Anh Nguyen-Huynh

Feasibility of spectral-domain phase- sensitive optical coherence tomography for middle ear vibrometry

We describe a novel application of spectral-domain phase-sensitive optical coherence tomography (SD PS-OCT) to detect the tiny motions of the middle ear structures, such as the tympanic membrane and ossicular chain, and their morphological features for differential diagnosis of CHL. This technique has the potential to provide meaningful vibration of ossicles with a vibration sensitivity of ≈ 0.5 nm at 1 kHz of acoustic stimulation. To the best of our knowledge, this is the first demonstration of depth-resolved vibration imaging of ossicles with a PS-OCT system at a nanometer scale.

Association of otosclerosis with Sp1 binding site polymorphism in COL1A1 gene: Evidence for a shared genetic etiology with osteoporosis

Hypothesis: There is an association between otosclerosis and osteoporosis. Background: Both osteoporosis and otosclerosis are common bone diseases to which relatively large portions of the population are genetically predisposed. Recently, a strong association has been described between osteoporosis and an Sp1 binding site of putative functional significance in the first intron of the COL1A1 gene. Methods: We applied polymerase chain reaction-based restriction enzyme analysis to determine the polymorphic distribution of the Sp1 site in 100 patients with otosclerosis and 108 control subjects. Results: This study showed a significant association between otosclerosis and the COL1A1 first intron Sp1 site. The allelic frequency of the Sp1 site is very similar between otosclerosis and osteoporosis. Conclusion: Some cases of otosclerosis and osteoporosis could share a functionally significant polymorphism in the Sp1 transcription factor binding site in the first intron of the COL1A1 gene.

Volumetric In Vivo Imaging of Microvascular Perfusion Within the Intact Cochlea in Mice Using Ultra-High Sensitive Optical Microangiography

Studying the inner ear microvascular dynamics is extremely important to understand the cochlear function and to further advance the diagnosis, prevention, and treatment of many otologic disorders. However, there is currently no effective imaging tool available that is able to access the blood flow within the intact cochlea. In this paper, we report the use of an ultrahigh sensitive optical micro-angiography (UHS-OMAG) imaging system to image 3-D microvascular perfusion within the intact cochlea in living mice. The UHS-OMAG image system used in this study is based on spectral domain optical coherence tomography, which uses a broadband light source centered at 1300 nm with an imaging rate of 47\thinspace 000 A-scans/s, capable of acquiring high-resolution B scans at 300 frames/s. The technique is sensitive enough to image very slow blood flow velocities, such as those found in capillary networks. The 3-D imaging acquisition time for a whole cochlea is ~ 4.1 s. We demonstrate that volumetric reconstruction of microvascular flow obtained by UHS-OMAG provides a comprehensive perfusion map of several regions of the cochlea, including the otic capsule, the stria vascularis of the apical and middle turns and the radiating arterioles that emanate from the modiolus.

Volumetric in vivo imaging of intracochlear microstructures in mice by high-speed spectral domain optical coherence tomography

There is considerable interest in developing new methods for in vivo imaging of the complex anatomy of the mammalian cochlea for clinical as well as fundamental studies. In this study, we explored, the feasibility of spectral domain optical coherence tomography (SD-OCT) for 3-D in vivo imaging of the cochlea in mice. The SD-OCT system employed in this study used a broadband light source centered at 1300 nm, and the imaging speed of the system was 47,000 A-scans per second using the InGaAs camera. The system was capable of providing fully processed, high-resolution B-scan images [512 (axial) x 128 (lateral) pixels] at 280 frames per sec. The 3-D imaging acquisition time for a whole cochlea was approximately 0.45 sec. The traditional SD-OCT structural imaging algorithm was used to reconstruct 3-D cochlear morphology. We demonstrated that SD-OCT can be successfully used for in vivo imaging of important morphological features within the mouse cochlea, such as the otic capsule and structures within, including Reissners membrane, the basilar membrane, tectorial membrane, organ of Corti, and modiolus of the apical and middle turns.

Factors associated with hearing loss in a normal-hearing guinea pig model of hybrid cochlear implants

The Hybrid cochlear implant (CI), also known as Electro-Acoustic Stimulation (EAS), is a new type of CI that preserves residual acoustic hearing and enables combined cochlear implant and hearing aid use in the same ear. However, 30-55% of patients experience acoustic hearing loss within days to months after activation, suggesting that both surgical trauma and electrical stimulation may cause hearing loss. The goals of this study were to: 1) determine the contributions of both implantation surgery and EAS to hearing loss in a normal-hearing guinea pig model; 2) determine which cochlear structural changes are associated with hearing loss after surgery and EAS. Two groups of animals were implanted (n = 6 per group), with one group receiving chronic acoustic and electric stimulation for 10 weeks, and the other group receiving no direct acoustic or electric stimulation during this time frame. A third group (n = 6) was not implanted, but received chronic acoustic stimulation. Auditory brainstem response thresholds were followed over time at 1, 2, 6, and 16 kHz. At the end of the study, the following cochlear measures were quantified: hair cells, spiral ganglion neuron density, fibrous tissue density, and stria vascularis blood vessel density; the presence or absence of ossification around the electrode entry was also noted. After surgery, implanted animals experienced a range of 0-55 dB of threshold shifts in the vicinity of the electrode at 6 and 16 kHz. The degree of hearing loss was significantly correlated with reduced stria vascularis vessel density and with the presence of ossification, but not with hair cell counts, spiral ganglion neuron density, or fibrosis area. After 10 weeks of stimulation, 67% of implanted, stimulated animals had more than 10 dB of additional threshold shift at 1 kHz, compared to 17% of implanted, non-stimulated animals and 0% of non-implanted animals. This 1-kHz hearing loss was not associated with changes in any of the cochlear measures quantified in this study. The variation in hearing loss after surgery and electrical stimulation in this animal model is consistent with the variation in human patients. Further, these findings illustrate an advantage of a normal-hearing animal model for quantification of hearing loss and damage to cochlear structures without the confounding effects of chemical- or noise-induced hearing loss. Finally, this study is the first to suggest a role of the stria vascularis and damage to the lateral wall in implantation-induced hearing loss. Further work is needed to determine the mechanisms of implantation- and electrical-stimulation-induced hearing loss.

Evidence-Based Practice: Management of Vertigo

The article focuses on the evidence basis for the management of benign paroxysmal positional vertigo, the most common diagnosis of vertigo in both primary care and subspecialty settings. An overview is presented, along with evidence-based clinical assessment, diagnosis, and management. Summaries of differential diagnosis of vertigo and outcomes are presented.

The Otology Data Collection Project Report from the CHEER Network

Objective. To describe and communicate data collected in the CHEER (Creating Healthcare Excellence through Education and Research) infrastructure proof-of-concept study to facilitate understanding of the potential capabilities of practice-based research networks and to present pilot data for development of future research initiatives. Study Design. Prospective observational study of CHEER infrastructure operational capacity using a convenience sample of all patients presenting to the practices with tinnitus, dizziness, or a combination of these symptoms. Setting. The CHEER network of community and academic practice sites. Subjects and Methods. The data collection exercise collected demographic, clinical, treatment, and health-related quality-of-life surveys on tinnitus, dizziness, and migraine disorders. Descriptive analysis of the data is presented. Results. Of the sites in the CHEER network, 73% (16/22) successfully enrolled subjects; a total of 1532 patients were enrolled in 8 months. Tinnitus alone, dizziness alone, and both occurred in 28%, 34%, and 29%, respectively. Patients complaining of tinnitus and dizziness had lower quality of life than those sufferers with 1 disorder. Migraine was associated with 27% of patients. The most frequent diagnoses for patients with tinnitus and dizziness were Ménière disease (34%), vertiginous migraine (18%), and benign paroxysmal positional vertigo (16%). Conclusion. Descriptive data on patients with common disorders can be rapidly collected within the framework of a practice-based research network. The data in this study provide valuable pilot information on the targeted disorders, providing a baseline for development of future epidemiological data and clinical trials.

CHEER National Study of Chronic Rhinosinusitis Practice Patterns: Disease Comorbidities and Factors Associated with Surgery

Objectives (1) Describe national patterns of chronic rhinosinusitis (CRS) care across academic and community practices. (2) Determine the prevalence of comorbid disorders in CRS patients, including nasal polyposis, allergic rhinitis, asthma, and cystic fibrosis. (3) Identify demographic, clinical, and practice type factors associated with endoscopic sinus surgery (ESS). Study Design Multisite cross-sectional study. Setting Otolaryngology’s national research network CHEER (Creating Healthcare Excellence through Education and Research). Subjects and Methods A total of 17,828 adult patients with CRS were identified, of which 10,434 were seen at community practices (59%, n = 8 sites) and 7394 at academic practices (41%, n = 10 sites). Multivariate logistic regression was used to evaluate the association between demographic, practice type, and clinical factors and the odds of a patient undergoing ESS. Results The average age was 50.4 years; 59.5% of patients were female; and 88.3% were Caucasian. The prevalence of comorbid diseases was as follows: allergic rhinitis (35.1%), nasal polyposis (13.3%), asthma (4.4%), and cystic fibrosis (0.2%). In addition, 24.8% of patients at academic centers underwent ESS, as compared with 12.3% at community sites. In multivariate analyses, nasal polyposis (odds ratio [OR], 4.28), cystic fibrosis (OR, 2.42), and academic site type (OR, 1.86) were associated with ESS (P < .001), while adjusting for other factors. Conclusions We describe practice patterns of CRS care, as well as demographic and clinical factors associated with ESS. This is the first study of practice patterns in CRS utilizing the CHEER network and may be used to guide future research.

Tonsillectomy Bleed Rates across the CHEER Practice Research Network Pursuing Guideline Adherence and Quality Improvement

Objectives (1) Compare postoperative bleeding in the CHEER network (Creating Healthcare Excellence through Education and Research) among age groups, diagnoses, and practice types. (2) Report the incidence of bleeding by individual CHEER practice site based on practice guidelines. Study Design Retrospective data collection database review of the CHEER network based on ICD-9 and CPT codes related to tonsillectomy patients. Setting Multisite practice–based network. Subjects and Methods A total of 8347 subjects underwent tonsillectomy as determined by procedure code within the retrospective data collection database, and 107 had postoperative hemorrhage. These subjects had demographic information and related diagnoses based on the CPT and ICD-9 codes collected. Postoperative ICD-9 and CPT codes were used to identify patients who also had postoperative bleed. Variables included age (<12 vs ≥12 years), diagnoses (infectious vs noninfectious), and practice type (community vs academic). Statistical analysis included multivariate logistic regression variables predictive of postoperative bleeding, with P < .05 considered significant. Results Thirteen sites contributed data to the study (7 academic, 6 community). There was postoperative bleeding for an overall bleed rate of 1.3%. Patients ≥12 years old had a significantly increased bleed rate when compared with the younger group (odds ratio, 5.98; 95% confidence interval: 3.79-9.44; P < .0001). There was no significant difference in bleed rates when practices or diagnoses were compared. Conclusion A site descriptor database built to expedite clinical research can be used for practice assessment and quality improvement. These data were also useful to identify patient risk factors for posttonsillectomy bleed.

Variation in the Use of Vestibular Diagnostic Testing for Patients Presenting to Otolaryngology Clinics with Dizziness

Objective We used a national otolaryngology practice–based research network database to characterize the utilization of vestibular function testing in patients diagnosed with dizziness and/or a vestibular disorder. Study Design Database review. Setting The Creating Healthcare Excellence through Education and Research (CHEER) practice-based research network of academic and community providers Subjects and Methods Dizzy patients in the CHEER retrospective database were identified through ICD-9 codes; vestibular testing procedures were identified with CPT codes. Demographics and procedures per patient were tabulated. Analysis included number and type of vestibular tests ordered, stratified by individual clinic and by practice type (community vs academic). Chi-square tests were performed to assess if the percentage of patients receiving testing was statistically significant across clinics. A logistic regression model was used to examine the association between receipt of testing and being tested on initial visit. Results A total of 12,468 patients diagnosed with dizziness and/or a vestibular disorder were identified from 7 community and 5 academic CHEER network clinics across the country. One-fifth of these patients had at least 1 vestibular function test. The percentage of patients tested varied widely by site, from 3% to 72%; academic clinics were twice as likely to test. Initial visit vestibular testing also varied, from 0% to 96% of dizzy patients, and was 15 times more likely in academic clinics. Conclusion There is significant variation in use and timing of vestibular diagnostic testing across otolaryngology clinics. The CHEER network research database does not contain outcome data. These results illustrate the critical need for research that examines outcomes as related to vestibular testing.