DEFINITIONS
External otitis: Inflammation or infection of the outer ear, including the external auditory canal and/or auricle.
Acute otitis media: The rapid onset of signs and symptoms of acute inflammation in the middle ear.
Acute mastoiditis: The rapid onset of signs and symptoms of acute inflammation in the mastoid air cells inside the temporal bone, frequently associated with acute otitis media.
Chronic draining ear: Infection of the middle ear with a perforated tympanic membrane and persistent otorrhea from the middle ear.
Cholesteatoma: Keratinized squamous epithelium that has become trapped within the middle ear or mastoid, often associated with a chronic infection.4
ANATOMY AND PHYSIOLOGY OF THE EAR
Experiencing normal sound conduction requires:1
- Sound production: An object vibrating in matter moves the air particles surrounding it, disseminating a pulse of vibration through the air.
- Pinna: The pinna (auricle) serves to collect these sound waves and direct them into the external auditory canal.
- External auditory canal: Disturbance of air flow passing through the unimpeded ear canal will reach the tympanic membrane.
- Tympanic membrane: In order for air pressures to be transmitted further, the tympanic membrane amplifies air vibration and converts it into a vibration of the ossicles.
- Ossicles: Include three bones, the malleus, incus, and stapes located within the middle ear, which transmit the mechanical vibration energy into the inner ear.The body's defense against infections and inflammation within the ear requires:
- Tragus and antitragus: Form a partial barrier to the entrance of the ear, preventing entry of large foreign bodies.
- Isthmus of the external auditory canal: A narrowed section of the ear canal at the junction of the bony and cartilaginous portions; blocks entry of larger foreign bodies.
- Hair: Located in the lateral portion of the external ear canal; help prevent entry of foreign particles deeper into the external auditory canal.
- Apopilosebaceous unit: Consists of the hair follicle, erector pili muscle, and its associated apocrine and sebaceous glands. Sloughed squamous epithelium combines with glandular secretions to produce cerumen, which contains saturated fatty acids and lysozyme. Cerumen is also acidic. These properties help in the formation of a primary barrier to infection of the canal.
- Immune system: A competent immune system is required to prevent bacterial, viral, and fungal infections.
Infection or inflammation of the ear can result in obstruction of one or more parts of the pathway. Signs to watch for are: “I have a fever and earache” and “This is not the first time.”
EAR INFECTIONS
Otitis media is the main reason for medical visits of preschool-aged children. This is due to the shorter and more horizontal angle of their eustachian tube, which increases susceptibility to bacterial infiltration of the middle ear.
Older patients tend to have a weaker immune system and are thus more susceptible to infection, particularly otitis externa.
This includes congenital craniofacial anomalies caused by diseases such as cleft palate, Down's syndrome, choanal atresia, Cri-du-chat syndrome, DiGeorge's syndrome, and microcephaly. Such abnormalities often lead to eustachian tube dysfunction, which increases the likelihood of middle ear infections (otitis media), cholesteatoma, and chronic otitis media, even after craniofacial deformities are surgically corrected.
An infection of the external auditory canal: Common symptoms include pruritus, fullness, pain, and loss of hearing. Commonly referred to as swimmer's ear, this is caused by anything that removes the protective lipid barrier from the canal, allowing room for microorganisms to invade the environment. Pathogens most commonly associated with acute otitis externa (AOE) include Pseudomonas aeruginosa and Staphylococcus aureus. Initial symptoms include itching in the canal that may be followed by scratching, leading to proliferation of bacteria. Ultimately, 6purulent discharge develops and infection may progress to, and involve, the auricle. Hallmark signs of AOE include tenderness of the tragus and/or the pinna. Furthermore, patients may present with lymphadenitis, cellulitis, or fever. Symptoms should have been present for < 6 weeks. On otoscopy, the ear canal is edematous and erythematous, and purulent otorrhea or skin debris may be present. The tympanic membrane is usually intact and mobile.
- If pain is present, use of an analgesic is recommended.
- Aural toilet should be performed.
- Clinician should prescribe topical preparation for therapy.
- Systemic antimicrobials should not be prescribed as part of the initial therapy for uncomplicated AOE, unless the infection progresses outside the ear canal.
- Topical therapies include antibiotic ear drops (cortisporin otic, ofloxacin, ciprofloxacin–dexamethasone) or acidifying agents (acetic acid).
- Patients with an infection that does not resolve with initial therapy within a few weeks should be reassessed to confirm the diagnosis of AOE.8
Chronic Otitis Externa
Chronic pruritus and scaling of the auditory canal predisposes the patient to recurrent episodes of AOE.2 Over time, the ear canal may become scaly and a marked thickening may be observed. A potential complication is that the ear canal may ultimately become obliterated.
Treatment
- Thorough and frequent cleaning of the external ear, removing any macroscopic objects and debris.
- Medications
- Analgesics as needed.
- Acetic acid ear drops or boric acid ear powder to reestablish acidity of the ear environment, which can be efficacious for treating both fungal and bacterial colonization.
- Occasional use of anti-inflammatory agents and oral steroids can be helpful to control chronic pruritus that leads to repeated self-inflicted ear canal trauma for some patients.
- Educating patients on how to avoid future episodes.
Fungal Otitis Externa
Mycotic infections of the external ear are usually opportunistic and superimpose on an underlying chronic condition, such as a bacterial infection.2 The most common causative organisms in mycotic infections are the Aspergillus species, with the Candida spp. following as a close second. Typical presentation includes white, black, or gray colonies, sometimes with visible hyphae.
Treatment
The first step involves thorough removal and cleaning of fungal debris. This is followed by acidifying the external ear with topical agents such as acetic acid to make the environment less inhabitable for the invading organism. Ototopical antifungals such as clotrimazole are used adjunctively to ensure resolution.
Viral Otitis Externa
Herpes zoster (or varicella-zoster) and herpes simplex are two examples of direct viral mediators of otitis externa. In the case of both herpes strains, the patient may experience symptoms of burning, itching, pain, or a localized headache.2 With herpes zoster, vesicles form, persist for some time, rupture, then dry and form a thin yellowish crust. Signs of herpes zoster oticus (Ramsay Hunt syndrome) include unilateral dermatopic distribution of vesicles, cranial nerve VII palsy, sensorineural hearing loss, and unilateral peripheral vestibulopathy.8
Human immunodeficiency virus (HIV) involves a more indirect effect on outer ear infections by causing systemic immunodeficiency, thereby increasing the susceptibility of patients to ear infections.
Treatment
Appropriate antiviral therapy is indicated.2 Topical antibiotics should be applied to the lesion only to prevent or treat a bacterial superinfection.
Necrotizing Otitis Externa (NOE; Malignant Otitis Externa or Skull Base Osteomyelitis)
A rare, potentially life-threatening condition that presents in patients of advanced age or in patients who are immunodeficient due to poorly controlled diabetes mellitus.2,4 NOE usually begins as an unresolved AOE. Progression of the infection leads to spread from the external auditory canal to the bone of the base of the skull and temporomandibular joint, resulting in osteomyelitis. Associated symptoms may include otalgia lasting over a month, trismus, purulent otorrhea despite adequate treatment for a typical otitis externa, and symptoms related to lower cranial nerve involvement. One hallmark symptom is a deep, boring pain at night. Signs of NOE include purulent otorrhea associated with granulation tissue and exposed bone within the external auditory canal, and cranial nerve (CN) involvement, particularly of CN VII, IX, X, and XI. The most common pathogen associated with NOE is P. aeruginosa. However, S. aureus, particularly methicillin-resistant strains (MRSA), is also a frequent cause of this condition. If untreated, the infection may progress to meningitis, brain abscess, and death. Prognosis is poor if treated late in the course of the infection. Classically, NOE was initially imaged and followed with radionuclide scans. Initial imaging was performed with a technetium Tc-99 bone scan of the skull base. Follow-up imaging was conventionally performed using red cells tagged with gallium. More recently, investigators have reported the use of computed tomography (CT) or magnetic resonance 9imaging (MRI) to provide initial diagnostic and follow-up imaging.4 Noncontrast CT of the temporal bone provides detailed information of the bony structures. Intracranial involvement can be visualized using MRI with contrast. Response to treatment can also be monitored by erythrocyte sedimentation rate (ESR), which can be drawn at initial diagnosis and then followed weekly or biweekly thereafter until it normalizes.
Granulation biopsies and culture swabs should be obtained, if possible.
- If P. aeruginosa or MRSA is present, treat with appropriate antibiotics. If not, the patient should be presumptively treated for P. aeruginosa. Modern treatment of NOE has been revolutionized by the use of oral fluoroquinolone antibiotics, which may allow outpatient treatment for this condition.
- The ear should be debrided carefully while visualized under a microscope.
- The immunocompromised state should be treated. If the patient is diabetic, glycemic status should be tightly controlled.
- Surgery is needed in only a minority of cases. The objective is not to remove all affected tissue; rather, it is to address a specific symptom that is refractory to medical therapy, such as pain or facial nerve palsy, and to reduce disease burden.
- The primary surgical goal is to remove the underlying necrotic tissue and to allow vascularized tissue to replace it.
- The onset of facial weakness may be alleviated by removal of granulation tissue, thus decompressing the facial nerve.
Acute Otitis Media (AOM)
An extremely common bacterial infection of the middle ear, especially among children; 85% of children will experience at least one episode of AOM.5 Acute, in this sense, refers to an 10infection that occurs de novo in a previously normal, uninfected ear. Factors that may be associated with AOM include upper respiratory tract infections, eustachian tube dysfunction, and impaired immunological status. Typical presentation includes fever, an edematous and erythematous tympanic membrane, exudative fluid in the middle ear cleft, white blood cell infiltration (suppuration), and pain in the middle ear. Complications associated with AOM, although uncommon, involve bacterial infiltration of surrounding regions, leading to mastoiditis, facial nerve palsy, meningitis, brain abscesses, or chronic otitis media. Otoscopy should be used to confirm the infection. If the tympanic membrane is intact, there should be purulent material present within the middle ear, with moderate to severe bulging of the tympanic membrane. If the tympanic membrane has ruptured, there will be purulent material within the external auditory canal and a perforation in the tympanic membrane. Tympanocentesis can be used to obtain bacterial samples for culture if the tympanic membrane is intact; however, this may not be necessary, except in very young infants or patients with severe immunosuppression. If the tympanic membrane has ruptured, cultures can be readily taken from the external auditory canal with a calcium alginate swab. Prognosis is often good.
Treatment5
- If otalgia is present, use of analgesics is indicated.
- Appropriate antibiotics should be prescribed in children with severe AOM.
- In cases of non-severe infection in older infants, children, and adults who are not immunosuppressed, the clinician should offer observation with close follow-up versus antibiotic therapy.
Acute Mastoiditis
A common complication of AOM in which the infection has spread from the middle ear to the mastoid air cells of the temporal bone.7 The presence of AOM, mastoid findings, and radiological findings is highly indicative of acute mastoiditis. The patient may develop a fever with pain behind and deep to the ear that is typically worse at night. On physical examination, the patient often has proptosis of the ipsilateral auricle, erythema, and tenderness to slight palpation of the mastoid, and may have fluctuance beneath the skin of the mastoid. Noncontrast CT of the temporal bones reveals fluid or soft tissue density within the ipsilateral mastoid air cells and middle ear. Severe acute mastoiditis may lead to erosion of the bone within the mastoid, breaking down the bony trabeculae between the mastoid air cells (coalescent mastoiditis) and eroding through the bone of the tegmen mastoideum, tegmen tympani, cerebellar plate, and the bone overlying the sigmoid sinus.
- Antibiotics may resolve mastoiditis if caught early and in a noncoalescent state.
- Myringotomy and tube placement, in addition to antibiotic therapy, is indicated for noncoalescent mastoiditis that is not associated with complications such as meningitis or brain abscess.
- Mastoidectomy, in addition to antibiotic therapy and myringotomy and tube placement, is indicated for patients with coalescent mastoiditis, or patients with complications of mastoiditis such as otitic meningitis and subdural or brain abscess. The timing of this surgery in patients with central complications of mastoiditis needs to be coordinated closely with the patient's neurosurgical and neurological care teams.
Chronic Draining Ear
This is also referred to as chronic suppurative otitis media.6 Infection of the middle ear usually starts with an acute episode 12of otitis media, which results in the perforation of the tympanic membrane. Further inflammation and infection develops as a result of bacterial infiltration and colonization of the middle ear via the perforation, leading to a chronic infection. Typical presentation includes draining ear (otorrhea), sudden hearing loss in the affected ear, fever, vertigo, and pain. The discharge may range from fetid and purulent to clear and serous. Granulation tissue may develop in the inner portion of the ear canal or the middle ear space. Chronic suppurative otitis media may also be associated with cholesteatoma (see further). The bacterial species typically responsible for these infections is P. aeruginosa.
Cerebrospinal fluid (CSF) otorrhea is a rare intracranial complication of chronic otitis media.6,7 Computed tomography imaging with fine, sub-millimeter cuts should be utilized to assess for erosive changes within the mastoid air cells and the surrounding bony structures, consistent with erosion of the bony tegmen by chronic infection. Fluid collected from the ear may also be sent to test for β-2-transferrin for confirmation of CSF otorrhea. However, this test is often not useful, as samples must be fairly large (often requiring 0.5–1 mL of fluid) and cannot have any red blood cells present within the fluid. Typically, it is very difficult to collect this volume of fluid, even with a definite CSF leak.
Treatment7
- Aspiration and cleaning of debris within the ear.
- Ototopical antibiotic agents such as topical quinolones are the first-line treatment.
- Oral antibiotics are also an effective means of treatment, but should be avoided as first-line therapy, given their systemic side effects and the epidemiological concerns with regard to the generation of resistant bacteria.
- Surgery: Mastoidectomy
Cholesteatoma
Non-cancerous cyst lined by stratified squamous epithelium that contains desquamated keratin.6 Most commonly, cholesteatomas infiltrate the middle ear and mastoid, but they may also involve other portions of the temporal bone. This accumulation of keratin can cause infection, otorrhea, hearing loss, and bone resorption leading to ossicular erosion, erosion of the bony external auditory canal wall, erosion of the bone separating the mastoid and middle ear from the brain, and erosion into the semicircular canals.6,7 Palsy of CN VII can occur as well. The most common symptoms of cholesteatoma are painless otorrhea that is unresponsive to antibiotics and a tympanic retraction perforation in the pars flaccida. Noncontrast CT of the temporal bones is the diagnostic method of choice, and is used to assess for bone erosion. MRI should be performed if cranial or dural involvement is suspected. Prognosis is favorable, with the majority of cases resolving postoperatively. The postoperative recidivism rate is high (up to 30% over the course of 10 years); therefore, patients should be followed long term for the recurrence of cholesteatomas and related signs and symptoms.
Treatment
All cholesteatomas should be excised surgically. Patients in whom surgery is not an option should regularly have their ears cleaned, although this neither completely treats nor prevents cholesteatomas.
Immunocompromised Patients
Patients with congenital or acquired immunocompromised states are likelier to develop ear infections.2–7 Isolated, superficial infections of the external and middle ear may progress to catastrophic variations of perichondritis, cellulitis, and erysipelas. These patients are also much more susceptible to necrotizing otitis externa.14
DIAGNOSTIC WORKUP (FLOWCHART 1.1)
Flowchart 1.1: Evaluation of otologic pain or otorrhea.
(TMJ: Temporomandibular joint; TM: Tympanic membrane).
History
“Do you have pain in your ear? When did it start? Does it go away and then return? Does your ear drain intermittently?”
“Have you experienced any itching, burning, or painful sensations inside the ear?”
“Is your hearing normal?”
“Are you dizzy?”
“Have you noticed any popping, ringing, or fullness in your ears?”
“Do you have a headache, fever, runny or stuffy nose, or cough?”
“Does your infant has problems feeding, sleeping, or is fussy, irritable, or vomiting?”
“Have you ever had problems with ear infections? Have you ever had ear surgery?”
“Do you have diabetes, rheumatoid arthritis, or an organ transplant? Are you on steroids on a long-term basis?”
Physical Examination
- Assessment of the external ear: Tenderness, erythema, and swelling.
- Otoscopic investigation: Look for signs of infection, macroscopic objects, inflamed ear canal, and colonies of bacteria or fungus. Assess the tympanic membrane for erythema, bulging, or perforation.
Audiology
An audiogram should be performed to determine whether the infection has impacted auditory function. Unless there is a perforation with purulent material within the external auditory canal, a tympanogram should also be performed to assess the tympanic membrane and middle ear.
REFERENCES
- Guss J, Ruckenstein, MJ. Infections of the external ear. In: Flint PW, Haughey BH, Lund VJ, et al. (Eds). Cummings Otolaryngology—Head & Neck Surgery, 5th edition. Philadelphia, PA: Mosby/Elsevier; 2010. pp. 1944–9.
- Rosenfeld RM, Schwartz SR, Cannon CR, et al. Clinical practice guideline: acute otitis externa. Otolaryngol Head Neck Surg. 2014;150(1 Suppl):S1–24.
- Peleg U, Perez R, Raveh D, et al. Stratification for malignant external otitis. Otolaryngol Head Neck Surg. 2007;137(2):301–5.
- Grainger J, Siddiq S, Prentice P. The diagnosis and management of acute otitis media: American Academy of Pediatrics Guidelines 2013. Arch Dis Child Educ Pract Ed. 2015;100(4):193–7.
- Chole RA, Sudhoff HH. Chronic otitis media, mastoiditis, and petrositis. In: Flint PW, Haughey BH, Lund VJ, et al (Eds). Cummings Otolaryngology—Head & Neck Surgery, 5th edition. Philadelphia, PA: Mosby/Elsevier; 2010. pp. 1963–78.
- El-Kashlan HK, Harker LA, Shelton C, et al. Complications of temporal bone infections. In: Flint PW, Haughey BH, Lund VJ, et al. (Eds). Cummings Otolaryngology—Head & Neck Surgery, 5th edition. Philadelphia, PA: Mosby/Elsevier; 2010:1979–98.
- Farrior J, Lee KJ. Noninfectious disorders of the ear. In: Lee KJ (Ed). Essential Otolaryngology: Head and Neck Surgery, 10th edition. New York, NY: McGraw-Hill; 2012. pp. 338–63.
SUGGESTED READING
- Linstrom JC, Lucente EF. Diseases of the external ear. In: Rosen CA, Johnson JT (Eds). Bailey's Head and Neck Surgery—Otolaryngology, 5th edition. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2014. pp. 2333–57.
- Meyer AT, Strunk Jr CL, Lambert RP. Cholesteatoma. In: Rosen CA, Johnson JT (Eds). Bailey's Head and Neck Surgery—Otolaryngology, 5th edition. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2014. pp. 2433–66.
- Pulcini C, Mahdyoun P, Cua E, et al. Antibiotic therapy in necrotising external otitis: case series of 32 patients and review of the literature. Eur J Clin Microbiol Infect Dis. 2012;31(12):3287–94.