Otitis Externa (OE)

Ahmed AlMumtin

MD

Anatomy and Physiology

• Consists of the auricle and EAM• Skin-lined apparatus• Approximately 2.5 cm in length• Ends at tympanic membrane

Anatomy and Physiology

• Auricle is mostly skin-lined cartilage• External auditory meatus

• Cartilage: ~40%, Bony: ~60%• S-shaped, Narrowest portion at bony-cartilage junction

Anatomy and Physiology

• EAC is related to various contiguous structures• Tympanic membrane• Mastoid• Glenoid fossa• Cranial fossa• Infratemporal fossa

Anatomy and Physiology

• Innervation: cranial nerves V, VII, IX, X, and greater auricular nerve

• Arterial supply: superficial temporal, posterior and deep auricular branches

• Venous drainage: superficial temporal and posterior auricular veins

• Lymphatics

Anatomy and Physiology

• Squamous epithelium

• Bony skin – 0.2mm• Cartilage skin

• 0.5 to 1.0 mm• Apopilosebaceous

unit

Otitis Externa

• Bacterial, viral or fungal infection of external auditory canal

• Categorized by time course• Acute• Chronic

Speculum findings:• the canal may be so swollen that a view into

the ear is impossible• In swimmers, divers and surfers, chronic water

exposure can lead to the growth of bony swellings in the canal known as exostoses. These can interfere with the drainage of wax and predispose to infection.

Differential diagnoses:

• Otitis media• Ramsay Hunt syndrome • Furuncle• Skull base osteomyelitis• Preauricular cyst and fistula• Lacerations• Atopic dermatitis• Cerumen impaction• Exostosis and osteoma• Foreign body• Acute (bullous) and chronic (granular) myringitis

Organisms

1. Pseudomonas species

2. Staphylococci

3. Streptococci/Gram negative rods

4. Fungi (Aspergillus/Candida species)

Labs/workup

Usually after failed empiric therapy:• bacterial and fungal culture• Adults with otitis externa: screening blood

glucose and/or a urine dipstick test to rule out occult diabetes.

• Additional tests (if available):• Gram stain of d/c• KOH prep smear (within 10 min)

Acute Otitis Externa (AOE)

• “swimmer’s ear”• Preinflammatory stage• Acute inflammatory stage

• Mild• Moderate• Severe

Factors contributing to AOE

• High humidity

• Water exposure

• Maceration of canal skin

• High environmental temperature

• Local trauma

• Perespiration

• Allergy

• Stress

• Removal of normal skin lipids

• Absence of cerumen

• Alkaline pH of canal

AOE: Preinflammatory Stage

• Oedema of stratum corneum and plugging of apopilosebaceous unit

• Symptoms: pruritus and sense of fullness• Signs: mild edema• Starts the itch/scratch cycle

AOE: Mild to Moderate Stage

• Progressive infection• Symptoms

• Pain• Increased pruritus

• Signs• Erythema• Increasing edema• Canal debris,

discharge

AOE: Severe Stage

• Severe pain, worse with ear movement

• Signs• Lumen obliteration• Purulent otorrhoea• Involvement of

periauricular soft tissue

AOE: Treatment

• Most common pathogens: P. aeruginosa and S. aureus, E.coli and proteus.!

• Four principles• Frequent canal cleaning; swap or suction• With sever EO, palcement of a wick made of sponge or

gauze provides a pathway for drops to be delivered to the EAC wall skin for 48-72 hours!

• Topical antibiotics, and if sever>> Systemic PO,ABT• Pain control• Instructions for prevention

AT A GLANCE. . .

• Ostalgia• Tenderness on palpation or manipulation

(tragus sign)• Ear fullness• Conductive hearing loss.• Erythaema of meatus and canal• Swelling and obstruction of canal• Crusting and discharge• Odor!

Furunculosis

• Acute localized infection• Lateral 1/3 of posterosuperior canal• Obstructed apopilosebaceous unit• Pathogen: S. aureus

Furunculosis: Symptoms

• Localized pain• Pruritus• Hearing loss (if lesion occludes canal)

Furunculosis: Signs

• Edema• Erythema• Tenderness• Occasional

fluctuance

Furunculosis: Treatment

• Local heat• Analgesics• Oral anti-staphylococcal antibiotics• Incision and drainage reserved for

localized abscess• IV antibiotics for soft tissue extension

- tri-adcortyle!

Erysipelas

• Acute superficial cellulitis

• Group A, beta hemolytic streptococci

• Skin: bright red; well-demarcated, advancing margin

• Rapid treatment with oral or IV antibiotics if insufficient response

Otomycosis

• Mostly in children who are exposed to warm, moist climates or who have a Hx of chronic use of antibiotic ear drops.

• Fungal infection of EAC skin

• Primary or secondary• Most common organisms:

Aspergillus and Candida

Otomycosis: Signs• Canal erythaema• Mild oedema• White, gray, green,

yellow or black fungal debris

• Often indistinguishable from bacterial OE

• Pruritus deep within the ear• Otorrhoea• Dull pain• Hearing loss (obstructive)• Tinnitus

Otomycosis: Symptoms

Otomycosis: Treatment

• Thorough cleaning and drying of canal• Topical antifungals (clotrimazole for eg.,

amphotericine B, oxytetracycline-polymyxin, and nystatin are very effective!)

• Acidifying of the EAC with drops like 2% acetic acid, 3% boric acid or sulzberger’s powder are also helpful in the t/t of fungal infections.

Necrotizing (malignant) External Otitis(NEO)

• Potentially lethal infection of EAC and surrounding structures

• Pseudomonas aeruginosa is the usual culprit

• Risk Factors:

- Diabetes Mellitus

- Elderly

- Immunocompromised state

- Human Immunodeficiency Virus (HIV)• Typically seen in diabetics and

immunocompromised patients

NEO: Signs & Symptoms• Similar to Otitis Externa except

• Severe, unrelenting Ear Pain and Headache• Persistent discharge• Does not respond to topical medications• Commonly associated with Diabetes Mellitus

• Granulation tissue in posterior and inferior canal• Pathognomonic for necrotizing otitis• Occurs at bone-cartilage junction

• Extra-auricular findings• Cervical Lymphadenopathy• Trismus (TMJ involvement)• Facial Nerve Palsy or paralysis (Bell's Palsy)

• Associated with poor prognosis

NEO: Dx, Prevention and T/T:

• Prognosis; Reportedly mortality 20-53%

• Dx: Hx, PE, Labs and Imaging:- Labs; FBC, Culture of discharge, ESR, Serum glucose, Serum

creatinine.- Radiology; CT, or MRI (ear),Tc 99m medronate methylene bone

scanning, Ga 67 scintography.

• Prevention:- Avoid use of cotton swabs in ear and other canal trauma.- Use caution when irrigating ear of high risk patients.- Treat eczema of ear canal and other pruritic dermatitis

NEO: Treatment

• Intravenous antibiotics for at least 4 weeks – with serial gallium scans monthly

• Local canal debridement until healed• Pain control• Use of topical agents controversial• Hyperbaric oxygen experimental• Surgical debridement for refractory cases

NEO: Diagnosis

• Cohen and Friedman – criteria from review: They were divided into two categories: obligatory and occasional. The obligatory criteria are: pain, edema, exudate, granulations, microabscess (when operated), positive bone scan or failure of local treatment often more than 1 week, and possibly pseudomonas in culture. The occasional criteria are diabetes, cranial nerve involvement, positive radiograph, debilitating condition and old age. All of the obligatory criteria must be present in order to establish the diagnosis. The presence of occasional criteria alone does not establish it. The importance of Tc99 scan in detecting osteomyelitis is stressed. When bone scan is not available, a trial of 1-3 weeks of local treatment is suggested. Failure to respond to such treatment may assist in making the diagnosis of MEO.

NEO: Mortality

• Death rate essentially unchanged despite newer antibiotics (37% to 23%)

• Higher with multiple cranial neuropathies (60%)

• Recurrence not uncommon (9% to 27%)• May recur up to 12 months after treatment

Perichondritis/Chondritis

• Infection of perichondrium/cartilage• Result of trauma to auricle• May be spontaneous (overt diabetes)• Usual pathogens include pseudomonas

species and mixed flora

Perichondritis: Symptoms• Pain over auricle and deep in canal• fever• Pruritus

Perichondritis: Signs• Tender auricle• Induration• Oedema• erythaema• Advanced cases

• Crusting & weeping• Involvement of soft

tissues

Perichondritis: Treatment

• Aspiration of the pus• Use antibiotics of gram-negative coverage, specifically

anitpseudomonals.• If frank chondritis develops, incisions should be made in

the cartilage in order to provide adequate drainage.• Mild: debridement, topical & oral antibiotic• Advanced: hospitalization, IV antibiotics• Chronic: surgical intervention with excision of necrotic

tissue and skin coverage

Relapsing Polychondritis

• Uncommon progressive inflammatory disorder that may affect children, but more commonly in adults.

• Episodic and progressive inflammation of cartilages• Autoimmune etiology?• External ear, larynx, trachea, bronchi, and nose may

be involved• Involvement of larynx and trachea causes

increasing respiratory obstruction

Relapsing Polychondritis

• Fever, pain• Swelling, erythaema• Arthralgia!• Tenderness of the nasal

septum may progress to complete destruction of the septum

Dx and T/t

• Weak +ve RF• ANA +ve• High ESR,• Anaemia• And difinitve Dx is made

by a biopsy from the affected cartilage

-Systemic steroids such as prednisolone-In resistant cases; dapsone, cyclophosphamide or azithioprine may be used

Herpes Zoster Oticus(Ramsay Hunt Syndrome)

• J. Ramsay Hunt described in 1907• Viral infection caused by varicella zoster• Infection along one or more cranial nerve

dermatomes (shingles).- herpes zoster of the pinna with otalgia.

- facial paralysis

- sensorineural hearing loss

- Bullus myringitis

- A vesicular eruption of the concha of the pinna and the EAC.

Symptoms

• Early: burning pain in one ear, headache, malaise and fever

• Late (3 to 7 days): vesicles, facial paralysis

Treatment• Corneal protection• Oral steroid taper (10 to 14 days)• Antivirals (eg. Valacyclovir)• Facial nerve decompression

(controversial)!

Bullous Myringitis

• Viral infection • Confined to tympanic membrane• Primarily involves younger children

Bullous Myringitis: Symptoms• Sudden onset of severe pain• No fever• No hearing impairment• Bloody otorrhoea (significant) if rupture

Bullous Myringitis: Signs• Inflammation limited to TM & nearby canal• Multiple reddened, inflamed blebs.• Hemorrhagic vesicles

Bullous Myringitis: Treatment• Self-limiting• Analgesics• Topical antibiotics to prevent secondary

infection• Incision of blebs is unnecessary

Chronic Otitis Externa

• Acute otitis externa occurs in 4 of every 1000 people per year

• Otitis externa is defined as chronic when the duration of the infection exceeds 4 weeks or when more than 4 episodes occur in 1 year

• Bacterial, fungal, dermatological aetiologies

COE: Symptoms• Unrelenting pruritus• Mild discomfort• Dryness, Crusting, and flaking of canal skin

COE: Signs

• Asteatosis• Dry, flaky skin• Hypertrophied skin• Mucopurulent otorrhoea

(occasional)

COE: Treatment

• Similar to that of AOE• Topical antibiotics, frequent cleanings• Topical Steroids• Surgical intervention

• Failure of medical treatment• Goal is to enlarge and resurface the EAC

Radiation-Induced Otitis Externa

• OE occurring after radiotherapy

• Often difficult to treat• Limited infection treated

like COE• Involvement of bone

requires surgical debridement and skin coverage

Granular Myringitis (GM)

• Deepithelization of the TM• Localized chronic inflammation of pars

tensa with granulation tissue• Sequela of primary acute myringitis,

previous OE, perforation of TM• Common organisms: Pseudomonas,

Proteus

GM: Symptoms• Foul smelling discharge from one ear• Often asymptomatic• Slight irritation or fullness• No hearing loss or significant pain

GM: Signs• TM obscured by pus • “peeping” granulations• No TM perforations

GM: Treatment

• Careful and frequent debridement• Topical anti-pseudomonal antibiotics• Occasionally combined with steroids• At least 2 weeks of therapy• May warrant careful destruction of granulation tissue if

no response

Eczema

• External clue to OE (atopic, contact and sebrrheoic) dermatitis

• Usual symptom is itching.• P/E; erythaema, oedema, flaking and crusting.• T/t:

- Local cleansing.- Usage of corticosteroid and drying agents.• Metal sensitivity is the most common form of chronic

dermatitis involving the ear.!• Nickel is the most common offending metal.• Women are affected more than men.

- Ear peircing is an important cause of primary sensitization to nickel.

Conclusions

• Careful History• Thorough physical exam• Understanding of various disease

processes common to this area• Vigilant treatment and patience

Questions/Comments?