Pathologic conditions of the external ear and auditory canal

Anatomy and Development of the Mammalian External Auditory Canal: Implications for Understanding Canal Disease and Deformity

The mammalian ear is made up of three parts (the outer, middle, and inner ear), which work together to transmit sound waves into neuronal signals perceived by our auditory cortex as sound. This review focuses on the often-neglected outer ear, specifically the external auditory meatus (EAM), or ear canal. Within our complex hearing pathway, the ear canal is responsible for funneling sound waves toward the tympanic membrane (ear drum) and into the middle ear, and as such is a physical link between the tympanic membrane and the outside world. Unique anatomical adaptations, such as its migrating epithelium and cerumen glands, equip the ear canal for its function as both a conduit and a cul-de-sac. Defects in development, or later blockages in the canal, lead to congenital or acquired conductive hearing loss. Recent studies have built on decades-old knowledge of ear canal development and suggest a novel multi-stage, complex and integrated system of development, helping to explain the mechanisms underlying congenital canal atresia and stenosis. Here we review our current understanding of ear canal development; how this biological lumen is made; what determines its location; and how its structure is maintained throughout life. Together this knowledge allows clinical questions to be approached from a developmental biology perspective.

Bacterial Otitis Externa in Patients Attending an ENT Clinic in Babol, North of Iran

Background

Acute otitis externa, an inflammatory condition of the external auditory canal, is a common clinical problem in general medicine.

Objectives

This study aimed to determine the etiology of otitis externa in patients from the Mazandaran province, north of Iran, which has a humid climate, as humidity can affect the prevalence of pathogenic microorganisms.

Patients and Methods

This cross-sectional study involved 116 patients with otitis externa. Two sets of samples were collected from their ears; one set was used for slide preparations, and the other for microbial culturing. After culturing, the microorganisms were identified by conventional methods.

Results

Patients between 35 and 44 years of age were most frequently affected (25.00%) by otitis externa (average age, 43.87 ± 18.08 years). Moreover, women (54.31%) were more frequently affected than men (45.69%). Upon direct investigation, Gram-positive bacilli were the most commonly identified microorganisms (22.41%). Furthermore, Bacillus spp. and coagulase-negative staphylococci (22.41% and 19.83%, respectively), were the organisms most frequently identified from cultures of otitis externa samples.

Conclusions

Direct examination and culture showed that a mixed infection of fungi and bacteria is the most common cause of otitis externa. The present study revealed that Bacilli spp. were the most abundant bacteria isolated from patients with otitis externa. Thus, it is recommended that both organisms should be considered as etiologic agents in protocols for treatment of otitis externa.

Fibroepithelial polyp of the external auditory canal: a case report and a literature review

This paper reports the first case of fibroepithelial polyp arising independently of the external auditory canal. A 16-year-old female patient presented to our clinic for aural fullness of the left side. Physical examination revealed a papillomatous tumor at the posterior wall of the inlet of the left external auditory canal. After biopsy, which yielded a diagnosis of benign papilloma, the patient underwent tumor excision. Final diagnosis was fibroepithelial polyp. One week after resection, aural fullness had resolved. Fibroepithelial polyp is a benign lesion and occurs mainly in the skin, ureteropelvic system, and genitals. In the head and neck area, there are reports on fibroepithelial polyp of the tongue, piriform fossa, inferior nasal turbinate, and tonsil, in addition to the skin, but none on independent fibroepithelial polyp of the external auditory canal. Excision of fibroepithelial polyp of the external auditory canal is advisable, especially in the presence of any symptoms, and should be preceded by confirmation of nonmalignancy by biopsy, if possible.

Declining susceptibility to neomycin and polymyxin B of pathogens recovered in otitis externa clinical trials

BACKGROUND

Otitis externa is usually treated empirically with topical neomycin/polymyxin B/hydrocortisone. The predominant pathogens associated with this infection are Pseudomonas aeruginosa and Staphylococcus aureus.

METHODS

Two multicenter clinical trials (one in adults and adolescents, and one in children), conducted between 1995 and 1996, compared neomycin/polymyxin B/hydrocortisone with ofloxacin for the treatment of otitis externa; two similar trials were conducted between 1999 and 2000. Assessments included the minimum inhibitory concentrations (MICs) of each antimicrobial drug for the major pathogens, bacterial eradication, and clinical efficacy.

RESULTS

The MICs of all bacterial isolates (including P. aeruginosa) for neomycin and polymyxin B increased markedly in the 1999 to 2000 studies compared with the 1995 to 1996 studies. In the later studies, mean MICs for all major pathogens tested had increased above the breakpoint for polymyxin B (> or = 4 microg/ml). In contrast, MICs of all isolates for ofloxacin remained similar between the two study periods and were within the susceptible range for this drug.

CONCLUSIONS

Although the bacterial eradication rates for both treatments in each study were equivalent, the clinical cure rate for neomycin/polymyxin B/hydrocortisone was lower (87%) than for ofloxacin (93%). Therefore, the organisms most often causing otitis externa appear to be developing resistance to neomycin and polymyxin B but not to ofloxacin.

The relation of patient satisfaction with treatment of otitis externa to clinical outcomes: development of an instrument

This survey was undertaken to develop a short, comprehensive measure of patient satisfaction with pharmacologic treatment for otitis externa and to assess the relationships between satisfaction, disease symptoms, and medication side effects. Otitis externa was diagnosed in 41 patients recruited from 6 sites; 34 patients completed and returned the study instruments and were included in the study. Patients or their caregivers administered polymyxin/neomycin/hydrocortisone ear drops prescribed by a physician and completed a daily diary for 10 days and a satisfaction questionnaire at the end of the treatment period. The main outcome measures were the subscale scores for patient satisfaction and their relation to medication side effects, symptoms of ear infection, activity limitations, pain, and adherence to prescription regimens. The questionnaire and its subscales demonstrated good psychometric properties (ie, reliability coefficients >0.75, except for 1 subscale). Overall satisfaction was found to be significantly correlated with relief of symptoms, ability to return to normal activities, ease of administration, and medication side effects. Satisfaction subscale scores were correlated with patient-reported severity of medication side effects and disease symptoms. More than half the patients took drops for more than the prescribed number of days, and one third took more than the prescribed number of drops per administration (ie, overadherence). The relation between satisfaction and adherence was weak, perhaps due to the high rates of overadherence. Our results demonstrate that patient satisfaction with otic medication can be assessed across various aspects of satisfaction and that it is correlated with reported disease symptoms and medication side effects. This type of multifaceted assessment may help physicians select between medications with different side-effect profiles and administration schedules. Larger studies are needed to evaluate the relationship between satisfaction with an otic medication and adherence to a medication regimen.