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PubMed1980

[Iontophoresis - local anesthesia at the ear canal and tympanic membrane (author's transl)].

Operations to the external ear canal and tympanic membrane necessitate sufficient local anesthesia. General sedation followed by infiltration anestesia, is rather time-consumming, can be painful due to the injection, and is not particularly satisfactory for the treatment of outpatients. The iontophorese-technique, however, of local anesthesia, is applicable particularly for the treatment of outpatients. Principally, the local anesthetic is transported in ionisised form to the nerve membrane, by means of calvanic currents through the healthy surface epithelial tissue of the external ear canal or the eardrum. The technique described for the first time in 1911 no longer shows toxic sides-effects since the introduction of improved electrodes and more modern local anesthetic. The anatomic, pharmacological, chemical and physical basics of the technique will be described. The lecture will be based on personal experience of the method, taken from large groups of patients over a period of more than two years, using equipment specially designed for this purpose.

Anesthesia, Local↗

PubMed1990

The normal microbial flora of the outer ear canal in healthy Norwegian individuals.

The microbial flora of the outer ear canal was determined for 77 healthy individuals (M = 44, F = 33). No growth of any microbe was found in 5% of males and 15% of females. Coagulase-negative staphylococci, dominated by Staphylococcus epidermidis, were the commonest microbe group found (83% of persons sampled). Staphylococcus aureus was found in 7% males and no females. Diptheroids were cultured from 32% of the samples. The only Gram-negative rod found was Hafnia alvei in 4% of individuals. No Vibrio spp. or anaerobic Gram-negative organisms were found. A variety of yeasts and moulds were seen, significantly (p = 0.02) more often in males. In a separate experiment, Malassezia furfur was found in 4/9 males and 0/10 females sampled. Various sampling techniques (dry swab, second dry swab, moist swab) that were compared showed broadly similar results. The normal flora of the outer ear canal is predominantly Gram-positive and the use of a dry swab seems to be a satisfactory method for sample-taking from this area.

Adolescent↗

PubMed1994

Measurement of acoustic impedance and reflectance in the human ear canal.

The pressure reflectance R (omega) is the transfer function which may be defined for a linear one-port network by the ratio of the reflected complex pressure divided by the incident complex pressure. The reflectance is a function that is closely related to the impedance of the 1-port. The energy reflectance R (omega) is defined as magnitude of [R]2. It represents the ratio of reflected to incident energy. In the human ear canal the energy reflectance is important because it is a measure of the inefficiency of the middle ear and cochlea, and because of the insight provided by its simple frequency domain interpretation. One may characterize the ear canal impedance by use of the pressure reflectance and its magnitude, sidestepping the difficult problems of (a) the unknown canal length from the measurement point to the eardrum, (b) the complicated geometry of the drum, and (c) the cross-sectional area changes in the canal as a function of distance. Reported here are acoustic impedance measurements, looking into the ear canal, measured on ten young adults with normal hearing (ages 18-24). The measurement point in the canal was approximately 0.85 cm from the entrance of the canal. From these measurements, the pressure reflectance in the canal is computed and impedance and reflectance measurements from 0.1 to 15.0 kHz are compared among ears. The average reflectance and the standard deviation of the reflectance for the ten subjects have been determined. The impedance and reflectance of two common ear simulators, the Brüel & Kjaer 4157 and the Industrial Research Products DB-100 (Zwislocki) coupler are also measured and compared to the average human measurements. All measurements are made using controls that assure a uniform accuracy in the acoustic calibration across subjects. This is done by the use of two standard acoustic resistors whose impedances are known. From the experimental results, it is concluded that there is significant subject variability in the magnitude of the reflectance for the ten ear canals. This variability is believed to be due to cochlear and middle ear impedance differences. An attempt was made at modeling the reflectance but, as discussed in the paper, several problems presently stand in the way of these models. Such models would be useful for acoustic virtual-reality systems and for active noise control earphones.

Acoustic Impedance Tests↗

PubMed1980

Carcinoma in situ of the ear canal.

A case of carcinoma in situ of the ear canal is presented. Review of the English literature failed to reveal a similar case. Wide local excision is the suggested mode of treatment.

Carcinoma in Situ↗

PubMedDate not supplied

Effects of ear canal pressure on threshold and growth of the acoustic reflex.

Acoustic reflex (AR) threshold and growth were measured in one ear for each of 20 normal-hearing individuals as pressure in the ear canal was varied between +/- 120 mm of H2O. These same parameters were studied in 10 of the subjects after disruption of the probe seal. Activating stimuli for AR threshold measures were 500, 1000, 2000, and 4000 Hz tones and broadband noise. The AR growth function was generated by a 500 Hz tone. As ear canal pressure was increased or decreased relative to the point of maximal compliance, systematic increases in AR threshold were observed for all activating stimuli. These mean pressure effects were relatively small (4 to 8 dB) and were essentially independent of stimulus composition. The ear canal pressure variations had no effect on the relative difference between tone and broadband noise AR thresholds. Absence of an airtight seal had a negligible effect on AR threshold. Growth of the AR was significantly altered by application of a relatively mild positive or negative canal pressure. Absence of a probe seal which had no effect on AR threshold was found to significantly reduce magnitude of the AR. These findings indicate that caution should be exercised during the measurement of AR growth to ensure both proper maintenance of desired canal pressure and canal-probe coupling.

Acoustic Impedance Tests↗

PubMedDate not supplied

Are ABH antigenic determinants on human outer ear canal epithelium responsible for Pseudomonas aeruginosa infections?

The outer ear canal expression of ABH human blood group antigens has been analyzed with a standardized routine histological procedure by monoclonal antibodies in the case of blood groups A and B, and a corresponding lectin in the case of blood group 0, respectively. In all 20 cases the blood groups were histochemically confirmed. Furthermore, Pseudomonas aeruginosa-specific inhibition experiments were performed with different sugar solutions as well as A-like substance incubating outer ear canal tissue sections with P. aeruginosa strain (No. 60) presenting lectin specificity for N-acetyl-galactosamine (GalNAc). P. aeruginosa lectins with GalNAc specificity apparently adhere to GalNAc as terminal blood group A determinant and indicate that patients presenting with blood group A may have a genetic predisposition to this form of otitis externa.

ABO Blood-Group System↗

PubMed1986

Effects of direction and rate of ear-canal pressure changes on tympanometric measures.

The effects of the direction (ascending and descending) and rate (12.5, 25.0, and 50.0 daPa/s) of ear-canal pressure changes on three tympanometric measures (peak static admittance, shape, and tympanometric peak pressure) were studied in 24 adults with normal middle-ear transmission systems. Susceptance, conductance, admittance, and phase angle data for the six conditions both at 226 and 678 Hz were obtained using a general purpose computer. Peak static admittance was significantly affected by both the rate and direction of pressure change as evidenced by a decrease in phase angle for ascending and for fast rates of ear-canal pressure change. Tympanometric shape was broader for descending pressure changes with less frequent notching both for descending and for slow rates of pressure change. Finally, the difference in peak pressure for the two directions of pressure change increased with the rate of ear-canal pressure change.

Acoustic Impedance Tests↗

PubMed1983

Threshold inaccuracies in an elderly clinical population: ear canal collapse as a possible cause.

In a sample of 80 persons in the 60-79-year age range, threshold shifts suggestive of collapsible ear canals were found in over one third of the subjects. A very conservative interpretation of the data suggests that at least 10-16% of these 60-79-year old elderly subjects have collapsible ear canals. Neither sex nor age was related significantly to prevalence. Results of this study indicate that in testing elderly persons there are threshold inaccuracies, relating possibly to collapsible ear canals, which, if not taken into account, may cause unacceptably large errors in both clinical and research applications.

Adult↗

PubMed1997

Benign osteonecrosis of the external ear canal.

Benign osteonecrosis (BON) of the external ear canal (EEC), also termed as focal or circumscribed necrotizing lesion, is an infrequent phenomenon with distinctive features and of an obscure origin. Five patients with BON of the EEC presented with aggressiveness and extension of varying degree including involvement of the middle ear. It seems that the disease might have a self limited course (two patients) though, at times, extensive measures including hyperbarric oxygen therapy (one patient) should be applied.

Adult↗

PubMed2004

Does static ear canal pressure influence pure tone pitch perception?

OBJECTIVE: That static ear canal air pressure (ECP) influences the frequency of spontaneous otoacoustic emissions (SOAEs) suggests that it may influence intracochlear, in addition to middle ear, processes. A previous study suggested that ECP influences pure tone pitch perception at 1,000 Hz, which was interpreted as indicating an effect on the cochlear place-frequency map. The present study extended investigations of this effect to 500 and 4,000 Hz. MATERIAL AND METHODS: Nine normal-hearing listeners performed interaural pitch matching with monaural ECPs of 0 and -300 daPa. RESULTS: Some indications of a small downward pitch shift (mean 0.2%) at 500 Hz were observed, which were marginally statistically significant at the 5% level. No pitch shifts were observed at 4,000 Hz. CONCLUSIONS: ECP does not influence pitch to the extent suggested previously or by SOAE frequency shifts. No evidence was found to support the notion that ECP influences the place-frequency map.

Acoustic Stimulation↗

PubMed1983

Electrophysiologic and behavioral studies of the cutaneous nerves of the concave surface of the pinna and the external ear canal of the dog.

The investigation used 2 methods to study the cutaneous innervation of the concave surface of the pinna of the dog: electrophysiologic and behavioral. The cutaneous innervation of the external ear canal was studied, using electrophysiologic methods. On one side of each dog, the area of remaining sensitivity for the 3 internal auricular branches of the facial nerve (InAuB-FN) was determined by sectioning the rostral auricular nerve, dorsal cutaneous branch of the second cervical nerve, and great auricular nerve and then examining the dogs 1 week later. The cutaneous area (CA) of each branch of the InAuB-FN was then determined electrophysiologically. These individual CA were combined to obtain a composite cutaneous area (Comp-CA) for the InAuB-FN. By comparing the Comp-CA with the area of remaining sensitivity, it was determined that they defined essentially the same regions. On the opposite side of each dog, the InAuB-FN were surgically transected and the resultant areas of anesthesia were determined approximately 1 week after the sectioning was done. The cutaneous region thus delineated represented a zone solely innervated by these branches of the FN. Next, the CA for the rostral auricular nerve, dorsal cutaneous branch of the second cervical nerve, and great auricular nerve to the pinna's concave surface were determined electrophysiologically in each dog. The cutaneous zone enclosed by the margins of the CA of these 3 nerves represented the composite autonomous zone for the InAuB-FN. The behaviorally determined area of anesthesia was essentially the same area as the composite autonomous zone. The skin lining the vertical portion of the external ear canal was supplied by all 3 branches of the InAuB-FN. The skin lining the horizontal portion of the external ear canal was supplied by the lateral branch of the InAuB-FN and the external acoustic meatus branch of the auriculotemporal nerve.

Animals↗

PubMed1994

Spatial distribution of sound pressure and energy flow in the ear canals of cats.

Spatial pressure distributions have been measured in the ear canals of ten cats and analyzed to obtain the energy reflection properties of the middle ear over a 10- to 25-kHz range of frequencies. Considerable intersubject variability is observed, much of which can be correlated with the condition of the tympanic membrane. For ears judged to be in good condition, reflection coefficients typically take values of about 0.2 between 15 and 25 kHz, indicating good matching of the dynamical properties of the auditory system to the ear canal sound field. At lower frequencies, the reflection coefficients tend to be somewhat higher and at higher frequencies the reflection coefficients increase quite rapidly with frequency. For ears judged to be in poorer condition, energy reflection coefficients of 0.5 and 0.9 were determined for the 15- to 25-kHz range. The variations of sound pressure along the canal (about 10 dB, even in well-coupled systems) confirm that single point pressure measurements may be inappropriate for defining the acoustical input at higher frequencies and new measures for specifying the input should be investigated. The net flow of acoustic energy into the auditory system, the sound power, is one possibility. Some initial measurements of sound power, obtained from analysis of the spatial pressure distributions, are presented.

Acoustic Stimulation↗

PubMedDate not supplied

[Hernia of the external ear canal of uncommon origin].

The temporo-mandibular joint is directly related to the anterior wall of the external ear canal. Therefore, defects in this wall may lead to herniation of the soft tissues of the temporo-mandibular joint into the external ear canal. Such herniation usually is secondary to external injuries, iatrogenic trauma, neoplasms, and so on, but it may also be congenital. We report a well-documented case of temporo-mandibular joint herniation into the external ear canal of probable congenital origin.

Ear Diseases↗

PubMed1975

Extramammary Paget's disease of the external ear canal in association with ceruminous gland carcinoma. A case report.

A case of extramammary Paget's disease of the external ear canal in association with ceruminous gland carcinoma is presented. Extramammary Paget's disease is not uncommonly seen in regions where apocrine glands are prevalent, with or without underlying apocrine gland carcinoma. This is the first case, to our knowledge, of this association in the external ear canal.

Adenocarcinoma↗

PubMed2005

Metastasis of colonic adenocarcinoma to the external ear canal: an unusual case with a complex-pattern of disease progression.

We report on a patient who developed far-ranging metastases of adenocarcinoma of the colon that followed a gradual cephalad progression, including the right external ear canal, and led to hearing loss. The patient was a 63-year-old white male with stage III adenocarcinoma of the colon. After 2 years with metastases elsewhere, he developed hearing loss on the right side. Physical examination of the head and neck showed a mass in the external ear canal, and biopsy confirmed adenocarcinoma. After removal, the patient's hearing improved. This case is interesting not only because of the unusual metastasis to the external ear canal, but also because of the patient's previous history of metastasis over the course of more than 2 years. The significance of such wide-ranging metastases is that metastasis of adenocarcinoma to the ear did not signal imminent death, and relief of the hearing loss it caused was possible.

Adenocarcinoma↗

PubMed2006

Chondroid syringoma of the external ear canal presenting as a cyst.

Chondroid syringoma of the external ear canal is a rare, usually firm or polypoid tumor, representing the cutaneous counterpart of pleomorphic adenoma of salivary glands. We report a very rare case of chondroid syringoma in a 40-year-old man who presented with a fluid-containing cyst in the external ear canal. Clinical and radiological examinations showed involvement of the whole external canal to the annulus. The cystic lesion was totally excised along with the overlying skin. The postoperative course was uneventful.

Adenoma, Pleomorphic↗

PubMed1993

External ear canal schwannoma: an unusual case report.

To the best of our knowledge, this is the first report of external ear canal schwannoma in the English literature. Several detailed clinical and pathological features were demonstrated. We suggest that if a tender, encapsulated mass is found in the external ear canal, the diagnosis of schwannoma should be taken into consideration.

Ear Canal↗

PubMed1989

Open-cavity mastoid surgery: its effect on the acoustics of the external ear canal.

Temporal bone studies have demonstrated that a modified radical mastoidectomy changes the resonant characteristics of the external auditory canal, but the effect has not been reported in patients. In 12 patients, performing open-cavity mastoid surgery for cholesteatoma changed the mean peak resonant frequency of the external ear canal from 2.5 to 2.2 kHz (p less than 0.02). This is in comparison with creating a modified radical mastoid cavity in 6 temporal bones which changed the mean peak resonant frequency of the external ear canal from 3.9 to 1.9 kHz. It is concluded that open-cavity mastoid surgery in patients changes the acoustics of the external ear canal less than in temporal bone studies.

Acoustics↗