Cochlear implants (CI) are commonly used to treat deafness in young children. While many factors influence the ability of a deaf child who is hearing through a CI to develop speech and language skills, an important factor is that the CI has to stimulate the auditory cortex. Obtaining behavioral measurements from young children with CIs can often be unreliable. While a variety of noninvasive techniques can be used for detecting cortical activity in response to auditory stimuli, many have critical limitations when applied to the pediatric CI population. We tested the ability of near-infrared spectroscopy (NIRS) to detect cortical responses to speech stimuli in pediatric CI users. Neuronal activity leads to changes in blood oxy-and de-oxyhemoglobin concentrations that can be detected by measuring the transmission of near-infrared light through the tissue. To verify the efficacy of NIRS, we first compared auditory cortex responses measured with NIRS and fMRI in normal-hearing adults. We then examined four different participant cohorts with NIRS alone. Speech-evoked cortical activity was observed in 100% of normal-hearing adults (11 of 11), 82% of normal-hearing children (9 of 11), 78% of deaf children who have used a CI >4 months (28 of 36), and 78% of deaf children who completed NIRS testing on the day of CI initial activation (7 of 9). Therefore, NIRS can measure cortical responses in pediatric CI users, and has the potential to be a powerful adjunct to current CI assessment tools.

Objective Selection of diagnostic tests for children with sensorineural hearing loss (SNHL) is influenced by clinical suspicion. Testing results reported in the literature are similarly biased. We evaluate the usefulness of a comprehensive diagnostic battery for each child. Study Design Retrospective review. Setting Tertiary care university hospital. Patients A total of 270 children referred for severe to profound SNHL between January 2002 and June 2009. Interventions Results of the following were reviewed: magnetic resonance imaging, computed tomography, renal ultrasound, electrocardiography, fluorescent treponemal antibody absorption test, connexin 26 sequencing, genetic consultation, and ophthalmologic consultation. Main Outcome Measure Diagnostic yield of each test was determined. Results Each diagnostic test or consultation was completed by at least 95% of patients for whom it was ordered. Magnetic resonance imaging revealed abnormalities explaining SNHL in 24% of patients. Computed tomography showed inner ear anomalies in 18% of patients. Biallelic connexin 26 mutations were found in 15%. Renal ultrasound found anomalies in 4% of patients. Electrocardiography found 1% of patients with prolonged QT intervals. Fluorescent treponemal antibody absorption test result was positive in 0.5%. Genetic consultation found a genetic cause for hearing loss in 25%. Ophthalmologic consultation found abnormalities associated with hearing loss in 8%. Conclusion Diagnostic radiologic imaging is the highest yielding test for evaluating children with SNHL. Connexin 26 sequencing identifies a nearly nonoverlapping subset of children compared with imaging. Specialty consultations, particularly from a clinical geneticist, can improve diagnostic yield. Other tests, although of lower diagnostic yield for SNHL, can identify important diseases that significantly affect patient health.

The relationship between dyslipidemia and hearing is unclear. This study was conducted to investigate whether elevated serum lipid levels impact auditory function in humans and in guinea pigs. In the human study, a cross-sectional study of 40 volunteers with dyslipidemia was conducted. Pure tone thresholds, distortion product otoacoustic emissions, and lipid profiles were analyzed. When controlled for patient age and sex, we found that elevated triglycerides were associated with reduced hearing. In the guinea pig study, a prospective study of animals fed a high-fat diet for 14 weeks was conducted. Although the high-fat diet led to a dramatic elevation in the average weight and total cholesterol in all animals (from 61 to 589 mg/dl), there were no meaningful changes in distortion product otoacoustic emission magnitudes. These results suggest that whereas chronic dyslipidemia associated with elevated triglycerides may reduce auditory function, short-term dietary changes may not. KeywordsCochlea; DPOAE; Hypercholesterolemia; Lipid Dyslipidemia is a well-known factor leading to coronary artery disease and atherosclerosis, and is a leading cause of myocardial infarction, stroke, and death in the United States. However, it is unclear whether dyslipidemia is associated with hearing loss. There are two primary lipoprotein fractions constituting total serum cholesterol: low-density lipoprotein cholesterol (LDL) and high-density lipoprotein cholesterol (HDL). Serum LDL transports cholesterol from the liver, via the circulatory system, to be deposited in other organs, specifically the arteries and heart. In contrast, HDL transports cholesterol from the organs and tissues back to the liver via the circulatory system. The HDL transport system is thought to be beneficial to the cardiovascular system because it reduces the formation of cholesterol plaques in major arteries. Elevated LDL and decreased HDL characterizes coronary artery disease. In addition, an elevated serum triglyceride level is often present, indicating a high level of fat in the bloodstream.Cholesterol is a vital component of eukaryotic cellular membranes because it stabilizes them and modulates lipid and protein translocation across the membrane. Specifically related to Copyright © 2006 NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript the cochlea, the lipid composition, fluidity, and stiffness of the outer hair cell lateral wall membrane have been shown to be important to its electromotile function and the cochlear amplifier (1-5). The lateral wall plasma membrane of the outer hair cell also seems to have less cholesterol than other cells (6). These data suggest that outer hair cell function may be particularly sensitive to dyslipidemic states. Histologic changes in the guinea pig cochlea in response to dyslipidemia have been identified in the strial marginal layer and in outer hair cells (7). Hypercholesterolemia may also decrease cochlear vascularity and cause hearing loss.We sought to determine whether dyslipidemia is a...

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Objectives/Hypothesis To examine the characteristics of pediatric cochlear implant channel malfunction preceding device failure. Study Design Retrospective review. Methods All pediatric patients who underwent cochlear implantation at a tertiary academic medical center were reviewed regarding device type, reason for replacement, time to replacement, and timing and pattern of channel faults in failed versus nonfailed devices. Results Between 1993 and 2008, 264 pediatric cochlear implantations were performed. With an average 894-day follow-up, the replacement rate was 9.5% (25/264). Reasons for replacement were device failure (6.4%), medical/surgical failure (2.3%), and obsolescence (0.8%). Replacement rates were comparable among Advanced Bionics (13.3%), Cochlear Corporation (6.3%), and MED-EL (10.3%) devices. Fifty-two cochlear implants developed at least one channel fault, and 13 eventually progressed to failure requiring replacement. MED-EL devices comprised 12 of these 13 failures. At the 12-month follow-up interval, one, three, and five channel faults predicted 40%, 75%, and 100% probabilities of eventual electrode failure, respectively. Channels destined to fail demonstrated small, yet statistically significant, impedance elevations 12 months before failure and large elevations 3 months before failure. Conclusions Replacement of cochlear implants in pediatric patients is common and is due to device malfunction about one half of the time. Earlier initial channel fault, earlier subsequent channel faults, adjacent channel faults, and a greater total number of channel faults were associated with the need for replacement surgery. Elevations in a channel’s impedance should raise the concern for an impending failure. These predictors can help the cochlear implant team when considering surgery to replace the device.