Recurrent missense variant identified in two unrelated families with MPZL2-related hearing loss, expanding the variant spectrum associated with DFNB111.

MPZL2-related hearing loss is a rare form of autosomal recessive hearing loss characterized by progressive, mild sloping to severe sensorineural hearing loss. Thirty-five previously reported patients had biallelic truncating variants in MPZL2, with the exception of one patient with a missense variant of uncertain significance and a truncating variant. Here, we describe the clinical characteristics and genotypes of five patients from four families with confirmed MPZL2-related hearing loss. A rare missense likely pathogenic variant [NM_005797.4(MPZL2):c.280C>T,p.(Arg94Trp)] located in exon 3 was confirmed to be in trans with a recurrent pathogenic truncating variant that segregated with hearing loss in three of the patients from two unrelated families. This is the first recurrent likely pathogenic missense variant identified in MPZL2. Apparently milder or later-onset hearing loss associated with rare missense variants in MPZL2 indicates that some missense variants in this gene may cause a milder phenotype than that resulting from homozygous or compound heterozygous truncating variants. This study, along with the identification of truncating loss of function and missense MPZL2 variants in several diverse populations, suggests that MPZL2-related hearing loss may be more common than previously appreciated and demonstrates the need for MPZL2 inclusion in hearing loss testing panels.

High-Dose Celecoxib for Pain After Pediatric Tonsillectomy: A Randomized Controlled Trial.

OBJECTIVE: Pediatric tonsillectomy causes significant postoperative pain. Newer nonsteroidal anti-inflammatory drugs such as celecoxib control pain without increasing bleeding risk, but in prior studies provided only modest pain reduction at standard doses. We aimed to determine if high-dose celecoxib (double the usual pediatric dose) is effective for pain, without increasing bleeding or other risks. STUDY DESIGN: Randomized double-blind trial. SETTING: Pediatric tertiary center. METHODS: Children aged 3 to 11 years undergoing total tonsillectomy were randomized to receive celecoxib (6 mg/kg/dose) or placebo, twice daily, for up to 10 days. All cases were supplemented with acetaminophen and oxycodone as needed. All participants and personnel were blinded to treatment group. Subjects recorded coanalgesic consumption, pain, diet, and activity. RESULTS: The celecoxib group (n = 68) consumed 0.72 mg/kg of oxycodone, as compared with 1.12 mg/kg in the placebo group (n = 62), a 36% difference that was not significant. However, multivariate analysis by treatment group, separate from pain levels, confirmed that this reduction was due to celecoxib treatment (P = .03). In subjects with more prolonged pain (n = 88), celecoxib reduced consumption by 52% (P = .02). Celecoxib showed greater benefit for subjects in the prolonged pain group than for those in the lesser pain group (P = .006). Incidence of adverse events was similar between groups. Minor hemorrhage occurred in 4.6% (5 placebo, 3 celecoxib). CONCLUSION: High-dose celecoxib is effective in controlling pain after tonsillectomy, with no adverse effects in this relatively small sample. It reduces narcotic consumption, and its impact appears greater in children with higher degrees of pain. Celecoxib can be considered an effective alternative to ibuprofen after tonsillectomy. This trial was registered at ClinicalTrials.gov: NCT02934191.

Gadolinium-based contrast agent for Magnetic Resonance Imaging as a predictor of postmeningitic hearing loss in children.

OBJECTIVE: To determine if Gadolinium-based enhanced Magnetic Resonance Imaging (GdMRI) can be used to predict sensorineural hearing loss (SNHL) in pediatric patients diagnosed with bacterial meningitis. STUDY: Design: Retrospective chart review. SETTING: Primary Children's Hospital, Salt Lake City, Utah. SUBJECTS: and Methods: We studied forty-two pediatric patients diagnosed with bacterial meningitis who underwent brain GdMRI during their index hospital admission and for whom ear specific audiometric data were available (August 2008-July 2018). A pediatric neuroradiologist, blinded to both disease and audiometric data, rated cochlear enhancement of each GdMRI (0-3; none to markedly enhanced). RESULTS: Ear specific MRI scores were statistically significantly related to ear specific hearing outcomes (p < 0.01). SNHL occurred in 19 out of 82 ears (12 out of 42 patients; 2 ears were excluded due to pre-existing SNHL in one ear and inability to read the GdMRI on the other ear). Ten of 19 ears (53%) that developed SNHL showed mild/moderate/marked enhancement (MRI score of 1, 2, or 3 respectively). Fifty-three of the 63 unaffected ears (84%) showed no enhancement (MRI score of 0). Ten of 13 (77%) ears that developed severe to profound SNHL showed mild/moderate/marked enhancement. GdMRI was 58% sensitive and 84% specific in predicting which ears would develop SNHL. GdMRI was 77% sensitive and 84% specific in identifying severe to profound SNHL. CONCLUSION: Our study demonstrates that GdMRI is a promising tool for predicting specifically severe-profound hearing loss in pediatric patients following bacterial meningitis infection.

Audiologic Phenotype and Progression in Pediatric STRC-Related Autosomal Recessive Hearing Loss.

OBJECTIVES: Sensorineural hearing loss (SNHL) is a common sensory deficit affecting pediatric populations. The majority of pediatric SNHL is genetic in etiology, with over 123 identified nonsyndromic causative genes. One such gene is STRC, which has been identified as the second most frequent autosomal recessive nonsyndromic gene associated with SNHL in multiple populations. The objective of this study was to investigate the phenotypic presentation and incidence of audiologic progression in pediatric patients with STRC-related hearing loss (HL). METHODS: Thirty-nine pediatric patients with confirmed HL and biallelic pathogenic STRC mutations were identified at two pediatric hospitals. A retrospective chart review was completed including demographics, medical history, genetic testing results, and audiologic data. HL progression was assessed using air conduction thresholds from pure-tone audiograms and auditory brain stem responses, and masked bone conduction thresholds from pure-tone audiograms. RESULTS: Thirty-six patients had homozygous STRC deletions. Three were compound heterozygotes. All patients had bilateral, symmetric SNHL. Baseline HL was mild in 39% of ears, moderate in 52%, and moderate-severe in 3%. Of the 31 patients for which sufficient data were available to evaluate progression, 18 (58%) had some degree of progressive HL. Among these 31 patients assessed for progression, the mean hearing threshold declined by 0.6 dB per year (95% confidence interval: 0.5, 0.8; P < .001). CONCLUSIONS: These biallelic STRC patients displayed HL ranging from mild to moderate-severe at baseline and progressing in 58%. The variability of the STRC phenotype and the possibility of audiologic progression should be considered in the clinical management of pediatric STRC-related SNHL. LEVEL OF EVIDENCE: 3 Laryngoscope, 131:E2897-E2903, 2021.

Drug delivery to the pediatric upper airway.

Pediatric upper airway disorders are frequently life-threatening and require precise assessment and intervention. Targeting these pathologies remains a challenge for clinicians due to the high complexity of pediatric upper airway anatomy and numerous potential etiologies; the most common treatments include systemic delivery of high dose steroids and antibiotics or complex and invasive surgeries. Furthermore, the majority of innovative airway management technologies are only designed and tested for adults, limiting their widespread implementation in the pediatric population. Here, we provide a comprehensive review of the most recent challenges of managing common pediatric upper airway disorders, describe the limitations of current clinical treatments, and elaborate on how to circumvent those limitations via local controlled drug delivery. Furthermore, we propose future advancements in the field of drug-eluting technologies to improve pediatric upper airway management outcomes.

Validation of a Parent Proxy Quality-of-Life Measure for Young Children With Hearing Loss.

OBJECTIVES: No hearing-related quality of life (QL) questionnaire currently exists for children < 7 years. This study aimed to develop and evaluate the construct validity and reliability of a new parent-proxy Preschool Hearing Environments and Reflection on Quality of Life (HEAR-QL) questionnaire. METHODS: Parents of children 2 to 6 years old with any hearing loss (HL) were recruited from multiple sites. To evaluate the new measure's construct validity, participants completed a 70-item preschool HEAR-QL and validated questionnaires measuring hearing and communication functioning (Parents' Evaluation of Aural/Oral Performance of Children), generic pediatric QL (Pediatric Quality of Life Inventory Parent Report, PedsQL), family functioning (PedsQL Family Impact Module), and parent well-being (Patient Reported Outcomes Measurement Information System Adult Global Report). Participants completed the preschool HEAR-QL 2 weeks later to measure test-retest reliability. Exploratory principal components analysis was used to reduce the number of items and determine the underlying HEAR-QL factor structure. Analysis of variance examined HEAR-QL differences by HL. RESULTS: Among 205 parents, 144 had children with bilateral HL, 50 had children with unilateral HL, 10 had children with normal hearing (NH), and one child's hearing status was unspecified. The 70-item questionnaire was reduced to 23 items with five underlying factors: Behavior and Attention, Hearing Environments, New Social Situations, Social Interactions, and Communication. Cronbach's alpha for each factor ranged from 0.80 to 0.91. Test-retest reliability was 0.93. Moderate-to-strong correlations (r > .300) were observed between each Preschool HEAR-QL factor and previously validated measures. Hearing Environments scores differed significantly between children with NH and any HL. CONCLUSION: Preschool HEAR-QL correlations with other measures supported its construct validity. Discriminant validity testing requires a larger sample of children with NH. LEVEL OF EVIDENCE: NA Laryngoscope, 131:663-670, 2021.

ESRP1 Mutations Cause Hearing Loss due to Defects in Alternative Splicing that Disrupt Cochlear Development.

Alternative splicing contributes to gene expression dynamics in many tissues, yet its role in auditory development remains unclear. We performed whole-exome sequencing in individuals with sensorineural hearing loss (SNHL) and identified pathogenic mutations in Epithelial Splicing-Regulatory Protein 1 (ESRP1). Patient-derived induced pluripotent stem cells showed alternative splicing defects that were restored upon repair of an ESRP1 mutant allele. To determine how ESRP1 mutations cause hearing loss, we evaluated Esrp1-/- mouse embryos and uncovered alterations in cochlear morphogenesis, auditory hair cell differentiation, and cell fate specification. Transcriptome analysis revealed impaired expression and splicing of genes with essential roles in cochlea development and auditory function. Aberrant splicing of Fgfr2 blocked stria vascularis formation due to erroneous ligand usage, which was corrected by reducing Fgf9 gene dosage. These findings implicate mutations in ESRP1 as a cause of SNHL and demonstrate the complex interplay between alternative splicing, inner ear development, and auditory function.

International Pediatric Otolaryngology Group (IPOG) consensus recommendations: Hearing loss in the pediatric patient.

OBJECTIVE: To provide recommendations for the workup of hearing loss in the pediatric patient. METHODS: Expert opinion by the members of the International Pediatric Otolaryngology Group. RESULTS: Consensus recommendations include initial screening and diagnosis as well as the workup of sensorineural, conductive and mixed hearing loss in children. The consensus statement discusses the role of genetic testing and imaging and provides algorithms to guide the workup of children with hearing loss. CONCLUSION: The workup of children with hearing loss can be guided by the recommendations provided herein.

Temporal bone radiology report classification using open source machine learning and natural langue processing libraries.

BACKGROUND: Radiology reports are a rich resource for biomedical research. Prior to utilization, trained experts must manually review reports to identify discrete outcomes. The Audiological and Genetic Database (AudGenDB) is a public, de-identified research database that contains over 16,000 radiology reports. Because the reports are unlabeled, it is difficult to select those with specific abnormalities. We implemented a classification pipeline using a human-in-the-loop machine learning approach and open source libraries to label the reports with one or more of four abnormality region labels: inner, middle, outer, and mastoid, indicating the presence of an abnormality in the specified ear region. METHODS: Trained abstractors labeled radiology reports taken from AudGenDB to form a gold standard. These were split into training (80 %) and test (20 %) sets. We applied open source libraries to normalize and convert every report to an n-gram feature vector. We trained logistic regression, support vector machine (linear and Gaussian), decision tree, random forest, and naïve Bayes models for each ear region. The models were evaluated on the hold-out test set. RESULTS: Our gold-standard data set contained 726 reports. The best classifiers were linear support vector machine for inner and outer ear, logistic regression for middle ear, and decision tree for mastoid. Classifier test set accuracy was 90 %, 90 %, 93 %, and 82 % for the inner, middle, outer and mastoid regions, respectively. The logistic regression method was very consistent, achieving accuracy scores within 2.75 % of the best classifier across regions and a receiver operator characteristic area under the curve of 0.92 or greater across all regions. CONCLUSIONS: Our results indicate that the applied methods achieve accuracy scores sufficient to support our objective of extracting discrete features from radiology reports to enhance cohort identification in AudGenDB. The models described here are available in several free, open source libraries that make them more accessible and simplify their utilization as demonstrated in this work. We additionally implemented the models as a web service that accepts radiology report text in an HTTP request and provides the predicted region labels. This service has been used to label the reports in AudGenDB and is freely available.

Children With Sensorineural Hearing Loss And Referral To Early Intervention.

OBJECTIVE: Sensorineural hearing loss (SNHL) is identified at a rate of 1-3 per 1,000 newborns in the United States. Timely referral to Early Intervention (EI) services is critical, as early EI referral has been shown to improve outcomes, including speech and language development, social and emotional development, and academic performance. The objective of this study was to determine the rate at which children diagnosed with SNHL at a large tertiary referral center were referred to EI, and, if so, by whom. In addition, we sought to determine the time from the diagnosis of SNHL to the completion of the referral, and what services were received. DESIGN: Prospective observational study METHODS: Data were collected by telephone survey and review of the electronic medical record RESULTS: Children with SNHL were referred to and participated in EI at a high rate. All children in this study (100%) were referred to EI. Most (92%) of the children were referred by 6 months of age, and almost all (98%) participated in EI. CONCLUSION: At our institution, children with SNHL are being consistently referred to EI, meeting the goals of the Early Hearing Detection and Intervention program. Future outcomes research can now be designed to determine whether achieving these benchmark goals improves children's academic performance, expressive and receptive language skills, and development as compared to age-matched, normal hearing peers.

Unilateral cochlear nerve deficiency in children.

OBJECTIVE: Cochlear nerve deficiency (CND) is increasingly diagnosed in children with sensorineural hearing loss (SNHL). We sought to determine the prevalence of CND, its imaging characteristics, and correlations with audiologic phenotype in children with unilateral SNHL. DESIGN: Case series with chart review. SETTING: Tertiary pediatric hospital. SUBJECTS/METHODS: In 128 consecutive children with unilateral SNHL who underwent high-resolution magnetic resonance imaging, the diameters, area, and signal intensity of the cochlear nerve (CN) were measured and normalized to the ipsilateral facial nerve. Presence of CND was determined by comparison to normative data. Relationships among hearing loss severity, progression, and nerve size were investigated. RESULTS: Cochlear nerve deficiency was present in 26% of children with unilateral SNHL. Its prevalence was higher (48%) in severe to profound SNHL, especially when in infants (100%). Width of the bony cochlear nerve canal (BCNC) correlated strongly with relative CN diameter, density, and area (R = 0.5); furthermore, a narrow BCNC (<1.7 mm) strongly predicted CND. Severity of hearing loss modestly correlated with nerve size, although significant variability was observed. Progression never occurred unless there were other inner ear malformations, whereas in the non-CND group, it occurred in 22%. Ophthalmologic abnormalities were very common (67%) in CND children, particularly oculomotor disturbances. CONCLUSION: Cochlear nerve deficiency is a common cause of unilateral SNHL, particularly in congenital unilateral deafness. Width of the BCNC effectively predicts CND, a finding useful when only computed tomography imaging is available. In an ear with CND, hearing can be expected to remain stable over time. Diagnosis should prompt evaluation by an ophthalmologist.

Macrophage migration inhibitory factor acts as a neurotrophin in the developing inner ear.

This study is the first to demonstrate that macrophage migration inhibitory factor (MIF), an immune system 'inflammatory' cytokine that is released by the developing otocyst, plays a role in regulating early innervation of the mouse and chick inner ear. We demonstrate that MIF is a major bioactive component of the previously uncharacterized otocyst-derived factor, which directs initial neurite outgrowth from the statoacoustic ganglion (SAG) to the developing inner ear. Recombinant MIF acts as a neurotrophin in promoting both SAG directional neurite outgrowth and neuronal survival and is expressed in both the developing and mature inner ear of chick and mouse. A MIF receptor, CD74, is found on both embryonic SAG neurons and adult mouse spiral ganglion neurons. Mif knockout mice are hearing impaired and demonstrate altered innervation to the organ of Corti, as well as fewer sensory hair cells. Furthermore, mouse embryonic stem cells become neuron-like when exposed to picomolar levels of MIF, suggesting the general importance of this cytokine in neural development.

Venous malformations of the temporal bone are a common feature in CHARGE syndrome.

OBJECTIVES/HYPOTHESIS: CHARGE (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities, and Ear abnormalities and/or deafness) syndrome is a genetic disorder with prominent otolaryngologic features including choanal atresia and inner ear malformations. Recent experience with venous malformations during cochlear implant surgery prompted this study to define the spectrum of venous abnormalities in CHARGE and their surgical implications in otology. STUDY DESIGN: Retrospective review of medical and radiologic records from databases of patients with CHARGE syndrome from three tertiary care academic medical centers. METHODS: Eighteen patients with CHARGE for whom temporal bone CT scans were available were included in the review. RESULTS: Venous anomalies of the temporal bone were present in 10 of 18 (56%) patients. The most common were large emissary veins (n = 5). In two of these cases, these veins were associated with an ipsilateral a hypoplastic sigmoid sinus or jugular foramen. Other abnormalities included an aberrant petrosal sinus, venous lakes in proximity to the lateral venous sinus, condylar canal veins, and jugular bulb abnormalities, including a high riding bulb obscuring the round window niche and a dehiscent jugular bulb. In four of six patients undergoing cochlear implantation, the course of the aberrant vessel necessitated a change in the surgical approach, either during mastoidectomy or placement of the cochleostomy. CONCLUSIONS: Temporal bone venous abnormalities are a common feature in CHARGE syndrome. The pattern of venous abnormality suggests that there is a failure of the sigmoid sinus/jugular bulb to fully develop, resulting in persistence of emissary veins. Recognition of these abnormal venous structures during otologic surgery is critical to avoiding potentially catastrophic bleeding.

Early prediction of postmeningitic hearing loss in children using magnetic resonance imaging.

OBJECTIVE: To determine whether early gadolinium-enhanced magnetic resonance imaging (GdMRI) can reliably detect meningitic labyrinthitis and thereby predict which children are at high risk for hearing loss. Permanent sensorineural hearing loss (SNHL) remains a common sequela of bacterial meningitis, and early diagnosis of the associated suppurative labyrinthitis can be difficult, especially in critically ill, sedated patients and young children. DESIGN: Retrospective cohort study. SETTING: Tertiary pediatric hospital. PARTICIPANTS: Twenty-three survivors of bacterial meningitis (median age, 15 months [range, 3 months-14 years]) who had undergone brain GdMRI during the acute disease and had subsequent ear-specific audiometric data. MAIN OUTCOME MEASURE: Blinded to disease and outcome, a neuroradiologist rated the relative enhancement of each cochlea on T1-weighted images using a 4-point scale. Scores were then correlated with the degree of hearing loss on subsequent testing. RESULTS: Sensorineural hearing loss occurred in 15 of 46 ears (8 of 23 patients). Enhancement on GdMRI was detected in 13 of the 15 ears that later developed SNHL but was absent in all 31 unaffected ears. Thus, GdMRI was 87% sensitive and 100% specific for predicting which ears would develop permanent SNHL. In the subgroup with pneumococcal meningitis (n = 15), GdMRI was 100% sensitive and 100% specific. Labyrinthine enhancement was detectable as early as 1 day after diagnosis. CONCLUSION: Gadolinium-enhanced MRI detected meningitic labyrinthitis at early stages and accurately predicted which patients would later develop hearing loss.

Etiology of unilateral neural hearing loss in children.

OBJECTIVE: Unilateral sensorineural hearing loss (SNHL) can be caused by a variety of lesions of the inner ear and central nervous system. An inner hair cell or neural site of pathology must be suspected when otoacoustic emissions (OAEs) are present, and inconsistent with audiologic data. We reviewed unilateral neural hearing loss (UNHL) in children, to better understand its etiology, clinical and audiologic features. DESIGN: Retrospective series. SETTING: Tertiary pediatric center. METHODS: From a database of 480 children with unilateral SNHL, 148 had OAE data. Patients with a neural pattern (present OAEs in the affected ear) were reviewed. OUTCOME MEASURES: Clinical course, audiologic data, imaging findings. RESULTS: Of 148 patients with OAE data, 11 (7.4%) had the unilateral neural phenotype. Most had stable, severe-to-profound loss in the affected ear. MRI determined an etiology in all 10 patients who received it. Absent cochlear nerves were remarkably common, being found in eight patients (73%). Tumors, previously unsuspected, were identified in the other two patients who received MRI. CONCLUSIONS: Cochlear nerve aplasia appears by far the most common cause of UNHL in children. As in adults, mass lesions must also be considered in children with unilateral SNHL with a neural pattern. As both lesions elude diagnosis on CT, MRI is the better modality for evaluating this condition.

Real-time intraoperative computed tomography to assist cochlear implant placement in the malformed inner ear.

OBJECTIVE: Cochlear implantation is increasingly being performed in children with inner ear malformations. In severe cochleovestibular anomalies, such as severe partitioning defects and common cavity dysplasia, positioning of the electrode array can be hazardous, with inadvertent placement into the internal auditory canal (IAC) or carotid canal being well known. We describe a case in which real-time intraoperative computed tomographic scanning was used to help achieve proper electrode positioning in a child with a severe malformation. PATIENT: Child with common cavity malformations undergoing cochlear implantation. INTERVENTION: Intraoperative computed tomography used during implantation procedure. MAIN OUTCOME MEASURE: Use of technique in determining electrode position. RESULTS: A 10-year-old patient with bilateral common cavity malformations presented with declining performance in a functioning implant placed 7 years earlier. The family elected implantation of the contralateral ear. Via a posterior labyrinthotomy approach, a straight array was placed into the common cavity. Intraoperative computed tomographic scanning was immediately performed on the operating room table, showing that the array was in the IAC. A second attempt with a different insertion angle also resulted in IAC placement. In a third attempt, the electrode was advanced as a loop, grasping the tip through an adjacent second labyrinthotomy. Computed tomography confirmed good position against the outer wall of the cavity. CONCLUSION: Real-time intraoperative computed tomography is a new technology with many potential applications in surgery. In our patient, it allowed rapid and accurate determination of electrode position and helped achieve ideal placement in a severely malformed inner ear.

Intracranial complications of sinusitis in children and adolescents and their outcomes.

OBJECTIVE: To gain insight into patterns of presentation, imaging, microbiological aspects, therapy, disease course, and outcome of intracranial complications of sinusitis (ICS), which are challenging conditions with the potential to cause significant morbidity and mortality. We reviewed our experience with ICS in children and adolescents. DESIGN: Consecutive case series with a mean follow-up of 12 months. SETTING: Tertiary pediatric referral center. PATIENTS: Consecutive sample of 25 children and adolescents treated for 35 intracranial complications (mean age, 13.2 years [range, 4-18 years]). INTERVENTIONS: Medical and surgical management. MAIN OUTCOME MEASURES: Survival and temporary and permanent neurologic sequelae. RESULTS: Most patients were adolescents (n = 19; 76%) and male (n = 19; 76%). Epidural abscess was most common (13 complications), followed by subdural empyema (n = 9), meningitis (n = 6), encephalitis (n = 2), intracerebral abscess (n = 2), and dural sinus thrombophlebitis (n = 2). Abscesses were primarily located in the frontal or frontoparietal regions. Magnetic resonance imaging was extensively used and was superior to contrast computed tomography in diagnosis. All patients received intravenous antibiotics, 21 underwent endoscopic sinus surgery, and 13 underwent neurosurgical drainage. Only 1 death occurred from sepsis secondary to meningitis (mortality, 4%). Overall, neurologic outcome was excellent. Although 10 patients (40%) had neurologic deficits, most resolved within 2 months. Only 2 patients had permanent neurologic sequelae. Among ICS, epidural abscess appeared to be a distinct clinical entity. Epidural abscesses typically presented without specific neurologic symptoms or signs, were more often associated with orbital complications, and had outcomes considerably better than the other ICS. CONCLUSION: Intracranial complications of sinusitis are challenging, but prognosis can be favorable in children and adolescents by using aggressive medical and surgical management.

Chronic Pseudomonas infections of cochlear implants.

OBJECTIVE: To discuss chronic, refractory Pseudomonas infections of cochlear implants and their management. DESIGN: Retrospective case series. SETTING: Two university-based cochlear implant programs. PATIENTS: Twenty-eight-year-old (Case 1) and 4-year-old (Case 2), different devices. INTERVENTIONS: Medical and surgical management. MAIN OUTCOME MEASURES: Clinical course. RESULTS: Both patients had delayed presentations, 4 months and 3 years postimplantation, respectively, with fluctuating scalp edema and pain resistant to multiple courses of oral antibiotics. Infections began as localized granulation and progressed to complete encasement of both devices with rubbery, poorly vascularized tissue. In each case, two different strains of multiresistant Pseudomonas aeruginosa were cultured. Infections progressed despite local debridement and targeted antipseudomonal antibiotic coverage, and sensitive organisms continued to appear in cultures of refractory granulation tissue. Both patients underwent partial explantation, with the electrode array left in the cochlea, then received 2 to 3 more months of further medical therapy and observation and then were reimplanted successfully with new devices. Both have shown excellent performance and no sign of recurrent infection. CONCLUSIONS: Infections of cochlear implants are uncommon, and cases of successful conservative management without device explantation have been reported. However, our experience and the implanted device literature suggest that chronic Pseudomonas infections may represent a distinct clinical entity, likely to fail protracted therapy and ultimately require device removal. Fortunately, successful reimplantation is possible.

Molecular characterization of conditionally immortalized cell lines derived from mouse early embryonic inner ear.

Inner ear sensory hair cells (HCs), supporting cells (SCs), and sensory neurons (SNs) are hypothesized to develop from common progenitors in the early embryonic otocyst. Because little is known about the molecular signals that control this lineage specification, we derived a model system of early otic development: conditionally immortalized otocyst (IMO) cell lines from the embryonic day 9.5 Immortomouse. This age is the earliest stage at which the otocyst can easily be separated from surrounding mesenchymal, nervous system, and epithelial cells. At 9.5 days post coitum, there are still pluripotent cells in the otocyst, allowing for the eventual identification of both SN and HC precursors--and possibly an elusive inner ear stem cell. Cell lines derived from primitive precursor cells can also be used as blank canvases for transfections of genes that can affect lineage decisions as the cells differentiate. It is important, therefore, to characterize the "baseline state" of these cell lines in as much detail as possible. We characterized seven representative "precursor-like" IMO cell populations and the uncloned IMO cells, before cell sorting, at the molecular level by polymerase chain reaction (PCR) and immunocytochemistry (IHC), and one line (IMO-2B1) in detail by real-time quantitative PCR and IHC. Many of the phenotypic markers characteristic of differentiated HCs or SCs were detected in IMO-2B1 proliferating cells, as well as during differentiation for up to 30 days in culture. These IMO cell lines represent a unique model system for studying early stages of inner ear development and determining the consequences of affecting key molecular events in their differentiation.