The most common cause of pain in the external ear is acute otitis externa. It affects 3% to 10% of the patient population. The pain is caused by inflammation and edema of the ear canal skin, which is normally adherent to the bone and cartilage of the auditory canal. The inflammatory reaction can be caused by bacteria, fungi, or contact dermatitis (see eTable 19-2 online).
Cerumen protects the canal by forming an acidic coat that helps prevent infection. Factors that predispose to otitis externa include absence of cerumen, often from excessive cleaning by the patient; water, which macerates the skin of the auditory canal and raises the pH; and trauma to the skin of the auditory canal from foreign bodies or use of cotton swabs.
When a bacterial organism is suspected, treatment consists of cleaning the ear canal of any debris or drainage and then instilling antibiotic drops with or without steroids. Because the most common bacterial organisms in this infection are Pseudomonas aeruginosa and Staphylococcus aureus, drops containing ciprofloxacin or neomycin/polymyxin B are effective against these pathogens, combined with a steroid to decrease inflammation, pain, and pruritus (Ciprodex, Cortisporin, Coly-Mycin, Pediotic). A recent study found Ciprodex to be more effective against P. aeruginosa than neomycin/poly-myxin B/hydrocortisone (Dohar et al., 2009).
The clinician must use judgment in assessing the severity of the infection and treat accordingly. If the infection spreads beyond the auditory canal, oral antimicrobials are indicated. If clinical improvement is not apparent after 48 hours, the patient needs to be reexamined for additional treatment or referral to an otorhinolaryngologist.
Fungal infections compose less than 10% of external otitis cases. The most common fungi are Aspergillus niger and Candida species and are more prevalent in tropical climates. Itching is a more common complaint than pain in fungal ear infections. Thorough cleaning of the ear canal is the primary duty of the physician in this infection. Drops that are effective include 2% acetic acid with or without a steroid. Clotrimazole drops or powder can also be used to treat fungal infections of the canal (van Bolen et al., 2003).
Approximately 90% of necrotizing (malignant) otitis externa is seen in immunocompromised patients such as diabetic patients, patients with acquired immunodeficiency syndrome (AIDS), and those receiving chemotherapy. Systemic antibiotics are mandatory in these cases. Antipseudo-monal antimicrobials should be administered intravenously in the hospital setting, and surgical debridement is often necessary. Complications from necrotizing otitis externa include facial nerve palsy, mastoiditis, meningitis, and even death (Quick, 1999).
Other conditions that affect the external auditory canal include impacted cerumen, seborrheic dermatitis, psoriasis, contact dermatitis, and staphylococcal furunculosis. Symptoms and signs include pruritus, edema, scaling, crusting, oozing, and fissuring of the external auditory canal. Treatment of the underlying disease is the primary goal. Cortico-steroid preparations are indicated for seborrheic dermatitis, psoriasis, and contact dermatitis. Oral antibiotics and sometimes incision and drainage are required for staphylococcal furunculosis.
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