results of cochlear implantation in children with congenital single sided deafness (SSD), with an emphasis on children implanted before and after 6 years of age. STUDY DESIGN: Retrospective study. SETTING: Tertiary referral center. SUBJECTS: Twenty one children with congenital SSD who were implanted aged 10 months to 11;3 years. INTERVENTION: Unilateral cochlear implantation. MAIN OUTCOME MEASURES: Speech recognition in noise via the German Oldenburg Sentence Test for Children (OlKiSa), lateralization ability, and subjective evaluation of hearing results using self- and third-party assessment questionnaires. RESULTS: Significant improvements of all three aspects of true binaural hearing were found. The most striking improvement was the combined head shadow effect by 2.11 dB (squelch effect: 0.95 dB, summation effect 0.98 dB). An improvement of lateralization ability was also demonstrated. Parents had a high overall level of satisfaction with their children's cochlear implantation. Subjective benefit was verified in all three subscales of the Speech, Spatial, and Qualities of Hearing Questionnaire. No significant difference was found between subjects implanted before the age of 6 with those implanted later. Three of the five subjects with a follow-up of greater than 3 years were limited users or nonusers. CONCLUSIONS: Cochlear implant (CI) provision provides children with congenital SSD with significant audiological and subjective benefits which can be seen even in children implanted after the age of 3;6. The problem of limited use and nonuser, however, should not be ignored and has to be considered for further studies.

The role of bone conduction hearing aids in congenital unilateral hearing loss: A systematic review.

OBJECTIVES: To systematically review the literature on the audiological and/or quality of life benefits of a bone conduction hearing aid (BCHA) in children with congenital unilateral conductive or sensorineural deafness. METHODS: A systematic search was performed according to the PRISMA guidelines using the PubMed, Medline, and Embase databases. Data were collected on the following outcomes of interest: speech reception threshold, speech discrimination, sound localization, and quality of life measures. Given the heterogeneity of the data for quantitative analysis, the results are qualitatively summarized. RESULTS: Eight studies were included in the review. Four studies examined the audiological outcomes associated with bone conduction hearing aid implantation. There was a consistent gain in speech reception thresholds and speech discrimination, especially in noisy environments. Results pertaining to sound localization was inconsistent. The studies that examined quality of life measures reported a high usage rate of BCHAs among children. Quality of life improvements are reported with suggested benefit in the subdomain of learning. CONCLUSION: Given the potential benefits of a BCHA, along with the fact that it can be safely trialed using a headband, it is reasonable to trial a BCHA in children with congenital unilateral deafness. Should the trial offer audiological and/or quality of life benefits for the individual child, then BCHA implantation can be considered.

Sound Localization in Patients With Congenital Unilateral Conductive Hearing Loss With a Transcutaneous Bone Conduction Implant.

OBJECTIVE: There is no consensus regarding the benefit of implantable hearing aids in congenital unilateral conductive hearing loss (UCHL). This study aimed to measure sound source localization performance in patients with congenital UCHL and contralateral normal hearing who received a new bone conduction implant. STUDY DESIGN: Evaluation of within-subject performance differences for sound source localization in a horizontal plane. SETTING: Tertiary referral center. PATIENTS: Five patients with atresia of the external auditory canal and contralateral normal hearing implanted with transcutaneous bone conduction implant at the Medical University of Vienna were tested. INTERVENTION: Activated/deactivated implant. MAIN OUTCOME MEASURE: Sound source localization test; localization performance quantified using the root mean square (RMS) error. RESULTS: Sound source localization ability was highly variable among individual subjects, with RMS errors ranging from 21 to 40 degrees. Horizontal plane localization performance in aided conditions showed statistically significant improvement compared with the unaided conditions, with RMS errors ranging from 17 to 27 degrees. The mean RMS error decreased by a factor of 0.71 (p < 0.001). CONCLUSION: Analysis revealed improved sound localization performance in a horizontal plane with the activated transcutaneous bone conduction implant. Some patients with congenital UCHL might be capable of developing improved horizontal plane localization abilities with the binaural cues provided by this device.

A comparison of the brainstem auditory evoked response in healthy ears of unilaterally deaf dogs and bilaterally hearing dogs.

AIMS: Auditory plasticity in response to unilateral deafness has been reported in various animal species. Subcortical changes occurring in unilaterally deaf young dogs using the brainstem auditory evoked response have not been evaluated yet. The aim of this study was to assess the brainstem auditory evoked response findings in dogs with unilateral hearing loss, and compare them with recordings obtained from healthy dogs. METHODS: Brainstem auditory evoked responses (amplitudes and latencies of waves I, II, III, V, the V/I wave amplitude ratio, wave I-V, I-III and III-V interpeak intervals) were studied retrospectively in forty-six privately owned dogs, which were either unilaterally deaf or had bilateral hearing. The data obtained from the hearing ears in unilaterally deaf dogs were compared to values obtained from their healthy littermates. RESULTS: Statistically significant differences in the amplitude of wave III and the V/I wave amplitude ratio at 75 dB nHL were found between the group of unilaterally deaf puppies and the control group. The recordings of dogs with single-sided deafness were compared, and the results showed no statistically significant differences in the latencies and amplitudes of the waves between left- (AL) and right-sided (AR) deafness. CONCLUSIONS: The recordings of the brainstem auditory evoked response in canines with unilateral inborn deafness in this study varied compared to recordings from healthy dogs. Future studies looking into electrophysiological assessment of hearing in conjunction with imaging modalities to determine subcortical auditory plasticity and auditory lateralization in unilaterally deaf dogs are warranted.

Cochlear implantation in children with congenital unilateral deafness: Mid-term follow-up outcomes.

OBJECTIVES: Although cochlear implantation is widely used to treat unilateral deafness in adults, very little literature exists on its use and effects on the paediatric population. This report adds to the literature showing the mid-term follow-up outcomes achieved by these children. MATERIAL AND METHODS: Three children with congenital unilateral deafness were studied after implantation. Speech perception in noise, and sound localization ability were evaluated using age-appropriate materials. RESULTS: The preliminary data of our small group of 3 children with congenital unilateral profound hearing loss revealed that up to 3 years post-implantation, congenitally deaf children who received a cochlear implant after 4 years of age do not demonstrate binaural hearing benefits. CONCLUSION: Early intervention in the prelingual phase may be crucial for the development of binaural hearing.