Otitis externa on human ear Pathophysiology

A brief explanation on the most common pathology affecting the ear on daily clinical practice
Which is an otitis externa

1. OTITIS EXTERNA Dr Masoud 1

2. Otitis externa Otitis externa is an inflammation of the external auditory meatus (EAM). can be divided according to the cause as follows; a. Infectious otitis eterna Circumscript otits externa ( furuncle). Diffuse otitis externa . Malignant otitis externa . b. Reactive otitis externa . Eczematous otitis externa . . Seborrhoeic otitis externa . 2

3. Circumscript otitis externa . This infection affects the outer one third of the ear canal. Normally presents with painful boils and furuncle s(due to infection of hair follicle). When boils ripe burst and the ear discharges pus. Causes : Staphylococcus aureus , Pseudomonas aeruginosa . Symptoms & signs : Pain - out of proportion to the visible lesion. Swelling - hyperemic skin. Hearing impairment - due to meatal occlusion by the furuncle. Treatment. Antibiotics, Analgesics depending with severity, Incision and drainage. 3

4. Diffuse otitis externa . An inflammation of the entire external ear canal. Results to oedema and blockage of the canal( commonly referred to as " swimmer's ear “). The causative organisms are initially fungi ( Aspegillus fumigatus , Aspegillus nigra and Candida albicans ). May complicate by mixed bacterial superinfection like Staphylococcus aureus and Pseudomonas aeuruginosa . 4

5. Predisposing factors : Skin laceration. Self inflicted. Ear wash or instruments. Hot humid atmosphere. Swimming. Discharge of chronic suppurative Otitis media. 5

6. Symptoms. Itching. Discharges (scanty). Pain (usually moderate, sometimes severe, increased by jaw movement). Hearing loss. Signs. Meatal oedema . Moist debris, often smelly Red desquamated skin and oedema of the meatal walls and often the tympanic membrane . Otorrhoea . 6

7. Management of diffuse otitis externa . Ear swab - identification of the offending microorganism. Magnesium sulphate pack to reduce edema. Aural toilet - to clear the debris. Ear drops - antibiotic and steroid . Antifungal ear drops. Prevention of recurrence. Prevent water entering the ears. Silicone rubber earplugs. Avoidance of scratching and poking the ears . 7

8. … Otomycosis . Otomycosis is a fungal infection of the ear. Predesposing factors . Moisture in the ear. Prolonged use of antibiotic ear drops. Immune supression . Causative organisms . Aspergillus spp (commonest A.niger ) Candida albicans . Symptoms; Itching. Pain. Otorrhoea - brownish or blackish discharges. Deafness due to collection of discharge. 8

9. Signs. Early - cotton like growth. Late - wet newspaper like mass. Colour may be white in Candida spp. and grey, brown or black in Aspergillus spp ). Management. Ear swab for c/s. Antifungal ear drops for at least two weeks. Cleaning of ear to remove debris. Antipruritic agents. Analgesics. 9

10. Malignant otitis externa . Is a progressive necrotising infection. starts in the external ear. involves tissues of the base of skull, temporal bone and cranial nerves. Primarily occurs in immune suppressed people eg . Elderly, diabetics, AIDS. Causative organism Pseudomonas aeruginosa . 10

11. Clinical features . Severe otalgia Granulation tissue protruding through the floor of ear canal wall at the bone cartilaginous junction Extension to involve bone structures of temporal bone, base of skull and intracranium . Cranial nerve VII paralysis. Can involve other cranial nerves at jugular foramen . Intracranial spread present with headache, fever neck stiffness and altered level of consciousness. 11

12. Investigation. Swab for culture and sensitivity. CT scan-skull and the brain. Treatment. Aggressive medical treatment. Antipseudomonas antibiotics eg Ciprofloxacillin intravenous for six weeks. Surgical debridment and dressing. 12

13. Complications of malignant otitis externa . Osteomyelitis of the temporal bone and skull base. Facial nerve paralysis at stylomastoid foramen. Last 4 cranial nerves paralysis at the jugular foramen. Meningitis. Brain abscess. Septicaemia. 13

14. Reactive otitis externa . Eczematous otitis externa . Is an allergic dermatitis of the external auditory meatus . Clinical features . Irritation and oedema of the canal. Weeping eczema with crusting occurs in chronic cases. Secondary infection may lead to acute otitis externa . Canal stenosis due to oedema and fibrosis. Fissuring and scalling . 14

15. Treatment Topical steroids. Antibiotics locally and systematically. Antihistamines. Squamous debris covering the skin of the external auditory canal can be noted. 15

16. Seborrheic dermatitis . A chronic inflammatory skin disease. Unknown etiology with a predilection for areas of the skin rich with sebaceous glands . Affection of the ear is often distributed along the concha, scaphoid region, EAC, and postauricular crease. Cause has been associated with Pityrosporum ovale and Malassezia furfur Clinical Findings . Greasy scales overlying erythematous. Often pruritic plaques. The distribution often involves the scalp, forehead, eyebrows, glabella, and nasolabial folds. Scaling of the scalp is common. Superimposed infection and edema may also occur. 16

17. Differential Diagnosis . Seborrheic dermatitis may be confused with atopic or psoriatic dermatitis, and scaling within the EAC may be confused with external otitis or otomycosis . Treatment: steroid with antibiotic ointment or drops. Aural toilet. Ketoconazole shampoo. 17

18. THANKS 18