Pediatric Auditory Brainstem Implant Surgery: A New Option for Auditory Habilitation in Congenital Deafness?

INTRODUCTION: The auditory brainstem implant (ABI) is a neuroprosthetic device that provides sound sensations to individuals with profound hearing loss who are not candidates for a cochlear implant (CI) because of anatomic constraints. Herein we describe the ABI for family physicians. METHODS: PubMed was searched to identify articles relevant to the ABI, as well as articles that contain outcomes data for pediatric patients (age <18 years) who have undergone ABI surgery. RESULTS: The ABI was originally developed for patients with neurofibromatosis type 2 (NF2) who become deaf from bilateral vestibular schwannomas. Over the past decade, indications for an ABI have expanded to adult patients without tumors (without NF2) who cannot receive a CI and children with no cochlea or cochlear nerve. Outcomes among NF2 ABI users are modest compared to cochlear implant patients, but recent studies from Europe suggest that some non-tumor adult and pediatric ABI users achieve speech perception. CONCLUSION: The ABI is a reasonable surgical option for children with profound hearing loss due to severe cochlear or cochlear nerve deformities. Continued prospective data collection from several clinical trials in the U.S. will provide greater understanding on long term outcomes that focus on speech intelligibility.

Amblyaudia: Review of Pathophysiology, Clinical Presentation, and Treatment of a New Diagnosis.

OBJECTIVE: Similar to amblyopia in the visual system, "amblyaudia" is a term used to describe persistent hearing difficulty experienced by individuals with a history of asymmetric hearing loss (AHL) during a critical window of brain development. Few clinical reports have described this phenomenon and its consequent effects on central auditory processing. We aim to (1) define the concept of amblyaudia and (2) review contemporary research on its pathophysiology and emerging clinical relevance. DATA SOURCES: PubMed, Embase, and Cochrane databases. REVIEW METHODS: A systematic literature search was performed with combinations of search terms: "amblyaudia," "conductive hearing loss," "sensorineural hearing loss," "asymmetric," "pediatric," "auditory deprivation," and "auditory development." Relevant articles were considered for inclusion, including basic and clinical studies, case series, and major reviews. CONCLUSIONS: During critical periods of infant brain development, imbalanced auditory input associated with AHL may lead to abnormalities in binaural processing. Patients with amblyaudia can demonstrate long-term deficits in auditory perception even with correction or resolution of AHL. The greatest impact is in sound localization and hearing in noisy environments, both of which rely on bilateral auditory cues. Diagnosis and quantification of amblyaudia remain controversial and poorly defined. Prevention of amblyaudia may be possible through early identification and timely management of reversible causes of AHL. IMPLICATIONS FOR PRACTICE: Otolaryngologists, audiologists, and pediatricians should be aware of emerging data supporting amblyaudia as a diagnostic entity and be cognizant of the potential for lasting consequences of AHL. Prevention of long-term auditory deficits may be possible through rapid identification and correction.

Systematic Review of Nontumor Pediatric Auditory Brainstem Implant Outcomes.

OBJECTIVE: The auditory brainstem implant (ABI) was initially developed for patients with deafness as a result of neurofibromatosis type 2. ABI indications have recently extended to children with congenital deafness who are not cochlear implant candidates. Few multi-institutional outcome data exist. Herein, we aim to provide a systematic review of outcomes following implantation of the ABI in pediatric patients with nontumor diagnosis, with a focus on audiometric outcomes. DATA SOURCES: PubMed, Embase, and Cochrane. REVIEW METHODS: A systematic review of literature was performed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) recommendations. Variables assessed included age at implantation, diagnosis, medical history, cochlear implant history, radiographic findings, ABI device implanted, surgical approach, complications, side effects, and auditory outcomes. RESULTS: The initial search identified 304 articles; 21 met inclusion criteria for a total of 162 children. The majority of these patients had cochlear nerve aplasia (63.6%, 103 of 162). Cerebrospinal fluid leak occurred in up to 8.5% of cases. Audiometric outcomes improved over time. After 5 years, almost 50% of patients reached Categories of Auditory Performance scores >4; however, patients with nonauditory disabilities did not demonstrate a similar increase in scores. CONCLUSION: ABI surgery is a reasonable option for the habilitation of deaf children who are not cochlear implant candidates. Although improvement in Categories of Auditory Performance scores was seen across studies, pediatric ABI users with nonauditory disabilities have inferior audiometric outcomes.

Increasing Competitiveness for an Otolaryngology Residency: Where We Are and Concerns about the Future.

For graduating medical students, securing a residency in otolaryngology-head and neck surgery has become exceedingly difficult. This commentary explores the ways that applicants and residency programs are reacting to the increasing competitiveness in applying to, interviewing for, and matching to an otolaryngology residency. The commonly held perceptions of applicants are compared to perspectives held by residency program directors and resident selection committees. Unintended consequences of the growing trend for medical students to add a research year to their curriculum are presented. Some cautions and suggestions about how to improve the application and selection process are offered.

Direct visualization of the murine dorsal cochlear nucleus for optogenetic stimulation of the auditory pathway.

Investigation into the use of virus-mediated gene transfer to arrest or reverse hearing loss has largely been relegated to the peripheral auditory system. Few studies have examined gene transfer to the central auditory system. The dorsal cochlear nucleus (DCN) of the brainstem, which contains second order neurons of the auditory pathway, is a potential site for gene transfer. In this protocol, a technique for direct and maximal exposure of the murine DCN via a posterior fossa approach is demonstrated. This approach allows for either acute or survival surgery. Following direct visualization of the DCN, a host of experiments are possible, including injection of opsins into the cochlear nucleus and subsequent stimulation by an optical fiber coupled to a blue light laser. Other neurophysiology experiments, such as electrical stimulation and neural injector tracings are also feasible. The level of visualization and the duration of stimulation achievable make this approach applicable to a wide range of experiments.

Epidemiology of otologic diagnoses in United States emergency departments.

OBJECTIVES/HYPOTHESIS: Otologic complaints may place a significant burden on emergency departments (EDs) in the United States; however, few studies have comprehensively examined this discrete patient population. We aimed to identify utilization of EDs by patients with primary otologic complaints. STUDY DESIGN: Retrospective analysis of the Nationwide Emergency Department Sample (NEDS) from 2009 through 2011. METHODS: The NEDS database was queried for patient encounters with a primary otologic diagnosis based on International Classification of Diseases, Ninth Revision codes (380-389). Weighted estimates for demographics, diagnostic characteristics, socioeconomic status, and trends over time were extracted. Predictors of mortality and admission were determined by multivariable logistic regression. RESULTS: A weighted total of 8,611,282 visits between 2009 and 2011 were attributed to otologic diagnoses, representing 2.21% of all ED visits. Stratified by patient age, otologic diagnoses encompassed 1.01% and 6.79% of all adult and pediatric ED visits, respectively. The majority of patients were treated and released (98.17%). The average age of patients presenting with an otologic complaint was 17.9 years (standard error = 0.23). Overall, 62.7% of patients who presented with an otologic complaint were 0 to 17 years old. The most common diagnoses among all age groups included otitis media not otherwise specified (NOS) (60.6%), infected otitis externa NOS (11.8%), and otalgia NOS (6.8%). CONCLUSIONS: We provide a comprehensive overview of otologic complaints that are an overlooked diagnostic category in public health research. NEDS data demonstrate a significant number of visits related to otologic complaints, especially in the pediatric population, that are nonemergent. LEVEL OF EVIDENCE: 4

Auditory brainstem implant candidacy in the United States in children 0-17 years old.

OBJECTIVES: The auditory brainstem implant (ABI) is an option for hearing rehabilitation in profoundly deaf patients ineligible for cochlear implantation. Over the past decade, surgeons have begun implanting ABIs in pediatric patients who are unable to receive cochlear implants due to congenital or acquired malformations of the inner ear. No study has examined the potential population-level demand for ABIs in the United States (US). Herein, we aim to quantify the potential need for pediatric ABIs. METHODS: A systematic literature review was conducted to identify studies detailing the rates of congenital cochlear and/or cochlear nerve (CN) anomalies. Absolute indications for ABI include bilateral cochlea or CN aplasia (Group A), and relative indications for ABI include bilateral cochlea or CN hypoplasia (Group B). Data was subsequently correlated to the US Census Bureau, the National Health Interview Survey, and the Gallaudet Research Institute to provide an estimation of pediatric ABI candidates. RESULTS: Eleven studies documented rates of bilateral findings. Bilateral cochlea aplasia was identified in 0-8.7% of patients and bilateral CN aplasia in 0-4.8% of patients (Group A). Bilateral cochlea hypoplasia was identified in 0-8.7% of patients and bilateral CN hypoplasia in 0-5.4% of patients (Group B). Using population-level sensorineural hearing loss data, we roughly estimate 2.1% of potential implant candidates meet absolute indications for an ABI in the United States. CONCLUSION: Congenital cochlear and cochlear nerve anomalies are exceedingly rare. This study provides the first preliminary estimate of cochlea and CN aplasia/hypoplasia at the population level albeit with limitations based on available data. These data suggest the need for dedicated ABI centers to focus expertise and management.

Systematic review of outcomes following observational and operative endoscopic middle ear surgery.

OBJECTIVES: Middle ear surgery increasingly employs endoscopes as an adjunct to or replacement for the operative microscope. We provide a systematic review of endoscope applications in middle ear surgery with an emphasis on outcomes, including the need for conversion to microscope, audiometric findings, length of follow-up, as well as disease-specific outcomes. DATA SOURCES: PubMed, Embase, and Cochrane CENTRAL database. METHODS: A literature review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis recommendations. Articles were categorized based on study design, indication, and use of an endoscope either as an adjunct to or as a replacement for a microscope. Qualitative and descriptive analyses of studies and outcomes data were performed. RESULTS: One-hundred three articles met inclusion and exclusion criteria. Of the identified articles, 38 provided outcomes data. The majority of these studies were moderate quality, retrospective, case-series reports. The indications for use of the endoscope were broad, with the most common being resection of cholesteatoma. In cholesteatoma surgery, endoscope approaches routinely identified residual cholesteatoma in primary and second-look cases. Other outcomes, including robust audiometric data, operating room times, wound healing, and quality of life surveys were not well described. CONCLUSIONS: Endoscopes have consistently been used as an adjunct to the microscope to improve visualization of the tympanic cavity. Recent reports utilize the endoscope exclusively during surgical dissection; however, data comparing patient outcomes following the use of an endoscope to a microscope are lacking. Areas in need of additional research are highlighted. LEVEL OF EVIDENCE: NA