Otitis externa is an infection of the external auditory canal.
- Incidence: 4 of 1000 people annually in the United States
- Approximately 10% of people develop otitis externa in their lifetime.
- Occurs in all age groups
- Most common in children
- More likely to occur in the summer because of:
- Participation in water activities
- Bacterial infection (most cases):
- Pseudomonas aeruginosa
- Staphylococcus aureus
- Staphylococcus epidermidis
- Proteus vulgaris
- Escherichia coli
- Fungal infection (rare):
- Candida albicans
- Aspergillus niger
- Swimming or other water exposure
- Hot, humid weather
- Trauma (including cleaning with cotton swabs)
- Ear canal occlusion:
- Foreign body
- Hearing aids
- Dermatologic conditions:
- Contact dermatitis
- Radiation therapy
Defense mechanisms of the ear
- Tragus and conchal cartilage → prevent the entrance of foreign bodies
- Hair follicles and isthmus narrowing → stop the entry of contaminants
- Cerumen → creates an acidic environment → inhibits bacterial and fungal growth
Pathogenesis of otitis externa
- Breakdown of the skin–cerumen barrier is caused by:
- Damage to epithelium
- ↓ Quantity and quality of cerumen
- Moisture accumulation
- Obstruction of the ear canal
- ↑ pH of the ear canal → ear canal becomes a prime breeding ground for microscopic organisms → infection
- Inflammation and edema of the skin → purulent exudate
Clinical Presentation and Diagnosis
- Ear pain
- Discharge (otorrhea)
- Hearing loss
- Tenderness with tragal pressure
- Pain with manipulation of the auricle
- Edema and erythema of the ear canal
- Yellow, white, gray, or brown purulent debris
- On pneumatic otoscopy, the tympanic membrane is mobile.
The diagnosis of otitis externa is based on the history and physical examination. Culture of the ear canal or discharge is indicated for severe, recurrent, or chronic cases.
- Remove cerumen, desquamated skin, and purulent material.
- Protect ear from water.
- Pain relief:
- Opioids for severe pain
- Topical antibiotic otic drops:
- Polymyxin B plus neomycin
- Combined preparations with topical steroids can help with pruritus and inflammation.
- An ear wick can be placed to facilitate medication delivery in patients with significant ear canal edema.
- Symptom improvement begins about 36–48 hours after initiation of treatment.
- Completely resolves in about 6 days
- Erythema, edema, and warmth develop around the auricle.
- Pain is mild.
- Systemic symptoms are absent.
Malignant otitis externa
Also known as necrotizing otitis externa, this is an invasive, life-threatening infection of the external auditory canal and skull base.
- Almost always caused by Pseudomonas aeruginosa
- Risk factors:
- Diabetes mellitus
- Extreme otalgia and otorrhea
- Granulation tissue may be visible in the inferior portion of the external auditory canal.
- Can lead to cranial nerve palsies if the disease progresses to osteomyelitis of the skull base and temporomandibular joint
- Cultures of ear canal drainage
- CT scan:
- Bony erosion
- Middle ear radiolucency
- Biopsy to rule out malignancy
- IV antibiotic therapy:
- Cefepime or ceftazidime
- Surgical debridement is rarely needed for extensive infection.
- Cranial nerve palsies
- Brain abscess
- Dural sinus thrombophlebitis
- Contact dermatitis: Persistent edema and erythema of the ear canal and auricle despite adequate otitis externa treatment can indicate an allergic reaction. This reaction can be caused by ototopical medication, cosmetics, or shampoos. Pruritus and erythema are the primary symptoms, and vesicles can be seen, usually due to rubbing and itching. The diagnosis is made clinically. Management involves cessation of the causative substance.
- Chronic suppurative otitis media: a complication of persistent acute otitis media with perforation: Symptoms include otorrhea, otalgia, hearing loss, tinnitus, or vertigo. The diagnosis is made clinically. The tympanic membrane is often partially visible and not movable by pneumatic insufflation. A tympanic membrane perforation or retraction pockets may also be seen. Management primarily involves topical fluoroquinolones.
- Carcinoma of the ear canal: a rare disease that should always be considered if there is an abnormal growth in the ear canal or a lack of response to prolonged otitis externa therapy: Common symptoms of carcinoma of the ear canal include mild pain and bloody otorrhea. A friable lesion with surrounding purulence on an otoscopic exam may be seen. Hearing loss and facial paralysis are late signs. Diagnosis is made clinically and confirmed by biopsy.
- Psoriasis: an inflammatory skin condition that commonly involves the external ear canal and leads to redness and scaling that often extends to the conchal bowl and auricle: The clinical appearance of psoriasis in the external auditory canal varies. The diagnosis is made clinically. Management can include steroids and retinoids. More severe cases may require high-dose steroids, light therapy, or biologics.
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