AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

External ear infections require otoscopic examination that must be performed in conjunction with evaluation of related structures such as the external ear and the head and neck. For example, examine the auricle for swelling, deformity, and erythema; the face for evidence of facial nerve paresis or other cranial neuropathy; and the neck for masses.

Tools

The otoscope consists of a head and a handle and is used to examine the external auditory canal (EAC), tympanic membrane, and middle ear. A magnifying lens enhances the clinician's view. One of 2 heads for the otoscope may be used. A diagnostic head is fixed to the otoscope, which does not allow use of microinstruments through the scope, while a working or operating head has a magnifying lens that can slide to the side, enabling passage of microinstruments through the speculum into the EAC and middle ear. A pneumatic attachment on the diagnostic head allows for assessment of tympanic membrane motion by generating positive pressure in the external canal, causing the tympanic membrane to deflect medially. When pressure is released, the tympanic membrane expands laterally. This technique is an important tool in the diagnosis of middle ear effusions, vascular lesions, and inner ear fistulas.

Technique

To best view the tympanic membrane in an adult, retract the auricle posteriorly and superiorly to straighten the EAC. In a child, pull the auricle posteriorly. Remove any debris or cerumen to allow for an adequate examination. Examine the external canal for masses, skin changes, and otorrhea; then, examine all parts of the tympanic membrane (eg, pars tensa, pars flaccida). Next, ascertain the motion of the tympanic membrane by pneumatic otoscopy. Lastly, attempt a thorough examination of the middle ear contents through the tympanic membrane, although this examination may be limited by the opacity of the tympanic membrane itself.

Pathophysiology

Anatomy

The external ear consists of the auricle and the EAC. The auricle is composed of elastic cartilage with the overlying skin attached directly to the perichondrium. The EAC has a cartilaginous framework in its outer third, while its inner two thirds is bony. The skin over the cartilaginous canal is thicker than that over the bony canal and contains apopilosebaceous units, which produce cerumen. Apopilosebaceous units are composed of both apocrine and eccrine glands that secrete their products around the base of a hair follicle. The EAC is related to the mandibular fossa anteriorly, mastoid air cells posteriorly, middle cranial fossa superiorly, and parotid gland inferiorly.

Glandular secretions from the apopilosebaceous unit combine with sloughed squamous epithelium (cerumen) to coat the external ear canal and maintain an acidic pH. This cerumen coat migrates from the isthmus of the external canal to the lateral part of the canal. Use of cotton swabs and excessive cleaning of the ear canal can disrupt this protective coating, leading to external ear infection.

Disorders of the EAC include otitis externa, otomycosis (fungal otitis externa), and eczematoid (psoriatic otitis externa). Otitis externa is a dermatitis most often caused by a bacterial pathogen, commonly a pseudomonal or staphylococcal species.

Otomycosis is most commonly due to infection with an Aspergillus species. Pseudomonal infection produces green or yellow purulent otorrhea. Aspergillus otomycosis appears as a fine white mat topped by black spheres. In addition to otorrhea, erythema and edema of the EAC are common. In severe cases, soft tissue stenosis may be present. Extension of the infection from the EAC may manifest as cellulitic skin changes involving the concha of the auricle and the tragus. In most cases, treatment consists of acidification of the ear canal with drops, with or without topical antibiotics, although systemic antibiotics may be necessary as well.

Eczematoid is somewhat different in that it is not due to an infectious pathogen. This condition often manifests as a moist, white, granular otorrhea on an erythematous base. Eczematoid often responds to topical steroid drops but may be chronic or recurrent.

Embryology

Auricle: The auricle begins to form during the sixth week of gestation by a consolidation of portions of the mesoderm of the first and second branchial arches, giving rise to the His hillocks. The first 3 hillocks are derived from the first arch, and the second 3 are from the second arch. The auricle reaches adult shape by the twentieth week of gestation, but the adult size is not reached until age 9 years.

EAC: The EAC begins to form during the eighth week of gestation, when the surface ectoderm of the first pharyngeal groove thickens and grows toward the middle ear. This core of tissue begins to resorb by the 21 weeks' gestation to form a channel that is complete by 28 weeks' gestation. The canal reaches adult size by age 9 years and ossifies completely by age 3 years.

Frequency

United States

Otitis externa is a common disorder, but frequency, sex, and age predilection is unknown.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

Usually a history of preceding ear trauma in the form of forceful ear cleaning, use of cotton swabs, or water in the ear canal is present.

Severe throbbing pain with ear discharge follows, which can then lead to a hearing loss due to occlusion of the ear canal.

Physical

Pseudomonal infection produces purulent otorrhea that may be green or yellow, while Aspergillus otomycosis looks like a fine white mat topped by black spheres. In addition to otorrhea, erythema and edema of the EAC is common. In severe cases, soft tissue stenosis may be present. Extension of the infection from the EAC may manifest as cellulitic skin changes involving the concha of the auricle and the tragus.

Causes

Common predisposing causes are swimming, forceful cleaning of the ear, and trauma.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Ramsay Hunt syndrome

This condition, more accurately known as herpes zoster oticus, is caused by varicella-zoster viral infection. Ramsay Hunt syndrome is characterized by facial nerve paralysis and sensorineural hearing loss, with bullous myringitis and a vesicular eruption of the concha of the pinna and the EAC. A painful otitis externa may be present as well. Treatment includes use of an antiviral agent (eg, valacyclovir) and systemic steroids. The role of facial nerve decompression remains controversial.

Furuncle

Staphylococcal infection of a hair follicle is the usual cause of a furuncle. This infection occurs in the lateral cartilaginous hair-bearing portion of the EAC. On otoscopic examination, a furuncle is a localized infection, which may develop into an abscess, rather than the diffuse inflammatory process characteristic of otitis externa.

Skull base osteomyelitis

This serious infection, also known as malignant otitis externa, occurs most often in patients who are diabetic or immunocompromised. The pathogenic bacteria are usually Pseudomonas aeruginosa. Other predisposing conditions include arteriosclerosis, immunosuppression, chemotherapy, steroid use, and other immunodeficient states. The diagnosis is strongly suggested by a history of diabetes mellitus, severe otalgia, cranial neuropathies, and characteristic EAC findings.

The EAC may be filled with friable granulation tissue, which is primarily found inferiorly. Because this presentation may be identical to that of a soft tissue malignancy, prudence dictates a tissue biopsy, even if a history of diabetes mellitus is present. Bare bone of the EAC floor may be exposed; small bony sequestra may be observed as well.

CT scanning demonstrates bone erosion, and gallium scanning can be performed at points throughout treatment to monitor resolution. Treatment consists of administration of an antipseudomonal IV antibiotic such as ceftazidime (in some cases) or oral ciprofloxacin (in less dramatic cases). Extended treatment for at least 6 weeks is most appropriate. Hyperbaric oxygen therapy may also be effective. Surgical debridement is reserved for granulation tissue and bony sequestra.

Preauricular cyst and fistula

Abnormal development of the first and second branchial arch may result in the formation of a preauricular cyst or fistula, which may manifest as persistent discharge or recurrent infection. A draining sinus may be present anterior to the tragus; when infected, the cyst distends with pus and the overlying skin is erythematous. These lesions are managed by complete surgical excision if they become repeatedly infected. The facial nerve is at risk of injury during the excision of these lesions because of the close relationship of the preauricular cyst or fistula to the superior branches of the facial nerve within the parotid gland.

First branchial cleft anomalies have a more complex embryologic origin than preauricular cysts and fistulas. These lesions may not have an obvious sinus tract on the skin and may manifest as an abscess extending deeply into the EAC, parotid, and/or neck.

Lacerations

Full-thickness auricular lacerations may be observed after blunt or sharp trauma. These injuries are managed surgically by closing both the perichondrium and the skin. In contrast, external canal lacerations may occur after attempts at cleaning the ear canal using cotton-tipped applicators. These lacerations are usually managed by microscopically placing any skin flaps in their normal position, packing the ear canal, and administering topical antibiotic drops.

Atopic dermatitis

Drug sensitivity to topical antibiotic solutions is well known. Neomycin allergy occurs in up to 5% of patients treated with the medication. Suspect drug sensitivity if worsening of symptoms associated with skin excoriation and weeping occurs in the distribution of the topical medication exposure after application of drops.

Metal sensitivity also manifests as excoriation, erythema, and edema around the exposure site (eg, a piercing hole). A common allergen is nickel, an impurity that may be present in precious metals. Atopic dermatitis is managed by removal of the allergen, such as an earring, and beginning topical steroid and antibiotics if the wound is secondarily infected. The diagnosis of metal sensitivity is confirmed by performing a skin patch test.

Cerumen impaction

Cerumen impaction is the most common abnormality found on otoscopic examination, yet only a small proportion of the general population requires regular disimpaction because the EAC has the innate ability to produce and clear itself of cerumen. Cerumen may vary in color and consistency and may exist with other pathologies. Of note, debris in the EAC from cholesteatoma or tumors may be confused with cerumen, indicating that considerable care is required when attempting debridement of the EAC. Debridement may be accomplished with microinstruments or by aspirating the ear canal contents with a No 5 or No 7 Barton suction, while under direct vision through the otoscope or microscope. Irrigation of the ear canal is another option, but use of a pressurized irrigation system entails the risk of trauma.

Exostosis and osteoma

The 2 most common bony lesions of the EAC, exostoses and osteomas, differ histologically and clinically. Exostoses tend to arise from the anterior and/or posterior floor of the medial EAC. Exostoses have a sessile base and are covered with normal-appearing skin. Both anterior and posterior exostoses may be found simultaneously.

Osteomas may arise from any region of the bony EAC and often are pedunculated. Osteomas may also be either single or multiple and are covered by normal skin. Exostosis and osteomas require surgical treatment only if they are so large that they lead to a conductive hearing loss or intractable otitis externa.

Foreign body

Foreign bodies are not infrequently encountered in the EAC. In children, parts of toys or even food may be found in the EAC, and, thus, appearance varies. In adults, fragments of cotton swabs are the most common finding. Erythema and edema surrounding the foreign body are commonly present. Using microinstruments, the foreign body may be removed under a microscope, depending on the patient's ability to cooperate.

Acute (bullous) and chronic (granular) myringitis

Acute myringitis is usually caused by a mycoplasma or viral infection and is observed in adults and children. It is characterized by hemorrhagic bullae involving the tympanic membrane and a flulike syndrome. It is self-limiting and requires pain and fever management.

Chronic myringitis is defined as deepithelization of the tympanic membrane, granulation tissue formation, and discharge. Treatment includes topical application of eardrops, a caustic solution in unresponsive cases, and mechanical removal of polypoidal granulations.

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• A formal bacterial and fungal culture, Gram stain, or KOH prep smear of the ear canal confirms the causative agent. This is typically obtained in refractory cases when empiric therapy has been unsuccessful.
• Blood work is usually unnecessary.

Imaging Studies

• Imaging studies are not required for otitis externa.
• In patients with malignant otitis media, CT scanning or MRI of the temporal bone and triple-phase bone scanning and gallium scanning are performed.

Histologic Findings

Histologic examination of the skin of the external canal shows acute inflammation with exudate.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

In most cases, treatment consists of acidification of the ear canal with drops, with or without topical antibiotics, although systemic antibiotics may also be necessary. Eczematoid or psoriatic otitis externa often responds to topical steroid drops but may be chronic or recurrent. The ear may require frequent suction debridement under a microscope. If significant canal edema develops, an Oto-Wick may be required to allow delivery of otopical medications into the medial canal. Otitis externa can be very painful and may require narcotic analgesics to control pain.

Surgical Care

Surgical debridement is usually reserved for malignant otitis externa or for complications of otitis externa such as external canal stenosis.

Consultations

Refractory otitis externa requires an otolaryngology consult.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Commonly used topical eardrops are acetic acid drops, which change the pH of the ear canal; antibacterial drops, which control bacterial growth; and antifungal preparations. Oral or parenteral antibiotics are reserved for severe cases.

Drug Category: Acidifying eardrops

Acidifying eardrops reduce ear canal pH, which retards microbial growth.

Drug Category: Antibiotic eardrops

These eardrops treat bacterial infection and reduce canal edema.

Drug Category: Antifungal agents

These agents are used to treat otomycosis refractory to acidification drops.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Outpatient Care

• The patient requires suctioning of the EAC on a weekly basis until debris has been removed.

In/Out Patient Meds

• Topical eardrops are the mainstay of both inpatient and outpatient treatment. Oral antibiotics or antifungal agents are usually reserved for refractory cases.

Deterrence/Prevention

• Otitis externa can be prevented by avoiding use of cotton-tipped swabs or objects such as bobby pins to clean ears. Use of cotton-tipped swabs or bobby pins can cause excoriation of the canal skin that can lead to otitis externa.

Prognosis

• The prognosis of uncomplicated otitis externa is uniformly good. Patients with malignant otitis externa have a more guarded prognosis.

Patient Education

• Educate patients to keep the ear dry and to refrain from the use of cotton-tipped swabs or home remedies, such as ear candles, to remove ear cerumen.
• For excellent patient education resources, visit eMedicine's Ear, Nose, and Throat Center Center. Also, see eMedicine's patient education article Swimmer's Ear.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Failure to diagnosis an EAC malignancy is a common pitfall associated with otitis externa. Refer patients with refractory otitis externa to an otolaryngologist for management and possible ear canal biopsy.

Special Concerns

• Otitis externa in patients who are diabetic or immunocompromised can progress to skull base osteomyelitis.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

• Brook I. Treatment of otitis externa in children. Paediatr Drugs. Oct-Dec 1999;1(4):283-9. [Medline].
• Mirza N. Otitis externa. Management in the primary care office. Postgrad Med. May 1996;99(5):153-4, 157-8. [Medline].
• Morden NE, Berke EM. Topical fluoroquinolones for eye and ear. Am Fam Physician. Oct 15 2000;62(8):1870-6. [Medline].
• Selesnick SH. Otitis externa: management of the recalcitrant case. Am J Otol. May 1994;15(3):408-12. [Medline].
• Tierney MR, Baker AS. Infections of the head and neck in diabetes mellitus. Infect Dis Clin North Am. Mar 1995;9(1):195-216. [Medline].

Article Last Updated: Oct 10, 2007