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PubMed1982

Effect of diving and diving hoods on the bacterial flora of the external ear canal and skin.

The bacterial flora of the external ear canals and posterior auricular skin surfaces were investigated in a group of 26 divers after 25 dry-suit dives in harbor water and 20 dry-suit dives in clear test tank test. A control group of 16 divers wore rubber hoods 19 times for a similar period (25 to 30 min) but did not dive. The protective effect of 2% acetic acid was tested by instilling it in the left ear of 14 divers and 8 nondivers. Staphylococcus epidermidis, Propionibacterium acnes, alpha-hemolytic streptococci, and enteric gram-negative rods were the predominant isolates from skin and ear samples. After the divers dove or after they wore hoods without going in the water, there was a substantial increase in the number of these organisms on the skin (46.9%) or in the external ears (43.8%) of the divers. However, an increase in the bacterial counts in the external ear canals occurred in only 13.6% of the individuals treated prophylactically with acetic acid drops. Although no gram-negative rods were recovered from the skin or external ear canals of divers in clear tank water, 23 strains were isolated after the dives in harbor water. Identical gram-negative isolates also were recovered from the harbor water. Gram-negative organisms also were recovered from three newly acquired skin lacerations, where they persisted for at least 24 h. Our data show the acquisition of gram-negative rods when dives were made in polluted water. The data also demonstrate the increase in bacterial counts that occurs when rubber diving rods are worn (in or out of water) and that this increase can be controlled by pretreatment of ears with acetic acid.

Acetates↗
PubMed1999

The use of two pedicled skin flaps in the surgical treatment of acquired atresia of the outer ear canal.

Surgical treatment of acquired atresia of the outer ear canal remains in some cases troublesome. Based on previous experience, we have refined the existing surgical technique to obtain better results. In four patients we used two pedicled skin flaps for the treatment of total mature post-inflammatory atresia of the outer ear canal. We raised two well-vascularized pedicled skin flaps with the distal 1.5-2 cm thinned to the level of a full-thickness skin graft. All patients showed complete primary healing with stable coverage and near to complete air-bone gap closure.

Ear Canal↗
PubMed2001

Two-step external ear canal construction in atresia as part of auricular reconstruction.

OBJECTIVES: One of the common complications of atresia surgery is restenosis of the surgically constructed external ear canal. To avoid this complication, a new two-step technique of creating an external ear canal was developed and evaluated. STUDY DESIGN: Prospective clinical evaluation. PATIENTS AND METHODS: Thirty-six patients with third-degree microtia and aural atresia have been treated this way. In the first step, the canal is drilled into the petrous bone, a Silastic cylinder is inserted and wrapped into pieces of cartilage and bone dust. In the second step several months later, the implant is removed and a slightly smaller tube covered with a split thickness skin graft is inserted. RESULTS: Except the first three patients operated with a slightly different technique, none of the following 33 patients showed a severe restenosis. Instead, all had a nice, smooth external ear canal. CONCLUSION: With this two-step technique of creating a new external ear canal in atresia, we could avoid one of the major complications of this kind of surgery. The external ear canal is either necessary for the reconstructed middle ear or it can be used to adapt a (behind or in the ear) hearing aid. By integrating this technique into a three-step concept for auricular reconstruction, the patient does not need any additional operation, and his or her rehabilitation from ear malformation can be enhanced.

Adult↗
PubMed2000

Acoustic mechanisms that determine the ear-canal sound pressures generated by earphones.

In clinical measurements of hearing sensitivity, a given earphone is assumed to produce essentially the same sound-pressure level in all ears. However, recent measurements [Voss et al., Ear and Hearing (in press)] show that with some middle-ear pathologies, ear-canal sound pressures can deviate by as much as 35 dB from the normal-ear value; the deviations depend on the earphone, the middle-ear pathology, and frequency. These pressure variations cause errors in the results of hearing tests. Models developed here identify acoustic mechanisms that cause pressure variations in certain pathological conditions. The models combine measurement-based Thévenin equivalents for insert and supra-aural earphones with lumped-element models for both the normal ear and ears with pathologies that alter the ear's impedance (mastoid bowl, tympanostomy tube, tympanic-membrane perforation, and a "high-impedance" ear). Comparison of the earphones' Thévenin impedances to the ear's input impedance with these middle-ear conditions shows that neither class of earphone acts as an ideal pressure source; with some middle-ear pathologies, the ear's input impedance deviates substantially from normal and thereby causes abnormal ear-canal pressure levels. In general, for the three conditions that make the ear's impedance magnitude lower than normal, the model predicts a reduced ear-canal pressure (as much as 35 dB), with a greater pressure reduction with an insert earphone than with a supra-aural earphone. In contrast, the model predicts that ear-canal pressure levels increase only a few dB when the ear has an increased impedance magnitude; the compliance of the air-space between the tympanic membrane and the earphone determines an upper limit on the effect of the middle-ear's impedance increase. Acoustic leaks at the earphone-to-ear connection can also cause uncontrolled pressure variations during hearing tests. From measurements at the supra-aural earphone-to-ear connection, we conclude that it is unusual for the connection between the earphone cushion and the pinna to seal effectively for frequencies below 250 Hz. The models developed here explain the measured pressure variations with several pathologic ears. Understanding these mechanisms should inform the design of more accurate audiometric systems which might include a microphone that monitors the ear-canal pressure and corrects deviations from normal.

Audiometry↗
PubMed2006

Comparison of 4 fixation and staining methods for the cytologic evaluation of ear canals with clinical evidence of ceruminous otitis externa.

BACKGROUND: Swab cytology of ear canals is one of the most useful and rapid methods to assess the presence of external ear infections. Smears are generally stained with rapid Romanowsky-type stains, with or without prior heat fixation. OBJECTIVES: The aim of this study was to compare 4 different methods of fixation and staining of ear swab cytology samples from dogs. METHODS: Eight dogs with otitis externa were selected from a dermatology referral population. A cotton swab was used to obtain ceruminous material from 12 ear canals. Four smears of each swab were prepared on glass slides (randomly identified as A, B, C, or D) and air-dried for cytologic examination. Samples marked A were stained with Dip Quick (Jorgensen Laboratories Inc, Loveland, CO, USA) after heat fixation; samples marked B were stained without heat fixation; samples marked C were heat-fixed and dipped only in the counterstain (the blue reagent) of Dip Quick; and samples marked D were dipped only in the counterstain, without heat fixation. Ten high-power fields (hpf; X100 oil immersion objective) in each slide were evaluated by 2 observers, and total numbers of keratinocytes, yeast, bacteria, and neutrophils were counted. Statistical comparison was performed using an ANOVA model applied after verifying the normal distribution of the data, and using nonparametric sign tests and Wilcoxon signed rank tests. RESULTS: No statistically significant differences were observed in the numbers of keratinocytes, yeast, bacteria, or neutrophils among the 4 staining methods (P > .05), although significant interobserver differences were found. CONCLUSION: We conclude that heat fixation does not improve the quality of ceruminous ear swab samples for cytologic evaluation, and propose a 1-step dip in the blue reagent alone as a rapid method of staining samples from canine ear canals.

Animals↗
PubMedDate not supplied

Ear canal collapse: a case presentation.

The effects of collapse of the external ear canals due to pressure from earphones have been documented and discussed by several authors during the past 2 decades. This report presents a case of ear canal collapse in a child and demonstrates the value of impedance audiometry in cases of collapse of the external ear canal.

Acoustic Impedance Tests↗
PubMed1977

Effect of systemic antibiotics on the microbial flora of the external ear canal in hospitalized children.

The effect of antibiotic therapy and hospitalization on the external ear canal flora was investigated in 131 children. Fifty-eight percent of the patients receiving antibiotic therapy had Gram-negative bacilli or yeasts in their external ear canal, compared with 17% of the patients who were hospitalized for ten days or longer and only 3% of the patients who were hospitalized for short periods. Antibiotic therapy is the major factor in determining the colonization rate of the external ear canal with potentially pathogenic flora. Children under 1 year of age seem to be the most susceptible group to this shift of flora.

Anti-Bacterial Agents↗
PubMed1985

Optical method for measurement of ear canal length.

A noninvasive optical method using an operating microscope was developed to measure the length of an ear canal under both open and occluded conditions. The method is based on the optical measurement of the distance between a reference point at the eardrum and a second point on the lateral aspect of an earmold-occluded ear canal. To estimate the occluded canal length, the length of the earmold is then subtracted from results of the previous measurement. The method was also used to determine the open ear canal length (the lateral reference point was the ear canal entrance), and averaged results agreed closely with previously reported data.

Adult↗
PubMed2001

Isolating the auditory system from acoustic noise during functional magnetic resonance imaging: examination of noise conduction through the ear canal, head, and body.

Approaches were examined for reducing acoustic noise levels heard by subjects during functional magnetic resonance imaging (fMRI), a technique for localizing brain activation in humans. Specifically, it was examined whether a device for isolating the head and ear canal from sound (a "helmet") could add to the isolation provided by conventional hearing protection devices (i.e., earmuffs and earplugs). Both subjective attenuation (the difference in hearing threshold with versus without isolation devices in place) and objective attenuation (difference in ear-canal sound pressure) were measured. In the frequency range of the most intense fMRI noise (1-1.4 kHz), a helmet, earmuffs, and earplugs used together attenuated perceived sound by 55-63 dB, whereas the attenuation provided by the conventional devices alone was substantially less: 30-37 dB for earmuffs, 25-28 dB for earplugs, and 39-41 dB for earmuffs and earplugs used together. The data enabled the clarification of the relative importance of ear canal, head, and body conduction routes to the cochlea under different conditions: At low frequencies (< or =500 Hz), the ear canal was the dominant route of sound conduction to the cochlea for all of the device combinations considered. At higher frequencies (>500 Hz), the ear canal was the dominant route when either earmuffs or earplugs were worn. However, the dominant route of sound conduction was through the head when both earmuffs and earplugs were worn, through both ear canal and body when a helmet and earmuffs were worn, and through the body when a helmet, earmuffs, and earplugs were worn. It is estimated that a helmet, earmuffs, and earplugs together will reduce the most intense fMRI noise levels experienced by a subject to 60-65 dB SPL. Even greater reductions in noise should be achievable by isolating the body from the surrounding noise field.

Adult↗
PubMed1988

A computer simulation of hearing aid response and the effects of ear canal size.

The response of a hearing aid is affected by many factors which include the head and outer ear, the microphone, amplifier, and receiver used in the hearing aid, the properties of the ear canal and the eardrum, and acoustic feedback through the vent. This article presents a computer simulation of an in-the-ear (ITE) hearing aid that includes all of the above factors. The simulation predicts the pressure at the eardrum for a frontal free-field sound source. The computer model was then used to determine the effects on the hearing aid response due to variations in the size of the ear canal. The simulation indicates that, for an unvented hearing aid, changes in the size of the ear canal shift the overall sound-pressure level at the eardrum but have only small effects on the shape of the frequency response. The situation is more complicated when a vent is present, however, since changes in the size of the ear canal that cause apparently small perturbations in the acoustic feedback signal may, nonetheless, have large effects on the overall system response.

Computer Simulation↗
PubMed1979

[Petromastoid clearance using plastic surgery in the surveillance of large cavities. Re-suture of the ear canal (author's transl)].

The lesions met with in chronic otitis media and especially in cholesteatoma, can be extremely widespread and, after petromastoid clearance there is a large resulting cavity which is impossible to survey by the usual route of the ear canal. A plastic surgical technique on the ear canal, is described which allows an easy surveillance without esthetic damage. It consists of a resection of a part of the cartilage of the ear canal with conservation of the skin of the inner and outer ear canal. This skin is used to re-suture the piece of cartilage which has been sectioned.

Cholesteatoma↗
PubMed1983

Bacterial colonization of the nose and external ear canal in newborn infants.

The bacterial flora of the nose and external ear canal of 132 newborn infants, aged 3 days and 4 to 7 days, was examined. Cultures taken from the nose showed the following pattern of bacterial colonization: normal flora (39%); potentially pathologic gram-positive microorganisms (23%); gram-negative enteric rods (16%); and sterile cultures (22%). The most frequent bacterial cultures from nostrils were Staphylococcus epidermidis (39%); Staph. aureus (11%) and Escherichia coli (8%). The cultures from the external ear canal showed normal flora (37%); potentially pathologic gram-positive microorganisms (5%); gram-negative enteric rods (24%); and sterile cultures (34%). The most frequent bacteria cultured from the ear canal were: Staph. epidermidis (37%); E. coli (8%); and Klebsiella pneumoniae (7.5%). Of several factors studied, the type of delivery, Apgar score and the duration of hospitalization were found to have a significant influence on the pattern of bacterial colonization.

Apgar Score↗
PubMed2003

Irritated seborrheic keratosis of the external ear canal.

Although a seborrheic keratosis is not rare on the skin of the trunk, extremities, head and neck of an elderly person, it is uncommon to originate in the external ear canal. Even rarer, an irritated subtype may arise in this location. We report the case of a 63-year-old man with an irritated seborrheic keratosis arising in the right external ear canal, who first presented with a bloody discharge from his right ear canal 3 years and 10 months before the subsequent operation. Macroscopically, a dome-like, black elevation was found at the anterior wall of the right external ear canal. A biopsy showed an exophytic papillomatous, hyperkeratotic growth of basaloid cells which revealed some nuclear atypism and mitosis. Squamous eddies and moderate inflammatory infiltrate were noted. Some cellular atypism made us suspect an irritated seborrheic keratosis. Because the patient hated the extirpation, he remained untreated for 3 years and 3 months following his first presentation. The biopsy and a surgical resection of his second presentation confirmed the diagnosis of irritated seborrheic keratosis. Immunohistochemical analysis of Ki-67, p53 and papillomavirus was performed to elucidate its character. We emphasize that irritated seborrheic keratosis does occur in the external ear canal and may cause some diagnostic difficulty. Pathologists should be aware of this fact and avoid overdiagnosis.

Ear Canal↗
PubMed2000

Tests of some common assumptions of ear-canal acoustics in cats.

The accuracy of ear-canal admittance and reflectance as measures of the ear's properties depends on the acoustic effects of the canal. Here, measurements of acoustic admittance at different canal locations in domestic cats are used to test three common assumptions. (1) Can a uniform-tube model of the canal represent spatial variations in admittance? Data from cats support this assumption for frequencies below 3 kHz, where the admittance inferred at the tympanic membrane (TM) based on a uniform-tube model differs by less than 3 dB in magnitude and 0.07 periods in angle from the admittance measured at the TM; for higher frequencies greater differences occur. (2) Do large static air pressures in the canal make the middle ear rigid without affecting the properties of the canal space? The measurements reported indicate that large negative static pressures reduce the low-frequency compliance of the cat middle ear to about 10% of the compliance of the canal air volume. Static displacements of the acoustic probe, TM, and canal walls with static pressure may affect estimates of the canal volume and middle-ear compliance by as much as 15% to 20%. (3) Is the acoustic-reflectance magnitude constant with position along the canal? Reflectance data from cat ear canals generally support this idea, except within a frequency region near 0.5 kHz for which there is evidence of energy loss. These results demonstrate that noninvasive measurements in the canal describe middle-ear acoustic properties to within tolerances that depend on the effects of the canal.

Acoustics↗
PubMed1986

Soft-wall reconstruction of the posterior external ear canal wall.

A simple method of reconstructing a previously removed posterior ear canal with an autogenous, bilaminar membrane is described. The resulting air-filled mastoid cavity is an anatomic extension of the middle ear cleft and is separated from the ear canal by a functional barrier that is continuous with the tympanic membrane. The acoustic characteristics of an associated tympanoplasty are not significantly altered, and many of the problems that are associated with an exteriorized cavity are avoided. In contradistinction to other methods of mastoid obliteration or reconstruction, the semitransparent nature of the soft canal wall allows inspection of the underlying cavity for residual or recurrent disease. The technique can be used to repair either a newly created cavity or a previous radical (or modified radical) mastoidectomy defect. The functional results of thirty ears reconstructed in this fashion are detailed. A variable amount of soft-wall retraction was noted postoperatively in 47% of the ears; however, the long-term functional results in these cases remain satisfactory.

Connective Tissue↗
PubMed1999

Wound contamination and antimicrobial susceptibility of bacteria cultured during total ear canal ablation and lateral bulla osteotomy in dogs.

OBJECTIVE: To detect contamination of wound sites from surgical handling of excised tissues during total ear canal ablation and lateral bulla osteotomy in dogs, and to compare susceptibility of bacterial isolates to cefazolin with susceptibility to other antimicrobial agents. DESIGN: Prospective clinical study. ANIMALS: 13 dogs. PROCEDURE: Dogs were treated surgically for otitis externa and media via total ear canal ablation and lateral bulla osteotomy. Specimens for aerobic bacterial culture were obtained from SC tissue immediately following skin incision, tissues excised from the osseous bulla (after transection of the horizontal ear canal and lateral bulla osteotomy), and from SC tissue prior to skin closure. Antimicrobial susceptibility of bacterial isolates to various antibiotics was determined by use of a broth dilution assay. RESULTS: There was a significant association between isolation of Streptococcus canis and Escherichia coli from specimens from the osseous bulla and specimens from the SC tissues prior to skin closure, indicating contamination of the SC tissues during surgery. Seventy percent of bacterial isolates were susceptible to cefazolin. CLINICAL IMPLICATIONS: Measures to limit bacterial contamination resulting from tissue handling during total ear canal ablation and lateral bulla osteotomy are necessary. Bacteriologic culture of tissue of the osseous bulla and determination of antimicrobial susceptibility are recommended. Administration of cefazolin alone may not be efficacious for antimicrobial prophylaxis.

Animals↗
PubMed1984

Changes in the bacterial flora of the external ear canal from the wearing of occlusive equipment.

External otitis has been associated with wearing obstructive gear covering the earlobe and external ear canal. In this study we investigated the changes in the bacterial flora of the external ear canal after wearing rubber hoods. The bacterial flora of external ear canals surfaces was investigated in a group of 19 volunteers who wore rubber hoods for a period of 25 to 30 minutes while doing manual work. The protective effect of 2% acetic acid was tested by instilling it in the left ear of all participants. Staphylococcus epidermidis, Propionibacterium acnes, and alpha-hemolytic streptococci were the predominant isolates from the ear samples. After hoods were worn, there was a substantial increase in the number of these organisms in 7 (36.8%) of the external ears. However, an increase in the bacterial counts in the external ear canals occurred in only 2 (10.5%) of the individuals treated prophylactically with acetic acid drops (P less than 0.02).

Acetates↗
PubMed1996

Sound transmission to and within the human ear canal.

Sound transmission to the eardrum from various points in the external ear was measured by means of probe microphone technique. Twelve human subjects participated, and three directions of sound incidence were included. For the major part of the audio frequency range the transmission to the eardrum proved independent of direction from points at the centerline of the ear canal, including the entrance (open or blocked). The results further suggested that the region with independent transmission extends some millimeters outside the entrance plane. The transmission from the free field to the eardrum was divided into a directional-dependent part and two directional-independent parts: (1) the transmission from the free field to the blocked entrance, (2) a pressure division between the radiation impedance and the ear-canal input impedance, and (3) the transmission along the ear canal. All parts of the transmission were seen to be highly individual. The first part was shown to be uncorrelated with any of the other parts, whereas mutual dependence of parts (2) and (3) resulted in a smaller variation in the combined transmission than for the parts in separate. The standard deviation between subjects for head-related transfer functions (HRTFs) measured at the eardrum, the open entrance, and the blocked entrance was studied, and the lowest values were found for the blocked-entrance HRTFs. It is concluded, that the blocked entrance is the most suitable point for measurements of HRTFs and for binaural recordings, since sound at this point includes the complete spatial information, and in addition to that the minimum amount of individual information.

Adult↗