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'''Otitis externa''' is [[inflammation]] of the [[The_ear#Outer_Ear_.28pinna.2C_ear_canal.2C_surface_of_eardrum.29|outer ear canal]]<ref>The reader should note that [[inflammation]] and [[infection]] are not synonymous.</ref> It usually presents as one or more of the complaints of an earache, a persistent itch in the ear, a runny ear, deafness of the affected ear, or red and swollen skin in or around the ear canal or external ear. It is most often an acute condition, almost always an infection of the skin and subcutaneous tissue of the canal, which may spread to involve the skin surrounding the ear, the face and neck, the local lymph glands and the salivary glands. Uncomplicated recovery is the norm, but in diabetics and immunocompromised persons rapid spread is potentially dangerous and requires prompt treatment. Chronic otitis externa affects fewer persons, is often a manifestation of a general inflammatory skin disease (for instance soborrheic dermatitis), and may be defined as signs or symptoms of otitis externa that lasts for more than four months, or occurring more than four times per year. The body of this article concerns acute otitis externa, the chronic disease will be described separately in its own section. When the causes of the illness are understood, then it is clear that most cases of otitis externa could be prevented by proper preventative measures.


{{Infobox_Disease |
==Anatomy and physiology pertinent to understanding otitis externa==
  Name          = {{PAGENAME}} |
The external ear canal serves to protect the middle and inner ear from injury, while providing an air passage for the conduction of sound, together with the [[The ear#Outer Ear (pinna, ear canal, surface of eardrum)|pinna]] amplifying and improving directional localisation of sound. Being a blind-ending tube, it is vulnerable to blockage and infection. Certain characteristics reduce the risk of infection occurring. The skin lining the external ear shows a unique pattern of growth, growing in a sideways direction, moving as a sheet of tissue from the eardrum end to the outer opening. This mass movement of the epithelial layer of cells carries with it cellular and foreign debris which may collect on the skin of the inner part to where it may be easily picked off at the outer opening – a self-cleaning mechanism which is foiled when an object like an earbud is pushed from the outside inwards. The skin is covered by a layer of cerumen (wax) produced by the skin glands of the outer third of the canal. This wax is a barrier to infection of the skin by virtue of its water repellancy, relatively acidic pH of 6.9, and its content of lyzosyme.<ref>Tsikoudas A, Jasser P, England RJ. Are topical antibiotics necessary in the management of otitis externa? Clin Otolaryngol Allied Sci 2002;27:260-2.</ref> Hairs occur on the skin of the outer third, serving to prevent entry of foreign material to the inner two thirds.
  Image          = |
  Caption        = |
  DiseasesDB    = 9401 |
  ICD10          = H60 |
  ICD9          = {{ICD9|380.1}}-{{ICD9|380.2}} |
  ICDO          = |
  OMIM          = |
  MedlinePlus    = 000622 |
  eMedicineSubj  = ped |
  eMedicineTopic = 1688 |
  eMedicine_mult = {{eMedicine2|emerg|350}} |
}}
'''Otitis externa''' ("swimmer's ear") is an [[inflammation]] of the outer [[ear]] and ear canal. Along with [[otitis media]], external otitis is one of the ''two'' human conditions commonly called "earache". Inflammation of the [[skin]] of the ear canal is the essence of this disorder. If inflammation progresses to infection, the ear canal may fill with swollen tissue and drainage.  Once the ear canal is blocked,  hearing will be dampened (conductive [[hearing impairment]]) until the condition improves. In very severe cases, the skin infection can spread to the face (facial [[cellulitis]]) and to the major [[salivary gland]] in the cheek ([[parotitis]]). In that situation, moving the jaw and eating become painful. In its mildest forms, external otitis is so common that some ear nose and throat physicians have suggested that most people will have an episode at some point in life. In many individuals, for the reasons discussed below, the condition is recurrent and will happen several times in a lifetime.


Ordinarily, inflammation of the ear canal skin starts off with the loss of protective oils and ear wax ([[cerumen]]) along with minor injury to the skin. That injury often stem from attempts at self-cleaning or scratching using cotton swabs, hair pins or other implements small enough to fit in the ear canal. Prolonged water exposure (either swimming in clean water or exposure to extremely high humidity) is enough'' alone'' to both decrease the protective barrier of ear wax and to cause tiny breaks in the waterlogged skin, hence the name, "swimmer's ear". Since the swollen ear canal skin often is both itchy and painful, and sometimes associated with a feeling that something is stuck in the ear, a vicious cycle of self-cleaning or scratching can perpetuate the condition. Wax glands shut down the production of protective cerumen when the canal skin is inflamed, and weeks are required for the outer ear to completely return to normal production of protective oils after even a short bout of moderately severe external otitis. During this recovery period, the skin is markedly more vulnerable to becoming re-infected. For these reasons, among others, some people are prone to recurrent external otitis with exposure to water.
Anatomically,the skin of the inner two-thirds of the ear canal is extremely thin, and closely overlies the bone. The lack of underlying fat and supporting tissue makes this skin vulnerable to scratches, tears and cracking. At the junction of the bony and cartilaginous parts, the adult ear canal makes a turn forwards and downwards, forming a bend where larger bits of material can get stuck. The outer third has thicker skin, supported by cartilage and fatty tissue and containing hair follicles and skin glands. It is therefore less commonly the site of origin of an otitis externa.


There is a rare and serious form of external otitis called necrotizing external otitis, in which the bone of the skull surrounding the ear canal becomes infected. Although the name of this condition contains the words "external otitis" it is a very different disease than the common swimmer's ear, it is a form of [[osteomyelitis]] . Instead of being a condition that most people are subject to, necrotizing external otitis (also called malignant otitis) is a life-threatening disorder that only affects individuals with severe diabetes and major disorders of the immune system.  This rare complication of external otitis is discussed under Complications, below.<ref>{{cite journal | author = Beers S, Abramo T | title = Otitis externa review. | journal = Pediatr Emerg Care | volume = 20 | issue = 4 | pages = 250-6 | year = 2004 | id = PMID 15057182}}</ref>
==Incidence and pathology==
Most cases of early acute otitis externa heal with simple measures such as stopping swimming, with or without eardrops such as 2% vinegar, or 70% alcohol (or a mixture of the two) as preventative and therapeutic treatment. These cases seldom come to the attention of health services, which has the consequence that estimates of the incidence of otitis externa are unreliable.
==Symptoms==
 
Pain is the predominant complaint and the only symptom directly related to the severity of external otitis. Unlike middle ear infections ([[otitis media]]), ''the pain of external otitis is worsened when the outer ear is touched''. Pushing the tragus (that tablike portion of the auricle that projects out just in front of the ear canal opening), so typically causes pain in this condition as to be ''diagnostic'' of external otitis on physical examination. Both otitis media and external otitis patients may experience ear discharge and itchiness. When enough discharge in the ear canal is present to clog the opening, external otitis may cause temporary conductive hearing loss.
Acute otitis externa is common, with an incidence of approximately 13 per 1000 patients in general practice in the Netherlands<ref>Rooijackers-Lemmens E, Van Wijngaarden JJ, Opstelten W, Broen A, Romeijnders ACM. NHG-standaard otitis externa. Huisarts Wet 1995;28(6): 265-71.</ref> and Britain,<ref name=rowlands2001>Rowlands S, Devalia H, Smith C, Hubbard R, Dean A. Otitis externa in UK general practice: a survey using the UK General Practice Research Database. Br J Gen Pract 2001;51: 533-8.</ref> and 4 per 1000 in the United States.<ref>Osguthorpe JD, Nielsen DR. Otitis Externa: Review and Clinical Update. Am Fam Physician 2006;74(9):1510-6.</ref> A study of more than 40,000 cases in 30,000 persons over a year in British general practices showed a prevalence in females of 1.3%, and males 1.16%, the highest yearly prevalence being in persons 25 and 75 years of age. More than 20% had more than one episode.<ref name=rowlands2001 /> As skin infections go, and for the volume of the infected tissue, otitis externa has a significant morbidity (negative effect on general health). In a swimming-associated outbreak of 94 cases, a third suffered a median of four days of loss of normal activities, while slightly more than one fifth took to their beds for a median of three days.<ref>van Asperen IA, de Rover CM, Schijven JF, Oetomo SB, Schellekens JF, van Leeuwen NJ, et al. Risk of otitis externa after swimming in recreational fresh water lakes containing Pseudomonas aeruginosa. BMJ 1995;311:1407-10.</ref>


Because the symptoms of external otitis promote many people to attempt to clean out the ear canal (or scratch it) with slim implements, and self-cleaning attempts generally lead to additional trauma of the injured skin, rapid worsening of the condition often occurs. Worsening is also common in the vacationeer who continues holiday swimming despite symptoms of mild external otitis.
For acute otitis externa, a common initiating event is water carried into the external ear canal, and in contact with the thin skin for prolonged periods. This leads to maceration of the skin lining the canal. Moist macerated skin is a good culture medium for the organisms carried in with infected water. The association of otitis externa with swimming or diving, especially in contaminated water, has given rise to the common name of “swimmer’s ear” or “diver’s ear”. Repeated contact with water increases the risk of maceration and infection by reducing the protective layer of cerumen, while decreasing the acidity of the skin in the outer ear. On the other hand, excessive wax may promote trapping of water in the canal. Humid weather and warm temperatures increase the likelihood of skin maceration, and the incidence of acute otitis media. The second important cause of initial infection is mechanical injury to the skin by objects such as hearing aids and ear plugs, or “instruments” persons use to clean out their ears.<ref>Beers SL, Abramo TJ. Otitis externa review. Pediatr Emerg Care 2004;20:250-6. PMID 15057182</ref> The offending instrument may be anything from a fingernail to a matchstick to a cotton earbud (this may of course be equally risky for causing an ear drum perforation). Apart from damage due to attempts at cleaning the canal, the skin may be scratched in an attempt to alleviate the itch of mild otitis externa, or the perceived blockage of the canal, leading to exacerbation of the condition. Less commonly, conditions such as eczema or psoriasis disrupt the continuity of the skin, allowing invasion of pathogenic bacteria (a case of an acute infection following chronic inflammation).


==Causes, incidence, and risk factors==  
Whatever the initiating event, the bacteria multiply and cause an acute infection and inflammation of the skin and subcutaneous tissue (cellulitis). The ear canal swells shut and the ear develops a discharge. At this stage the person may complain of hearing loss in the affected ear, as well as tinnitus (a persistent ringing in the ear) which is caused by the occluded ear canal. If the infection is not contained, it may in severe cases spread along the subcutaneous tissue, causing a cellulitis of the neck and the side of the face. Local lymph glands become acutely inflamed, and the parotid salivary gland enlarged and tender (so-called diffuse external otitis<ref name=lucente>Lucente FE et al : Malignant Otitis externa : a dangerous misnomer.  Otolaryngol Head Neck Surg. 1982 Mar-Apr;90(2):266-9.</ref>). In such cases, differentiation from malignant otitis externa (see the next paragraph) purely on grounds of the examination may be difficult.


[[Swimming]] in polluted water is a common way to contract swimmer's ear, but it is also possible to contract swimmer's ear from water trapped in the ear canal after a shower, especially in a humid climate. Even without exposure to water, the use of objects such as cotton swabs or other small objects to clear the ear canal is enough to cause breaks in the skin, and allow the condition to develop. Once the skin of the ear canal is inflamed, external otitis can be drastically enhanced by either scratching the ear canal with an object, or by allowing water to remain in the ear canal for any prolonged length of time.  
Acute or chronic otitis externa may progress to affect the cartilage of the ear (chondritis), or the bones surrounding the ear canal (osteomyelitis). The latter tends to be progressive and difficult to cure, with a risk of infection spreading through the bone to other parts of the skull and even the central nervous system. This malignant or necrotising form of otitis externa is more common in diabetics or immune compromised persons, and requires aggressive treatment, both surgical and medical.<ref>Hannley MT, Denneny JC III, Holzer SS. Use of ototopical antibiotics in treating 3 common ear diseases. Otolaryngol Head Neck Surg 2000;122:934-40.</ref>


The two factors that are required for external otitis to develop are (1) the presence of germs that can infect the skin and (2) impairments in the integrity of the skin of the ear canal that allow infection to occur. If the skin is healthy and uninjured, only exposure to a high concentration of pathogens, such as submersion in a pond contaminated by sewerage, is likely to set off an episode. However, if there are chronic skin conditions that affect the ear canal skin, such as [[atopic dermatitis]], [[ seborrheic dermatitis]], [[psoriasis]] or abnormalities of [[keratin]] production, or if there has been a break in the skin from trauma, even the normal bacteria found in the ear canal may cause infection and full-blown symptoms of external otitis.(Kang K, Stevens SR. Pathophysiology of atopic dermatitis. Clin Dermatol 2003;21:116–121.)
For a few weeks after an episode of acute otitis externa the outer ear is susceptible to becoming infected more easily than normal. The skin itself is thinned and lacks a normal outer protective keratin layer, while wax production decreases markedly, even after all infection has disappeared. Therefore repeat exposure to the precipitating circumstances is likely to cause another bout of the disease.


The incidence of otitis externa is high. In the Netherlands, it has been estimated at 12-14 per 1000 population per year, and has been shown to affect more than 1% of a sample of the population in the United Kingdom over a 12 month period.<ref>{{cite journal | author = van Balen F, Smit W, Zuithoff N, Verheij T | title = Clinical efficacy of three common treatments in acute otitis externa in primary care: randomised controlled trial. | journal = BMJ | volume = 327 | issue = 7425 | pages = 1201-5 | year = 2003 | id = PMID 14630756}}''[http://bmj.bmjjournals.com/cgi/content/full/327/7425/1201 Full text]''</ref>
The organisms implicated in otitis externa are most commonly opportunistic pathogens, that is, organisms that do not cause disease in healthy tissue, but can infect tissue where the immunity is reduced. Macerated skin, scratches and loss of cerumen represent such local loss of immunity, while diabetes, AIDS and chemotherapy are systemic causes. Pseudomonas aeruginosa is found in up to 50% of cases, other bacterial infections (Staphylococcus epidermides, Staphylococcus aureus, and Streptococcus pyogenes) account for 40%, and fungi about 10%.<ref>Stroman DW, Roland PS, Dohar J, Burt W. Microbiology of normal external auditory canal. Laryngoscope 2001;111(11 pt 1):2054-9.</ref><ref>Roland PS, Stroman DW. Microbiology of acute otitis externa. Laryngoscope. 2002:112(7 Pt 1);1166-77. PMID 12169893</ref><ref>Qarah S, Cunha BA. Pseudomonas Aeruginosa Infections. eMedicine Infectious Diseases. http://www.emedicine.com/med/topic1943.htm. Updated 2005-12-12.</ref>


===How The Shape and Characteristics of the External Ear Can Lead to External Otitis===
==Symptoms==
Ear discomfort is the usual symptom of otitis externa. This may be an itch and mild pain, or, in advanced cases, severe pain requiring strong analgesics. When not just minor, pain is disproportionate to the volume of inflamed tissue, because the tissue is confined to a small volume and impinges on bony boundaries, so that increased local pressure and irritation of periosteum occurs early on. Since the pinna and the tragus is connected to the cartilage of the outer third of the ear, and that to the skin, movement of these structures causes pain from distortion of the inflamed skin. This extreme sensitivity to movement is generally not found in uncomplicated otitis media, the other common cause of earache.


The outer ear canal starts at the opening on each side of the head that allows the entry of sound; the skin-lined canal extends in as far as the tympanic membrane (ear drum). The surface of the ear drum is also skinlike, and is continuous with that of the ear canal. There are two distinct parts to the ear canal, the outer portion, which lines the cartilage portion of the ear canal that travels through the soft tissues of the head, and the inner portion, which lines the bony ear canal that travels through the skull. The bony ear canal can be seen on preserved specimens of the skull. The skin that is most easily inflamed is the delicate skin of the inner portion, the thin closely applied skin of the bony ear canal, which is perhaps the only skin of the body that ordinarily should never be touched!
A discharge from the ear commonly occurs, but is usually not the primary complaint. It can vary from a mild watery consistency and colour, to thick, yellow or white, to a bloody purulent discharge.


The skin of the ear drum surface and the ear canal is much like skin anywhere on the body, it is waterproof because of layers of keratin at its surface. These surface layers are shed, but  do not  normally build-up in the ear canal. That's because of the way that the skin grows: migrating outward along the canal to the surface of the head and bringing any surface debris with it.
Redness and swelling can usually be seen in the ear canal. The swelling may obscure the canal completely, so that the ear feels blocked up and deaf, and be a source of tinnitus. The outer ear and surrounding tissue may show these symptoms and signs of inflammation, depending on the spread of the infection. The signs of a diffuse otitis externa can be confused with malignant otitis externa.<ref name=lucente />


The outer ear canal skin is much thicker and more resilient to injury than the skin of the bony canal. This outer canal skin has a thick layer of subcutaneous tissue cushioning it, and contains both hairs and cerumen glands. The cerumen glands produce ear wax that is normally protective.
Bacterial otitis externa is associated more severe local symptoms and morbidity than other causes. The person with acute bacterial otitis externa may feel ill, complain of headache, and develop a moderate fever, usually less than 38.3&deg;C. More severe illness would prompt the examining person to look for complications.


A [[folliculitis]] of one of the hairs of the outer portion of the ear canal can be the start of a bout of external otitis. Impaction of cerumen that abuts up against the delicate skin of the bony canal, or attempts to remove the impacted wax, can also be the initial event.
==Some predisposing factors, and associated preventative measures==
Anyone can develop oitits externa, and mild forms may go undiagnosed in persons who experience simply an itchy ear for a while. There are, however certain activities, circumstances and medical conditions where the risk for the disease increases. All of the risks apply also to immunocompromised persons, the chronically ill and diabetics – groups also at increased risk for the complications of otitis externa. Such persons should take particular care to avoid activities which predispose to otitis externa, or be particular about preventative measures when such conditions are unavoidable.


The S-shape of the ear canal, the presence of hair in the outer part, and the outward migration of skin all combine to help shed water from the ear canal and keep shed skin from building up within the canal, as well as to keep water from pooling in the innermost canal. In some minor malformations of the ear canal or auricle, the size and shape of the canal may pre-dispose allowing water that enters the ear to remain, or to inhibit the normal shedding of supperficial skin and cerumen from the ear canal. In such cases, the individual may have a predispostion to recurrent external otitis.
Where the person is engaged in activities that entail prolonged exposure of the external ear canal to water, the protective cerumen on the skin in the canal may be gradually washed away, leaving the skin unprotected. Loose surface keratin can now absorb moisture, becoming macerated and effectively a culture medium for bacteria. Since the pH of the ear increases at the same time, there is no protection against such growth. Swimmers and divers are clearly at risk, and regular swimming remains the most significant risk factor for acute otitis externa, with fresh water being more of a problem than sea water or chlorinated pools.<ref>Calderon R, Mood EW. An epidemiological assessment of water quality and `swimmer's ear.' Arch Environ Health 1982;37(5): 300-5.</ref><ref>Springer GL, Shapiro ED. Fresh water swimming as a risk factor for otitis externa: a case controlled study. Arch Environ Health 1985;40: 202-6.</ref><ref>Agius AM, Pickles JM, Burch KL. A prospective study of otitis externa. Clin Otolaryngol 1992;17: 150-4.</ref> Water which is considered safe by the standards for fecal coliform contamination may contain high numbers of organisms that may cause infection of a damaged external ear canal, but the precise correlation is not clear.<ref>Van Asperen IA, De Rover CM, Schijven JF, Oetomo SB, Schellekens JF, Van Leeuwen NJ, et al. Risk of otitis externa after swimming in recreational fresh water lakes containing Pseudomonas aeruginosa. BMJ 1995;311: 1407-10.</ref> Spells of hot weather, with high humidity and excessive sweating present a similarly increased risk of developing acute otitis externa. Preventing water getting into the ears would logically be the best preventative measure for those who love swimming. This can be achieved by the use of a well-fitting bathing cap, or properly fitted ear plugs, but hard or ill-fitting ear plugs may exacerbate the problem. It is unfortunately not known how effective this “logical” measure is in preventing the disease. Measures used after swimming include thorough drying of the ears and the use of acidifying ear drops. Drop containing alcohol, and Burow’s solution (5% [[aluminium]] subacetate solution) both have an astringent action, but may be irritating, especially if the skin is not entirely normal. Drying the ears using an ordinary hair dryer set on its lowest heat is effective, while battery powered hot air ear dryers are marketed. Following an attack of ititis externa, the use of acidic ear drops before and after swimming is often recommended, for at least three weeks, and in the long term if the infection tends to recur.


===Pathogens - The Disease-Causing Germs===
Direct trauma to the skin of the inner two thirds of the external ear canal is easily inflicted, especially near the junction with the outer third, where the canal makes a change of direction and the skin becomes thin and tightly applied to the underlying bone. The habit of personally cleaning one’s ears is more dangerous than beneficial, and while kitchen matches, the classroom protractors, and the beautician’s beautiful nails are clearly dangerous instruments, the soft tips of cotton ear buds are deceptively harmless, and one of the very common causes of hurting the soft skin lining the bony canal – as well as the ear drum. Ironically, damage is not infrequently done by “beneficial” acts, such as inserting a hearing aid earpiece or wearing ear plugs in an attempt to prevent noise-related hearing damage or prevent water from getting into the ear canal. Foreign bodies that lodge in the external ear are an important cause in young children, and in mentally retarded persons. The danger here is not always the presence of the object, but do-it-yourself or kindly third party efforts to remove the object. The same applies to adults, where an enormous variety of objects such as insects, seeds or bit of wood cuttings can get stuck in the outer ear. If these are not removed atraumatically under direct vision, then the scene may be set for damage to the outer and middle ear, including an episode of acute otitis externa a day or two later.
The bacterial pathogens at the top of the list are Pseudomonas aeruginosa and Staphylococcus aureus, followed by a great number of other gram-positive and gram-negative species.<ref>{{cite journal | author = Roland P, Stroman D | title = Microbiology of acute otitis externa. | journal = Laryngoscope | volume = 112 | issue = 7 Pt 1 | pages = 1166-77 | year = 2002 | id = PMID 12169893}}</ref> Candida albicans and Aspergillus species are the most common fungal pathogens responsible for the condition.


==Diagnosis==
Health workers are not blameless with respect to damaging the external ear canal. A professional person who removes wax or any other object from an ear using sharp instruments under inadequate vision runs the risk of causing injury. If that is not diagnosed and treated to prevent infection, the situation is no better than if the patient had done the scratching himself. The incorrect use of an otoscope is another entirely iatrogenic cause. Even syringing of the ears should be considered a predisposing condition for otitis externa, by washing away protective wax and altering the pH in the ear canal. Many health workers recommend the prophylactic use of acidic ear drops for a few days following such a procedure.


When the physician looks in the ear, the canal appears red and swollen in well-developed cases of acute external otitis. The ear canal may also appear [[eczema]]-like, with scaly shedding of skin. Touching or moving the outer ear increases the pain, and this manuever on physical exam is very important in establishing the clinical diagnosis. It may be difficult for the physician to see the [[eardrum]] with an [[otoscope]] at the initial examination because of narrowing of the ear canal from inflamation and the presence of drainage and debris. Sometimes the diagnosis of external otitis is presumptive and return visits are required to fully examine the ear. Culture of the drainage may identify the bacteria or fungus causing infection, but may also be misleading and is not part of the routine diagnostic evaluation.
The last group of risk factors is to a large extent beyond the direct control of a person. This is where a general dermatological condition has affected the skin of the ear. In many of these cases the person would be suffering from a chronic, low grade inflammation of the outer ear canal. The itch that this causes may lead to scratching activities which set off the acute otitis externa, or an acute exacerbation of the primary disease may disrupt the integrity of the skin. Conditions which can be included here are acne, atopic dermatitis, contact dermatitis, eczema, lupus erythematosus, psoriasis, and seborrheic dermatitis.<ref>Shea CR. Dermatologic diseases of the external auditory canal. Otolaryngol Clin North Am 1996;29:783-94.</ref> A person should be aware that allergic contact dermatitis may be confined to only the skin of the outer ear, so that the diagnosis may be missed because there are no symptoms or signs of dermatitis elsewhere. Immune-mediated otitis can occur in response to the metals contained in earrings or studs, chemicals in cosmetics and hair care products, solvents used in the plastics used to make hearing aids, and medications in ear drops (especially antibiotics). Apart from the allergic risk of antibiotic ear drops, alteration of the skin bacteria may lead to fungal infections, usually after prolonged use of these drops. Persisting with the antibiotic treatment only worsens the condition.


The diagnosis may be missed in early cases because the examination of the ear, with the exception of pain with manipulation, is normal or nearly normal. In some cases of early external otitis, the most striking visual finding in the ear canal is the lack of cerumen. As a moderate or severe case of externa otitis resolves, weeks may be required before the ear canal again shows a normal amount of cerumen.
==Diagnosis==
When a person presents with complaints of ear discomfort, itching, pain, a discharge, or a deaf or ringing ear, the doctor would take a history of how and when the symptoms started, how they have developed and what contributory factors there may be – this would include previous ear problems, treatments, other illnesses, accidents and injuries, as well as daily activities and sport. During the examination, the patient may be surprised that the doctor does not look only at the sore ear, but there are good reasons for this. A general assessment for signs of systemic illness, including the temperature, pulse rate, and signs of toxicity, would be done. If a severe headache and fever is present, the signs of meningitis would be sought. The neck, face, jaw, sinuses, nose, mouth and throat would be examined for accompanying problems, specifically for pain on movement or palpation, discharges, colour changes, swelling, and tenderness of skin and glands, all of which may indicate spread of the infection. The unaffected ear may often be examined before the one that is causing the problem, which may cause the patient to doubt whether the doctor had heard the complaint correctly. While the comment that “it’s not that ear” is entirely appropriate, the healthy ear may be examined first to assess what is normal for the patient, and to make her more comfortable with an examination which may turn out to hurt somewhat on the affected side.


===Differentiating between otitis externa and otitis media===
On the affected side, the presence and the nature of any ear discharge would be noted, as well as the colour and texture of the skin outside the ear. Swelling of the external ear structures can be seen without resorting to any painful contact. If the pinna is not inflamed, the examiner may pull gently on it, to see whether that causes the ear canal to hurt. Alternatively, light pressure may be applied to the tragus (the triangular bit of skin-covered cartilage that sticks out in front of the external ear canal, opposite the pinna). This pain on movement of the external ear structures is virtually diagnostic of otitis externa, but it does not mean that this is the complete diagnosis, that is, the person may be suffering from more than just outer ear infection.


The second type of common "earache" is [[otitis media]], and this inflammation of the [[tympanic membrane]] and [[middle-ear space]] is usually clinicaly distinct from otitis externa. However, the conditions are sometimes confused - particularly when there is drainage from the ear ([[otorrhea]]). In middle-ear infections, drainage only occurs if the tympanic membrane has either a perforation or retraction pocket. When there is chronic suppurative [[otitis media]], with or without [[cholesteatoma]], the drainage in the ear canal may appear identical to drainage from external otitis. In otitis media, however, there is no tenderness of the ear - no increased pain with pulling the auricle or pushing the tragus.  
The redness and swelling of the external ear canal may be obvious on just looking at the ear, and an examination with an otoscope would be attempted to visualise the precise nature of the material in the ear canal (for instance a foreign body or fungal growth), ascertain the patency of the canal, and attempt to determine the appearance of the ear drum – specifically if it shows a perforation. Depending on the facilities available, the examiner may use an ordinary hand-held otoscope, or may need to make use of an examining microscope. It would often be necessary to remove debris and pus from the canal before anything can be seen, and for this a low suction catheter is preferably used, so that further damage to the inflamed skin and bleeding may be prevented as much as possible. If a proper examination cannot be done without causing intolerable pain, and the diagnosis was reasonably certain, then treatment would be started anyway. An appointment for a more complete examination would usually be scheduled for when the pain and swelling has subsided enough to enable effective otoscopy. At the follow-up examination the canal would once more be cleaned, and another attempt made to see what the ear drum looks like. Such follow-up examination may need to be repeated. Flushing the ear, as is done for clearing ear wax, should never be done unless the examiner is certain that the ear drum is intact. Flushing may also further hurt the already irritated skin.
Children with ear tubes who develop an episode of otitis media despite having open myringotomy tubes generally will develop drainage through the tubes. This is not external otitis, but otitis media.


Quinolone antibiotics in topical form (ear drops) have been shown to be of benefit in stopping discharge from otitis media through an open eardrum, and so some treatments for otitis  externa may be of benefit to otitis media.( Macfadyen CA. Acuin JM. Gamble C. Topical antibiotics without steroids for chronically discharging ears with underlying eardrum perforations. [Review] [157 refs] [Journal Article. Meta-Analysis. Review] Cochrane Database of Systematic Reviews. (4):CD004618, 2005.) The main pitfall of having a case of otitis media misdiagnosed as otitis externa is that a serious infection of the middle-ear may have complications and [[sequelae]] over time. Additionally, many types of topical ear drops that are safe and effective for use in the ear canal can be irritating and even damaging if allowed past the ear drum into the more delicate internal membranes of the middle-ear, prompting the warning that such topical preparations ''should not be used unless the tympanic membrane is known to be intact''. For both reasons, caution is given against self-treatment of "earache" without proper medical evaluation.
In the presence of a severely swollen canal, ear drops may not be able to reach the infected tissue. In such cases the doctor may place a thin cotton lint or wick past the obstructed area, to carry medication to the whole length of the ear canal. This serves also as a path for drainage of remaining inflammatory fluid.


If there is prolonged drainage of noxious substances from the middle ear through the ear drum, then the skin of the ear canal may become secondarily inflamed. In this situation, one that occurs only in individuals with severe chronic otitis media, ''both'' external otitis and otitis media are present at that same time.  Prolonged care by a qualified specialist is generally required.
In the adult patient a urine or blood test for diabetes would be part of a routine investigation, but otherwise special investigations such as laboratory studies and x-rays are not necessary for an uncomplicated otitis externa; the diagnosis and treatment is based on the history and the physical findings. On the other hand, severe infections with systemic toxicity would require appropriate investigation to identify underlying causes and diagnose dangerous infections.


==Treatment==  
==Treatment==  
The goals of treatment would be to treat the pain, cure the acute infection, and advise the patient (or responsible persons) on how to prevent recurrences. Treatment starts when the ear is being examined for the first time, by removing as much debris and exudate as can comfortably be done. At this stage a wick may be inserted to facilitate the penetration of ear drops. Local medication would mostly be inserted at the same time. Where debris cannot be removed satisfactorily, and especially where the ear drum cannot be seen, the ear examination may need to be repeated until a satisfactory response has been observed. In the majority of cases the patient would be given oral medication for pain, and ear drops to treat the ear infection. Systemic antibiotics may sometimes be necessary, as when infection has spread outside of the range of penetration of ear drops, or the patient is at a high risk for the disease spreading (for instance with chemotherapy and depressed white cell counts).


The goal of treatment is to cure the infection and to return the ear canal skin to a healthy condition. When external otitis is very mild, in its initial stages, simply refraining from swimming or washing the hair for a few days, and keeping all implements out of the ear, usually results in cure. For this reason, external otitis is called a self-limiting condition. However, if the infection is moderate to severe, or if the climate is humid enough that the skin of the ear remains moist, spontaneous improvement may not occur.  
===Pain===
There is a paucity of scientific information on the best treatments for the pain of otitis externa, which is somewhat strange when one considers that is what most patients complain about when they ask for treatment. Fortunately, it can be assumed with reasonable certainty that recommendations for conditions such as a tooth abscess or severe cellulitis elsewhere would be effective. Local heat is frequently helpful in reducing pain, and may be applied using a warmed water bottle. There is a definite risk of causing skin burns, since the pain from thermal skin damage may be masked by the pain of the otitis, so that care should be taken to test the temperature on an area of unaffected skin such as the fore-arm. The object used may of course become contaminated with bacteria; it should be thoroughly cleaned after every use. Oral medications for pain would include paracetamol (acetaminophen), anti-inflammatory drugs (aspirin and equivalents), and opiates (morphine-like drugs, such as codeine), the type and dosage depending on the age of the person, concomitant illnesses, severity of the pain, and the preferences of the patient and doctor. Combinations of different classes of analgesics generally give the best response with minimal side-effects. The duration of pain can be shortened by local cortisone-containing drops, as well as by effective anti-infective treatment.


The use of topical solutions and suspensions in the form of ear drops is the mainstay of treatment for external otitis. These drops both physically wash collected debris from shed skin and infected drainage from the ear canal, and contain substances that either kill pathogenic germs, stop them from multiplying, or do both. The drops generally contain drying substances (astringents), acidifying agents, antibiotics and/or anti-fungal agents. Some prescription drops also contain anti-inflammatory steroids. Although there is evidence that steroids are effective at reducing the length of treatment time required, fungal otitris may be aggravated by the use of topical steroids.  
===Anti-infective treatment===
The use of antibiotic ear drops is the preferred first line of treatment when infection is not wide-spread (in wide-spread cases topical antibiotics would not reach all of the infected tissue), and the patient does not have an underlying disease that represents a risk for serious complications.<ref>Hannley MT, Denneny JC III, Holzer SS. Use of ototopical antibiotics in treating 3 common ear diseases. Otolaryngol Head Neck Surg 2000;122:934-40.</ref> In some cases, acetic acid alone is adequate.<ref name="pmid20091565">{{cite journal| author=Kaushik V, Malik T, Saeed SR| title=Interventions for acute otitis externa. | journal=Cochrane Database Syst Rev | year= 2010 | volume=  | issue= 1 | pages= CD004740 | pmid=20091565
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=clinical.uthscsa.edu/cite&email=badgett@uthscdsa.edu&retmode=ref&cmd=prlinks&id=20091565 | doi=10.1002/14651858.CD004740.pub2 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref> The specific preparation used is determined by what infecting agent is suspected, by patient sensitivity or allergy, and by the presence or absence of a perforated ear drum. Since tissue concentrations of active drug in the ear canal may reach levels three orders of magnitude greater than what can be achieved by systemic use, the problem of potential ototoxicity – specifically damage to the auditory nerve by aminoglycoside antibiotics – is a concern. Whatever antibiotic is used, the treatment should be followed conscientiously.<ref>Weber PC, Roland PS, Hannley M, Freidman R, Manolidis S, Matz G, et al. The development of antibiotic resistant organisms with the use of ototopical medications. Otolaryngol Head Neck Surg 2004;130(3 suppl):S89-94.</ref> Equally important, the drops must be able to reach the infected tissue. If the ear canal is partially closed, the use of a wick facilitates penetration of medication. Keeping the affected ear upwards for a while following insertion of the drops, and gently pressing on the tragus in a pumping action, improves the penetration of drops. In children, the application by another person is recommended. The ear drops both combat infection and wash out debris from the ear canal, so that sufficient drops may be used to run out freely after application – absorbent paper or cotton wool on the ear would soak up excess liquid when the person gets up. It may be noted here that the large database of cases analysed by Rowlands et al<ref name=rowlands2001 /> shows that persons who receive corticosteroid only ear drops recover as well as those who receive antibiotic and steroid drops, but details of the degree of infection is not known (that is, the doctors may have used steroids only for milder cases). Drying and anti-infective agents such as Burow’s solution seem to be effective in clearing up even complicated local infections, but discomfort on application may limit the use thereof.<ref>Kashiwamura M. Chida E. Matsumura M. Nakamaru Y. Suda N. Terayama Y. Fukuda S. The efficacy of Burow's solution as an ear preparation for the treatment of chronic ear infections. Otology & Neurotology. 2004:25(1):9-13.</ref> Steroids would not be used for suspected fungal infections.


When the condition has progressed to the point where the ear canal is blocked, a physician may have to begin treatment by clearing the ear under otoscopic examination and placing a thin strip of an absorbant material (ear wick) into the ear canal. In severe cases of external otitis, an otologist is needed to carefully clean out the ear canal under microscopic visualization. In such severe cases, in which drainage is abundant enough to recurrently block the ear canal, a qualified health professional may aspirate the ear several times a week for the first two or three weeks of treatment. Do note that it is imperative that there is visualization of an intact [[tympanic membrane]].  Use of certain medications with a ruptured tympanic membrane can cause tinnitus, vertigo, dizziness and hearing loss in some cases.
Systemic antibiotics, whether by mouth or by injection, may be deemed necessary when extensive spread or a local complication has occurred, the patient shows signs of systemic toxicity from the infection, or the patient is at increased risk of systemic infection due to decreased immunity and there is some doubt whether local drops would reach all of the infected tissue.  


Although the acute infection of external otitis generally resolves in a few days with topical washes and antibiotics, weeks are required before the ear canal skin is fully normal. The glands of the outer skin of the ear canal will not begin producing cerumen again until the skin is not only no longer infected, but no longer inflamed. Once healed completely, the ear canal is again self-cleaning. Until then, slight irritation can be enough to cause external otitis to flare again.
The symptoms should resolve completely within a week. If reduction in symptoms and signs does not begin within 2 days of starting treatment, culture of the ear fluid should be undertaken to establish the sensitivity of the offending organism, and one should search for local complications or unsuspected persistent aggravating or predisposing factors. Together with a lack of improvement, the presence of a perforated ear drum and suspicion of bony spread of the infection (persistent severe pain and headache) may prompt a referral to an ear nose and throat surgeon.


Effective medications include [[eardrops]] containing [[antibiotic]]s to fight infection, and [[corticosteroid]]s to reduce itching and inflammation. The first line is a topical preparation such as 2% acetic acid or a topical antibiotic solution containing antibiotics such as aminoglycoside, polymyxin or fluoroquinolone.  It is possible to have both a bacterial and fungal ear infection, and many of the topical treatments are designed to cure both.
===Preventative measures===
For those that do consult a health professional, advice on preventative measures should be part of the treatment. Education of the public who may not have suffered from the disease is desirable, particularly including parents and sportsmen (for instance at schools, and swimming or diving clubs).


Ear drops used abundantly help in clearing out the shed skin and dead bacteria in the ear canal, as well as in directly fighting the infection by interfering with the growth of bacteria. If the ear canal is very swollen, a wick may be applied in the ear to allow the drops to travel to the end of the canal. Occasionally, pills may be used in addition to the topical medications. [[Analgesics]] may be used if pain is severe. Putting something warm against the ears may reduce pain.
The preventative measures described in the section on [[Otits externa#Some predisposing factors, and associated preventative measures.| predisposing factors]] apply to persons who have had a previous episode of otitis externa or not. The most important of these measures are to dry the ears after swimming or diving, and to avoid any activities that may disrupt the continuity of the skin in the external ear canal (“picking and pushing is perforating”). Particular care should be taken where the person has suffered an episode of acute otitis externa in the preceding three weeks. Ear plugs on their own may be insufficient to prevent episodes of external otitis. In humid weather, and in persons who sweat a lot, the use of astringent drops may be superior to acidification alone.


===Non-prescription remedies===
It is the responsibility of health authorities to check public swimming places for bacterial load, but private pools and saunas represent an unmonitored risk. Persons should take note of any known cases of otitis externa in those who have used the facility recently.


Provided it is not too severe, recurrent otitis externa can often be successfully treated by non-prescription means, at low cost. ''When symptoms recur in an individual who has had a previous diagnosis made'', the use of non-prescription drops along with precautions to keep water out of the ear is generally effective. Self-treatment with non-prescription remedies is dangerous in individuals who have not been previously evaluated for the condition, because the tympanic membrane may not be intact, and because the true condition may be otitis media with drainage. Drops and water precautions may actually resolve otitis media with drainage for a period of time, while allowing an undiagnosed [[cholesteatoma]] to progress, or complications of otitis media to develop.
Awareness of the potential of jewellery and chemical substances for causing local immune-mediated inflammation may help solve difficult cases and prevent recurrence.


Effective solutions for the ear canal include acicifying and drying agents, used either singly or in combination. When the ear canal skin is inflamed from the acute otitis externa, the use of dilute acetic acid may be painful.  
===Self treatment===
It is not recommended that a person self-treat otitis externa, but persons with chronic or frequently repeating conditions often do this anyway. It should be noted that problems such as an ear drum perforation or a cholesteatoma may have developed since last the ear was examined, especially if there is an underlying problem that causes repeated episodes of otitis. This may make self treatment dangerous, with the potential for causing damage to the middle ear. Any symptoms of local spreading or systemic illness such as headache and fever would argue strongly against attempting self-treatment. Should a person decide to ignore this advice and self-treat with a solution such as 2% acetic acid or Burow's, then the potential for harm caused by inadequate treatment may be reduced if the rule is followed that drops are used therapeutically at least four times a day, and for at least three days after all symptoms have resolved. This is quite different from the preventative use of drops, where one application every day or two after swimming may have been prescribed. Furthermore, where a person has accepted self-responsibility for this condition, the attention of a health worker should be sought as soon as possible when symptoms do not begin to resolve within two days, or progress in spite of treatment, or any new symptoms appear, or symptoms persist for a week. In geographical locations where a doctor may not be available, a community nursing sister or pharmacist or the expedition medic may be qualified to at least look into the ear to exclude major perpetuating factors such as a foreign body, may be able to clean the ear, and may be able to supply appropriate antibiotics.


Burow's solution is an effective remedy against both bacterial and fungal external otitis. This is a buffered mixture of aluminum sulfate and acetic acid, and is available without prescription in the United States.
Non-prescription remedies should be used only for prevention, not therapeutically, unless the treatment has been advised by a qualified health worker.


Kashiwamura M. Chida E. Matsumura M. Nakamaru Y. Suda N. Terayama Y. Fukuda S. The efficacy of Burow's solution as an ear preparation for the treatment of chronic ear infections. [Clinical Trial. Journal Article] Otology & Neurotology. 25(1):9-13, 2004
==Complicated otitis externa==
The main complications of acute external otitis are spread of the infection to other soft tissues, persistent chronic infection, and the development of skull bone infection (termed malignant or necrotizing otitis externa, or osteitis of the base of the skull). Spread to soft tissue of the head and neck is managed as for any infection of those tissues. The development of chronic otitis externa may follow an episode of the acute disease, or its onset may be insidious, either from a localised allergic dermatitis or as part of a general inflammatory dermatitis.  


===Prevention===
===Chronic otitis externa===
Persistent or chronic otitis externa is usually not due to infection, but rather to chronic skin conditions, which includes local skin allergies, especially contact dermatitis. In the person suffering from atopic dermatitis, such unexpected activities as eating the foods which contain unknown allergens may be responsible for the condition. While inadequate treatment of infection may lead to the persistence of symptoms of inflammation, it may be the antibiotic drops themselves causing a cell-mediated allergic reaction in the ear – a case of an infectious dermatitis going on to become a chronic allergic dermatitis. A chronic ear discharge and itching may follow the placement of middle ear ventilation tubes (“grommets”), and the cause is likely only to be diagnosed by a thorough ear examination.


The stategies for preventing acute external otitis are similar to those for treatment.
Treatment may be best managed by input from both an ear nose and throat surgeon, and a dermatologist. An accurate diagnosis is essential for the best outcome, and a number of special tests may be required before such a diagnosis is established. The treatment would vary widely, from surgery to standard preventative treatment as for acute external otitis, and the outcome depends mainly on the treatability of the cause.
* Dry the ear thoroughly after exposure to moisture. This can be accomplished by the use of drops containing dilute alcohol or Burow's solution. The use of dilute alochol drops is not recommended except for prevention, as the solution is painful if the skin is inflamed by an acute episode.
* Avoid swimming in polluted water.
* Avoid washing the hair or swimming if very mild symptoms of acute external otitis begin
* Although the use of [[earplugs]] when swimming and shampooing the hair may help prevent external otitis, there are important details in the use of plugs. Hard and poorly fitting ear plugs can scratch the ear canal skin and set off an episode. When earplugs are used during an acute episode, either disposable plugs are recommended, or used plugs must be cleaned and dried properly to avoid contaminating the healing ear canal with infected discharge. One simple method of fabricating soft waterproof disposable ear plugs is with cotton balls and petrolueum jelly. These jelly coated cotton balls are NOT inserted into the ear canal, but pressed into the auricle to cover the opening of the canal.


==Prognosis==
===Osteomyelitis of the base of the skull===
Otitis externa responds well to treatment, but complications may occur if it is not treated. Individuals with underlying [[diabetes]] or disorders of the immune system are more likely to get complications, including malignant otitis externa. In these individuals, rapid examination by a physician is very important.
This highly dangerous condition is known by three names: necrotising otitis externa<ref> Evans IT, Richards SH Malignant (necrotising) otitis externa. J Laryngol Otol. 1973 Jan;87(1):13-20. PMID: 4683554.</ref> occurs when acute otitis externa spreads to cause osteomyelitis of the base of the skull,<ref>Meltzer PE, Kelemen G. Pyocyaneous osteomyelitis of the temporal bone, mandible and zygoma. Laryngoscope 1959;169:1300-16.</ref> which is also called malignant otitis externa.<ref name=chandler1968>Chandler JR: Malignant external otitis. Laryngoscope 1968 Aug; 78(8): 1257-94</ref> “Necrotising” refers to the death of affected tissue, “malignant” refers to the bad behaviour and poor outcome of the infection, “osteitis of the base of the skull” points out which tissue is infected where in the body. Osteomyelitis of the skull base is dangerous not only because it destroys bone, but because, in addition to affecting the full thickness of the bones and their periosteum, it involves the underlying dura, the major vessels and cranial nerves of the base of the skull, and the surrounding soft tissue. The group of persons who were originally described as being at risk for developing this complication of otitis externa are older diabetics, but it is now apparent that all persons who are immuno-compromised (chemotherapy, leukemia, HIV infection) are at risk, though the disease has slightly different characteristics in persons with AIDS.<ref>Ress BD, Luntz M, Telischi FF, Balkany TJ, Whiteman ML. Necrotizing external otitis in patients with AIDS. Laryngoscope 1997;107:456-60.</ref> Radiation therapy to the bones of the skull is also associated with the disease. The symptoms and signs include severe, continuous pain felt deep inside the ear, and headache over the temple area. The pain seems out of proportion to the observed changes in the external ear canal and varies in the course of a day, being more severe at night. There may be a purulent, possibly foul smelling discharge from the ear. The patient may have difficulty swallowing or speaking, and possibly paralysis of one side of the face. The area directly below the ear canal is tender. When the external ear canal is examined, the ear drum is usually seen to be intact. Bare bone, areas where the external ear canal is denuded of skin, was reported in all of six cases seen in an Indian hospital over 10 years.<ref>Sardesai RB, Krishnakumar T. Malignant otitis external - our experience. Indian Journal of Otolaryngology and Head and Neck Surgery. 2002 April-June;54(2),132-5.</ref> A growth of red, friable granulation tissue, located at the junction of the inner bony canal and the outer cartilaginous part, in the lower part (floor) of the external ear canal, is considered to be diagnostic of the condition. There may be demonstrable loss of function of various cranial nerves, while disturbance of mental function may indicate that the brain is affected. In spite of the severity of the condition, fever is not usually present.<ref name=nussenbaum>Nussenbaum B, Roland PS, MDExternal Ear, Malignant External Otitis. eMedicine Specialties, Otolaryngology and Facial Plastic Surgery, External Ear Diseases. http://www.emedicine.com/Ent/topic203.htm Last Updated: April 14, 2006</ref> The offending organism is almost always pseudomonas aeruginosa. Twenty years ago the mortality was still reported as 53%,<ref>Chandler JR, Grobman L, Quencer R, Serafini A. Osteomyelitis of the base of the skull. Laryngoscope. 1986 Mar;96(3):245-51. PMID: 3485233</ref> but improved antibiotics have reduced that to approximately 10%. Diseases that this condition need to be differentiated from include a number of cancers, shingles of the ear, and Paget’s disease of bone.
There are two explanations offered for why diabetics are so susceptible to osteomyelitis of the base of the skull. The first is that the occlusion of small blood vessels found in diabetics predisposes them to necrosis of bone, while at the same time decreasing delivery of antibiotic drugs to the affected tissue. The second is the decreased effectiveness of leukocytes found in diabetics. Both these reasons are equally valid for explaining the tendency of diabetics to develop infections and gangrene right at the other end of their bodies, in the feet. The statistic that 50% of cases of malignant otitis externa in diabetics have a recent history of having a traumatic ear wash out, suggests that these patients had been suffering from a non-specific discomfort of the ear for a while before the osteitis started (hence the washout), and that it was aggravated or spread by injury incurred during the lavage.<ref name=nussenbaum />


==Complications==
The course of the untreated disease is a steady progression of symptoms and signs eventually leading to death. There is a progressive involvement of the cranial nerves. While loss of movement on one side of the face (cranial nerve VII) is not a fatal condition, loss of swallowing and laryngeal reflexes (Cranial nerves V (trigeminal), VII (facial), X (vagus), XI (accessory), and XII (hypoglossal)) may lead to aspiration into the lungs of secretions, food or regurgitated stomach content. Such events may lead to pneumonia. Following the cranial nerve palsies, meningitis, brain abscesses, and thromboses of the cerebral arteries, veins and sinuses can occur, which may be rapidly fatal. Given the age and co-morbid conditions that these diabetic patients may suffer from, the person is at risk for intercurrent acute illness of the lungs, heart and kidneys, not directly related to the disease in their head. <ref name=chandler1968 />
* Chronic otitis externa
===Necrotizing External Otitis  (Malignant otitis externa)===
This rare form of external otitis only occurs in individuals with severe diabetes or severely compromised immune systems. Rather than being a superficial infection of the outer ear, this is an osteomyelitis of the skull base and can extend deeply into the head. Malignant otitis externa begins as a soft tissue infection of the external auditory canal, but soon goes deeper into the bone. Granulation tissue forms on the floor of the canal at the bony-cartilaginous junction. Unlike middle ear infections that involve bone, spread is not into the mastoid, but to compact bone along the middle with eventual extension to the petrous apex. There is often granulation tissue visible in the ear canal, typically at the junction of the bony and cartilaginous canals. Biopsies of affected bone show new bone formation adjacent to areas of destruction. The otic capsule exhibits significant resistance to involvement of the disease and middle ear structures are rarely involved until late in the disease course.<ref>{{cite journal | author = Sreepada G, Kwartler J | title = Skull base osteomyelitis secondary to malignant otitis externa. | journal = Curr Opin Otolaryngol Head Neck Surg | volume = 11 | issue = 5 | pages = 316-23 | year = 2003 | id = PMID 14502060}}</ref>
* Spread of infection to other areas of the body


When the diagnosis is suspected, the special investigations which may be done include laboratory tests for the underlying causative diseases, assessment of the hematological and immune response to the infection, and baseline measurements of the function of vital organs such as the kidneys, which are necessary for planning and following up treatment and the course of the disease. Testing for the type of organism and its sensitivity to different antibiotics is essential, while a biopsy of the granulation tissue in the ear canal is needed to examine for possible cancer. Radio-isotope imaging studies (“scintiscans”) that can detect bone resorption and deposition and spread of inflammation – depending on the isotope technique used – are valuable to confirm the diagnosis, as well as to determine the response to treatment. Computer tomographic x-ray studies (“CT scans”) can show bone destruction and alterations in density, as well as alterations in soft tissues such as abscesses. They are not very sensitive to early changes, detecting osteomyelitis only after 30% of the bone density has been lost. Magnetic resonance imaging (“MRI scans”) usually shows soft tissue changes more clearly than CT, but visualises bone changes poorly. Neither one of the last two techniques is suitable for determining the response to treatment on a weekly or monthly basis. The person suspected of having osteomyelitis of the skull base may therefore be subjected to a battery of tests for diagnosis, and a different set of tests for follow-up at different intervals.


Treatment is aimed at eliminating the primary source for the infection (external ear canal), treating any underlying systemic disease effectively, managing the person’s pain, distress and fear, eliminating the bacteria from the bone and soft tissue which has been invaded, treating the complications of nerve paralysis and effects of infection on the nervous system, and planning for preventative measures in the future. The treatment of each one of these aims follows standard recommendations, and a description of all the possible therapies is outside the scope of this article. Aggressive medical management is the present recommendation for acute disease, with surgery rarely being necessary except to treat abscesses and remove sequestered bone.<ref>Sreepada G, Kwartler J. Skull base osteomyelitis secondary to malignant otitis externa. Curr Opin Otolaryngol Head Neck Surg. 2003:11(5);316-23. PMID 14502060</ref> Accurate control of blood glucose levels, aggressive treatment of the otitis externa, and adequate doses of appropriate antibiotics for a suitable length of time can cure up to 90% of cases. Frequent bacterial cultures is invaluable for selecting the antibiotic treatment, since sensitivities of the organism may change during therapy. Hyperbaric oxygen therapy is recommended by some, but has not been proven to improve the outcome of the disease. The duration of therapy is determined by blood tests and by isotope scans which can show the elimination of infection and inflammation, treatment being continued for a week after tests have returned to normal. Duration of treatment varies from 4-17 weeks, and follow-up isotope scans and blood tests have to be done to eliminate reactivation of disease.<ref>Benecke JE Jr. Management of osteomyelitis of the skull base. Laryngoscope. 1989 Dec; 99(12): 1220-3</ref>


==References==
==References==
<references/>
{{reflist|2}}[[Category:Suggestion Bot Tag]]
 
==External links==
*[http://www.seattlechildrens.org/child_health_safety/health_advice/swimmers_ear.asp What to do if your child has swimmer's ear], from Seattle Children's Hospital
 
 
[[Category:Health Sciences Workgroup]]

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Otitis externa is inflammation of the outer ear canal[1] It usually presents as one or more of the complaints of an earache, a persistent itch in the ear, a runny ear, deafness of the affected ear, or red and swollen skin in or around the ear canal or external ear. It is most often an acute condition, almost always an infection of the skin and subcutaneous tissue of the canal, which may spread to involve the skin surrounding the ear, the face and neck, the local lymph glands and the salivary glands. Uncomplicated recovery is the norm, but in diabetics and immunocompromised persons rapid spread is potentially dangerous and requires prompt treatment. Chronic otitis externa affects fewer persons, is often a manifestation of a general inflammatory skin disease (for instance soborrheic dermatitis), and may be defined as signs or symptoms of otitis externa that lasts for more than four months, or occurring more than four times per year. The body of this article concerns acute otitis externa, the chronic disease will be described separately in its own section. When the causes of the illness are understood, then it is clear that most cases of otitis externa could be prevented by proper preventative measures.

Anatomy and physiology pertinent to understanding otitis externa

The external ear canal serves to protect the middle and inner ear from injury, while providing an air passage for the conduction of sound, together with the pinna amplifying and improving directional localisation of sound. Being a blind-ending tube, it is vulnerable to blockage and infection. Certain characteristics reduce the risk of infection occurring. The skin lining the external ear shows a unique pattern of growth, growing in a sideways direction, moving as a sheet of tissue from the eardrum end to the outer opening. This mass movement of the epithelial layer of cells carries with it cellular and foreign debris which may collect on the skin of the inner part to where it may be easily picked off at the outer opening – a self-cleaning mechanism which is foiled when an object like an earbud is pushed from the outside inwards. The skin is covered by a layer of cerumen (wax) produced by the skin glands of the outer third of the canal. This wax is a barrier to infection of the skin by virtue of its water repellancy, relatively acidic pH of 6.9, and its content of lyzosyme.[2] Hairs occur on the skin of the outer third, serving to prevent entry of foreign material to the inner two thirds.

Anatomically,the skin of the inner two-thirds of the ear canal is extremely thin, and closely overlies the bone. The lack of underlying fat and supporting tissue makes this skin vulnerable to scratches, tears and cracking. At the junction of the bony and cartilaginous parts, the adult ear canal makes a turn forwards and downwards, forming a bend where larger bits of material can get stuck. The outer third has thicker skin, supported by cartilage and fatty tissue and containing hair follicles and skin glands. It is therefore less commonly the site of origin of an otitis externa.

Incidence and pathology

Most cases of early acute otitis externa heal with simple measures such as stopping swimming, with or without eardrops such as 2% vinegar, or 70% alcohol (or a mixture of the two) as preventative and therapeutic treatment. These cases seldom come to the attention of health services, which has the consequence that estimates of the incidence of otitis externa are unreliable.

Acute otitis externa is common, with an incidence of approximately 13 per 1000 patients in general practice in the Netherlands[3] and Britain,[4] and 4 per 1000 in the United States.[5] A study of more than 40,000 cases in 30,000 persons over a year in British general practices showed a prevalence in females of 1.3%, and males 1.16%, the highest yearly prevalence being in persons 25 and 75 years of age. More than 20% had more than one episode.[4] As skin infections go, and for the volume of the infected tissue, otitis externa has a significant morbidity (negative effect on general health). In a swimming-associated outbreak of 94 cases, a third suffered a median of four days of loss of normal activities, while slightly more than one fifth took to their beds for a median of three days.[6]

For acute otitis externa, a common initiating event is water carried into the external ear canal, and in contact with the thin skin for prolonged periods. This leads to maceration of the skin lining the canal. Moist macerated skin is a good culture medium for the organisms carried in with infected water. The association of otitis externa with swimming or diving, especially in contaminated water, has given rise to the common name of “swimmer’s ear” or “diver’s ear”. Repeated contact with water increases the risk of maceration and infection by reducing the protective layer of cerumen, while decreasing the acidity of the skin in the outer ear. On the other hand, excessive wax may promote trapping of water in the canal. Humid weather and warm temperatures increase the likelihood of skin maceration, and the incidence of acute otitis media. The second important cause of initial infection is mechanical injury to the skin by objects such as hearing aids and ear plugs, or “instruments” persons use to clean out their ears.[7] The offending instrument may be anything from a fingernail to a matchstick to a cotton earbud (this may of course be equally risky for causing an ear drum perforation). Apart from damage due to attempts at cleaning the canal, the skin may be scratched in an attempt to alleviate the itch of mild otitis externa, or the perceived blockage of the canal, leading to exacerbation of the condition. Less commonly, conditions such as eczema or psoriasis disrupt the continuity of the skin, allowing invasion of pathogenic bacteria (a case of an acute infection following chronic inflammation).

Whatever the initiating event, the bacteria multiply and cause an acute infection and inflammation of the skin and subcutaneous tissue (cellulitis). The ear canal swells shut and the ear develops a discharge. At this stage the person may complain of hearing loss in the affected ear, as well as tinnitus (a persistent ringing in the ear) which is caused by the occluded ear canal. If the infection is not contained, it may in severe cases spread along the subcutaneous tissue, causing a cellulitis of the neck and the side of the face. Local lymph glands become acutely inflamed, and the parotid salivary gland enlarged and tender (so-called diffuse external otitis[8]). In such cases, differentiation from malignant otitis externa (see the next paragraph) purely on grounds of the examination may be difficult.

Acute or chronic otitis externa may progress to affect the cartilage of the ear (chondritis), or the bones surrounding the ear canal (osteomyelitis). The latter tends to be progressive and difficult to cure, with a risk of infection spreading through the bone to other parts of the skull and even the central nervous system. This malignant or necrotising form of otitis externa is more common in diabetics or immune compromised persons, and requires aggressive treatment, both surgical and medical.[9]

For a few weeks after an episode of acute otitis externa the outer ear is susceptible to becoming infected more easily than normal. The skin itself is thinned and lacks a normal outer protective keratin layer, while wax production decreases markedly, even after all infection has disappeared. Therefore repeat exposure to the precipitating circumstances is likely to cause another bout of the disease.

The organisms implicated in otitis externa are most commonly opportunistic pathogens, that is, organisms that do not cause disease in healthy tissue, but can infect tissue where the immunity is reduced. Macerated skin, scratches and loss of cerumen represent such local loss of immunity, while diabetes, AIDS and chemotherapy are systemic causes. Pseudomonas aeruginosa is found in up to 50% of cases, other bacterial infections (Staphylococcus epidermides, Staphylococcus aureus, and Streptococcus pyogenes) account for 40%, and fungi about 10%.[10][11][12]

Symptoms

Ear discomfort is the usual symptom of otitis externa. This may be an itch and mild pain, or, in advanced cases, severe pain requiring strong analgesics. When not just minor, pain is disproportionate to the volume of inflamed tissue, because the tissue is confined to a small volume and impinges on bony boundaries, so that increased local pressure and irritation of periosteum occurs early on. Since the pinna and the tragus is connected to the cartilage of the outer third of the ear, and that to the skin, movement of these structures causes pain from distortion of the inflamed skin. This extreme sensitivity to movement is generally not found in uncomplicated otitis media, the other common cause of earache.

A discharge from the ear commonly occurs, but is usually not the primary complaint. It can vary from a mild watery consistency and colour, to thick, yellow or white, to a bloody purulent discharge.

Redness and swelling can usually be seen in the ear canal. The swelling may obscure the canal completely, so that the ear feels blocked up and deaf, and be a source of tinnitus. The outer ear and surrounding tissue may show these symptoms and signs of inflammation, depending on the spread of the infection. The signs of a diffuse otitis externa can be confused with malignant otitis externa.[8]

Bacterial otitis externa is associated more severe local symptoms and morbidity than other causes. The person with acute bacterial otitis externa may feel ill, complain of headache, and develop a moderate fever, usually less than 38.3°C. More severe illness would prompt the examining person to look for complications.

Some predisposing factors, and associated preventative measures

Anyone can develop oitits externa, and mild forms may go undiagnosed in persons who experience simply an itchy ear for a while. There are, however certain activities, circumstances and medical conditions where the risk for the disease increases. All of the risks apply also to immunocompromised persons, the chronically ill and diabetics – groups also at increased risk for the complications of otitis externa. Such persons should take particular care to avoid activities which predispose to otitis externa, or be particular about preventative measures when such conditions are unavoidable.

Where the person is engaged in activities that entail prolonged exposure of the external ear canal to water, the protective cerumen on the skin in the canal may be gradually washed away, leaving the skin unprotected. Loose surface keratin can now absorb moisture, becoming macerated and effectively a culture medium for bacteria. Since the pH of the ear increases at the same time, there is no protection against such growth. Swimmers and divers are clearly at risk, and regular swimming remains the most significant risk factor for acute otitis externa, with fresh water being more of a problem than sea water or chlorinated pools.[13][14][15] Water which is considered safe by the standards for fecal coliform contamination may contain high numbers of organisms that may cause infection of a damaged external ear canal, but the precise correlation is not clear.[16] Spells of hot weather, with high humidity and excessive sweating present a similarly increased risk of developing acute otitis externa. Preventing water getting into the ears would logically be the best preventative measure for those who love swimming. This can be achieved by the use of a well-fitting bathing cap, or properly fitted ear plugs, but hard or ill-fitting ear plugs may exacerbate the problem. It is unfortunately not known how effective this “logical” measure is in preventing the disease. Measures used after swimming include thorough drying of the ears and the use of acidifying ear drops. Drop containing alcohol, and Burow’s solution (5% aluminium subacetate solution) both have an astringent action, but may be irritating, especially if the skin is not entirely normal. Drying the ears using an ordinary hair dryer set on its lowest heat is effective, while battery powered hot air ear dryers are marketed. Following an attack of ititis externa, the use of acidic ear drops before and after swimming is often recommended, for at least three weeks, and in the long term if the infection tends to recur.

Direct trauma to the skin of the inner two thirds of the external ear canal is easily inflicted, especially near the junction with the outer third, where the canal makes a change of direction and the skin becomes thin and tightly applied to the underlying bone. The habit of personally cleaning one’s ears is more dangerous than beneficial, and while kitchen matches, the classroom protractors, and the beautician’s beautiful nails are clearly dangerous instruments, the soft tips of cotton ear buds are deceptively harmless, and one of the very common causes of hurting the soft skin lining the bony canal – as well as the ear drum. Ironically, damage is not infrequently done by “beneficial” acts, such as inserting a hearing aid earpiece or wearing ear plugs in an attempt to prevent noise-related hearing damage or prevent water from getting into the ear canal. Foreign bodies that lodge in the external ear are an important cause in young children, and in mentally retarded persons. The danger here is not always the presence of the object, but do-it-yourself or kindly third party efforts to remove the object. The same applies to adults, where an enormous variety of objects such as insects, seeds or bit of wood cuttings can get stuck in the outer ear. If these are not removed atraumatically under direct vision, then the scene may be set for damage to the outer and middle ear, including an episode of acute otitis externa a day or two later.

Health workers are not blameless with respect to damaging the external ear canal. A professional person who removes wax or any other object from an ear using sharp instruments under inadequate vision runs the risk of causing injury. If that is not diagnosed and treated to prevent infection, the situation is no better than if the patient had done the scratching himself. The incorrect use of an otoscope is another entirely iatrogenic cause. Even syringing of the ears should be considered a predisposing condition for otitis externa, by washing away protective wax and altering the pH in the ear canal. Many health workers recommend the prophylactic use of acidic ear drops for a few days following such a procedure.

The last group of risk factors is to a large extent beyond the direct control of a person. This is where a general dermatological condition has affected the skin of the ear. In many of these cases the person would be suffering from a chronic, low grade inflammation of the outer ear canal. The itch that this causes may lead to scratching activities which set off the acute otitis externa, or an acute exacerbation of the primary disease may disrupt the integrity of the skin. Conditions which can be included here are acne, atopic dermatitis, contact dermatitis, eczema, lupus erythematosus, psoriasis, and seborrheic dermatitis.[17] A person should be aware that allergic contact dermatitis may be confined to only the skin of the outer ear, so that the diagnosis may be missed because there are no symptoms or signs of dermatitis elsewhere. Immune-mediated otitis can occur in response to the metals contained in earrings or studs, chemicals in cosmetics and hair care products, solvents used in the plastics used to make hearing aids, and medications in ear drops (especially antibiotics). Apart from the allergic risk of antibiotic ear drops, alteration of the skin bacteria may lead to fungal infections, usually after prolonged use of these drops. Persisting with the antibiotic treatment only worsens the condition.

Diagnosis

When a person presents with complaints of ear discomfort, itching, pain, a discharge, or a deaf or ringing ear, the doctor would take a history of how and when the symptoms started, how they have developed and what contributory factors there may be – this would include previous ear problems, treatments, other illnesses, accidents and injuries, as well as daily activities and sport. During the examination, the patient may be surprised that the doctor does not look only at the sore ear, but there are good reasons for this. A general assessment for signs of systemic illness, including the temperature, pulse rate, and signs of toxicity, would be done. If a severe headache and fever is present, the signs of meningitis would be sought. The neck, face, jaw, sinuses, nose, mouth and throat would be examined for accompanying problems, specifically for pain on movement or palpation, discharges, colour changes, swelling, and tenderness of skin and glands, all of which may indicate spread of the infection. The unaffected ear may often be examined before the one that is causing the problem, which may cause the patient to doubt whether the doctor had heard the complaint correctly. While the comment that “it’s not that ear” is entirely appropriate, the healthy ear may be examined first to assess what is normal for the patient, and to make her more comfortable with an examination which may turn out to hurt somewhat on the affected side.

On the affected side, the presence and the nature of any ear discharge would be noted, as well as the colour and texture of the skin outside the ear. Swelling of the external ear structures can be seen without resorting to any painful contact. If the pinna is not inflamed, the examiner may pull gently on it, to see whether that causes the ear canal to hurt. Alternatively, light pressure may be applied to the tragus (the triangular bit of skin-covered cartilage that sticks out in front of the external ear canal, opposite the pinna). This pain on movement of the external ear structures is virtually diagnostic of otitis externa, but it does not mean that this is the complete diagnosis, that is, the person may be suffering from more than just outer ear infection.

The redness and swelling of the external ear canal may be obvious on just looking at the ear, and an examination with an otoscope would be attempted to visualise the precise nature of the material in the ear canal (for instance a foreign body or fungal growth), ascertain the patency of the canal, and attempt to determine the appearance of the ear drum – specifically if it shows a perforation. Depending on the facilities available, the examiner may use an ordinary hand-held otoscope, or may need to make use of an examining microscope. It would often be necessary to remove debris and pus from the canal before anything can be seen, and for this a low suction catheter is preferably used, so that further damage to the inflamed skin and bleeding may be prevented as much as possible. If a proper examination cannot be done without causing intolerable pain, and the diagnosis was reasonably certain, then treatment would be started anyway. An appointment for a more complete examination would usually be scheduled for when the pain and swelling has subsided enough to enable effective otoscopy. At the follow-up examination the canal would once more be cleaned, and another attempt made to see what the ear drum looks like. Such follow-up examination may need to be repeated. Flushing the ear, as is done for clearing ear wax, should never be done unless the examiner is certain that the ear drum is intact. Flushing may also further hurt the already irritated skin.

In the presence of a severely swollen canal, ear drops may not be able to reach the infected tissue. In such cases the doctor may place a thin cotton lint or wick past the obstructed area, to carry medication to the whole length of the ear canal. This serves also as a path for drainage of remaining inflammatory fluid.

In the adult patient a urine or blood test for diabetes would be part of a routine investigation, but otherwise special investigations such as laboratory studies and x-rays are not necessary for an uncomplicated otitis externa; the diagnosis and treatment is based on the history and the physical findings. On the other hand, severe infections with systemic toxicity would require appropriate investigation to identify underlying causes and diagnose dangerous infections.

Treatment

The goals of treatment would be to treat the pain, cure the acute infection, and advise the patient (or responsible persons) on how to prevent recurrences. Treatment starts when the ear is being examined for the first time, by removing as much debris and exudate as can comfortably be done. At this stage a wick may be inserted to facilitate the penetration of ear drops. Local medication would mostly be inserted at the same time. Where debris cannot be removed satisfactorily, and especially where the ear drum cannot be seen, the ear examination may need to be repeated until a satisfactory response has been observed. In the majority of cases the patient would be given oral medication for pain, and ear drops to treat the ear infection. Systemic antibiotics may sometimes be necessary, as when infection has spread outside of the range of penetration of ear drops, or the patient is at a high risk for the disease spreading (for instance with chemotherapy and depressed white cell counts).

Pain

There is a paucity of scientific information on the best treatments for the pain of otitis externa, which is somewhat strange when one considers that is what most patients complain about when they ask for treatment. Fortunately, it can be assumed with reasonable certainty that recommendations for conditions such as a tooth abscess or severe cellulitis elsewhere would be effective. Local heat is frequently helpful in reducing pain, and may be applied using a warmed water bottle. There is a definite risk of causing skin burns, since the pain from thermal skin damage may be masked by the pain of the otitis, so that care should be taken to test the temperature on an area of unaffected skin such as the fore-arm. The object used may of course become contaminated with bacteria; it should be thoroughly cleaned after every use. Oral medications for pain would include paracetamol (acetaminophen), anti-inflammatory drugs (aspirin and equivalents), and opiates (morphine-like drugs, such as codeine), the type and dosage depending on the age of the person, concomitant illnesses, severity of the pain, and the preferences of the patient and doctor. Combinations of different classes of analgesics generally give the best response with minimal side-effects. The duration of pain can be shortened by local cortisone-containing drops, as well as by effective anti-infective treatment.

Anti-infective treatment

The use of antibiotic ear drops is the preferred first line of treatment when infection is not wide-spread (in wide-spread cases topical antibiotics would not reach all of the infected tissue), and the patient does not have an underlying disease that represents a risk for serious complications.[18] In some cases, acetic acid alone is adequate.[19] The specific preparation used is determined by what infecting agent is suspected, by patient sensitivity or allergy, and by the presence or absence of a perforated ear drum. Since tissue concentrations of active drug in the ear canal may reach levels three orders of magnitude greater than what can be achieved by systemic use, the problem of potential ototoxicity – specifically damage to the auditory nerve by aminoglycoside antibiotics – is a concern. Whatever antibiotic is used, the treatment should be followed conscientiously.[20] Equally important, the drops must be able to reach the infected tissue. If the ear canal is partially closed, the use of a wick facilitates penetration of medication. Keeping the affected ear upwards for a while following insertion of the drops, and gently pressing on the tragus in a pumping action, improves the penetration of drops. In children, the application by another person is recommended. The ear drops both combat infection and wash out debris from the ear canal, so that sufficient drops may be used to run out freely after application – absorbent paper or cotton wool on the ear would soak up excess liquid when the person gets up. It may be noted here that the large database of cases analysed by Rowlands et al[4] shows that persons who receive corticosteroid only ear drops recover as well as those who receive antibiotic and steroid drops, but details of the degree of infection is not known (that is, the doctors may have used steroids only for milder cases). Drying and anti-infective agents such as Burow’s solution seem to be effective in clearing up even complicated local infections, but discomfort on application may limit the use thereof.[21] Steroids would not be used for suspected fungal infections.

Systemic antibiotics, whether by mouth or by injection, may be deemed necessary when extensive spread or a local complication has occurred, the patient shows signs of systemic toxicity from the infection, or the patient is at increased risk of systemic infection due to decreased immunity and there is some doubt whether local drops would reach all of the infected tissue.

The symptoms should resolve completely within a week. If reduction in symptoms and signs does not begin within 2 days of starting treatment, culture of the ear fluid should be undertaken to establish the sensitivity of the offending organism, and one should search for local complications or unsuspected persistent aggravating or predisposing factors. Together with a lack of improvement, the presence of a perforated ear drum and suspicion of bony spread of the infection (persistent severe pain and headache) may prompt a referral to an ear nose and throat surgeon.

Preventative measures

For those that do consult a health professional, advice on preventative measures should be part of the treatment. Education of the public who may not have suffered from the disease is desirable, particularly including parents and sportsmen (for instance at schools, and swimming or diving clubs).

The preventative measures described in the section on predisposing factors apply to persons who have had a previous episode of otitis externa or not. The most important of these measures are to dry the ears after swimming or diving, and to avoid any activities that may disrupt the continuity of the skin in the external ear canal (“picking and pushing is perforating”). Particular care should be taken where the person has suffered an episode of acute otitis externa in the preceding three weeks. Ear plugs on their own may be insufficient to prevent episodes of external otitis. In humid weather, and in persons who sweat a lot, the use of astringent drops may be superior to acidification alone.

It is the responsibility of health authorities to check public swimming places for bacterial load, but private pools and saunas represent an unmonitored risk. Persons should take note of any known cases of otitis externa in those who have used the facility recently.

Awareness of the potential of jewellery and chemical substances for causing local immune-mediated inflammation may help solve difficult cases and prevent recurrence.

Self treatment

It is not recommended that a person self-treat otitis externa, but persons with chronic or frequently repeating conditions often do this anyway. It should be noted that problems such as an ear drum perforation or a cholesteatoma may have developed since last the ear was examined, especially if there is an underlying problem that causes repeated episodes of otitis. This may make self treatment dangerous, with the potential for causing damage to the middle ear. Any symptoms of local spreading or systemic illness such as headache and fever would argue strongly against attempting self-treatment. Should a person decide to ignore this advice and self-treat with a solution such as 2% acetic acid or Burow's, then the potential for harm caused by inadequate treatment may be reduced if the rule is followed that drops are used therapeutically at least four times a day, and for at least three days after all symptoms have resolved. This is quite different from the preventative use of drops, where one application every day or two after swimming may have been prescribed. Furthermore, where a person has accepted self-responsibility for this condition, the attention of a health worker should be sought as soon as possible when symptoms do not begin to resolve within two days, or progress in spite of treatment, or any new symptoms appear, or symptoms persist for a week. In geographical locations where a doctor may not be available, a community nursing sister or pharmacist or the expedition medic may be qualified to at least look into the ear to exclude major perpetuating factors such as a foreign body, may be able to clean the ear, and may be able to supply appropriate antibiotics.

Non-prescription remedies should be used only for prevention, not therapeutically, unless the treatment has been advised by a qualified health worker.

Complicated otitis externa

The main complications of acute external otitis are spread of the infection to other soft tissues, persistent chronic infection, and the development of skull bone infection (termed malignant or necrotizing otitis externa, or osteitis of the base of the skull). Spread to soft tissue of the head and neck is managed as for any infection of those tissues. The development of chronic otitis externa may follow an episode of the acute disease, or its onset may be insidious, either from a localised allergic dermatitis or as part of a general inflammatory dermatitis.

Chronic otitis externa

Persistent or chronic otitis externa is usually not due to infection, but rather to chronic skin conditions, which includes local skin allergies, especially contact dermatitis. In the person suffering from atopic dermatitis, such unexpected activities as eating the foods which contain unknown allergens may be responsible for the condition. While inadequate treatment of infection may lead to the persistence of symptoms of inflammation, it may be the antibiotic drops themselves causing a cell-mediated allergic reaction in the ear – a case of an infectious dermatitis going on to become a chronic allergic dermatitis. A chronic ear discharge and itching may follow the placement of middle ear ventilation tubes (“grommets”), and the cause is likely only to be diagnosed by a thorough ear examination.

Treatment may be best managed by input from both an ear nose and throat surgeon, and a dermatologist. An accurate diagnosis is essential for the best outcome, and a number of special tests may be required before such a diagnosis is established. The treatment would vary widely, from surgery to standard preventative treatment as for acute external otitis, and the outcome depends mainly on the treatability of the cause.

Osteomyelitis of the base of the skull

This highly dangerous condition is known by three names: necrotising otitis externa[22] occurs when acute otitis externa spreads to cause osteomyelitis of the base of the skull,[23] which is also called malignant otitis externa.[24] “Necrotising” refers to the death of affected tissue, “malignant” refers to the bad behaviour and poor outcome of the infection, “osteitis of the base of the skull” points out which tissue is infected where in the body. Osteomyelitis of the skull base is dangerous not only because it destroys bone, but because, in addition to affecting the full thickness of the bones and their periosteum, it involves the underlying dura, the major vessels and cranial nerves of the base of the skull, and the surrounding soft tissue. The group of persons who were originally described as being at risk for developing this complication of otitis externa are older diabetics, but it is now apparent that all persons who are immuno-compromised (chemotherapy, leukemia, HIV infection) are at risk, though the disease has slightly different characteristics in persons with AIDS.[25] Radiation therapy to the bones of the skull is also associated with the disease. The symptoms and signs include severe, continuous pain felt deep inside the ear, and headache over the temple area. The pain seems out of proportion to the observed changes in the external ear canal and varies in the course of a day, being more severe at night. There may be a purulent, possibly foul smelling discharge from the ear. The patient may have difficulty swallowing or speaking, and possibly paralysis of one side of the face. The area directly below the ear canal is tender. When the external ear canal is examined, the ear drum is usually seen to be intact. Bare bone, areas where the external ear canal is denuded of skin, was reported in all of six cases seen in an Indian hospital over 10 years.[26] A growth of red, friable granulation tissue, located at the junction of the inner bony canal and the outer cartilaginous part, in the lower part (floor) of the external ear canal, is considered to be diagnostic of the condition. There may be demonstrable loss of function of various cranial nerves, while disturbance of mental function may indicate that the brain is affected. In spite of the severity of the condition, fever is not usually present.[27] The offending organism is almost always pseudomonas aeruginosa. Twenty years ago the mortality was still reported as 53%,[28] but improved antibiotics have reduced that to approximately 10%. Diseases that this condition need to be differentiated from include a number of cancers, shingles of the ear, and Paget’s disease of bone. There are two explanations offered for why diabetics are so susceptible to osteomyelitis of the base of the skull. The first is that the occlusion of small blood vessels found in diabetics predisposes them to necrosis of bone, while at the same time decreasing delivery of antibiotic drugs to the affected tissue. The second is the decreased effectiveness of leukocytes found in diabetics. Both these reasons are equally valid for explaining the tendency of diabetics to develop infections and gangrene right at the other end of their bodies, in the feet. The statistic that 50% of cases of malignant otitis externa in diabetics have a recent history of having a traumatic ear wash out, suggests that these patients had been suffering from a non-specific discomfort of the ear for a while before the osteitis started (hence the washout), and that it was aggravated or spread by injury incurred during the lavage.[27]

The course of the untreated disease is a steady progression of symptoms and signs eventually leading to death. There is a progressive involvement of the cranial nerves. While loss of movement on one side of the face (cranial nerve VII) is not a fatal condition, loss of swallowing and laryngeal reflexes (Cranial nerves V (trigeminal), VII (facial), X (vagus), XI (accessory), and XII (hypoglossal)) may lead to aspiration into the lungs of secretions, food or regurgitated stomach content. Such events may lead to pneumonia. Following the cranial nerve palsies, meningitis, brain abscesses, and thromboses of the cerebral arteries, veins and sinuses can occur, which may be rapidly fatal. Given the age and co-morbid conditions that these diabetic patients may suffer from, the person is at risk for intercurrent acute illness of the lungs, heart and kidneys, not directly related to the disease in their head. [24]

When the diagnosis is suspected, the special investigations which may be done include laboratory tests for the underlying causative diseases, assessment of the hematological and immune response to the infection, and baseline measurements of the function of vital organs such as the kidneys, which are necessary for planning and following up treatment and the course of the disease. Testing for the type of organism and its sensitivity to different antibiotics is essential, while a biopsy of the granulation tissue in the ear canal is needed to examine for possible cancer. Radio-isotope imaging studies (“scintiscans”) that can detect bone resorption and deposition and spread of inflammation – depending on the isotope technique used – are valuable to confirm the diagnosis, as well as to determine the response to treatment. Computer tomographic x-ray studies (“CT scans”) can show bone destruction and alterations in density, as well as alterations in soft tissues such as abscesses. They are not very sensitive to early changes, detecting osteomyelitis only after 30% of the bone density has been lost. Magnetic resonance imaging (“MRI scans”) usually shows soft tissue changes more clearly than CT, but visualises bone changes poorly. Neither one of the last two techniques is suitable for determining the response to treatment on a weekly or monthly basis. The person suspected of having osteomyelitis of the skull base may therefore be subjected to a battery of tests for diagnosis, and a different set of tests for follow-up at different intervals.

Treatment is aimed at eliminating the primary source for the infection (external ear canal), treating any underlying systemic disease effectively, managing the person’s pain, distress and fear, eliminating the bacteria from the bone and soft tissue which has been invaded, treating the complications of nerve paralysis and effects of infection on the nervous system, and planning for preventative measures in the future. The treatment of each one of these aims follows standard recommendations, and a description of all the possible therapies is outside the scope of this article. Aggressive medical management is the present recommendation for acute disease, with surgery rarely being necessary except to treat abscesses and remove sequestered bone.[29] Accurate control of blood glucose levels, aggressive treatment of the otitis externa, and adequate doses of appropriate antibiotics for a suitable length of time can cure up to 90% of cases. Frequent bacterial cultures is invaluable for selecting the antibiotic treatment, since sensitivities of the organism may change during therapy. Hyperbaric oxygen therapy is recommended by some, but has not been proven to improve the outcome of the disease. The duration of therapy is determined by blood tests and by isotope scans which can show the elimination of infection and inflammation, treatment being continued for a week after tests have returned to normal. Duration of treatment varies from 4-17 weeks, and follow-up isotope scans and blood tests have to be done to eliminate reactivation of disease.[30]

References

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