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LESSON 66

Outer ear disorders

Year 1
Spring semester
Otorhinolaryngology
Outer and middle ear disorders
Duration: 10:15

In this lesson, we look at common disorders of the ear canal: impacted wax and its effect on hearing, otitis externa (swimmer's ear) and otomycosis, and exostosis (surfer's ear) and osteoma. For each one, we discuss what the audiologist should watch for, which tests to postpone and when to refer to a physician.

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Hello, and welcome to the AIHEAR Audiology Academy.
In this lesson, we learn the common disorders of the ear canal and how they affect hearing.
We will look at impacted wax, otitis externa, otomycosis, exostosis and osteoma from the audiologist's point of view.
The ear canal runs from the auricle to the tympanic membrane and is about two and a half centimeters long in adults.
The outer third is cartilage; cerumen glands and hairs are found only in this part.
The inner two thirds are bone, covered by thin, sensitive skin.
The canal skin slowly migrates outward from the center of the eardrum and carries wax out; this is how the ear cleans itself.
The curved shape of the canal and its narrow bony part make it easy for wax and foreign bodies to get stuck here.
Most of the disorders in this lesson arise when this system breaks down or when the canal becomes narrower.
In this lesson, we group the disorders of the ear canal under four headings.
The first is impacted wax, or cerumen impaction, in which earwax builds up and blocks the canal.
The second is otitis externa, an inflammation of the ear canal.
The third is otomycosis, a fungal infection of the ear canal.
The fourth is exostosis and osteoma, which are benign bony growths in the bony canal.
Cerumen, or earwax, is a natural secretion that keeps the canal skin moist and protects it from germs and insects.
Normally, skin migration and jaw movement carry it out of the canal on their own.
The American Academy of Otolaryngology guideline defines impaction as wax buildup that causes symptoms or prevents an ear exam.
It is more common in hearing aid and earbud users, older adults, young children and people with cognitive problems.
A narrow or curved canal and extra hair in the canal also make it harder for wax to come out.
Cotton swabs often push wax deeper instead of removing it and pack it into the bony part.
The same guideline also advises against ear candling; it has no proven effect and carries risks such as burns.
When wax partly blocks the canal, hearing is often not clearly affected.
In this example, however, the right ear canal is fully blocked; air conduction thresholds are between thirty five and fifty decibels HL.
Bone conduction thresholds are normal, so the loss is conductive.
In a five-person study by Roeser and colleagues, partial occlusion raised high-frequency thresholds by about ten to seventeen decibels.
With complete occlusion, low frequencies were also affected, and the average loss reached about thirty to forty five decibels.
This is why people often notice the loss suddenly, when wax swells after a shower or a swim and closes the canal completely.
Impacted wax is often first noticed during otoscopy before testing.
The finding is recorded; if the canal is fully blocked, tympanometry, otoacoustic emissions and ear impressions are not done.
For removal, the person is referred to a physician or authorized clinician; guidelines describe drops, irrigation and manual removal.
After removal, the canal and eardrum are examined again for a perforation or irritation of the canal.
The hearing test is done in a clean ear, so a temporary loss caused by wax is not confused with a true loss.
The earmold or dome of a hearing aid closes the canal, so it keeps wax from moving out.
Wax can block the receiver and sound outlet, making the hearing aid quieter or silencing it completely.
Wax in the canal can also reflect sound and increase acoustic feedback, the whistling of the hearing aid.
This is why the guideline recommends otoscopy at every visit for people who use hearing aids.
Instead of using cotton swabs, users are taught to change the wax filter regularly and to clean the sound outlet.
Otitis externa is an inflammation of the ear canal skin; it is common in swimmers, so it is also called swimmer's ear.
The most typical sign is pain that gets worse when the tragus is pressed or the auricle is pulled.
Itching, discharge, and redness and swelling of the canal skin are also common.
If swelling and debris narrow the canal, a feeling of fullness and a conductive hearing loss are added.
The most common causes are the bacteria Pseudomonas aeruginosa and Staphylococcus aureus.
Moisture, cleaning that irritates the canal, skin conditions and devices that close the canal increase the risk.
No insert earphone, probe or impression material is placed in an inflamed, painful ear.
Ear impressions and routine tests are usually postponed until healing; if needed, air conduction can be tested with supra-aural earphones.
Treatment belongs to the physician; whether to use the hearing aid during treatment is also planned with the physician.
In an older, diabetic or immunocompromised person, persistent severe pain can be a warning sign of necrotizing otitis externa.
This serious infection can spread to the skull base and cause facial palsy; such a case is referred to a physician without delay.
Otomycosis, sometimes simply called ear fungus, is a fungal infection of the ear canal.
Compared with bacterial otitis externa, itching and fullness are more prominent, and pain is usually milder.
Aspergillus species can form black or gray specks, while Candida can form a white or cream-colored, cotton-like mass.
Long-term use of antibiotic drops, a humid climate and frequently wetting the ear increase the risk.
Diagnosis, cleaning and treatment belong to the physician; if a fungal mass blocks the canal, a conductive loss may appear.
An exostosis is a benign bony growth in the bony part of the ear canal, located close to the eardrum.
Exostoses are usually multiple and broad-based, and they often appear in both ears.
They are linked to repeated cold water exposure and are common in surfers, swimmers and divers, so they are also called surfer's ear.
An osteoma, by contrast, is usually a single, one-sided bony mass on a narrow stalk.
An osteoma usually sits farther out, near the junction of the bony and cartilaginous parts.
Both are benign and often cause no symptoms unless the canal becomes severely narrowed.
Unless the canal is clearly narrowed, hearing is usually normal.
However, wax and water are easily trapped in a narrow canal; when it becomes blocked, a conductive loss appears.
Trapped water and wax set the stage for recurrent otitis externa.
A narrow canal makes probe placement and ear impressions difficult; impression material can get stuck behind the growths.
When the growths severely narrow the canal, the decision on surgery belongs to the ENT physician.
A tip from practice: otoscopy is the last safety check before you put anything in the ear.
If you see wax, inflammation, fungus or a bony growth in the canal, do not place a probe, insert earphone or impression material.
In ear impressions especially, material can get stuck in a narrow or irregular canal, and removing it may require surgery.
Record the finding, refer to a physician and schedule the test for a suitable time.
Wax causes a conductive loss when it fully blocks the canal; partial occlusion mainly affects the high frequencies.
Otitis externa is an inflammation of the canal skin; pain that increases when the tragus is pressed is typical.
In otomycosis, itching is prominent, and a cotton-like, speckled appearance may form.
Exostoses are linked to cold water and are multiple and bilateral; an osteoma is usually single and on a stalk.
Test yourself: When wax partly blocks the canal, which frequencies are affected most?
The correct answer is B: high frequencies.
Low frequencies are clearly affected only when the canal is fully blocked, which is why people often notice the loss suddenly.
In the next lesson, we move behind the tympanic membrane to see the acute, effusive and chronic types of otitis media.
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Prerequisites

LESSON 55 Otoscopy Basics: How to Look Inside the Ear

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