Otitis externa
Inflammation of the outer ear
Mr James W Fairley BSc MBBS FRCS MS
Consultant ENT Surgeon
Sandyhurst House Sandyhurst Lane
Ashford Kent TN25 4NX
tel 01233 642244 fax 01233 662840
www.entkent.com
Last updated 20 March 2008
© 2007 - 2008 JW Fairley
What is otitis externa?
Chronic otitis externa. Eczema with secondary infection, painful fissuring of the skin at the opening of the ear canal.
Discharge from an acute otitis media and perforated eardrum causing a runny ear and secondary otitis externa in an infant
Otitis externa (Oh-tight-iss ex-turn-ah) is inflammation of the outer ear.
Otitis externa is sometimes called swimmer's ear or surfer's ear. Water in the ear will often trigger an attack. Otitis externa in humid climates has been called Singapore Ear.
Otitis externa affects the skin of the ear canal. The ear canal skin is easily damaged. If you poke cotton buds or hair grips down your ear, this may damage the skin surface. Otitis externa is often due to misguided attempts to clean or scratch an itchy ear.
The ear canal can also become inflamed because of general skin conditions, such as
- dermatitis
- eczema
- psoriasis
Sometimes otitis externa is caused by more deep seated disease, such as cholesteatoma. In otitis media, discharge from the middle ear, coming through a perforated eardrum, causes inflammation of the ear canal skin.
We can't tell whether a discharging ear is simply otitis externa, or a more deep seated problem like cholesteatoma, until the whole of the eardrum has been seen. This is one of the reasons why it is important to clean the ear canal thoroughly, usually by microsuction.
Another important reason for cleaning the ear canal thoroughly is to break the vicious circle of
- inflammatory swelling
- shedding of dead layers of skin
- formation of pus
- more inflammatory swelling
In established otitis externa, dead skin and infected material should be removed to give medications a proper chance to work.
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The normal ear and hearing
- The human ear is divided into three parts: outer, middle and inner ear.
-
The outer ear funnels sound waves in air to the eardrum.
- The eardrum is a paper-thin membrane, shaped like a miniature satellite dish, 8-10 mm diameter.
- The eardrum or tympanic membrane forms the boundary between outer and middle ear.
Normal left eardrum (tympanic membrane)
- The eardrum vibrates when sounds arrive through the external ear canal.
- The vibrations are transmitted to the inner ear via three small bones (ossicles) suspended in the middle ear.
- The inner ear acts like a microphone, turning sound vibrations into electrical signals which are sent to the brain in the nerve of hearing.
- The inner ear is also concerned with balance.
- To hear normally, the eardrum and ossicles must be able to move easily.
- For this to occur, the middle ear must contain air at the same atmospheric pressure as the outer ear.
- The air in the middle ear comes from the back of the nose, via the Eustachian tube.
How the normal ear canal cleans and protects itself
The normal ear is self cleaning. It is protected by a thin layer of wax. A small amount of ear wax is healthy. Wax is made in the outer third only.
The ear canal conveyor belt: outward migration of ear canal skin
If you paint a dot of ink in the middle of someone's eardrum, then go back a week later and look at it, it will have moved toward the edge. Gradually, over a few weeks, it will work its way further out, until it passes the edge of the eardrum and passes into the ear canal skin. Eventually it works its way along the ear canal, to the outside. This slow outward movement prevents a build-up of dead layers of skin from blocking the ear canal.
The surface skin cells of the eardrum and ear canal are dead. All over the body, surface layers of dead skin are constantly renewed and replaced. Beneath the surface, new layers of skin cells are growing up. As they mature, the cells become flatter and flatter. When they reach the surface, they dry out and die, forming thin flakes called squames. Like dead dried leaves on a tree in autumn, the tiny flakes of dead skin are now ready to fall off.
A snake sheds its outer layer of dead skin all in one go. We humans shed it a bit at a time, in flakes. There is lots of it. Most of the dust in your home is made up of those flakes of dead skin that have dropped off. If skin squames kept dropping off inside your ear canal, they would end up blocking it. So, the normal ear has a special way to get rid of the dead skin layers.
Ear canal skin grows in such a way that the outer layers are slowly moved outwards, like a conveyor belt.
When normal ear canal skin migration fails
In otitis externa, the conveyor belt either stops, or doesn't go fast enough to cope with the increased rate of turnover of skin cells. This results in a build-up of layer upon layer of dead skin. While the dead skin stays dry, few germs can digest it. But if it gets wet and soggy, it becomes the perfect place for a biofilm to form. Many different types of germ can take advantage of this food source. Although you can catch germs from dirty water, often it is your own resident germs who cause the trouble. Many bacteria live quietly in normal skin. When warm, moist conditions favour their growth, they take the opportunity to breed.
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Causes of otitis externa
Some people are more prone to get otitis externa than others. Something then triggers it off.
Mildew on a bathroom window blind. Humid air and lack of ventilation encouraged this mixed fungal growth on the damp surface of the fabric. A similar process happens in the skin of the ear canal in otitis externa.
Otitis externa is often brought on, or made worse, by the following
- Getting the ears wet. Ear infections following
- swimming
- dunking the head in the bath
- ear syringing
are common triggers.
- Digging, poking or scratching the ears.
- Getting hot and bothered, especially having to rush about in a hot, humid climate.
- Stress.
Sometimes, otitis externa is due to more deep seated disease affecting the middle ear or inner ear.
Occasionally, otitis externa will first come to medical attention as a result of complications from the more serious disease.
Infection is often, but not always, present. Local infection of the skin may be caused by
- bacteria - such as Staphylococcus aureus - the germ that causes boils and impetigo
- fungi - such as Aspergillus niger, Aspergillus fumigatus
- viruses - especially herpes zoster, the germ that causes shingles and chicken pox.
The reaction of the skin to the infection may result in a vicious circle of inflammation, swelling, shedding of dead skin which provides food for the germs. Further irritation of the skin results from the toxic products of the infecting organism. This speeds up skin metabolism and produces more layers of dead skin, which is food for the germs.
Left facial paralysis due to herpes zoster virus infection. The left external ear broke out in painful blisters at the onset of facial weakness. This condition is also known as Ramsay Hunt syndrome.
Same patient as above, Ramsay Hunt syndrome. Painful skin blisters in the left ear due to herpes zoster virus associated with facial paralysis. The same virus causes shingles and chicken pox. The herpes zoster virus can lie dormant in nerve roots for decades. It can be re-activated by stress or reduced immunity.
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Symptoms
Common symptoms of otitis externa include
- Itch. An itchy ear may be the first symptom.
- Pain. Earache, varying from mild discomfort to severe, incapacitating pain.
- Blockage. The ear feels blocked, or there may be a feeling of pressure.
- Discharge from the ear. Can be profuse, runny, or small amounts. Sometimes smelly, a bit like cheesy feet.
- Deafness. Varies from slight to severe, but there is usually some loss of hearing.
- Tinnitus. Noises in the ear, or in the head.
Less common symptoms of more severe forms of otitis externa include
- Bleeding from the ear. Especially in bullous myringitis.
- Visible swelling of the outer ear (pinna) sometimes with blistering of the skin.
- Swelling of the glands in front, behind or below the ear.
Otitis externa is often brought on, or made worse, by the following
- Getting the ears wet. Ear infections following swimming, dunking the head in the bath, or ear syringing, are common in otitis externa.
- Digging, poking or scratching the ears.
- Getting hot and bothered, especially having to rush about in a hot, humid climate.
- Stress.
Sometimes, otitis externa is the presenting sign of a more severe disease affecting the middle ear or inner ear. Occasionally, otitis externa will first come to medical attention as a result of complications from the more serious disease.
- Sudden onset of severe vertigo may be due to the disease eroding into the lateral semicircular canal of the inner ear.
- Sudden onset of severe deafness can be due to the disease eroding into the inner ear.
- A paralysed face could be due to the disease affecting the facial nerve in the ear.
- Meningitis - severe headache, stiff neck and photophobia - may be the presenting feature of the disease.
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Signs
Otitis externa. Diffuse desquamative type. Layers of wet soggy white shed skin are partially blocking the ear canal. Red swollen inflamed skin is preventing a proper view of the eardrum. The debris must be cleaned to see the eardrum. Until the eardrum has been fully examined, it is impossible to know whether or not there is an underlying middle ear disease such as cholesteatoma.
Otitis externa secondary to infected
grommet or ventilation tube. Mucoid discharge with bubbles from middle ear.
Otitis externa. Suspicious for infected cholesteatoma. Red granulation tissue overlying the bone of the left ear canal, behind the eardrum. Layers of wet soggy white shed skin are stuck to the eardrum. The debris must be cleaned to see the eardrum. In this case it was too painful to complete the cleaning in out-patients. Microsuction under a general anaesthetic confirmed the diagnosis.
Otitis externa. Mixed fungal and bacterial infection. Viewed with operating microscope
c =
conidiophores
m =
mycelium
p =
pus
Conidiophores (coe-
nid-ee-oh-fours) are the fruiting body of the fungus. Like mushrooms, but microscopic. In this case, small round beige drumsticks are typical of the aspergillus (asp-er-
Jill-us) flavus fungus.
The mycelium (my-
seal-ee-um) is the mat of fine white wispy fibres, rather like cotton wool. It is the equivalent of roots for the fungus. The mycelium spreads across the surface. Rarely it can invade deeper. Many fungi share the same appearance of the mycelium. A similar mould grows on and spoils stored food, especially in humid conditions.
Pus is the thick creamy pale green fluid clinging to the walls of the ear canal. It is made of mixed bacteria, some live, some dead, some digested and broken down. There are also partially digested skin and inflammatory cells from the body, and toxic chemical waste released from both the bacteria and the body's own defences. Pus fills the killing fields in the ongoing war between humans and micro-organisms.
Medical signs are things that can be seen or noticed during examination by the doctor. There are several signs of otitis externa, but no one single appearance. Otitis externa can take many forms, and may evolve from one form to another.
- discharge
- build up of debris
- swelling
- reddening
- narrowing of the ear canal
Until otitis externa has been treated, it is impossible to know if we are dealing with an underlying middle ear condition such as cholesteatoma, because the eardrum is not visible. The ear canal is swollen and blocked with infected material and dead skin.
Diagnosis
Ear swabs
Taking a swab, and sending it to the microbiology lab for conventional microscopy, culture and sensitivity is of very limited value in otitis externa.
The reason for taking a swab is to find out
- which germs are causing the infection
- whether the germs are sensitive or resistant to antibiotics
The taking of swabs appears to be logical and scientific. Unfortunately, it isn't.
Swab-taking and antibiotic prescription does not help much in a biofilm disease like otitis externa.
In practice, a whole bunch of different bugs are likely to be there, joining in the party.
- Which one is responsible?
- Are they all guilty?
Taking a swab from a chronic infection is like making arrests at the scene of a riot. Those who survive the journey to the police station will be identified.
- Bugs that grow from the swab were definitely there.
- Others may well have been there too.
- Some guilty parties may not have been picked up.
- Some may be on the swab, but not grow in the lab.
When several different germs grow from one swab, deciding between culprits and innocent bystanders is a matter of judgement. That judgement is made on the basis of partial and biased evidence. So, the microbiology lab report, which invariably takes time, needs to be taken with a very large pinch of salt. The result can easily mislead doctors without specialist experience into thinking that the prescription of an antibiotic, to which the germ that happened to grow is sensitive in the lab, will cure the problem. Many times, it won't.
Why antibiotics don't cure otitis externa
The reason antibiotics don't always help much is because otitis externa is much more than a simple infection. It is a vicious circle of infection, inflammation, swelling, shedding of dead skin, more infection, and so on. Antibiotics taken by mouth don't penetrate at all well into the layers of dead skin debris and pus that block the ear canal in otitis externa. Nor do antibiotic drops.
A build-up of organic waste matter with multiple organisms growing inside a rubbish bin. This smelly debris needs to be physically cleaned out. Just pouring in cleaning fluid is not enough.
Physical cleaning of the debris is needed. It's a bit like having a dirty rubbish bin. You can pour some bleach in and it will stop it smelling, but not for long. Really you need to scrape out the muck, then apply the cleaning fluid. Then it gets a chance to work.
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Medical treatments
Inflammation can be treated medically with steroids. Drugs for infection and inflammation of the ear are given in three main ways:
- topical - ear drops and sprays, ointments
- by mouth - medicine and tablets
- by injection - intravenous antibiotics may be needed in more severe infections, especially if the inflammation spreads into the surrounding structures.
If you are prescribed ear drops, make sure you use them properly, otherwise they probably won't work.
How to use ear drops
Correct position for putting in eardrops
Tragal massage
- Ear drops must be inserted correctly, otherwise they may not work.
- Eardrops should be applied at body temperature.
- To get the drops to body temperature, put the bottle in your pocket for 15 - 20 minutes before use
- The patient should lie on his side with the affected ear uppermost.
- Any discharge should be mopped gently away with a cotton bud.
- Pull the ear gently backwards to funnel the drops into the ear canal.
- You then massage the tragus (the piece of skin that sticks out just in front of the ear canal like an open trapdoor) to force the drops right down to the eardrum.
- It is rather like plunging a blocked sink.
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Microsuction treatment
Microsuction of the ear as an out-patient procedure
Wax removal using microsuction
Wax removal using a fine round ended hook
An alternative to microsuction often used in children with runny, discharging ears is to gently mop out the ear with a cotton wool applicator. Illumination is from light shone over the child's shoulder and focussed onto the ear by a head mirror worn by the surgeon. The view is nothing like as good, and we can't normally reach right down to the eardrum, but it is less scary for the child.
Microsuction is an examination and treatment of the ear using a high powered binocular operating microscope. We use very fine delicate instruments, including a miniature vacuum cleaner. This Hoovering of the ear is usually done as an out-patient procedure. Sometimes, and especially in younger children, it is done as a day case surgery under general anaesthetic. Microsuction of the ear is carried out
- to diagnose the condition of the ear accurately using
- binocular vision for 3-d stereoscopic view
- high power magnification
- very bright illumination
- to remove material blocking the ear canal such as
- wax
- infected debris, pus and fungal material
- dead skin layers including cholesteatoma
- foreign bodies
- to apply medication to the ear
Having microsuction treatment: What to do
You may be asked to use ear drops beforehand. This will make the treatment easier for you.
- You do need to lie very still.
- Despite all our efforts to be as gentle as possible, it will be noisy, and may be painful.
- It usually causes some short lived vertigo, lasting no more than a minute or so.
- Don't get up until the nurse says so - you may be dizzy.
- You should be ok to drive afterwards but may need to wait until any dizziness has settled.
Repeated microsuction may be needed. Rather like going to the dentist, very few people look forward to the experience, but it is effective and necessary.
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Use of medicated ear wicks
Pope wick before and after use with crocoidle forceps.
Pope wick held in crocodile forceps ready to be placed in a swollen narrow ear canal to treat otitis externa.
Pope wick expanded in the ear canal to treat diffuse otitis externa.
When the ear canal skin is very swollen, drops will not penetrate. In cases of severe swelling and narrowing, a wick can be very useful. Modern materials such as Merocel allow a small wick to be inserted. Like a tampon, the wick is small and tightly compressed when dry. When the wick gets wet, it swells up. The wick soaks up discharge, and also soaks up ear drops. This helps the medication to reach the skin surface around the wick. The wick may be left in place for several days, up to a week. During this time, the patient will need to apply ear drops as directed. Sometimes the wick will fall out by itself, but usually it is removed by the specialist under the microscope. A further examination under the microscope, and microsuction treatment, follows. In difficult cases a series of wicks may be needed. It can be quite painful to put in a wick when the ear canal is very tender and swollen, but the pain lasts only a few seconds and the relief is worth it.
Application of ointment dressing
Syringe with anti-fungal anti-bacterial and steroid ointment for application to the ear canal skin
Sometimes, and especially in fungal cases, an ointment based dressing is the most useful method of treatment. This is normally applied under high powered microscopic control, following the removal of as much debris as possible. Tri-Adcortyl ® ointment contains antifungal, antibacterial and a steroid in order to reduce the inflammatory response of the skin. It can be left in the ear canal for weeks.
What can I do to help myself?
Never dunk your head in the bath water. Detail from Le bain, Alfred Stevens, Musee d'Orsay, Paris
Roll a piece of cotton wool about the size of the tip of your thumb in a tub of Vaseline. Make sure it is well coated.
Place the Vaseline-coated cotton wool in the bowl of the outer ear. Don't push it right down the ear canal.
Ear plugs held in place by neoprene headband for active swimming
Earol olive oil spray applied to ear canal to soften wax
During the time you have active otitis externa
- Keep your ears dry.
- The worst kind of water is bath water - it contains germs from the rest of the body and irritant soap.
- Never dunk your head in the bath.
- Plug your ears with cotton wool balls rolled in Vaseline® to provide a waterproof seal when showering or hair washing.
- Don't swim or dive.
- Don't put anything in your ears, except the drops or spray you have been prescribed.
- If you have been prescribed ear drops, make sure you use them properly.
- Avoid digging, poking and scratching your ears.
To prevent further attacks of otitis externa
- Keep water out of your ears.
- Use cotton wool balls rolled in Vaseline for showering and hair washing.
- Never dunk your head in the bath water.
- For swimming, wear some well fitting silicone rubber earplugs such as Kapiseal® or Ear Putty®
- A neoprene headband such as the Ear Band-it® will help stop the ear plugs from falling out.
- If you have a long term problem with otitis externa, and want to swim, you may prefer to buy a custom made ear mold from an audiologist.
- Don't scractch itchy ears.
- Never poke anything down your ear canal - the skin is very delicate and easily damaged.
- Avoid cotton buds or similar methods for cleaning your ears.
- Use olive oil drops or ear spray to help soften wax.
- Try to avoid excess stress (easier said than done).
- Some patients - those who lack the normal self-cleaning conveyor belt of the ear canal - need periodic treatment with microsuction to remove a build up of dead skin.
Audiometry (Hearing tests)
Child hearing test in a sound proofed booth
Tuning fork test - part of Rinne's test. Bone conduction of sound is often better than air conduction if the ear canal is blocked in otitis externa.
Hearing tests are part of the assessment of any ear condition. Pure tone audiometry with air conduction and bone conduction is the main test we use. The test doesn't diagnose the condition, but does tell us how much hearing has been lost. It also tells us whether it is a conductive hearing loss (usually due to blockage of the ear canal in otitis externa) or a sensorineural hearing loss due to damage to the inner ear. We need to measure and know how much hearing has been lost, and how much remains, to help advise on the likely outcome of treatment. If the loss of hearing is due to damage to the inner ear, it will definitely be permanent. A conductive loss can ususally be improved in otitis externa. Hearing tests before and after treatment are important in assessing the results of what we do.
Hearing aids and BAHA osseointegrated auditory implant
Bone Anchored Hearing Aid components - BAHA diagram courtesy of Cochlear / Entific.
If you have otitis externa and need to wear a hearing aid, you have a problem. Wearing a normal hearing aid will make otitis externa worse. Blocking the ear canal with a hearing aid mould makes it moist. This encourages germs. Just imagine the state of your feet if you wore plastic shoes all day. Many otitis externa patients find that they can't wear hearing aids because they cause infection, with painful, discharging ears. They have to stop wearing the hearing aid, get treatment for the infection with microsuction and antibiotic / steroid ear drops, and are unable to hear properly for weeks. Once the infection clears up, they go back to wearing the hearing aid, then the whole miserable cycle repeats itself. The situation is worse if both ears are affected. Some audiologists try to get around the problem of blockage by using loose fitting or vented moulds. This often results in feedback and whistling when the volume is turned up. Modern digital hearing aids can be porgrammed to stop feedback, allowing a more open fitting. However, even partial blockage of the ear canal reduces ventilation and encourages infection. A bone conductor hearing aid uses bone conduction to put sound directly into the inner ear, bypassing the middle ear problem. Old fashioned bone conductor hearing aids are placed on metal springs like an Alice band, or sometimes built into a pair of spectacles. They are cumbersome, and very uncomfortable to wear for any length of time, because they have to press very hard. They can cause pain, headaches and ulceration of the skin. Sound quality is muffled by the soft tissue of the scalp. The most effective way of getting around this problem is to put sound directly into the bone of the skull, by the titanium screw of a BAHA osseointegrated auditory implant.
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Disclaimer
All information and advice on this website is of a general nature and may not apply to you. There is no substitute for an individual consultation. We recommend that you see your General Practitioner if you would like to be referred.
