Small Ear Canal Research Articles

Real-ear attenuation of custom-fit earplugs with the communications earplug (CEP)

Hearing loss is one of the most common occupational injuries in the Department of Defense. One reason is limited access to adequate hearing protection during combat operations. Even if traditional pre-formed foam earplugs are used during combat, approximately 15% of the military population remains unprotected because the pre-formed earplugs do not adequately fit extremely small ear canals, extremely large ear canals, or ear canals with sharp turns. Custom-fit earplugs provide a potential solution for this hard-to-fit population. However, producing traditional wax-dipped custom-fit earplugs in a combat environment is not always practical. Fortunately, methodology exists to scan ear impressions to create a digital data set, transmit this data to a remote manufacturer via the Internet, and fabricate a set of custom-fit earplugs. The purpose of this study was to investigate how the attenuation provided by custom-fit earplugs created using the digital scanning technique compares to the attenuation provided by custom-fit earplugs created using the traditional wax-dipped technique when used with the CEP. Results show the digitally scanned custom-fit earplugs provide significantly poorer attenuation than the traditional wax-dipped custom-fit earplugs. Comply Canal Tip foam earplugs were also evaluated and shown to provide significantly greater attenuation than custom-fit earplugs manufactured by either method.

A comparison of tympanometry with 226 Hz and 1000 Hz probe tones in children with Down syndrome

Background For children with Down syndrome, the incidence of hearing loss may be as high as 78% [1], therefore the American Academy of Pediatrics recommends regular screening for the presence of hearing abnormalities. Tympanometry is used as an indication of middle ear pathology. In our experience, Down's patients’ tympanograms do not always correlate with otoscopic findings. Down's patients have joint laxity, small ear canals, anterior tympanic membrane orientation and softer tissue composition, all factors thought to affect tympanogram results in infants. Because the use of the 1000 Hz tympanometry is widely recognized as standard procedure in the evaluation of infants aged 0–6 months, we propose it may have greater reliability in testing patients with Down syndrome. Objective Compare the results of visual inspection of the tympanic membrane by a Pediatric Otolaryngologist to the results of tympanometry at traditional probe tone (226 Hz) and at the infant probe tone (1000 Hz). Methods Institutional Review Board – approved prospective study of 26 subject-ears in patients with Down syndrome aged 6 months–18 years but recent stable middle ear/Eustachian tube function using physical examination and tympanometric probe tones at 226 Hz and 1000 Hz. Subject-ears were examined with record of “clear of effusion,” showed the presence of “fluid,” or were to be “excluded.” Blinded to ear exam results, tympanometry was then completed with record of which Jerger classification tympanogram was found at each frequency. Results Although the sensitivity of each test was 1, the specificity of the 1000 Hz tympanometry (100%) in this study was markedly improved compared to the specificity of the 226 Hz tympanometry (71%) ( p = 0.016). Conclusions This pilot study demonstrated evidence that tympanometry in children with Down syndrome may be more reliable at 1000 Hz than at 226 Hz in detecting the presence of middle ear effusion beyond infancy. Use of the 1000 Hz probe tone yielded fewer false positives for disease (type B tympanograms in the setting of absent middle ear disease). Further studies of a larger patient population are needed to corroborate these results.

Postauricular Twin Flap for Canal Wall Reconstruction after Canal Wall Down in Chronic Otitis Media with Small Canal

Objective: Propose the postauricular twin flap consisting of an anteriorly based periosteal flap and soft tissue flap for reconstruction of the canal wall in patients with chronic otitis media and small ear canal in which a canal down procedure is required. Method: A retrospective review was performed in patients undergoing canal wall reconstruction with postauricular twin flap and type I tympanoplasty after canal wall down from 2009 to 2010. Shape of the canal after reconstruction, pre- and postoperative audiogram, and postoperative complications such as infection, delayed healing, and dehiscence of the wall were evaluated. Results: Seven ears of 7 patients underwent the canal wall reconstruction procedure after canal down and type I tympanoplasty. The ages of the patients ranged from 19 to 63 years. The mean duration of follow-up was 13.3 months with a range of 9 to 18 months. The shape of the canal was maintained in all ears, and no dehiscence of the canal wall was found in all seven ears. Postoperative hearing was variable depending on the hearing of preoperation, but no worsening was observed. Mean improvement of postoperative air conduction was 21.8 dB, and that of postoperative air-bone gap was 16.4 dB. Conclusion: The postauricular twin flap is thin and flexible enough to support the posterior surface of the canal skin and to fill the space remaining after surgery. The twin flap procedure for the reconstruction of the external ear canal showed a high success rate.

Infections and immunodeficiency in Down syndrome

Down syndrome (DS) is the most common genetic disease and presents with cognitive impairment, cardiac and gastrointestinal abnormalities, in addition to other miscellaneous clinical conditions. DS individuals may have a high frequency of infections, usually of the upper respiratory tract, characterized by increased severity and prolonged course of disease, which are partially attributed to defects of the immune system. The abnormalities of the immune system associated with DS include: mild to moderate T and B cell lymphopenia, with marked decrease of naive lymphocytes, impaired mitogen-induced T cell proliferation, reduced specific antibody responses to immunizations and defects of neutrophil chemotaxis. Limited evidence of genetic abnormalities secondary to trisomy of chromosome 21 and affecting the immune system is available, such as the potential consequences of gene over-expression, most significantly SOD1 and RCAN1. Secondary immunodeficiency due to metabolic or nutritional factors in DS, particularly zinc deficiency, has been postulated. Non-immunological factors, including abnormal anatomical structures (e.g. small ear canal, tracheomalacia) and gastro-oesophageal reflux, may play a role in the increased frequency of respiratory tract infections. The molecular mechanisms leading to the immune defects observed in DS individuals and the contribution of these immunological abnormalities to the increased risk of infections require further investigation. Addressing immunological and non-immunological factors involved in the pathogenesis of infectious diseases may reduce the susceptibility to infections in DS subjects.

Considerations in early amplification: Selection, fitting, validation, counseling

The implementation of universal newborn hearing screening programs has increased the number of infants diagnosed with hearing loss and referred for amplification in the first few weeks of life. There is compelling evidence that children born with hearing loss who have been identified and begun intervention by 6 months of age will have significantly better language development than their later-identified peers. 1-3 The challenges of fitting appropriate amplification on this population include limited behavioral response to sound, possible complicating middle ear fluid, parental uncertainties, possible existence of additional handicaps, and limited resources to support and pay for hearing aids. Despite these issues, there is consensus that the diagnosis of congenital hearing loss should be completed in the first 3 months of life and be followed immediately with the consideration of hearing aid use. 4 As access to follow-up from newborn hearing screening improves, pediatric audiologists are faced with recommending technology for infants during their early weeks of life. The options available to them are expanding rapidly as amplification technology grows and diversifies. Outcome studies of children fitted with advanced amplification features are not common and cannot keep up with the features being introduced to the market. Most infants are fitted with the goal of providing audibility for environmental speech to enhance speech and language development and with the expectation that patients will use their hearing aids daily. The pediatric audiologist’s role is to share information on hearing loss and available amplification technology with the parents and their medical and support team. Parents depend on various professionals to acquire the information and tools they need to become empowered, informed consumers. Reaching decisions about the choice of technology for an infant includes examining available features and selecting what might be the best fit for the infant given all the available information and circumstances.

Susceptibility to hearing loss: Physiological, physical, behavioral and probabilistic factors

The problem of susceptibility to hearing loss is important from both scientific and legal perspectives. In developing and validating a mathematical model of the ear to predict auditory hazard [Price and Kalb, J. Acoust. Soc. Am. 100, 2674 (1996)] it has become critical to identify the sources of variance in hearing loss data. In turn, the model has provided the capacity for insight into processes that are operative. For very intense sounds, losses are virtually instantaneous and both the physical characteristics of the ear and the details of the moment matter. Physiological characteristics such as small ear canals, thick ear drums, active middle ear muscles and narrow annular ligaments promote less loss. Physical details such as the azimuth of the source and the head-related transfer function are also important. Behavioral patterns are critical too—the near-sighted risk-taker may hammer much closer to the unprotected ear than the far-sighted hearing conservationist. And last, the probabilistic details of the impulse itself can be critical. For example, gunfire impulses with the same peak pressures and durations, from the same weapon, may nevertheless differ by a factor of 5 in their predicted effect, due to the details of turbulent flow.

The effect of middle ear resonant frequency, ear canal resonance, and ear canal volume on TEOAE

It is well known that there is a large inter-individual variability in the size of the TEOAE. Quantifying the sources of variability can help to determine the influences of some of the factors that can affect test results. The difference found in TEOAE may be due to the difference in size and shape of the ear rather than cochlear mechanics. The effect of ear canal volume between the probe and the tympanic membrane influences the intensity and spectrum of the stimulus as well as the characteristics of the response. A small ear canal volume should result in a higher stimulus sound-pressure level. This can determine both the effectiveness of the evoking stimulus as well as the response that is measured. We will report results of the study of the relation between ear canal volume, ear canal resonant frequency, and resonant frequency of the middle ear on TEOAE for 20 normal hearing young adults. The purpose is to determine if the characteristics associated with TEOAE are influenced by middle ear resonance and ear canal resonance and volume. By quantifying some of the variables that can effect TEOAE the test interpretation may be clarified.

Surgically confirmed clinical otosclerosis among the Chinese.

We report herein on 163 cases of surgically confirmed otosclerosis among Chinese. Our results suggest significant racial differences between Chinese and whites in respect to the incidence of this disease, and the likelihood of a family history. Surgical and histopathological findings, while confirming otosclerosis identical to that experienced in whites, suggest that generally the disease is milder among Chinese. The sex ratio, age range, and bilateral involvement, on the other hand, were discovered to be basically similar between the two races. A detailed description is given of the postauricular surgical technique used, and it is argued that it may be more suitable in cases where there is a small ear canal, since the results achieved (80% success rate) are comparable with other reports.

The Isotretinoin Teratogen Syndrome

Two infants with prominent frontal bossing, hydrocephalus, microphthalmia, and small, malformed, low-set, undifferentiated ears were born to mothers who had taken isotretinoin in the first trimester of pregnancy. A Dandy-Walker malformation, microcephaly, hypertelorism, small ear canals, cleft palate, small mouth, and congenital heart disease were also observed. Isotretinoin is a potent teratogen in man; maternal ingestion early in pregnancy leads to a distinct clinical pattern of anomalies. ( JAMA 1984;251:3267-3269)

The Isotretinoin Teratogen Syndrome

Two infants with prominent frontal bossing, hydrocephalus, microphthalmia, and small, malformed, low-set, undifferentiated ears were born to mothers who had taken isotretinoin in the first trimester of pregnancy. A Dandy-Walker malformation, microcephaly, hypertelorism, small ear canals, cleft palate, small mouth, and congenital heart disease were also observed. Isotretinoin is a potent teratogen in man; maternal ingestion early in pregnancy leads to a distinct clinical pattern of anomalies.

Removal of Ear Wax—A Technological Advance

The problem of washing impacted wax from the ear canal has been the most cumbersome and unpleasant task the pediatrician performs. Now using the Water Pik (manufactured by Aqua Tec Corp., Denver, Colorado) this task has been made easy and pleasant. The nozzle of this little machine directs a fine intermittent stream, the pressure of which can be varied and controlled, and can be directed easily into even the small ear canals. The addition of an off and on foot switch into the electrical circuit facilitates still more the ease of operation.