Cigarette- and snus-modified association between unprotected exposure to noise from hunting rifle caliber weapons and high frequency hearing loss. A cross-sectional study among swedish hunters.

AIM: To investigate in this cross-sectional study among Swedish hunters if tobacco use modifies the previously observed association, expressed as prevalence ratio (PR), between unprotected exposure to impulse noise from hunting rifle caliber (HRC) weapons and high-frequency hearing impairment (HFHI). SETTINGS AND DESIGN: A nationwide cross-sectional epidemiologic study was conducted among Swedish sport hunters in 2012. MATERIALS AND METHODS: The study was Internet-based and consisted of a questionnaire and an Internet-based audiometry test. RESULTS: In all, 202 hunters completed a questionnaire regarding the hearing test. Associations were modeled using Poisson regression. Current, daily use of tobacco was reported by 61 hunters (19 used cigarettes, 47 moist snuff, and 5 both). Tobacco users tended to be younger, fire more shots with HRC weapons, and report more hunting days. Their adjusted PR (1-6 unprotected HRC shots versus 0) was 3.2 (1.4-6.7), P < 0.01. Among the nonusers of tobacco, the corresponding PR was 1.3 (0.9-1.8), P = 0.18. P value for the interaction was 0.01. The importance of ear protection could not be quantified among hunters with HRC weapons because our data suggested that the HFHI outcome had led to changes in the use of such protection. Among hunters using weapons with less sound energy, however, no or sporadic use of hearing protection was linked to a 60% higher prevalence of HFHI, relative to habitual use. CONCLUSION: Tobacco use modifies the association between exposure to unprotected impulse noise from HRC weapons and the probability of having HFHI among susceptible hunters. The mechanisms remain to be clarified, but because the effect modification was apparent also among the users of smokeless tobacco, combustion products may not be critical for this effect.

Shooting history and presence of high-frequency hearing impairment in swedish hunters: A cross-sectional internet-based observational study.

The aim of this cross-sectional study among Swedish hunters was to examine the association between shooting history and presence of high-frequency hearing impairment (HFHI). All hunters registered with an e-mail address in the membership roster of the Swedish Hunters' Association were invited via e-mail to a secure website with a questionnaire and an Internet-based audiometry test. Associations, expressed as prevalence ratio (PR), were multivariately modelled using Poisson regression. The questionnaire was answered by 1771 hunters (age 11-91 years), and 202 of them also completed the audiometry test. Subjective severe hearing loss was reported by 195/1771 (11%), while 23/202 (11%) exhibited HFHI upon testing with Internet-based audiometry. As many as 328/1771 (19%) had never used hearing protection during hunting. In the preceding 5 years, 785/1771 (45%), had fired >6 unprotected gunshots with hunting rifle calibers. The adjusted PR of HFHI when reporting 1-6 such shots, relative to 0, was 1.5 [95% confidence interval (CI) 1.1-2.1; P = 0.02]. We could not verify any excessive HFHI prevalence among 89 hunters reporting unprotected exposure to such gunshot noise >6 times. Nor did the total number of reported rifle shots seem to matter. These findings support the notion of a wide variation in individual susceptibility to impulse noise; that significant sound energy, corresponding to unprotected noise from hunting rifle calibers, seems to be required; that susceptible individuals may sustain irreversible damage to the inner ear from just one or a few shots; and that use of hearing protection should be encouraged from the first shot with such weapons.

The use of radiology in middle ear and temporal bone surgery.

A nationwide survey was performed in Sweden regarding the way that practicing otosurgeons utilize radiological imaging before and after performing surgery of the middle ear and temporal bone. Sixty-six surgeons from 30 different otorhinolaryngology departments participated in the study. These represented all hospitals in Sweden where ear surgery is performed to some degree. A questionnaire was designed consisting of 18 questions that were assigned to 4 different groups. Questions in group 1 assessed the general conditions regarding imaging services in the local hospital. Questions in group 2 illuminated the level of tuition and competence development when it comes to judging radiological examinations. Group 3 questions mirrored the clinical routines when ordering various specific investigations. In group 4, the questions were aimed at describing which type of information the surgeons wanted to obtain from the imaging investigations. The answers gave a good picture of how Swedish otosurgeons use the services offered by their local radiological departments. One of the conclusions is that, although there is consensus regarding certain types of examinations in specific conditions, there is a great variation in how surgeons utilize radiological imaging in many of the most common clinical conditions. It is obvious that the routines regarding the use of radiology in conjunction with ear surgery vary from place to place and also between different surgeons. Whether a consensus can be reached in the future regarding this issue remains to be seen.

Hypoglossal schwannoma-successful reinnervation and functional recovery of the tongue following tumour removal and nerve grafting.

OBJECTIVE: Hypoglossal nerve schwannomas are rare tumours that usually cause ipsilateral hypoglossal palsy. This report describes such lesions in two patients and suggests nerve grafting as part of the treatment regimen. METHOD: Two patients with intra- and extra-dural hypoglossal schwannomas respectively were treated by direct surgery via a postero-lateral approach to the posterior fossa, hypoglossal canal and carotid sheath. Following tumour removal, sural nerve grafting was used to reconstruct the nerves. Unexpectedly, muscle bulk and motor function returned within 6 months in both patients. CONCLUSION: Nerve grafting was highly successful in achieving functional recovery following surgery for hypoglossal nerve schwannomas.

Evaluation of an internet-based hearing test--comparison with established methods for detection of hearing loss.

BACKGROUND: Hearing impairment is most accurately measured by a clinical pure-tone audiogram. This method is not suitable for large-scale, population-based epidemiological studies as it requires that study participants visit a clinic with trained personnel. An alternative approach to measuring hearing ability is self-estimation through questionnaires, but the correlation to clinical audiometric tests varies. OBJECTIVE: To evaluate an Internet-based hearing test pilot compared to a question about self-estimated hearing and the feasibility of using an Internet-based hearing test and an Internet-based questionnaire in a population of 560 members of the Swedish Hunters' Association in the age group 20-60 years. METHODS: An invitation was mailed to the participants in March 2007 together with the URL to the study Web site, a personal username, and a password. The Web site included the questionnaire, the hearing test, and instructions for participating in the study. The hearing test resembles a clinical audiogram presenting 6 tones between 500 and 8000 Hz. Tones are presented between 0 and 60 dB, and the participant responds to the tones by pressing the space bar. The hearing test requires headphones and is based on JAVA programming. Before the participant can start the hearing test, it has to be calibrated against a reference person with good hearing between 15 and 35 years of age. RESULTS: After 5 months, 162 out of 560 (29%) had answered the questionnaire, out of which 88 (16%) had completed the hearing test. Those who actively declined participation numbered 230 out of 560 (41%). After removing duplicates and hearing tests calibrated by unreliable reference data, 61 hearing tests remained for analysis. The prevalence of hearing impairment from the Internet-based hearing test was 20% (12 out of 61), compared to 52% (32 out of 61) from the self-estimated question. Those who completed the hearing test were older than the non-participants, and more had headphones (P = .003) and the correct version of the JAVA program (P = .007) than those who only answered the questionnaire. CONCLUSIONS: Though an Internet-based hearing test cannot replace a clinical pure-tone audiogram conducted by a trained audiologist, it is a valid and useful screening tool for hearing ability in a large population carried out at a low cost.

Wideband reflectance associated with otitis media in infants and children with cleft palate.

Wideband reflectance (WBR) is a method of middle-ear analysis that may provide more information and provide a more detailed look at the middle-ear system than tympanometry. WBR has the potential to improve efficiency of newborn hearing screening programs by reducing time needed to accurately diagnose middle-ear status. This prospective study compares wideband reflectance results with 226-Hz and 1000-Hz tympanometry and distortion product otoacoustic emissions in a group of infants and children with cleft lip and palate, who have not been treated with myringotomy or tubes. Results are also compared to normative data in children of similar ages using the same instrument and methods. Results demonstrate that wideband reflectance showed the highest level of agreement (88%) with DPOAE results.

Distribution of different collagen types in the rat's tympanic membrane and its suspending structures.

BACKGROUND: The objective of the study was to investigate the histological distribution of collagens in the healthy rat's tympanic membrane. METHODS: Immunohistochemical analysis of collagen type I, II, III, and IV in the tympanic membranes in healthy adult female Sprague-Dawley rats. The staining was semiquantified using light microscopy in a blinded fashion, not knowing what type of collagen the slide had been stained for. RESULTS: The pars tensa of the tympanic membrane was mainly stained for collagen type II and IV. The fibrous annulus could on immunohistochemistry be subdivided into an inner and an outer portion. The inner portion of the fibrous annulus was mainly stained for collagen type II, whereas the outer portion was most strongly stained for collagen type III and collagen type IV. The test-retest reliability of the semiquantative method was 81%. CONCLUSION: Collagen type II and IV are the major collagen constituents of the pars tensa of the tympanic membrane. The outer portion of the fibrous annulus has collagen type III and IV as its major constituents, whereas the inner portion is made up of collagen type II.

Posterior canal dehiscence syndrome caused by an apex cholesteatoma.

OBJECTIVE: To compare audio-vestibular findings caused by a dehiscence of the posterior semicircular canal with those found in the superior canal dehiscence syndrome. STUDY DESIGN: Case report. SETTING: University hospital, tertiary referral center. PATIENT: The 44-year-old woman suffered from a gradual hearing loss with pulse-synchronous tinnitus as well as sound and pressure-induced vertigo. INTERVENTION: Audio-vestibular testing and high-resolution computed tomography. MAIN OUTCOME MEASURE: The superior canal dehiscence syndrome is caused by failure of normal postnatal bone development in the middle cranial fossa leading to absence of bone at the most superior part of the superior semicircular canal. The typical features for this syndrome are sound- and pressure-induced vertigo with torsional eye movements, pulse synchronous tinnitus and apparent conductive hearing loss in spite of normal middle-ear function. We present a patient with very similar symptoms and findings who, instead, had a posterior semicircular canal dehiscence caused by an apex cholesteatoma. CONCLUSION: Patients with semicircular canal dehiscence have common auditory-vestibular features regardless of which of the two vertical semicircular canals is affected. The only obvious difference between the two is the vertical component of the sound and pressure-induced eye movements (which beats in opposite directions).

Pars flaccida displacement pattern in otitis media with effusion in the gerbil.

HYPOTHESIS: Our hypothesis is that otitis media with effusion causes stiffness loss in the pars flaccida of the tympanic membrane. This loss of stiffness may be persistent and may trigger the development of retraction pockets and cholesteatoma. BACKGROUND: Otitis media with effusion is a very common disease in childhood. It can cause minor to moderate hearing loss and delayed speech development. Otitis media with effusion is a risk factor for retraction pocket formation. METHODS: Otitis media with effusion was induced unilaterally in 15 gerbils by obstructing the eustachian tube with glue. The contralateral ears served as normal controls. As a measure of mechanical stiffness, pars flaccida peak displacement versus pressure was used. The displacement measurements were made with moire interferometry. This is a noncontacting optical technique with which the displacement of an object can be measured in real time. RESULTS: The mean peak displacement of the pars flaccida in the group with otitis media with effusion was increased threefold as compared with normal controls. This difference was statistically significant. CONCLUSION: There was a loss of mechanical stiffness in the pars flaccida caused by otitis media with effusion. This loss of stiffness may be persistent and may predispose for retraction pocket formation and cholesteatoma development.

Cochlear hair cell loss in single-dose versus continuous round window administration of gentamicin.

CONCLUSIONS: Gentamicin-induced cochlear hair cell loss depends on local middle ear administration kinetics and the total drug dose. Single-dose gentamicin instillation in the middle ear is associated with a high variation in hair cell loss. OBJECTIVE: To compare the effects of single-dose and continuous round window administration of gentamicin on cochlear hair cell loss in a guinea pig model. MATERIAL AND METHODS: Two methods for drug administration to the inner ear were used. In groups of five animals, a total dose of 0.8 or 3.2 mg of gentamicin was either instilled as a single dose directly into the round window niche or administered continuously over a 1-week period using a pump-catheter system. Continuous administration was achieved by means of a posterior tympanotomy and subcutaneous placement of an osmotic pump fitted with a catheter. The tip of the catheter was fixed in the round window niche. One group of five animals served as controls and received a saline infusion. The animals were sacrificed after 1 week and hair cell loss was determined microscopically after dissection and phalloidin labelling of the basilar membrane and organ of Corti. RESULTS: Quantitation of cochlear hair cell loss revealed a dose-dependent effect of gentamicin. With both treatment modalities the higher dose induced a higher percentage of hair cell loss. There was inner and outer hair cell loss in all four groups that received gentamicin. With the single-dose instillation, hair cell loss was distributed irregularly from the round window membrane towards the cochlear apex, whereas continuous administration induced hair cell loss close to the round window membrane. Single-dose instillation induced greater hair cell loss than continuous administration at the same dose. The inter-individual variation in hair cell loss was highest following single-dose instillation.

High-frequency hearing, tinnitus, and patient satisfaction with stapedotomy: A randomized prospective study.

Otosclerosis is a common disorder that leads to conductive hearing loss. Most patients with otosclerosis also have tinnitus, and surgical treatment is known to improve hearing as well as tinnitus. Some patients however experience worsening of tinnitus after the operation, but there are no known factors that allow surgeons to predict who will be at risk. In this prospective observational study on 133 patients undergoing stapedotomy, we show that postoperative air conduction thresholds at very high stimulus frequencies predict improvement of tinnitus, as assessed with proportional odds logistic regression models. Young patients were significantly more likely to experience reduction of tinnitus and patients whose tinnitus became better were also more satisfied with the outcome of the operation. These findings have practical importance for patients and their surgeons. Young patients can be advised that surgery is likely to be beneficial for their tinnitus, but a less positive message should be conveyed to older patients.

A randomised, double blind trial of N-Acetylcysteine for hearing protection during stapes surgery.

BACKGROUND: Otosclerosis is a disorder that impairs middle ear function, leading to conductive hearing loss. Surgical treatment results in large improvement of hearing at low sound frequencies, but high-frequency hearing often suffers. A likely reason for this is that inner ear sensory cells are damaged by surgical trauma and loud sounds generated during the operation. Animal studies have shown that antioxidants such as N-Acetylcysteine can protect the inner ear from noise, surgical trauma, and some ototoxic substances, but it is not known if this works in humans. This trial was performed to determine whether antioxidants improve surgical results at high frequencies. METHODS: We performed a randomized, double-blind and placebo-controlled parallel group clinical trial at three Swedish university clinics. Using block-stratified randomization, 156 adult patients undergoing stapedotomy were assigned to intravenous N-Acetylcysteine (150 mg/kg body weight) or matching placebo (1:1 ratio), starting one hour before surgery. The primary outcome was the hearing threshold at 6 and 8 kHz; secondary outcomes included the severity of tinnitus and vertigo. FINDINGS: One year after surgery, high-frequency hearing had improved 2.7 ± 3.8 dB in the placebo group (67 patients analysed) and 2.4 ± 3.7 dB in the treated group (72 patients; means ± 95% confidence interval, p = 0.54; linear mixed model). Surgery improved tinnitus, but there was no significant intergroup difference. Post-operative balance disturbance was common but improved during the first year, without significant difference between groups. Four patients receiving N-Acetylcysteine experienced mild side effects such as nausea and vomiting. CONCLUSIONS: N-Acetylcysteine has no effect on hearing thresholds, tinnitus, or balance disturbance after stapedotomy. TRIAL REGISTRATION: ClinicalTrials.gov NCT00525551.

Allografted fetal dorsal root ganglion neuronal survival in the guinea pig cochlea.

Neural grafting is a potential strategy to help restore auditory function following loss of spiral ganglion cells. As a first step towards the reconstruction of a neural pathway from the cochlea to the brainstem, we have examined the survival of fetal dorsal root ganglion (DRG) neurons allografted into the cochlea of adult guinea pigs. In some animals implantation of DRGs was combined with a local infusion of neurotrophic substances whereas in others auditory sensory receptors were chemically destroyed prior to DRG implantation by injection of the ototoxin neomycin into the middle ear. The results show that many transplanted DRG neurons attached close to the cochlear spiral ganglion neurons. The survival of the implant was significantly increased by treatment with neurotrophic factors, but not reduced by the absence of auditory sensory structures. This study shows that implanted sensory neurons can survive heterotopic grafting immediately adjacent to the eighth cranial nerve, thereby providing a basis for further studies of the anatomical and functional influence of neural grafts in the inner ear.

A model for implanting neuronal tissue into the cochlea.

Immature dorsal root ganglion (DRG) neurons have previously been shown to survive implantation to the cavity of extirpated adult native DRG, send axons via the dorsal root into the host spinal cord and make functional sypnatic connections. Regeneration or replacement of the auditory nerve would provide a major intervention in the clinical treatment of severe hearing impairment. In this study we have exploited the potential of fetal DRG neurons to survive allografting into the cochlea of adult guinea pigs. In some animals implantation of fetal DRGs was combined with infusion of neurotropic substances into the cochlea. Survival of the implanted DRG neurons was found in the majority of grafted animals. Treatment with neurotrophic factors significantly increased the number of surviving implanted DRG neurons. However, even in the absence of neurotrophic substances survival of DRG neurons was found in a majority of the animals, indicating the presence of endogenous growth promoting factors within the cochlea and/or an intrinsic capacity of fetal DRG neurons themselves to survive in this heterotropic location.

Stress as a trigger of attacks in Menière's disease. A case-crossover study.

BACKGROUND: Menière's disease is defined as the presence of recurrent, spontaneous episodic vertigo, hearing loss (HL), aural fullness, and tinnitus. The occurrence of attacks is unpredictable. The etiology is still unknown, but the disease has a pathologic correlate in hydropic distension of the endolymphatic system. Earlier studies have shown increased incidence of stress on the same day as vertigo attacks, but it has not been determined whether stress occurring on the day of the vertiginous episode came before or after the onset of the vertigo. METHODS: A case-crossover study including 46 patients with active Menière's disease. MAIN OUTCOME MEASURE: Relative risks with 95% confidence intervals (CI). FINDINGS: During the study period, 153 Menière's attacks were reported. Twenty-four (52%) of the 46 patients reported attacks. Twelve of the 153 (8%) attacks occurred within 3 hours after exposure to emotional stress. The relative risk of having an attack was 5.10 (95% CI 2.37-10.98) during 3 hours after being exposed to emotional stress. Twenty-nine percent of the patients with attacks had at least one attack after exposure to emotional stress. For mental stress, the relative risk was 4.16 (95% CI 1.46-11.83) and the hazard period 1 hour, but only five attacks were exposed. No excess risk was found after physical stress. INTERPRETATION: Being exposed to emotional stress increases the risk of getting an attack of Menière's disease during the next hour, and the hazard period is possibly extended up to 3 hours.

Factors influencing quality of life in patients with Ménière's disease, identified by a multidimensional approach.

PURPOSE: To evaluate self-reported quality of life in Ménière's disease patients by a multidimensional approach and to identify predictors of the results. STUDY DESIGN: Cross-sectional. SETTING: Tertiary referral hospital centers. PATIENTS: One hundred-twelve patients with Ménière's Disease. MAIN OUTCOME MEASURE: Questionnaires concerning quality of life: Short Form 12 (SF-12) including the Mental Component Summary (MCS-12) and the Physical Component Summary (PCS-12), Hospital Anxiety and Depression Scale (HAD), Sickness Impact Profile (SIP), the Function Level Scale (FLS) from the American Association of Otology's criteria for reporting results of treatment of Ménière's Disease, Vertigo Symptom Scale (VSS), Hearing Disability Handicap scale (HDHS), Tinnitus Severity Questionnaire (TSQ), and Sense of Coherence (SOC) Scale. RESULTS: The Ménière's patients rated their quality of life significantly worse than did healthy reference groups in both the physical and the psychosocial dimensions. The SOC affected the results of the HAD, the MCS-12, and the psychosocial dimension of the SIP. The VSS affected the results of PCS-12, both dimensions of the SIP, and the FLS. The speech perception subscale of the HDHS affected the MCS-12, and tinnitus severity affected the HAD anxiety subscale. The results of the FLS correlated with the physical dimension of quality of life. CONCLUSION: The Ménière's patients experienced a worse quality of life than did healthy subjects. Vertigo mainly influenced the physical dimension, whereas tinnitus and hearing loss influenced the psychosocial dimension. Sense of coherence had an impact on the psychosocial dimension. The FLS was not sensitive enough to serve as an outcome of treatment results but needed to be complemented by quality of life instruments.

Pars flaccida displacement pattern in purulent otitis media in the gerbil.

HYPOTHESIS: Our hypothesis is that purulent otitis media and otitis media with effusion cause stiffness loss of the tympanic membrane. This loss of stiffness may be persistent and precede the development of retraction pockets and cholesteatoma. BACKGROUND: Postinflammatory changes such as retraction pockets and cholesteatoma develop in the pars flaccida and in the pars tensa of the tympanic membrane. In our previous experimental studies, stiffness changes were shown to develop early in the pars tensa in response to purulent otitis media and otitis media with effusion. These changes are suggested to be precursors to a later development of retraction pockets and cholesteatoma. In the clinical situation, retraction pockets are often found in the pars flaccida only. The aim of the current study was thus to investigate whether stiffness changes appear also in the pars flaccida during purulent otitis media. METHODS: Streptococcus pneumoniae type 3 was injected into the middle ear to induce purulent otitis media. As a measure of pars flaccida stiffness, peak displacement versus middle ear pressure was used. The peak displacement measurements were obtained from full-field moiré; interferometry, which is a noncontacting optical technique for deformation measurements. RESULTS: Ears with purulent otitis media showed increased peak displacement of the pars flaccida at a middle ear pressure of 200 daPa, compared with normal controls. CONCLUSION: There was a decreased mechanical stiffness of the pars flaccida in acute purulent otitis media. This decreased stiffness may predispose for future retraction pocket formation and cholesteatoma development.

Structural tympanic membrane changes in secretory otitis media and cholesteatoma.

BACKGROUND: Otitis media may predispose for retraction pathologic abnormality later in life. A weakening of the collagen fiber bundles in the lamina propria of the tympanic membrane (TM) is a prerequisite for the formation of a retraction pocket. Various collagen types have different tensile strength. The collagen-type distribution in the TM during otitis media and cholesteatoma has not been reported before. MATERIALS AND METHODS: The collagen contents of TM biopsies from child patients with longstanding secretory otitis media without retraction pockets were compared with pars tensa cholesteatomas using immunohistochemical staining for collagen Types I to IV. The histology was also investigated using transmission electron microscopy. RESULTS: The outer epithelium was in some biopsies thickened with evidence of edema. The biopsies showed an intact lamina propria with positive immunohistochemical staining for collagen Types I to III and showed normal collagen fiber bundles on electron microscopy. The outer epithelium of the cholesteatomas showed marked thickness variations and signs of edema. There was a presence of normal collagen fiber bundles in smaller parts of all cholesteatomas, positive for collagen Types I to II. In other parts, only scattered collagen fibers were found. CONCLUSION: Tympanic membrane biopsies from patients with longstanding secretory otitis media may show a thickening of the outer epithelium. Collagen Types I to III are present in the lamina propria, and no ultrastructural changes of the collagen fiber bundles are observed. Collagen is found in cholesteatomas in the remnants of the lamina propria, with positive staining for collagen Types I and II, whereas Type III seems to be lacking.

An internet-based hearing test for simple audiometry in nonclinical settings: preliminary validation and proof of principle.

OBJECTIVE: To investigate the validity and reproducibility of a newly developed internet-based self-administered hearing test using clinical pure-tone air-conducted audiometry as gold standard. STUDY DESIGN: Cross-sectional intrasubject comparative study. SETTING: Karolinska University Hospital, Solna, Sweden. PATIENTS: Seventy-two participants (79% women) with mean age of 45 years (range, 19-71 yr). Twenty participants had impaired hearing according to the gold standard test. INTERVENTIONS: Hearing tests. MAIN OUTCOME MEASURES: The Pearson correlation coefficient between the results of the studied Internet-based hearing test and the gold standard test, the greatest mean differences in decibel between the 2 tests over tested frequencies, sensitivity and specificity to diagnose hearing loss defined by Heibel-Lidén, and test-retest reproducibility with the Pearson correlation coefficient. RESULTS: The Pearson correlation coefficient was 0.94 (p < 0.0001) for the right ear and 0.93 for the left (p = 0.0001). The greatest mean differences were seen for the frequencies 2 and 4 kHz, with -5.6 dB (standard deviation, 8.29), and -5.1 dB (standard deviation, 6.9), respectively. The 75th percentiles of intraindividual test-gold standard differences did not exceed -10 dB for any of the frequencies. The sensitivity for hearing loss was 75% (95% confidence interval, 51%-90%), and the specificity was 96% (95% confidence interval, 86%-99%). The test-retest reproducibility was excellent, with a Pearson correlation coefficient of 0.99 (p < 0.0001) for both ears. CONCLUSION: It is possible to assess hearing with reasonable accuracy using an Internet-based hearing test on a personal computer with headphones. The practical viability of self-administration in participants' homes needs further evaluation.

Collagen type distribution in the healthy human tympanic membrane.

BACKGROUND: A weakening of the collagen fibers of the lamina propria of the tympanic membrane is a prerequisite for the formation of a retraction pocket. The various collagen types differ in tensile strength. The distribution of the different collagen types in the lamina propria of the healthy human tympanic membrane has not been reported before. METHODS: Immunohistochemical staining for collagen Types I, II, III, and IV in healthy human tympanic membranes harvested during translabyrinthine surgery for acoustic neuroma. The staining was semiquantified using light microscopy. RESULTS: Collagen Type II was the most abundant collagen of the lamina propria. When subdividing the staining between the 2 fiber layers of the lamina propria, it was observed that the inner layer was enriched with Type III relative to Type II, as reflected in staining patterns. In the outer radial fiber layer of the lamina propria, staining for collagen Type II was predominant.The fibrous annulus could be subdivided into an inner and an outer portion by immunohistochemistry. The inner portion stained strongest for collagen Type II and to a lesser extent for Type I. The outer portion stained strongest for collagen Type III and Type I. CONCLUSION: The differences in distribution of collagen types in the different fiber layers of the lamina propria suggest that the lattice of connective tissue supporting the tympanic membrane is not uniform. Understanding the differences in collagen type distribution and in the physical properties of the individual collagen types themselves may contribute to a comprehensive model of retraction pocket pathogenesis.