OTITIS EXTERNA

Dr. Mohammed Shafeeq

Definition

● It is a generalised condition of the skin in EAC characterised by general oedema & erythema which may be associated with itchy discomfort with or without ear discharge.

External auditory canal - Anatomy

● Bottom of concha to TM● 24mm along posterior border● Divided into:

● Outer/cartilaginous part● Inner/bony part

● Outer part – upwards, backwards & medially● Inner part – downwards,forwards & medially

● Cartilaginous part:● 8mm, outer 1/3rd● Fissures of Santorini● Skin is thick with ceruminous & sebaceous glands● Hair is confined to this region

● Bony part:● 16mm, inner 2/3rd● Tympanic portion of temporal bone● Skin is thin, with thin layer of sq epithelium ● Devoid of hair/ceruminous glands● Isthmus● Anterior recess● Foramen of Huschke

Pathogenesis

Clinical course of otitis externa can be divided into:

● Pre-inflammatory stage● Acute inflammatory stage● Chronic inflammatory stage

● Pre-inflammatory stage:

protective lipid/acid balance is lost

stratum corneum – oedematous

blocks sebaceous/apocrine glands

-- aural fullness/itching

disruption of epithelial layer

-- invasion of pathogens

● A/c inflammatory stage:

3 grades – mild / moderate / severe

Pre-inflammatory phase –> acute inflammation

progressive thickening exudate, increasing oedema

oblitertion of lumen, increasing pain

severe stages – auricular changes & cervical lymphadenopathy

● C/c inflammatory stage:

resistant inflammations lasting > 3weeks

thickening of external canal skin

fibrous canal stenosis

Pre-disposing factors● Anatomical - narrow EAC

(hereditary/iatrogenic/exostoses), obstruction of normal meatus (keratosis obturans/FB/hearing aids)

● Dermatological - eczema,seborrhoeic dermatitis● Allergic – long term topical medications● Physiological – humidity, immunocompromised● Traumatic – skin maceration(swimming), ear

probing, laceration, radiotherapy● Microbiological – active COM, exposure to

P.aeruginosa or fungi

Microbiology

● Pseudomonas species -- 50-65%● Other Gram negative organisms – 25-35%● Staphylococcus aureus – 15-30%● Streptococci – 9-15%

Classification (etiological basis)● INFECTIVE group

● Bacterial– Localised otitis externa (furuncle)– Diffuse otitis externa– Malignant otitis externa

● Fungal– Otomycosis

● Viral– Herpes zoster oticus– Otitis externa haemmorhagica

● REACTIVE group

● Eczematous otitis externa● Seborrhoeic otitis externa● Neurodermatitis

Acute localised otitis externa

● Infection of a hair follicle (furuncle)● begin as folliculitis-->small abscess/furuncle● Staphylococcus aureus● Lateral cartilaginous (outer 1/3rd) portion of EAC

Acute localised otitis externa (contd...)

● Symptoms – severe pain/discharge/hearing loss/aural fullness

● O/E – tragal tenderness/oedematous EAC/enlarged, tender preauricular LN

● Furuncle in posterior meatal wall --> oedema over mastoid --> obliteration of retroauricular groove

Acute localised otitis externa (contd...)

Treatment:● Early cases without abscess formation,

● Systemic antibiotics● Topical antibiotics+corticosteroids● Analgesics/local hot fomentation/ear pack with

10% icthammol glycerine● If abscess has formed,

● Incision & Drainage● Topical antibiotic ointment with/without oral antibiotics

● Recurrent furunculosis

● R/o diabetes, staphylococcal skin infection, nasal vestibule harbouring staphylococci

Acute diffuse otitis externa

● Swimmer's ear● Commonest form of otitis externa● Usual pathogens – Pseudomonas aeruginosa,

Staphylococcus aureus, Proteus mirabilis● Symptoms – pain/itching/aural fullness/hearing loss

● O/E – tenderness/ narrow EAC with congested, oedematous skin/ clear or purulent exudates

Acute diffuse otitis externa (contd...)Treatment:

● Ear toilet

● Medicated wicks -● Antibiotic-steroid prepration● Acidifying/antiseptic agents – gentian violet● Mild astingent – 8% aluminium acetate/3% silver nitrate

● Antibiotics -● Topical antibiotics – (neomycin/ciprofloxacin/ofloxacin)

with/without corticosteroids● Broad spectrum systemic antibiotics

● Analgesics● Avoid water entry/avoid usind cotton buds/avoid digital

manipulation of ear canal

Chronic otitis externa

● Low grade, diffuse infection of EAC persisting for months/years

● Pruritis, dry hypertrophic skin of EAC leading to post inflammatory stenosis

● Causes are bacterial/fungal infections, also include skin conditions seborrhoeic dermatitis, psoriasis, neurodermatitis, sensitization to an topical ear drops

Chronic otitis externa (contd...)

Treatment:GOAL – prevent stenosis & restore normal skin in EAC

● Frequent inspection & debridment of EAC

● Antibiotic-corticosteroid topical applications

● EAC can be painted with gentian violet/ triamcinolone/ nystatin

● Treat underlying causes – seborrhoea, psoriasis, neurodermatitis

Chronic otitis externa (contd...)Surgical treatment:

In case of medical treatment failure with canal stenosis

● Canalplasty with skin grafting – restore canal patency and hearing

Procedure:

➔ Abnormal skin is removed entirely

➔ Denuded canal is enlarged using diamond bur

➔ Split thickness graft is harvested from medial surface of upper arm with a dermatome

➔ Graft placed on exposed suface

➔ 'rosebud' type of packing is done over skin graft and left for 2 weeks

➔ Crusting may occur for several weeks, requires removal till complete healing

Chronic otitis externa (contd...)

Preventive measures:● Patients instructed not to use cotton swabs or

any other objects to canal● Swimmers instructed to use ear plugs and

advised to use alcohol-vinegar (1:1) drops after swimming

Malignant (necrotizing) otitis externa

● Progressive, lethal infection of EAC, surrounding tissue and skull base

● Elderly diabetic/ immunocompromised pts.● Pseudomonas aeruginosa

Malignant otitis externa (contd...)

Pathophysiology:● Infection begins in EAC --> cellulitis, chondritis,

osteitis, osteomyelitis● May spread to osseus auditory canal & skull

base through fissures of Santorini --> replacement of compact bone with granulation tissue

● Facial N paalysis – stylomastoid foramen involvement

● CN IX, X, XI palsies - jugular foramen involvement

● Jugular V thrombosis-->lateral sinus thrombosis

Malignant otitis externa (contd...)

● Symptoms:

purulent discharge/excruciating pain/facial N palsy/

CN IX,X,XI palsy

● O/E:

granulation tissue in floor of EAC at bony-cartilaginous junction is typical otoscopic finding

● Investigations:

C&S of discharge

CT scan

Gallium scan

Malignant otitis externa (contd...)

Treatment:● Hospitilization

● Control of diabetes

● Antibiotics -

● Aminoglycosides + penicillin/cephalosporins● Quinolones

● Daily debridement of EAC

● Surgery -

● Debridement of devitalised tissue/bone● Mastoidectomy with facial N decompression /

subtotal petrosectomy

Fungal otitis externa (Otomycosis)

● Fungal infection of EAC● Aspergillus niger – black headed filamented growth

Aspergillus fumigatus – brown

Candida albicans – white/creamy deposits

● Secondary fungal infection may be seen in pts using topical antibiotics for otitis externa/ middle ear suppuration

Fungal otitis externa (contd...)● Symptoms:

pruritis/ pain or discomfort in ear/ watery discharge with musty odour/ ear block

● O/E:

erythematous canal with black/grey/white fungal mass – 'wet piece of filter paper'

Fungal otitis externa (contd...)

Treatment:● Ear toilet● Antifungal agents – nystatin/clotrimazole● 2% salicylic acid● Ear must be kept dry● Secondary bacterial infections – antibiotic +

steroid prepration● Oral antifungals – refractory to topical agents

Herpes zoster oticus

● HSV – most frequent virus to affect EAC● HSV stay dominant in sensory ganglia –

reactivates in decreased immunocompetence● Blisters/vesicles on auricle, EAC, TM● Blisters – short lived, rupture, dry & heal

spontaneously● May develop CN VII, VIII palsy

Herpes zoster oticus (contd...)

● 'Ramsay Hunt Syndrome' – clinical syndrome with facial N palsy with or without hearing loss and dizziness owing to herpes zoster

● Treatment:

Self limiting, primarily supportive

Antivirals (acyclovir) & steroids can be used

Otitis externa haemmorhagica

● Formation of haemmorhagic bullae on TM and deep meatus

● Viral / seen in influenza epidemics● Severe ear pain / blood stain discharge● Treatment:

Analgesics

Antibiotics – secondary infections

Complications – Otitis Externa

● Cellulitis/ Perichondritis/ Chondritis● Medial canal fibrosis● Tympanic membrane perforation● Malignant otitis externa

Thank you