Differences Between Otitis Externa and Otitis Media: Diagnosis and Treatment
Otitis externa and otitis media are distinct ear infections affecting different anatomical locations, with otitis externa involving inflammation of the external auditory canal while otitis media affects the middle ear, requiring different diagnostic approaches and treatment strategies. 1
Anatomical Location and Diagnostic Features
Otitis Externa
- Involves inflammation of the external auditory canal, with possible extension to the pinna 1, 2
- Characterized by tenderness of the tragus and/or pinna (key diagnostic feature) 1
- Physical examination reveals diffuse ear canal edema and erythema 1
- Normal tympanic membrane mobility on pneumatic otoscopy 1
- May present with otorrhea or debris in the ear canal 1
- Most commonly caused by Pseudomonas aeruginosa and Staphylococcus aureus (98% of cases in North America) 2
Otitis Media
- Involves inflammation of the middle ear 1
- Characterized by rapid onset of signs and symptoms of middle ear inflammation 1
- Physical examination reveals bulging of the tympanic membrane 1
- Limited or absent mobility of the tympanic membrane on pneumatic otoscopy 1
- May show air-fluid level behind the tympanic membrane 1
- Distinct erythema of the tympanic membrane 1
- Commonly associated with viral upper respiratory infections and/or bacterial infections (Streptococcus pneumoniae, Moraxella catarrhalis, and non-typeable Haemophilus influenzae) 3
Key Differential Diagnostic Points
- Pain location: Otitis externa causes pain with manipulation of the tragus or pinna, while otitis media pain is not typically exacerbated by ear manipulation 1
- Pneumatic otoscopy: Critical for differentiation - good tympanic membrane mobility suggests otitis externa, while limited or absent mobility suggests otitis media 1
- Tympanic membrane appearance: In otitis externa, the tympanic membrane is typically normal unless the infection is severe; in otitis media, the tympanic membrane is often bulging and erythematous 1
Treatment Approaches
Otitis Externa Treatment
- Topical therapy is the mainstay of treatment for uncomplicated otitis externa 1, 2
- Aural toilet (cleaning) is necessary when the ear canal is obstructed to enhance drug delivery 1
- Topical antimicrobials deliver concentrations 100-1000 times higher than systemic therapy 2
- For adults and children ≥13 years: Ten drops (0.5 mL) of ofloxacin 0.3% instilled into the affected ear once daily for seven days 4
- For children 6 months to 13 years: Five drops (0.25 mL) of ofloxacin 0.3% instilled into the affected ear once daily for seven days 4
- Acidification with a topical solution of 2% acetic acid combined with hydrocortisone is effective in most cases 5
- Systemic antibiotics are not recommended as initial therapy unless there is extension beyond the ear canal or specific host factors (diabetes, immunocompromised state) 1, 2
Otitis Media Treatment
- Pain assessment and management is essential 1
- Antibiotic therapy recommended for bilateral or unilateral acute otitis media in children 6 months to 2 years 1
- For acute otitis media with tympanostomy tubes in children 1-12 years: Five drops (0.25 mL) of ofloxacin 0.3% instilled into the affected ear twice daily for ten days 4
- For chronic suppurative otitis media with perforated tympanic membranes in patients ≥12 years: Ten drops (0.5 mL) of ofloxacin 0.3% instilled into the affected ear twice daily for fourteen days 4
- Antibiotic therapy does not significantly benefit most patients with acute otitis media, but long-term prophylactic antibiotic therapy can reduce the risk of recurrence among high-risk children 3
Special Considerations and Risk Factors
Otitis Externa
- Factors that modify management include nonintact tympanic membrane, tympanostomy tube, diabetes, immunocompromised state, and prior radiotherapy 6
- Patients with diabetes or immunocompromised states require special consideration due to susceptibility to otomycosis and necrotizing otitis externa 6
- Necrotizing (malignant) otitis externa is an aggressive infection affecting primarily elderly, diabetic, or immunocompromised patients 6, 2
- Fungal otitis externa (otomycosis) is common in tropical countries, humid locations, after long-term topical antibiotic therapy, and in those with diabetes or immunocompromised states 6, 2
Otitis Media
- Vaccine development is a key direction for reducing the burden of otitis media 3
- Tympanostomy tubes or perforated tympanic membranes may lead to diffuse otitis externa due to purulent middle-ear secretions entering the external ear canal 6
Common Pitfalls and Caveats
- Otitis externa can mimic the appearance of acute otitis media due to erythema involving the tympanic membrane 1
- Reassessment is necessary if symptoms don't improve within 48-72 hours for both conditions 1
- Avoid confusing external otitis (H60 codes) with otitis media (H65-H67 codes) for proper coding and documentation 2
- Ear canal irrigation should be avoided in patients with diabetes or immunocompromised states as it may predispose to necrotizing otitis externa 6
- Topical antibiotic therapy is contraindicated in managing otomycosis (fungal otitis externa) as it is ineffective and may promote further fungal overgrowth 6