Wade W. Chien

Cochlear Implantation in Older Adults

Cochlear implants allow individuals with severe to profound hearing loss access to sound and spoken language. The number of older adults in the United States who are potential candidates for cochlear implantation (CI) is approximately 150,000 and will continue to increase with the aging of the population. Should CI be routinely recommended for these older adults, and do these individuals benefit from CI? We reviewed our 12-year experience with CI in adults aged ≥60 years (n = 445) at Johns Hopkins Medical Institutions to investigate the impact of CI on speech understanding and to identify factors associated with speech performance. Complete data on speech outcomes at baseline and 1 year post-CI were available for 83 individuals. Our results demonstrate that CI in adults aged ≥60 years consistently improved speech understanding scores, with a mean increase of 60.0% (SD 24.1) on HINT (Hearing in Noise Test) sentences in quiet. The magnitude of the gain in speech scores was negatively associated with age at implantation, such that for every increasing year of age at CI the gain in speech scores was 1.3 percentage points less (95% confidence interval [95% CI], 0.6–1.9) after adjusting for age at hearing loss onset. Conversely, individuals with higher pre-CI speech scores (HINT scores between 40% and 60%) had significantly greater post-CI speech scores by a mean of 10.0 percentage points (95% CI, 0.4–19.6) than those with lower pre-CI speech scores (HINT <40%) after adjusting for age at CI and age at hearing loss onset. These results suggest that older adult CI candidates who are younger at implantation and with higher preoperative speech scores obtain the highest speech understanding scores after CI, with possible implications for current United States Medicare policy. Finally, we provide an extended discussion of the epidemiology and impact of hearing loss in older adults. Future research of CI in older adults should expand beyond simple speech outcomes to take into account the broad cognitive, social, and physical functioning outcomes that are likely detrimentally affected by hearing loss and may be mitigated by CI. Abbreviations95% CI = 95% confidence interval, CI = cochlear implantation, CMS = Centers for Medicare & Medicaid Services, dB = decibel, GWAS = genome-wide association studies, HINT = Hearing in Noise Test, NHANES = National Health and Nutrition Examination Survey, PTA = pure tone average

Technical skills improve after practice on virtual‐reality temporal bone simulator

To assess whether practice on a virtual‐reality (VR) temporal bone simulator improves acquisition of technical skills in mastoid surgery.

Superior Canal Dehiscence Size: Multivariate Assessment of Clinical Impact

Objective To examine the association between dehiscence length in patients with superior semicircular canal dehiscence syndrome and their clinical findings, including objective audiometric and vestibular testing results. Study Design Retrospective study. Setting Tertiary referral center. Patients Patients included in this study were diagnosed with superior semicircular canal dehiscence syndrome and underwent surgical repair of the dehiscence through middle fossa craniotomy. The dehiscence length was measured intraoperatively in all cases. Main Outcome Measures Correlation between dehiscence length with pure-tone average (PTA), average bone-conduction threshold, maximal air-bone gap, cervical vestibular evoked myogenic potential thresholds, and presenting signs and symptoms. Results The correlation between dehiscence length and maximal air-bone gap was statistically significant on both univariate and multivariate regression analyses. The correlations between dehiscence length and PTA, average bone-conduction threshold, cervical vestibular evoked myogenic potential threshold, and presenting signs and symptoms were not statistically significant. Conclusion The dehiscence length correlated positively with the maximal air-bone gap in patients with superior semicircular canal dehiscence. The correlation was statistically significant. The dehiscence length did not correlate with the other variables examined in this study.

Vestibular Dysfunction in Patients with Enlarged Vestibular Aqueduct

Objective Enlarged vestibular aqueduct (EVA) is the most common inner ear malformation. While a strong correlative relationship between EVA and hearing loss is well established, its association with vestibular dysfunction is less well understood. In this study, we examine the effects of EVA on the vestibular system in patients with EVA. Study Design Prospective, cross-sectional study of a cohort ascertained between 1999 and 2013. Setting National Institutes of Health Clinical Center, a federal biomedical research facility. Subjects and Methods In total, 106 patients with unilateral or bilateral EVA, defined as a midpoint diameter greater than 1.5 mm, were referred or self-referred to participate in a study of the clinical and molecular aspects of EVA. Clinical history was ascertained with respect to the presence or absence of various vestibular signs and symptoms and history of head trauma. Videonystagmography (VNG), cervical vestibular evoked myogenic potential (cVEMP), and rotational vestibular testing (RVT) were performed to assess the vestibular function. Results Of the patients with EVA, 45% had vestibular signs and symptoms, and 44% of tested patients had abnormal VNG test results. An increased number of vestibular signs and symptoms was correlated with the presence of bilateral EVA (P = .008) and a history of head injury (P < .001). Abnormal VNG results also correlated with a history of head injury (P = .018). Conclusion Vestibular dysfunction is common in patients with EVA. However, not all patients with vestibular signs and symptoms have abnormal vestibular test results. Clinicians should be aware of the high prevalence of vestibular dysfunction in patients with EVA.

Gene therapy for sensorineural hearing loss.

Gene therapy is a promising treatment modality that is being explored for several inherited disorders. Multiple human gene therapy clinical trials are currently ongoing, but few are directed at hearing loss. Hearing loss is one of the most prevalent sensory disabilities in the world, and genetics play an important role in the pathophysiology of hearing loss. Gene therapy offers the possibility of restoring hearing by overcoming the functional deficits created by the underlying genetic mutations. In addition, gene therapy could potentially be used to induce hair cell regeneration by delivering genes that are critical to hair cell differentiation into the cochlea. In this review, we examine the promises and challenges of applying gene therapy to the cochlea. We also summarize recent studies that have applied gene therapy to animal models of hearing loss.

Gene Therapy Restores Hair Cell Stereocilia Morphology in Inner Ears of Deaf Whirler Mice.

Hereditary deafness is one of the most common disabilities affecting newborns. Many forms of hereditary deafness are caused by morphological defects of the stereocilia bundles on the apical surfaces of inner ear hair cells, which are responsible for sound detection. We explored the effectiveness of gene therapy in restoring the hair cell stereocilia architecture in the whirlin mouse model of human deafness, which is deaf due to dysmorphic, short stereocilia. Wild-type whirlin cDNA was delivered via adeno-associated virus (AAV8) by injection through the round window of the cochleas in neonatal whirler mice. Subsequently, whirlin expression was detected in infected hair cells (IHCs), and normal stereocilia length and bundle architecture were restored. Whirlin gene therapy also increased inner hair cell survival in the treated ears compared to the contralateral nontreated ears. These results indicate that a form of inherited deafness due to structural defects in cochlear hair cells is amenable to restoration through gene therapy.

Racial difference in cochlear pigmentation is associated with hearing loss risk.

Objectives The goals of this study are to characterize the distribution of melanin pigmentation in the human cochlea and to investigate differences in pigment content between races. Methods Human temporal bone specimens from the Johns Hopkins Temporal Bone Collection were examined. Demographic, clinical, and audiometric data were analyzed. Melanin pigmentation in the cochlea was quantified in each specimen. Results Nineteen African-American (AA) and 27 Caucasian specimens were selected for the study. The mean ages were 64 and 70 years for AA and Caucasian specimens, respectively (p = 0.21). At all cochlear turns, AA specimens contained significantly more pigmentation in the stria vascularis (p = 0.0003) and Rosenthal’s canal (p < 0.0001) compared with Caucasian specimens. Strial melanin content increased significantly with age. Cochlear pigmentation content was not associated with sex or hearing thresholds. Conclusion Melanin pigmentation is significantly more abundant in AA cochleae than in Caucasian cochleae. This study provides a detailed description of pigmentation in the cochlea and may help to explain the observed racial differences in hearing thresholds.

Prevalence, Characteristics, and Management of Swallowing Disorders following Cerebellopontine Angle Surgery:

Objective. To describe swallowing disorders encountered after cerebellopontine angle surgery and to explore variables associated with increased incidence of postoperative dysphagia. Study Design. Case series with chart review. Setting. Single academic medical institution. Subjects and Methods. Chart review of 181 consecutive patients undergoing surgical excision of cerebellopontine angle pathology from January 2008 to December 2010 at the Johns Hopkins Hospital. Presence and characteristics of dysphagia were determined by review of speech pathologist reports. Other clinical variables were extracted from the electronic medical record, and statistical analyses were applied to determine factors associated with postoperative dysphagia. Results. Immediate postoperative dysphagia was identified in 57 of 181 patients (31%). Oral, oropharyngeal, and pharyngeal deficits accounted for 51%, 37%, and 12% of dysphagic symptoms, respectively. Facial nerve weakness in the immediate postoperative period was noted in 91% of dysphagic subjects compared with 43% of those without. Mean House-Brackmann score for dysphagic individuals was 4 compared with 2 in the nondysphagic group. Diet alterations were required for 65% of dysphagic individuals, and an additional 9% required tube feeding. Common findings during videofluoroscopic swallowing studies were pharyngeal residue, reduced pharyngeal constriction, and anterior bolus loss. Abnormal penetration-aspiration scores (≥3) were found in 59% of those undergoing videofluoroscopic swallow studies. Conclusions. Oral and pharyngeal swallowing deficits are commonly encountered after cerebellopontine angle surgery. Consultation with the speech-language pathologist appears most critical for any individuals demonstrating postoperative cranial nerve dysfunction, particularly for those with evidence of facial nerve weakness. Early consultation may help to manage short- and long-term functional difficulties.

Cochlear gene transfer mediated by adeno-associated virus: Comparison of two surgical approaches

Gene therapy offers the possibility of delivering corrective genetic materials to the cochlea, potentially improving hearing. In animals, the most commonly used surgical methods for viral gene therapy delivery to the cochlea are the round window and the cochleostomy approaches. However, the patterns of viral infection and the effects on hearing have not been directly compared between these two approaches. In this study, we compare the patterns of cochlear infection and effects on hearing between these two surgical approaches using adeno‐associated virus serotype 2/8 (AAV8) as the gene delivery vehicle.

Risk Factors for Vagal Palsy following Cerebellopontine Angle Surgery

Objective Describe the incidence, risk factors, and outcomes of postoperative vagal palsy in patients undergoing surgical excision of cerebellopontine angle (CPA) tumors. Study Design Case series with chart review. Setting Academic tertiary care center. Subjects and Methods One hundred eighty-one consecutive patients undergoing surgical excision of CPA pathology from January 1, 2008, to December 31, 2010, at Johns Hopkins Hospital. Postoperative unilateral vagal palsy was identified by laryngoscopy or videofluoroscopy, and clinical variables were collected from medical records. Results Postoperative unilateral vagal palsy was identified in 19 of 181 (10%) patients. Vocal fold motion impairment (VFMI) in combination with pharyngeal palsy was more common than VFMI or pharyngeal palsy alone. Those with vagal palsy had a larger mean tumor size (30 mm) than those without vagal palsy (20 mm, P = .0002) and a significantly longer mean hospital stay (9 vs 5 days, P < .0001). Vagal palsy was not associated with tumor pathology, prior treatment (stereotactic radiation or prior surgery), or surgical approach (suboccipital craniotomy vs translabyrinthine approach). Significant rates of aspiration were observed in patients with vagal palsy (67%). Conclusion Voice and swallowing function can be affected by surgical excision of pathology of the CPA. Tumor size is an independent risk factor for postoperative vagal palsy, which in turn has important consequences for prolonged hospital stay, aspiration, and voice and swallowing impairment.