Daniel Choo

Enlarged vestibular aqueduct syndrome in the pediatric population.

Objective To correlate clinical and audiometric findings with the radiologic appearance in patients with enlarged vestibular aqueduct. Design A retrospective review of data from enlarged vestibular aqueduct patients identified in a pediatric hearing-impaired database of 1,200 patients. Setting A tertiary care pediatric referral center. Patients Subjects were included for study with a radiographic diagnosis of enlarged vestibular aqueducts in at least one ear by a pediatric neuroradiologist. Main Outcome Measures Audiometric evaluations and radiographic temporal bone measurements. Results Seventy-seven patients were identified with an enlarged vestibular aqueduct with a male-to-female ratio of 1:1.5. Patients were followed for a mean of 34 months (range, 0–179 months). Hearing loss was bilateral in 87% of cases. Vestibular symptoms were present in only three (4%) of the patients. Three patients (4%) suffered a sudden decrease in hearing after mild head trauma. Borderline enlargement of the vestibular aqueduct was associated with varying degrees of sensorineural hearing loss. Ninety-seven percent (64 of 66) of ears in control subjects with no sensorineural hearing loss had normal vestibular aqueduct measurements at the midpoint and operculum. Overall, the audiogram remained stable in 51% of ears, fluctuated in 28%, and progressively worsened in 21%. Measurements of the vestibular aqueduct at the midpoint and the operculum did not correlate with the audiometric threshold or the audiogram configuration. However, mean vestibular aqueduct size at the operculum was significantly larger in those with a progressive loss when compared with those with a fluctuating or stable hearing outcome. Conclusions Overall, audiometric thresholds remained generally stable, with sudden deterioration of hearing after head trauma seen in only three male patients. Progression of hearing loss after head trauma was not a significant finding in our patient population. Vestibular aqueduct opercular size alone showed a direct correlation with the audiometric outcome. Borderline enlarged vestibular aqueduct measurements appear to be associated with sensorineural hearing loss.

Pediatric cochlear implantation in auditory neuropathy.

Objective Auditory neuropathy (AN) is characterized by varying degrees of sensorineural hearing loss, an absent or severely abnormal auditory brainstem response, and normal otoacoustic emissions. The nomenclature for this condition reflects the concept that the site of lesion is proximal to the cochlea (e.g., cochlear nerve). Given this hypothesis, it is reasonable to expect limited benefit from cochlear implantation in patients with AN. However, a growing body of evidence shows the striking benefits of cochlear implantation in AN. To explore this topic, we reviewed our population of children with AN and, specifically, the performance results in those children having undergone cochlear implantation. Study Design A retrospective case review of those patients diagnosed with AN from 1993 to 2001. Setting A tertiary pediatric referral center. Patients A diagnosis of AN reported from the Center for Hearing and Deafness Research, Cincinnati, OH, database. Results Eighteen patients were diagnosed with AN (11 girls, 7 boys), with 3 sets of siblings, including 1 set of identical twins. Four patients with AN underwent implantation in the previous 5 years. Twelve out of the 18 patients had classic risk factors for AN (e.g., prematurity and hyperbilirubinemia). The degree of hearing loss varied in our patients, with a majority showing severe to profound deficits. All children with implants showed improvement in auditory and verbal development, but this improvement was variable. Conclusion The success of cochlear implantation in these patients suggests that some children with AN have an auditory system lesion that can be compensated for by cochlear implantation. This implies either an inner hair cell or inner hair cell–cochlear nerve junctional pathology that can be overcome by direct electrical stimulation.

The large vestibular aqueduct: A new definition based on audiologic and computed tomography correlation:

Objective The study goal was to determine the prevalence and clinical significance of a large vestibular aqueduct (LVA) in children with sensorineural hearing loss (SNHL). Study Design and Setting We conducted a retrospective review of a pediatric SNHL database. One hundred seven children with SNHL were selected and their radiographic and audiometric studies were evaluated. Radiographic comparisons were made to a group of children without SNHL. Results A vestibular aqueduct (VA) larger than the 95th percentile of controls was present in 32% of children with SNHL. Progressive SNHL was more likely to occur in ears with an LVA and the rate of progressive hearing loss was greater than in ears without an LVA. The risk of progressive SNHL increased with increasing VA size as determined by logistic regression analysis. Conclusions An LVA is defined as one that is ≥2mm at the operculum and/or ≥1 mm at the midpoint in children with nonsyndromic SNHL. An LVA appears to be more common than previously reported in children with SNHL. A linear relationship is observed between VA width and progressive SNHL. Significance The finding of an LVA in children with SNHL provides diagnostic as well as prognostic information.

Auditory Skills Development among Children with Developmental Delays and Cochlear Implants

Objectives: We sought to understand auditory skills outcomes in young children with cochlear implants and developmental delay. Methods: Children who received cochlear implants at less than 36 months of age were identified via chart review. Their postimplant auditory skills outcomes were measured with the Auditory Skills Checklist. Results: Of 35 children who received cochlear implants before the age of 36 months, 14 children (40%) had additional disabilities or some form of developmental delay. The 12-month postimplant data indicated progress in all groups of children. Children with additional disabilities had the same rate of auditory skills progress as children with no additional disabilities (β = 9.3 versus 9.3; p = 0.5). However, the children with additional disabilities tended to start at a lower baseline skills set (approximately 6 points lower) on the Auditory Skills Checklist. For children with average developmental quotients (at least 80), the rate of progress was twice that of children with a developmental quotient of less than 80, irrespective of a developmental disability (β = 9.9 versus 4.8; p = 0.03). Children with a developmental quotient of less than 80 were less likely to gain skills in discrimination and identification after the first postimplant year. Conclusions: Children with additional disabilities make progress in auditory skills, but may not develop higher auditory skills of identification and comprehension within the first 6 months after implantation. Categorizing children according to a cognitive developmental quotient may provide more predictive ability than does categorizing them by disability type.

Developmental expression of aquaporin 2 in the mouse inner ear

Objectives The maintenance of endolymph homeostasis is critical for the inner ear to perform its functions of hearing and maintaining balance. The identification and cloning of aquaporins (a family of water channel proteins) has allowed the study of a novel cellular mechanism potentially involved in endolymph homeostasis. The objective of the present study was to define the developmental temporal and spatial e‐pression pattern of aquaporin 2 (Aqp2) in the developing mouse inner ear.

Universal newborn hearing screening in 2010.

Purpose of reviewThe objectives of this review are to provide the reader with a current and concise review of the data and trends in universal newborn hearing screening. Within a relatively short period of time, the concept of screening all infants for hearing loss at the time of birth has evolved from a nascent process to a truly universal system in most developed countries. As a result, the focus and challenges of universal newborn hearing screening have shifted to topics of developing even more efficient and cost-effective approaches, and potentially melding physiologic hearing screenings with ancillary screening techniques. Recent findingsEnhancement of the universal newborn hearing screening process is likely to be accomplished by implementation of novel tools such as wideband reflectance technologies and intelligent incorporation of screening for common genetic and viral causes of congenital hearing loss. SummaryWith such a rapidly evolving process, it will be critical for clinicians to understand the benefits and limitations of various newborn hearing screening methodologies in order to determine the most appropriate management of children referred from their universal newborn hearing screening. This will entail a working knowledge of emerging audiologic tools as well as infectious and genetic causes of pediatric hearing loss.

Auditory Skills Checklist: Clinical Tool for Monitoring Functional Auditory Skill Development in Young Children with Cochlear Implants

Objectives: The Auditory Skills Checklist© (ASC) was developed to address the need for tools to evaluate functional auditory skill progress in very young children with sensorineural hearing loss. We describe the development, validation, and utility of the ASC for use in young children with cochlear implants. Methods: Using the ASC, we measured auditory skills in 37 subjects who received cochlear implants at no more than 36 months of age. Repeated measures analysis was conducted to determine expected auditory skill development after implantation. Interrater reliability was tested on a small subset. The ASC was compared to the Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) to determine its validity in measuring functional auditory skills. Results: The ASC had excellent internal consistency (Cronbachs alpha, 0.98) and interrater reliability (intraclass correlation coefficient, 0.99), and was highly correlated with the IT-MAIS (r = 0.90). According to the repeated measures analysis, children who received a cochlear implant at 36 months of age or earlier were expected to increase their ASC score by 8 points every 3 months (beta coefficient, 8.3; p < .001). Conclusions: The ASC is a clinically relevant and easily administered tool for assessing the functional auditory skills of young children with a cochlear implant. By assessing auditory skill development over time with the ASC, we can better realize expectations for a particular child based on his or her age, hearing loss level, and management strategies in place.

Expression of aquaporin 1 and 5 in the developing mouse inner ear and audiovestibular assessment of an Aqp5 null mutant.

To examine the potential roles of aquaporins 1 and 5 (AQP1 and AQP5, respectively) in inner ear development and function, we defined their spatial and temporal expression patterns in the developing mouse inner ear and examined the morphologic and physiologic effects of loss of Aqp5 function. Standard in situ hybridization (ISH) and immunohistochemical (IHC) assays were used for expression studies with routine morphologic, behavioral, and physiologic assessments of hearing and balance in Aqp5 null mutant mice. AQP1 was first detected at embryonic day 10.5 (E10.5) in the otocyst but eventually localized to specific nonsensory portions of the inner ear and connective tissue cells surrounding the membranous labyrinth. AQP5 displayed specific cochlear expression, first detectable at E15.5 in the nonsensory epithelium and later restricted to the lateral wall of the cochlear duct near the spiral prominence. AQP5 expression continued through postnatal periods with a change of expression domain to the stria vascularis between postnatal day 7 (P7) and P14. By in situ hybridization and immunohistochemical techniques, subtle differences between transcript and protein expression patterns were noted for both AQP1 and 5. Although AQP5 is dynamically expressed in the developing mouse inner ear, adult Aqp5 knockout mice show normal hearing when tested and normal inner ear structural development. These results suggest redundant or alternative mechanisms that likely regulate water homeostasis in the developing and mature inner ear.

Audiologic and temporal bone imaging findings in patients with sensorineural hearing loss and GJB2 mutations

Our objectives were to determine genotype‐phenotype correlations in patients with sensorineural hearing loss (SNHL) who undergo testing for GJB2 mutations and to examine the relationship of temporal bone anomalies seen on computed tomography (CT) and GJB2 mutations.

Actinomycosis of the Temporal Bone With Labyrinthine and Facial Nerve Involvement

Objectives: To demonstrate the clinical, radiologic, and pathologic findings of actinomycosis of the temporal bone.