Bone-anchored devices in single-sided deafness.

Single sided deafness (SSD) implies sensorineural hearing loss in one ear with normal contralateral hearing function. Traditionally, SSD patients have been overlooked due to a belief that the preserved functioning of the contralateral ear compensates for the nonhearing side. SSD patients however experience multiple audiological difficulties, particularly when the sound source is situated on the non-hearing side or in the presence of competing sounds. Through reviewing current literature, we describe the role of bone-anchored devices (Baha) in the management of SSD patients. Recent publications for Baha in SSD have demonstrated consistent objective and subjective improvement in audiologic metrics when compared to unaided conditions. There is also evidence of benefit provided by Baha by the Abbreviated Profile of Hearing Aid Benefit, in global measures of ease of communication, reverberation, and background noise, but not typically in aversiveness to sounds. Interestingly, despite some patients gaining minimal objective or subjective benefits, the majority of these patients still report improved quality of life and would recommend the procedure. Despite increasing evidence for the role of Baha in the management of SSD in the literature, much of these data are based on older technology. Further reports should specify the processor type used and the etiology of the hearing loss to ensure accuracy of future data.

Restoration of auditory nerve synapses in cats by cochlear implants.

Congenital deafness results in abnormal synaptic structure in endings of the auditory nerve. If these abnormalities persist after restoration of auditory nerve activity by a cochlear implant, the processing of time-varying signals such as speech would likely be impaired. We stimulated congenitally deaf cats for 3 months with a six-channel cochlear implant. The device used human speech-processing programs, and cats responded to environmental sounds. Auditory nerve fibers exhibited a recovery of normal synaptic structure in these cats. This rescue of synapses is attributed to a return of spike activity in the auditory nerve and may help explain cochlear implant benefits in childhood deafness.

Benign positional vertigo after cochlear implantation.

OBJECTIVE: To identify patients who underwent cochlear implantation (CI) and who subsequently developed benign positional vertigo (BPV) after the procedure and to identify any contributing factors. STUDY DESIGN AND SETTING: Academic tertiary referral center. Cochlear implant recipients' medical records were retrospectively reviewed to identify patients with both vertigo and, more specifically, BPV. Preoperative, intraoperative, and postoperative factors were studied vis-a-vis the development of BPV. RESULTS: BPV was newly diagnosed in 12 patients after CI. The etiology of hearing loss included presbycusis (16.6%), autoimmune inner ear disease (16.6%), congenital hearing loss (41.6%), Meniere's disease (8.3%), prematurity (8.3%), and idiopathic factors (8.3%). The onset of BPV varied after the procedure (mean +/- SD, 292 +/- 309 days). BPV symptoms did not affect implant performance. All patients were treated for BPV by Epley's maneuver and vestibular exercises. Symptoms disappeared in 11 patients and persisted in 1. CONCLUSIONS: BPV is an uncommon development after CI, although it occurs more frequently than in the general population. Two theories are proposed: the introduction of bone dust into the labyrinth and the dislodging of otoconia during surgery. The diagnosis, treatment, and prognosis of BPV after CI do not differ from those for non-CI-associated BPV. SIGNIFICANCE: Dizziness after CI usually develops as a result of vestibular hypofunction. BPV, which is a hyperfunctioning form of vestibular dysfunction, should be recognized as a possible sequelae of CI.

Hearing rehabilitation using the BAHA bone-anchored hearing aid: results in 40 patients.

OBJECTIVE: This study evaluates the U.S. experience with the first 40 patients who have undergone audiologic rehabilitation using the BAHA bone-anchored hearing aid. STUDY DESIGN: This study is a multicenter, nonblinded, retrospective case series. SETTING: Twelve tertiary referral medical centers in the United States. PATIENTS: Eligibility for BAHA implantation included patients with a hearing loss and an inability to tolerate a conventional hearing aid, with bone-conduction pure tone average levels at 60 dB or less at 0.5, 1, 2, and 4 kHz. INTERVENTION: Patients who met audiologic and clinical criteria were implanted with the Bone-Anchored Hearing Aid (BAHA, Entific Corp., Gothenburg, Sweden). MAIN OUTCOME MEASURES: Preoperative air- and bone-conduction thresholds and air-bone gap; postoperative BAHA-aided thresholds; hearing improvement as a result of implantation; implantation complications; and patient satisfaction. RESULTS: The most common indications for implantation included chronic otitis media or draining ears (18 patients) and external auditory canal stenosis or aural atresia (7 patients). Overall, each patient had an average improvement of 32+/-19 dB with the use of the BAHA. Closure of the air-bone gap to within 10 dB of the preoperative bone-conduction thresholds (postoperative BAHA-aided threshold vs. preoperative bone-conduction threshold) occurred in 32 patients (80%), whereas closure to within 5 dB occurred in 24 patients (60%). Twelve patients (30%) demonstrated 'overclosure' of the preoperative bone-conduction threshold of the better hearing ear. Complications were limited to local infection and inflammation at the implant site in three patients, and failure to osseointegrate in one patient. Patient response to the implant was uniformly satisfactory. Only one patient reported dissatisfaction with the device. CONCLUSIONS: The BAHA bone-anchored hearing aid provides a reliable and predictable adjunct for auditory rehabilitation in appropriately selected patients, offering a means of dramatically improving hearing thresholds in patients with conductive or mixed hearing loss who are otherwise unable to benefit from traditional hearing aids.

Safety and patient experience with transtympanic electrocochleography.

OBJECTIVES/HYPOTHESIS: Transtympanic electrocochleography (t-ECOG) is a sensitive diagnostic instrument used for Meniere's disease. It is sensitive by virtue of the recording electrode's position on the promontory of the cochlea where the signals are generated. There is concern about the invasive nature of t-ECOG in comparison to extratympanic recording techniques. The purpose of this study was to examine the safety issues, complications, and patient experience with t-ECOG. STUDY DESIGN: Observational study utilizing retrospective chart review and patient survey. METHODS: The medical records of 205 patients who underwent t-ECOG were reviewed for complications. Complications included persistent tympanic membrane perforation, hearing loss, otitis media, otitis externa, ear canal injury, hemotympanum, and pain. An additional 36 patients undergoing t-ECOG were surveyed on subjective measures such as pain during topical anesthesia of the tympanic membrane, during transtympanic placement of the needle electrode, and during the test procedure and overall experience with t-ECOG. RESULTS: There was one case of a nonhealed, persistent perforation in the setting of acute otitis media directly as a result of t-ECOG. Two patients developed otitis media, and three patients had ear pain for up to 5 days. All 36 patients felt the procedure to be tolerable with minimal discomfort. CONCLUSIONS: Transtympanic electrocochleography may be performed with good patient acceptance and infrequent complications.

Cost-utility analysis of the cochlear implant in children.

CONTEXT: Barriers to the use of cochlear implants in children with profound deafness include device costs, difficulty assessing benefit, and lack of data to compare the implant with other medical interventions. OBJECTIVE: To determine the quality of life and cost consequences for deaf children who receive a cochlear implant. DESIGN: Cost-utility analysis using preintervention, postintervention, and cross-sectional surveys conducted from July 1998 to May 2000. SETTING: Hearing clinic at a US academic medical center. PARTICIPANTS: Parents of 78 profoundly deaf children (average age, 7.5 years) who received cochlear implants. MAIN OUTCOME MEASURES: Direct and total cost to society per quality-adjusted life-year (QALY) using the time-trade-off (TTO), visual analog scale (VAS), and Health Utilities Index-Mark III (HUI), discounting costs and benefits 3% annually. Parents rated their child's health state at the time of the survey and immediately before and 1 year before implantation. RESULTS: Recipients had an average of 1.9 years of implant use. Mean VAS scores increased by 0. 27, from 0.59 before implantation to 0.86 at survey. In a subset of participants, TTO scores increased by 0.22, from 0.75 to 0.97 (n = 40) and HUI scores increased by 0.39, from 0.25 to 0.64 (n = 22). Quality-of-life scores were no different 1 year before and immediately before implantation. Discounted direct costs were $60,228, yielding $9,029 per QALY using the TTO, $7,500 per QALY using the VAS, and $5,197 per QALY using the HUI. Including indirect costs such as reduced educational expenses, the cochlear implant provided a savings of $53,198 per child. CONCLUSIONS: Cochlear implants in profoundly deaf children have a positive effect on quality of life at reasonable direct costs and appear to result in a net savings to society. JAMA. 2000;284:850-856

Intracanalicular schwannoma of the facial nerve: a manifestation of neurofibromatosis type 2.

Primary facial nerve tumors, which are relatively uncommon, can present a diagnostic dilemma based on their location and variable pattern of symptoms. Of primary cranial nerve tumors, schwannomas of the facial nerve rank third in frequency after those of the eighth and fifth cranial nerves. We report an illustrative case of an intracanalicular schwannoma associated with several central nervous system tumors, consistent with neurofibromatosis type 2. Initially assumed to be an eighth cranial nerve tumor, the schwannoma was found intraoperatively to arise from the facial nerve. Early diagnosis and treatment enabled excision of the tumor without sacrifice of the facial nerve. Facial nerve schwannomas can resemble acoustic schwannomas in their clinical presentation. Only a heightened level of clinical vigilance will point to the correct diagnosis and result in an optimal therapeutic outcome for patients with these rare tumors.

The societal costs of severe to profound hearing loss in the United States.

OBJECTIVE: Severe to profound hearing impairment affects one-half to three-quarters of a million Americans. To function in a hearing society, hearing-impaired persons require specialized educational, social services, and other resources. The primary purpose of this study is to provide a comprehensive, national, and recent estimate of the economic burden of hearing impairment. METHODS: We constructed a cohort-survival model to estimate the lifetime costs of hearing impairment. Data for the model were derived principally from the analyses of secondary data sources, including the National Health Interview Survey Hearing Loss and Disability Supplements (1990-91 and 1994-95), the Department of Education's National Longitudinal Transition Study (1987), and Gallaudet University's Annual Survey of Deaf and Hard of Hearing Youth (1997-98). These analyses were supplemented by a review of the literature and consultation with a four-member expert panel. Monte Carlo analysis was used for sensitivity testing. RESULTS: Severe to profound hearing loss is expected to cost society $297,000 over the lifetime of an individual. Most of these losses (67%) are due to reduced work productivity, although the use of special education resources among children contributes an additional 21%. Lifetime costs for those with prelingual onset exceed $1 million. CONCLUSIONS: Results indicate that an additional $4.6 billion will be spent over the lifetime of persons who acquired their impairment in 1998. The particularly high costs associated with prelingual onset of severe to profound hearing impairment suggest interventions aimed at children, such as early identification and/or aggressive medical intervention, may have a substantial payback.

Cost-utility of the cochlear implant in adults: a meta-analysis.

OBJECTIVE: To conduct a meta-analysis of the cost-utility of the cochlear implant in adults. DATA SOURCES: MEDLINE literature search, review of article bibliographies, and consultation with experts. STUDY SELECTION: Studies that reported (1) data on adults (age > or = 18 years) with bilateral, postlingual, profound deafness; (2) a health-utility gain from cochlear implantation on a scale from 0.00 (death) to 1.00 (perfect health); (3) a cost-utility ratio in terms of dollars per quality-adjusted life-year (QALY); and (4) at least 1 conventional statistical parameter (ie, SD, 95% confidence interval [CI], or P value). DATA EXTRACTION: From each study, we extracted the number of subjects, study design, health-utility instrument used, health-utility associated with profound deafness, health-utility gain from cochlear implantation, cost-utility of cochlear implantation, and reported statistical parameters. DATA SYNTHESIS: Weighted averages were calculated using a statistical weight of 1 per variance. Pooling 9 reports (n = 619), the health-utility of profoundly deaf adults without cochlear implants was 0.54 (95% CI, 0.52-0.56). Pooling 7 studies (n = 511), the health-utility of profoundly deaf adults after cochlear implantation was 0.80 (95% CI, 0.78-0.82). This improvement of 0.26 in health-utility resulted in a cost-utility ratio of $12,787 per QALY. CONCLUSIONS: Profound deafness in adults results in a substantial health-utility loss. Over half of that loss is restored after cochlear implantation, yielding a cost-utility ratio of $12,787 per QALY. This figure compares favorably with medical and surgical interventions that are commonly covered by third-party payers in the United States today.

A prospective study of the cost-utility of the multichannel cochlear implant.

CONTEXT: Prior clinical studies have indicated that cochlear implantation provides benefits to individuals with advanced sensorineural hearing loss who are unable to gain effective speech recognition with hearing aids. OBJECTIVE: To determine the cost per quality-adjusted life-year (QALY) for adults receiving multichannel cochlear implants. DESIGN: Prospective 12-month multicenter study using preference-based quality-of-life measures and total cost determinations, comparing profoundly hearing-impaired adult subjects with and without cochlear implants. SETTING: Hospital-based and patient-resource clinics. PATIENTS: Severely to profoundly hearing-impaired adult recipients of a cochlear implant and adults eligible for the device who had not yet received it. MAIN OUTCOME MEASURE: Clinical assessment of implant participants included medical and audiologic (speech understanding) data at the time of enrollment, 6 months, and 12 months. All participants' health-utility was assessed at the time of enrollment, 6 months, and 12 months using the Health Utility Index. One-year medical resource utilization and cost data included bills related to implants, patient diaries, charge estimates from clinical sites, and published literature. A decision model was developed to determine cost per QALY. RESULTS: Of the 84 enrolled adults, 62 (75%) completed the study. Mean health-utility scores at the time of enrollment were identical between groups. The marginal 12-month health-utility gain for implant recipients was 0.20; 90% of this improvement was achieved within 6 months. For patients with a mean 22-year life expectancy, the marginal cost per QALY was $14,670. CONCLUSIONS: Overall, multichannel cochlear implants significantly improved recipients' performance on measures of speech understanding and ratings of health-utility within 6 months of implantation. The multichannel cochlear implant yielded a very favorable cost per QALY.

Activity influences on neuronal connectivity within the auditory pathway.

HYPOTHESIS: Sensorineural hearing loss may be associated with altered patterns of neuronal connections within the central auditory pathway. STUDY DESIGN: The cat auditory system was used to address the relative importance of impulse traffic within the auditory nerve in maintaining central nervous system connections. METHODS: Acute, unilateral deafness was induced by tetrodotoxin intoxication of cochlear hair cells. Analysis focused on the structural patterns of contact between auditory nerve endings called end bulbs of Held and their target neurons. Specifically, end bulb morphology and target cell size within the cochlear nucleus were examined. Highly specialized synaptic contacts at this junction provide a powerful site for study. RESULTS: The principal finding was that abolished activity in the auditory nerve caused nerve endings to assume a different shape, typified by more branching and smaller terminal swellings. The new shape is one typically associated with only a subpopulation of fibers in normal-hearing cats--those exhibiting a high-threshold, low-spontaneous activity profile. This result implies that abolished activity alters patterns of nerve fiber contact with second-order neurons. Tetrodotoxin produced differential effects on subpopulations of target neurons within the brainstem and is interpretable on the basis of "weighing" synaptic inputs. Second-order neurons that receive large axosomatic inputs from their parent fiber were significantly smaller than neurons that receive small, axodendritic terminals. Thus, attenuated auditory activity may produce differential effects across the auditory pathway, thereby disrupting the normal balance of inputs into synaptic stations. CONCLUSIONS: Impulse traffic is a critical factor in the interaction between the ear and central auditory stations and appears necessary for the maintenance of key synapses. As hearing disorders with impaired comprehension may be modeled by studies of auditory deafferentation, these observations extend the possibility that changes in central neuronal connections underlie reduced capabilities for processing restored auditory input.

Trends in educational placement and cost-benefit considerations in children with cochlear implants.

OBJECTIVES: To study the effect of cochlear implantation on the use of educational resources by profoundly hearing-impaired children and to determine trends in educational cost vs benefit. DESIGN: Retrospective study and cost-benefit analysis. SETTING: Outpatient pediatric cochlear implant program in an academic institution (The Listening Center at Johns Hopkins University School of Medicine, Baltimore, Md), in collaboration with public schools in Maryland and surrounding states. PATIENTS OR OTHER PARTICIPANTS: School-aged children with profound prelingual hearing impairment without other clearly defined disabilities. Thirty-five children with multiple-channel cochlear prostheses and a comparison group of 10 children without implants from 'total communication' programs in the Maryland public school system. INTERVENTIONS: Multiple-channel cochlear implantation and at least 1 year of a systematic auditory skill development program at the Listening Center, compared with standard educational management of children with conventional amplification. MAIN OUTCOME MEASURES: Classroom placement and number of hours of special educational support used. RESULTS: A correlation was observed between the length of cochlear implant experience and the rate of full-time placement in mainstream classrooms (r = 0.10; P= .04). There was also a negative correlation between the length of implant experience and the number of hours of special educational support used by fully mainstreamed children (Pearson product moment correlation = -0.10; P = .03). Children with greater than 2 years of implant experience were mainstreamed at twice the rate or more of age-matched children with profound hearing loss who did not have implants. They were also placed less frequently in self-contained classrooms and used fewer hours of special education support. A cost-benefit analysis based on conservative estimates of educational expenses from kindergarten to 12th grade shows a cost savings of cochlear implantation and appropriate auditory (re)habilitation that ranges from $30000 to $200000. CONCLUSIONS: Cochlear implantation accompanied by aural (re)habilitation increases access to acoustic information of spoken language, leading to higher rates of mainstream placement in schools and lower dependence on special education support services. The cost savings that results from a decrease in the use of support services indicates an educational cost benefit of cochlear implant (re)habilitation for many children.