Otitis Externa in Primary Care
By Paul Evans, DO, FAAFP, FACOFP
ABSTRACT: Otitis externa (OE) is commonly seen in all age groups in the primary care setting. This article will outline basic concepts in the diagnosis and management of acute and chronic otitis externa, emphasizing recognition of a rare but serious variant, necrotizing otitis externa. The roles of osteopathic treatment and preventive measures are included.
Otitis externa is a commonly seen condition in primary care, affecting children, adults, and the elderly. It is caused by inflammation of the external auditory canal (EAC).1 The natural history of the condition is that it is usually self limiting. It can be acute or chronic. It can also present with eczematous features. Rarely, it can progress with extension to a serious condition, “malignant” or necrotizing otitis externa, most commonly in diabetics or other immunocompromised patients, causing systemic illness, cranial nerve palsies, local osteomyelitis, and even death.2 Increases in otitis externa are seen in warmer months, and are related to contact with water, excess humidity, and conditions that lower the protective cerumen barrier.
EAC trauma, swimming, use of a hearing aid or other devices that occlude the canal increase risk.3,4 Eczema, seborrhea, and psoriasis in the medical history are also predisposing conditions.5,6
Symptoms and Signs
Commonly, patients complain of ear pain, itching, purulent discharge, ear fullness, decreased hearing, and tinnitus. Physical examination may reveal an edematous and erythematous EAC, pain with pinnal retraction, and a purulent discharge with debris in the canal. Eczematous changes in and around the EAC are common.
Diagnostic Classifications
Acute otitis externa is usually infectious, with Staphylococcus aureus or pseudomonas aeruginosa as the most common isolates. Anaerobes and
fungal organisms such as Aspergillus and candida albicans may also play a role.7,8 Since most patients respond well to first line therapy, routine cultures are not necessary. If treatment of common infectious organisms fails, then noninfectious etiologies such as dermatologic disorders or trauma should be considered.
Chronic otitis externa is defined by duration of symptoms. OE that lasts longer than two months is defined as chronic. The etiologies are similar to those that cause acute OE. Chronicity may be due to failure to diagnose the correct cause, due to incorrect treatment agent, dosage, or duration. Reducing or eliminating predisposing factors is an important consideration.
Chronic purulent otitis media may be caused by perforation, furunculosis, eczema or other dermatological conditions. Another cause that should be kept in mind may be contact dermatitis associated with sensitivities for neomycin and other agents found in topical preparations.
Necrotizing otitis externa (NOE), or the “malignant” form of OE is a condition seen in immunocompromised patients, such as in elderly diabetics. Symptoms include severe ear pain, especially at night, and may include constitutional symptoms. Cranial nerve palsies may be present. A culture and pathologic examination of granulation tissue is essential.2,9 Early diagnosis and aggressive management is required as NOE can lead to osteomyelitis of the base of the skull and erosion through bone into CNS structures. Pseudomonas aeruginosa is the predominant pathogen.
Treatment
Acute otitis externa
Gentle cleaning and suctioning of discharge and debris improves efficacy of topical agents. Irrigation is controversial. Initial culture is not necessary.
Topical drops that contain a mild acid (e.g., Domeboro Otic, 4–6 drops q2–3h) or antibiotics and a steroid [e.g., neomycin, polymyxin B sulfate, and hydrocortisone (Cortisporin Otic suspension), 3–5 drops qid] are effective agents. Acidification lowers pH to inhibit Pseudomonas growth. Therapy should be used for about 7–10 days with sufficient quantity to contact all involved EAC tissues. If infection spreads to the concha or to the pre-auricular or infra-auricular area, systemic antibiotics should be considered. If a fungal etiology is suspected, topical nystatin and clotrimazole have been successful first-line agents.3,4,5,6
Cotton wicks may be used initially for a severely swollen EAC. They assist in reducing swelling and allow more topical therapy onto the affected canal tissues. After 48– 72 hours, the wick can usually be removed, with continuation of drops for the full 7–10 days.
Analgesia is an important component of management initially. A topical anesthetic [e.g., benzocaine, antipyrine, and dehydrated glycerin (Auralgan), 2–4 drops q1–2h as required], with simultaneous use of acetaminophen or ibuprofen, is usually successful. Uncommonly, short-term narcotic analgesics may be necessary.
Local antibiotic resistance patterns should be considered since an increase in methicillin resistant S. aureus has been reported and may affect treatment choices.10
Chronic Otitis Externa
Aural hygiene of the EAC is important. The canal should be cleaned of debris and kept dry when possible. Occlusive devices such as in-ear hearing aids, earplugs, earphones, and stethoscopes should be cleaned and their use limited. Bacterial and fungal cultures should now
be considered.
A screening potassium hydroxide (KOH) preparation can rapidly detect fungal elements, which suggests otomycosis.
If the patient has not shown response to treatment, and, compliance has been ensured with an appropriate regimen for the cultured pathogen, a change to another antibiotic is indicated. Mixed bacterial and fungal infections may require multiple drug therapy. Addition of topical steroids reduces inflammation and the accompanying symptoms.
If all medical therapy fails, surgical consultation is appropriate for consideration for conchomeatoplasty or another procedure as a last resort.
Necrotizing or Malignant
Otitis Externa
This rare condition requires early and aggressive therapy including consultation with an otolaryngologist. Hospitalization with antipseudomonal parenteral antibiotics (e.g., ceftazidime and gentamicin), careful debridement, and computed tomography (CT) or magnetic resonance imaging (MRI) to delineate the extent of bony or soft-tissue erosions are recommended. If the patient is diabetic, strict control of glucose is a goal. Meticulous debridement and topical antibiotics may complement oral or IV antimicrobial agents.
Special Considerations – Prevention
Infectious causes
Reducing moisture in the EAC and inducing a mildly acidic environment assists preventing OE. Over-the-counter preparations for preventing swimmer's ear that contain a drying agent and a mild acid are effective; similar home remedies can be made with a mixture of 50 percent isopropyl alcohol and 50 percent vinegar (5 percent acetic acid). When applied after moisture exposure, such a mixture is both efficacious and cost effective. (Beers 2004)
Noninfectious causes
Topical steroids for eczematous, allergic, or contact dermatitis is helpful. Patients who use occlusive EAC devices, such as hearing aids, earphones and earpieces, or stethoscopes, must maintain a high level of attention to cleanliness to avoid bacterial or fungal contamination.
Osteopathic considerations
Osteopathic techniques can be a valuable adjunct to antimicrobial therapy for OE. In particular, optimizing lymphatic drainage and improving local blood flow through auricular drainage techniques may decrease edema, increase the flow of immune system elements that are critical for resolution of infection, and decrease the duration of the illness. Lymphatic pump techniques also improve overall lymphatic flow systemically that will optimize homeostatic regulatory mechanisms, aiding the healing process.
Conclusion
A careful history and examination usually suffices in making the correct diagnosis without complex laboratory studies. Treatment strategies are successful in the vast majority of cases on the initial visit. A high index of suspicion for necrotizing otitis externa in elderly diabetics and immuno-compromised patients is important. Recognition and alleviation of contributing factors such as EAC allergic dermatitis, ear occlusion devices, and persistent moisture can alleviate most cases of chronic otitis externa. Otitis externa can be treated successfully in the primary care setting by all osteopathic family physicians.
Dr. Evans is a graduate of the Philadelphia College of Osteopathic Medicine in Philadelphia, Pennsylvania. He is currently the vice dean, chief academic officer, and professor of Family Medicine at the Georgia Campus, Philadelphia College of Osteopathic Medicine.
References