This document provides an overview of otitis externa (ear infection of the outer ear canal). It defines the condition and describes the anatomy of the external auditory canal. The stages of otitis externa are outlined from pre-inflammatory to acute and chronic. Common types are discussed including localized furuncles, diffuse acute infections, and chronic cases. Potential causes and the microbiology are summarized. Diagnosis, classification, signs and symptoms, and treatment approaches are covered for the main types of otitis externa infections. Complications are also briefly mentioned.

1. OTITIS EXTERNA
Dr. Mohammed Shafeeq

2. Definition
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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.

3. External auditory canal - Anatomy
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Bottom of concha to TM
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24mm along posterior border
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Divided into:
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Outer/cartilaginous part
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Inner/bony part
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Outer part – upwards, backwards & medially
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Inner part – downwards,forwards & medially

4. ●
Cartilaginous part:
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8mm, outer 1/3rd
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Fissures of Santorini
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Skin is thick with ceruminous & sebaceous glands
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Hair is confined to this region

5. ●
Bony part:
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16mm, inner 2/3rd
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Tympanic portion of temporal bone
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Skin is thin, with thin layer of sq epithelium
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Devoid of hair/ceruminous glands
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Isthmus
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Anterior recess
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Foramen of Huschke

6. Pathogenesis
Clinical course of otitis externa can be divided
into:
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Pre-inflammatory stage
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Acute inflammatory stage
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Chronic inflammatory stage

7. ●
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

8. ●
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

9. ●
C/c inflammatory stage:
resistant inflammations lasting > 3weeks
thickening of external canal skin
fibrous canal stenosis

10. Pre-disposing factors
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Anatomical - narrow EAC
(hereditary/iatrogenic/exostoses), obstruction of
normal meatus (keratosis obturans/FB/hearing aids)
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Dermatological - eczema,seborrhoeic dermatitis
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Allergic – long term topical medications
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Physiological – humidity, immunocompromised
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Traumatic – skin maceration(swimming), ear
probing, laceration, radiotherapy
Microbiological – active COM, exposure to
P.aeruginosa or fungi

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

12. Classification (etiological basis)
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INFECTIVE group
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Bacterial
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–
–
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Fungal
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Otomycosis
Viral
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–
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Localised otitis externa (furuncle)
Diffuse otitis externa
Malignant otitis externa
Herpes zoster oticus
Otitis externa haemmorhagica
REACTIVE group
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Eczematous otitis externa
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Seborrhoeic otitis externa
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Neurodermatitis

13. Acute localised otitis externa
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Infection of a hair follicle (furuncle)
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begin as folliculitis-->small abscess/furuncle
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Staphylococcus aureus
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Lateral cartilaginous (outer 1/3rd) portion of EAC

14. Acute localised otitis externa (contd...)
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Symptoms – severe pain/discharge/hearing
loss/aural fullness
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O/E – tragal tenderness/oedematous EAC/enlarged,
tender preauricular LN
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Furuncle in posterior meatal wall --> oedema over
mastoid --> obliteration of retroauricular groove

15. Acute localised otitis externa (contd...)
Treatment:
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Early cases without abscess formation,
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Systemic antibiotics
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Topical antibiotics+corticosteroids
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Analgesics/local hot fomentation/ear pack with
10% icthammol glycerine
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If abscess has formed,
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Incision & Drainage
Topical antibiotic ointment with/without oral antibiotics
Recurrent furunculosis
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R/o diabetes, staphylococcal skin infection, nasal
vestibule harbouring staphylococci

16. Acute diffuse otitis externa
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Swimmer's ear
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Commonest form of otitis externa
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Usual pathogens – Pseudomonas aeruginosa,
Staphylococcus aureus, Proteus mirabilis
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Symptoms – pain/itching/aural fullness/hearing loss
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O/E – tenderness/ narrow EAC with congested,
oedematous skin/ clear or purulent exudates

17. Acute diffuse otitis externa (contd...)
Treatment:
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Ear toilet
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Medicated wicks ●
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Acidifying/antiseptic agents – gentian violet
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Antibiotic-steroid prepration
Mild astingent – 8% aluminium acetate/3% silver nitrate
Antibiotics ●
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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

18. Chronic otitis externa
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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

19. Chronic otitis externa (contd...)
Treatment:
GOAL – prevent stenosis & restore normal skin in EAC
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Frequent inspection & debridment of EAC
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Antibiotic-corticosteroid topical applications
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EAC can be painted with gentian violet/ triamcinolone/
nystatin
Treat underlying causes – seborrhoea, psoriasis,
neurodermatitis

20. Chronic otitis externa (contd...)
Surgical treatment:
In case of medical treatment failure with canal stenosis
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Canalplasty with skin grafting – restore canal patency
and hearing
Procedure:
➔
Abnormal skin is removed entirely
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Denuded canal is enlarged using diamond bur
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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

21. Chronic otitis externa (contd...)
Preventive measures:
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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

22. Malignant (necrotizing) otitis externa
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Progressive, lethal infection of EAC,
surrounding tissue and skull base
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Elderly diabetic/ immunocompromised pts.
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Pseudomonas aeruginosa

23. Malignant otitis externa (contd...)
Pathophysiology:
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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
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Facial N paalysis – stylomastoid foramen involvement
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CN IX, X, XI palsies - jugular foramen involvement
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Jugular V thrombosis-->lateral sinus thrombosis

24. Malignant otitis externa (contd...)
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Symptoms:
purulent discharge/excruciating pain/facial N palsy/
CN IX,X,XI palsy
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O/E:
granulation tissue in floor of EAC at bony-cartilaginous
junction is typical otoscopic finding
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Investigations:
C&S of discharge
CT scan
Gallium scan

25. Malignant otitis externa (contd...)
Treatment:
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Hospitilization
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Control of diabetes
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Antibiotics ●
Aminoglycosides + penicillin/cephalosporins
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Quinolones
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Daily debridement of EAC
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Surgery ●
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Debridement of devitalised tissue/bone
Mastoidectomy with facial N decompression /
subtotal petrosectomy

26. Fungal otitis externa (Otomycosis)
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Fungal infection of EAC
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Aspergillus niger – black headed filamented growth
Aspergillus fumigatus – brown
Candida albicans – white/creamy deposits
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Secondary fungal infection may be seen in pts
using topical antibiotics for otitis externa/ middle
ear suppuration

27. Fungal otitis externa (contd...)
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Symptoms:
pruritis/ pain or discomfort in ear/ watery
discharge with musty odour/ ear block
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O/E:
erythematous canal with black/grey/white
fungal mass – 'wet piece of filter paper'

28. Fungal otitis externa (contd...)
Treatment:
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Ear toilet
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Antifungal agents – nystatin/clotrimazole
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2% salicylic acid
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Ear must be kept dry
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Secondary bacterial infections – antibiotic +
steroid prepration
Oral antifungals – refractory to topical agents

29. Herpes zoster oticus
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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

30. Herpes zoster oticus (contd...)
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'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

31. Otitis externa haemmorhagica
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Formation of haemmorhagic bullae on TM and
deep meatus
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Viral / seen in influenza epidemics
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Severe ear pain / blood stain discharge
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Treatment:
Analgesics
Antibiotics – secondary infections

32. Complications – Otitis Externa
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Cellulitis/ Perichondritis/ Chondritis
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Medial canal fibrosis
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Tympanic membrane perforation
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Malignant otitis externa

33. Thank you