OTITIS EXTERNA

Fahad zakwanMD5

introduction•Otitis externa (OE) is an inflammation or infection of external auditory canal (EAC), the auricle or both.• It is a common disease that can be found in all age groups•OE usually represents an acute bacterial infection of the skin of the ear canal but can also be caused by other bacteria, viruses, or a fungal infection.

•Several factors can contribute to EAC infection and the development of OE, including the following:•Absence of cerumen•High humidity•Retained water in ear canal• Increased temperature•Local trauma (eg, use of cotton swabs or hearing aids)

• Aquatic athletes are particularly prone to the development of OE because repeated exposure to water results in removal of cerumen and drying of the EAC. • Retained water in the ear canal can cause maceration of

the skin and a milieu conducive to bacterial or fungal proliferation. • OE occurs more often in the summer months, when

swimming is more common, and it is also common in tropical areas.• Individuals with allergic conditions (eg, eczema, allergic

rhinitis, and asthma) are also at significantly higher risk for OE

ClassificationOE may be classified as follows:•Acute diffuse OE•Acute localized OE•Chronic OE•Eczematous (eczematoid) OE•Necrotizing (malignant) OE •Otomycosis

Acute diffuse OE

• This is the most common form of OE, typically seen in swimmers; • it is characterized by rapid onset (generally within 48 hours) and symptoms of EAC inflammation (e.g, otalgia, itching, or fullness, with or without hearing loss or jaw pain) as well as: • tenderness of the tragus or pinna or diffuse ear

edema or erythema or both, with or without otorrhea, • regional lymphadenitis, • tympanic membrane erythema, or • cellulitis of the pinna

Acute localized OE

•This condition, also known as furunculosis, is associated with infection of a hair follicle

Chronic OE

•This is the same as acute diffuse OE but is of longer duration (>6 weeks)

Eczematous (eczematoid) OE

•This encompasses various dermatologic conditions (eg, atopic dermatitis, psoriasis, systemic lupus erythematosus, and eczema) that may infect the EAC and cause OE

Necrotizing (malignant) OE

•This is an infection that extends into the deeper tissues adjacent to the EAC; • it primarily occurs in adult patients who are immunocompromised (eg, as a result of diabetes mellitus or AIDS) and is rarely described in children; • it may result in cases of cellulitis and osteomyelitis

Otomycosis•Infection of the ear canal secondary to fungus species such as Candida or Aspergillus

Pathophysiology•OE is a superficial infection of the skin in the EAC. • The processes involved in the development of OE can be divided into the following 4 categories:• Obstruction (eg, cerumen buildup, surfer’s exostosis,

or a narrow or tortuous canal), resulting in water retention• Absence of cerumen, which may occur as a result of

repeated water exposure or overcleaning the ear canal• Trauma• Alteration of the pH of the ear canal

• If moisture is trapped in the EAC, it may cause maceration of the skin and provide a good breeding ground for bacteria. • This may occur after swimming (especially in contaminated water) or bathing—hence the common lay term “swimmer’s ear.” • It may also occur in hot humid weather. •Obstruction of the EAC by excessive cerumen, debris, surfer’s exostosis, or a narrow and tortuous canal may also lead to infection by means of moisture retention.

• Trauma to the EAC allows invasion of bacteria into the damaged skin. • This often occurs after attempts at cleaning the ear with a cotton swab, paper clip, or any other utensil that can fit into the ear. •Once infection is established, an inflammatory response occurs with skin edema. • Exudate and pus often appear in the EAC as well. • If severe, the infection may spread and cause a cellulitis of the face or neck.

Etiology•OE is most often caused by a bacterial pathogen; other varieties include fungal OE (otomycosis) and eczematoid (psoriatic) OE. • The most common causative bacteria are: • Pseudomonas species (38% of all cases),• Staphylococcus species,• Anaerobes,• gram-negative organisms.

•Fungal OE may result from overtreatment with topical antibiotics or may arise de novo from moisture trapped in the EAC. •It is caused by Aspergillus 80-90% of the time; •Candida and other organisms have also been isolated.

•Eczematoid (psoriatic) OE is associated with the following conditions:•Eczema•Seborrhea•Neurodermatitis•Contact dermatitis from earrings or hearing aid use•Sensitivity to topical medications

•Necrotizing OE occurs in patients who are immunocompromised and represents a true osteomyelitis of the temporal bone.• Risk factors for OE include the following:• Previous episodes of OE• Swimming, diving, or participating in aquatic activities• Use of earplugs or probing of the EAC• Hot, humid weather• Use of a hearing aid• Coexistence of eczema, allergic rhinitis, or asthma• Comorbidities such as diabetes mellitus, AIDS,

leukopenia, or malnutrition

Epidemiology• Although the infection can affect all age groups, OE appears to be most prevalent in the older pediatric and young adult population, with a peak incidence in children aged 7-12 years•OE affects both sexes equally. •No racial predilection has been established, though people in some racial groups have small ear canals, which may predispose them to obstruction and infection.

HistoryPatients with otitis externa (OE) may complain of the following:• Otalgia, ranging from mild to severe, typically

progressing over 1-2 days• Hearing loss• Ear fullness or pressure• Tinnitus• Fever (occasionally)• Itching (especially in fungal OE or chronic OE)

• Severe deep pain – If this is experienced by a patient who is immunocompromised or diabetic, be alerted to the possibility of necrotizing (malignant) OE•Discharge – Initially, the discharge may be clear and odorless, but it quickly becomes purulent and foul-smelling• Bilateral symptoms (rare)• Frequently, a history of exposure to or activities in water (e.g, swimming, surfing, and kayaking)•Usually, a history of preceding ear trauma (e.g, forceful ear cleaning, use of cotton swabs, or water in the ear canal)

Physical Examination• The key physical finding of OE is pain

upon palpation of the tragus (anterior to ear canal) or application of traction to the pinna (the hallmark of OE). • Examination reveals erythema, edema,

and narrowing of the external auditory canal (EAC), and a purulent or serous discharge may be noted. • Conductive hearing loss may be

evident. • Cellulitis of the face or neck or

lymphadenopathy of the ipsilateral neck occurs in some patients.

• The tympanic membrane may be difficult to visualize and may be mildly inflamed, but it should be normally mobile on insufflation. • Eczema of the pinna may be present.• Fungal OE results in severe itching but typically causes

less pain than bacterial OE does. A thick discharge that may be white or gray is often present. • pseudomonal infection produces purulent otorrhea that

may be green or yellow, • Aspergillus otomycosis looks like a fine white mat

topped by black spheres. Upon close examination, the discharge may contain visible fungal elements (eg, spores or hyphae) or have a fuzzy appearance.

ComplicationsComplications of OE are rare and may include the following:• Necrotizing OE (the most significant complication)• Mastoiditis• Chondritis of the auricle (from spread of acute OE to the

pinna, particularly in patients with newly pierced ears)• Bony erosion of the base of the skull• Central nervous system (CNS) infection• Cellulitis or lymphadenitis

Differential diagnosis• Ear canal trauma

• Otitis media

• Hearing loss

• Intracranial abscess

• Furuncle

• Preauricular cyst and fistula

• Lacerations

• Atopic dermatitis

• Cerumen impaction

• Foreign body

investigations• The patient’s history and physical examination usually provide sufficient information to allow the clinician to make the diagnosis of otitis externa (OE). Most persons with OE are treated empirically.• Thus, laboratory studies typically are not needed. However, Gram staining and culture of any discharge from the auditory canal may be helpful if the patient is immunocompromised, if the usual treatment measures are ineffective, or if a fungal cause is suspected.

Lab studies•Gram staining and culture of the canal discharge•Blood glucose check/urine dipstick test

CT, MRI, Bone Scan, and Gallium Scan• Imaging studies are not required for most cases of OE. However,

radiologic investigation may be helpful if an invasive infection such as necrotizing (malignant) OE is suspected or if the diagnosis of mastoiditis is being considered.

• High-resolution computed tomography (CT) is preferred and better depicts bony erosion.[6] Radionucleotide bone scanning and gallium scanning have been used to make the diagnosis. Magnetic resonance imaging (MRI), though not used as often, may be considered secondarily or if soft tissue extension is the predominant concern.[7]

Otoscopy• In cases of external ear infection, otoscopic examination must be performed in conjunction with evaluation of related structures (eg, the external ear and the head and neck).

The otoscope• An otoscope consists of a head and a handle and is

used to examine the external auditory canal (EAC), the tympanic membrane, and the middle ear. • A magnifying lens enhances the clinician’s view. • The following 2 types of head are available for the

otoscope:• Diagnostic head – This head is fixed to the otoscope and does

not allow the use of microinstruments through the scope• Working (operating head) – This head has a magnifying lens

that can slide to the side, enabling passage of microinstruments through the speculum into the EAC and the middle ear

• For optimal viewing of the tympanic membrane in an adult, retract the auricle posteriorly and superiorly to straighten the EAC; • for optimal viewing in a child, pull the auricle

posteriorly. • Remove any debris or cerumen to allow an adequate

examination. • Proceed with the examination as follows:• First, examine the EAC for masses, skin changes, and

otorrhea• Next, examine all parts of the tympanic membrane• Next, assess the motion of the tympanic membrane

by means of pneumatic otoscopy• Finally, attempt a thorough examination of the middle

ear contents through the tympanic membrane.

TREATMENTPrimary treatment of otitis externa (OE) involves: •management of pain, • removal of debris from the external auditory canal (EAC), •administration of topical medications to control edema and infection, and •avoidance of contributing factors.

•Most cases can be treated with over-the-counter analgesics and topical eardrops. •Commonly used eardrops include: •acetic acid drops, which change the pH of the ear canal; •antibacterial drops, which control bacterial growth; and •antifungal preparations. • topical steroid drops.

Removal of Debris From Ear Canal

• Removal of debris from the ear canal improves the effectiveness of the topical medication. •Gentle cleaning with a soft plastic curette or a small Frazier suction tip under direct vision is appropriate. • Irrigation with a mix of peroxide and warm water may be useful for removing debris from the canal, but only if the tympanic membrane is intact. • Any water instilled must be removed to keep from exacerbating the condition.

Pharmacologic therapyAvailable antiseptic preparations includes: •acetic and boric acids,•phenol, •aluminum acetate, •gentian violet, • thymol, •alcohol.

Available antibiotic preparations include: •ofloxacin, •ciprofloxacin,•chloramphenicol, •gentamicin

•Treat underlying course if it known.•Preparations with steroids help to reduce edema and otalgia. •Systemic antibiotics are indicated for infections that spread beyond the EAC.•Fungal infections need antifungal agents such as nystatin or clotrimazole.•Eczematous reactions of the pinna require application of anti allergic creams or ointments

•Medication may be instilled as drops twice a day, painted on the meatal walls with cotton wool on a wire wool carrier, inserted on an impregnated gauze wick, or insufflated as a powder after toilet. •Systemic antibiotics are never necessary. •Topical preparations should not be used for long periods (7–10 days at most). •There is, however, a case for applying drops intermittently (for example once a week) to try to prevent repeated relapses.

Surgical Debridement and Drainage• Surgical debridement of the ear canal is usually reserved for necrotizing OE or for complications of OE (eg, external canal stenosis). • It is often necessary in more severe cases of OE or in cases where a significant amount of discharge is present in the ear. • An otolaryngologist usually performs debridement using magnification and suction equipment. •Debridement is the mainstay of treatment for fungal infections.

•Occasionally, an abscess forms in the ear canal; this usually occurs in cases of OE caused by S aureus. •Treatment of the abscess is often accomplished by means of a simple incision and drainage procedure that is usually performed by an otolaryngologist using a needle or a small blade.

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