OTITIS EXTERNA

OTITIS EXTERNA

Current Diagnosis

•   Ear pain or itching

•   External ear tenderness

•   Clear or purulent discharge (otorrhea), and debris in ear canal

•   Possible ear canal edema

Current Therapy

•   Topical antibiotic therapy, with or without topical corticosteroid

•   Topical acetic acid (VoSol) less effective than topical antibiotics

•   Oral antibiotics usually unnecessary

•   Analgesic therapy

Epidemiology

Otitis externa is inflammation of the external auditory canal, usually caused by bacterial infection. It is a common problem in primary care, with an annual incidence of about 1% and lifetime incidence of about 10%. It affects both adults and children and is commonly known as “swimmer’s ear.”

Risk Factors

Increased moisture in the ear canal, often caused by swimming, hearing aids, or a humid environment, increases the risk of developing otitis externa. Trauma to the external canal (such as self- inflicted injury with a cotton swab) is also a risk factor. Genetic factors may play a role, and people with narrow external canals or absence of ear wax are at increased risk. Ear wax, which is acidic, is protective except when it causes total occlusion and a moist environment behind the occlusion.

Pathophysiology

Otitis externa is usually (98%) caused by bacteria: the most common culture results are Pseudomonas aeruginosa, Staphylococcus aureus, or polymicrobial. Fungi are an occasional cause. In most cases the infection is superficial, but infection can cause edema of the auditory canal and spread locally, causing cellulitis and even osteomyelitis.

Prevention

Topical acetic acid (VoSol),1 topical corticosteroids, water exclusion (wearing ear plugs while swimming), and aural toilet have not been evaluated in clinical trials. However, people who have recurrent otitis externa should be advised that water in the ear canal increases risk of developing otitis externa. If they swim, ear plugs may be helpful in preventing water from entering the ear canal. After swimming, the canal can be dried with a hair dryer on the lowest setting. Also, acetic acid 2% (VoSol)1 2 to 5 drops could be applied after swimming to reacidify the ear canal.

Clinical Manifestations

The main symptom of acute otitis externa is pain. Mild cases can present with only itching or ear fullness. Often there is otorrhea and debris in the external canal, which can obscure the tympanic membrane and cause hearing loss. There can be preauricular lymphadenopathy. Fever, if present, may indicate local cellulitis.

Diagnosis

Acute otitis externa is diagnosed clinically. It presents with pain, itching or fullness in the ear, appearing within a period of 48 hours, with duration of less than 3 weeks. Tenderness of the tragus or movement of the pinna is a key symptom. Otorrhea and canal erythema and edema may be present but are not necessary for diagnosis (Figure 1). If possible, debris should be cleared from the canal to allow visualization of the tympanic membrane to assess if it is intact.

FIGURE 1    Chronic otitis externa with debris in canal.

Granulation tissue at the bone-cartilage junction of the external canal (Figure 2), fever > 39 °C, and severe pain are signs of malignant otitis externa.

FIGURE 2    Necrotizing otitis with granulation tissue at  junction.

Differential Diagnosis

Though the diagnosis of otitis externa is usually clear-cut, a differential diagnosis should be considered when symptoms do not resolve with usual treatment or the symptoms are particularly severe (Table 1).

Table 1

Differential Diagnosis of Otitis Externa

Otitis media with perforated tympanic membrane

Malignant otitis externa

Contact dermatitis

Eczema

Psoriasis

Seborrhea

Ramsey-Hunt syndrome (otic herpes zoster)

Cellulitis

Treatment

Topical antibiotics (Table 2) with or without steroid are effective in treating otitis externa. Fluoroquinolones have not been shown to be clearly superior to other antibiotics. Topical 2% acetic acid (VoSol) is also effective, though significantly less effective when compared with antibiotic/steroid drops in terms of cure rate at 2 and 3 weeks (OR 0.29). Oral antibiotics are not helpful unless there are signs of local cellulitis, in which case an antibiotic effective against Pseudomonas and Staphylococcus should be chosen.

Table 2

Topical Antibiotics

Medication                                                          Dosing and Frequency     Notes
Ofloxacin 0.3% solution (Floxin Otic) 10 drops in ear 1 ×

/day × 7 days

Approved for cases of perforated tympanic membrane
Ciprofloxacin/dexamethasone (Ciprodex) Ciprofloxacin/hydrocortisone  (Cipro HC) 4 drops bid × 7 days Ciprodex approved for cases of perforated tympanic membrane
Neomycin/polymyxin B/hydrocortisone (Cortisporin Otic) 4 drops tid/qid × 7 days Neomycin can cause hypersensitivity reaction
Acetic acid 2% (Vosol Otic) 5 drops tid/qid × 7–14 days Less effective; can cause stinging when applied
Clotrimazole 1% otic6 4 drops qid × 7 days When a fungal cause is suspected

6  May be compounded by pharmacists.

To improve the penetrance of antibiotic drops, cotton ear wicks are often used when there is significant canal edema, but there have been no randomized controlled trials comparing this with antibiotic drops without ear wicks. Aural toilet by suctioning is recommended by specialists, but this option is often not available in primary care, and there have been no randomized controlled trials showing efficacy. If debris needs to be removed and suction is unavailable, gentle use of cotton-tipped swabs, ear cerumen curette or ear cerumen spoon is safer than irrigation, which is dangerous if the tympanic membrane is ruptured. If the tympanic membrane is perforated or cannot be visualized, topical ofloxacin (Floxin Otic) and ciprofloxacin/dexamethasone (Ciprodex, but not Cipro HC) are nonototixic and FDA approved for treatment.

Ciprofloxacin (Ciloxan), tobramycin (Tobrex) or gentamicin (Garamycin) ophthalmic drops are sometimes used off-label to treat otitis externa.

Pain can usually be controlled with nonsteroidal anti-inflammatory drugs or acetaminophen. Opioids can be considered when pain is severe.

Monitoring

Symptoms should improve significantly within the first 24 hours of treatment. The average time to complete resolution of symptoms is 6 days. If a patient is not improving by 48 to 72 hours, he or she should be reassessed and possibly referred to an otolaryngology specialist.

Patients at high risk for complications include those with diabetes, immunocompromised patients (such as in HIV), and the elderly.

Complications

Hypersensitivity reactions to otic antibiotics are possible, with neomycin being the most common agent. There will be pruritus and erythema, which can spread from the canal to the external ear. The causative antibiotic should be stopped and a preparation with another topic antibiotic and topical steroid should be used.

The most serious complication is malignant otitis externa, which is an extension of bacterial infection into local tissues and the mastoid or temporal bones, and can be life-threatening. It should be considered if there is fever (> 39 °C), disproportionate pain, and facial or other cranial nerve palsies. The causative organisms are similar to acute otitis externa (P. aeruginosa and S. aureus are most common). It occurs mostly in immunocompromised individuals, such as those with diabetes or HIV, or who are undergoing chemotherapy. Patients should be given parenteral antibiotics and managed in a hospital with ENT consultation. Culture with sensitivity and CT scanning are usually necessary for accurate diagnosis and management.

References

1.     Kaushik V., Malik T., Saeed S.R. Interventions for acute otitis externa. Cochrane Database Syst Rev. (1):2010;doi:10.1002/14651858.CD004740.pub2 CD004740.

2.     Rosenfeld R.M., et al. Clinical practice guideline: acute otitis externa. Otolaryngol Head Neck. 2014;150(1 Suppl):S1–S24.

3.     Schaefer P., Baugh R. Acute otitis externa: an update. Am Fam Physician. 2012;86:1055–1061.

1  Not FDA approved for this  indication

KNOWLEDGE BASE
About Genomic Medicine UK

Genomic Medicine UK is the home of comprehensive genomic testing in London. Our consultant medical doctors work tirelessly to provide the highest standards of medical laboratory testing for personalised medical treatments, genomic risk assessments for common diseases and genomic risk assessment for cancers at an affordable cost for everybody. We use state-of-the-art modern technologies of next-generation sequencing and DNA chip microarray to provide all of our patients and partner doctors with a reliable, evidence-based, thorough and valuable medical service.

X