Otitis Externa

The following are the more common signs and symptoms of otitis externa:

• Otalgia 
• Erythema
• Pruritus
• Fluid discharge from the ear (pus)
• Hearing impairment
• Swelling of the affected ear

Patients suspected with otitis externa are brought to the physician for initial evaluation of the outer ear for evident signs. An otoscopic examination is then conducted to see the inner canal and the condition of the tympanic membrane. In complicated cases of otitis externa, patients are usually referred to an otolaryngologist  for further evaluation and management.

Sample of secretions or ear debris may be taken for laboratory culture and sensitivity testing to determine the ideal antibiotics to be used in case the preliminary antibiotics prove to be ineffective. Imaging technique with computed tomography (CT) of the skull may be implored to elucidate the bony erosions with necrotizing cases of malignant otitis externa [7]. Magnetic Resonance Imaging (MRI) is indicated where suspected deep soft tissue involvement is entertained for better visualization [8].

Majority of otitis externa is treated medically while some cases may require surgical drainage as a treatment option.

These are the medical modalities available for the treatment of otitis externa:

• Analgesics: Patients may benefit from pain relievers like naproxen and ibuprofen. In severe cases of otitis externa, narcotics may be given to subdue the pain [9].
• Antibiotics: This is the mainstay on the treatment of otitis externa. Antibiotic therapy may be taken orally, eardrops form or in combination where the cure rate reaches 87-97% in uncomplicated case [10].
• Steroids: Severe inflammation may be controlled by the oral intake of steroids
• Antifungals: Fungal coinfection with otitis externa may need antifungal medications.
• Acidic solutions: Ear drops that may restore the normal pH of the ear to fend off invading bacteria.

The majority of otitis externa patient will resolve within 48-72 hours without complication after the administration of pharmacotherapy. Full recovery is usually expected within 7 to 10 days. Surgical drainage and debridement may be necessary to drain abscesses in the ear.

Untreated local infections may lead to malignant otitis externa which may complicate morbidity and cause mortality in severe forms. The necrotizing form of malignant otitis externa may reach a mortality rating of 20% especially among immune-compromised hosts and may even reach 50% if no medical interventions are done.

Complications

Otitis externa may give rise to any of the following given medical complications:

• Temporary auditory disturbance: Temporary hearing loss may be experienced during the inflammatory process which is usually due to impacted cerumen. This could resolve spontaneously within one week.
• Cellulitis: The uncontrolled spread of bacteria in contiguous structures like the face may sometimes occur. 
• Chronic otitis externa: Acute otitis externa with recurrent symptoms beyond 3 months becomes chronic otitis externa. This is caused by tougher bacterial strain which may be resistant to treatment, an allergic response, or a coinfection with a fungus.
• Necrotizing infection: The inward spread to the deeper tissue and the bones is severe complication of otitis externa which can cause mortality.
• Spread of infection: The uncontrolled infection may spread to the brain and cause abscess.

The most common cause of otitis externa is retained water in the ear that breeds the bacterial pathogen. Any break in the integrity of the skin of the ear canal can lead to the infection of the ear. Abrasions happen with frequent scratching, chronic use of ear piece and the ungentle application of cotton swabs during ear cleaning.

The accumulated cerumen may hold moisture and propagate the growth of bacterial organisms that may lead to infections. The majority of otitis externa is caused by bacterial infection; however, fungal (otomycosis) and psoriatic etiology may rarely initiate the disease process [1].

The most common pathogen in otitis externa is Pseudomonas aeruginosa representing 38% of cases followed by Staphylococcus species, anaerobes and gram-negative organisms [2].

In the United States, otitis externa has been recorded across all states with an average incidence of 4 cases per 1000 population per year [3]. Infection of the external ear abounds during the summer season where it’s warm and humid and presumably because water activities are common during this time [4]. Otitis externa are more prevalent in tropical countries than in temperate countries.

The disease affliction peaks at 7–12 years of age and is also common among young adults. The prevalence of otitis externa slightly peaks again beyond the age of 65 years old because of comorbid factors like diabetes and rheumatoid arthritis, and there is a large sector of elders that uses hearing aids which can propagate the infections. Patient with allergic rhinitis and asthma are more prone to otitis externa [5].

The pathophysiology in the development of otitis externa can be divided into four mechanisms of origin:

Obstructive: The accumulation of cerumen may accumulate water and moisture causing a maceration of the outer skin layer which invites bacterial invasion.

Drying: The absence of cerumen and loss of natural moisture of the ear canal skin due to frequent ear cleaning can cause fissuring and thinning of the skin membranes. The compromised skin layer may invite invading bacteria to cause the infection.

Trauma: Any break in the skin layer due to trauma from cotton wabs, fingernails or instruments may cause abrasion and eventual infection of the ear canal.

Alteration of skin natural pH: Patient on radiotherapy, chemotherapy and on chronic steroids use can alter the skin’s pH making it less resistant to bacterial invasion. Immuno-compromised patients may develop a severe necrotizing form of infection known as malignant otitis externa [6].

The best way to prevent water from accumulating in the ear canal is to wear ear plugs and swimming caps during swimming and diving activities. Practice tilting of one’s head in both directions after shower and swimming to rid-off excess water from both ears. Cleaning of ears must be done in moderation in up to once weekly to prevent the drying of the ear canal.

Otitis externa or outer ear infection is an infection of the outer ear canal. Patients must observe strict compliance in the intake of antibiotics to avoid antibiotic resistance of bacterial infection. One must call the attention of the attending physician if no improvements are observed after 3 days of treatment to merit reevaluation of treatment and prevent serious complications. Any notable discharges must also be reported to proper medical authorities for further investigation and evaluation.