Otitis media

Abstract

Otitis media (OM) or middle ear inflammation is a spectrum of diseases, including acute otitis media (AOM), otitis media with effusion (OME; 'glue ear') and chronic suppurative otitis media (CSOM). OM is among the most common diseases in young children worldwide. Although OM may resolve spontaneously without complications, it can be associated with hearing loss and life-long sequelae. In developing countries, CSOM is a leading cause of hearing loss. OM can be of bacterial or viral origin; during 'colds', viruses can ascend through the Eustachian tube to the middle ear and pave the way for bacterial otopathogens that reside in the nasopharynx. Diagnosis depends on typical signs and symptoms, such as acute ear pain and bulging of the tympanic membrane (eardrum) for AOM and hearing loss for OME; diagnostic modalities include (pneumatic) otoscopy, tympanometry and audiometry. Symptomatic management of ear pain and fever is the mainstay of AOM treatment, reserving antibiotics for children with severe, persistent or recurrent infections. Management of OME largely consists of watchful waiting, with ventilation (tympanostomy) tubes primarily for children with chronic effusions and hearing loss, developmental delays or learning difficulties. The role of hearing aids to alleviate symptoms of hearing loss in the management of OME needs further study. Insertion of ventilation tubes and adenoidectomy are common operations for recurrent AOM to prevent recurrences, but their effectiveness is still debated. Despite reports of a decline in the incidence of OM over the past decade, attributed to the implementation of clinical guidelines that promote accurate diagnosis and judicious use of antibiotics and to pneumococcal conjugate vaccination, OM continues to be a leading cause for medical consultation, antibiotic prescription and surgery in high-income countries.

Figure 1. Anatomy of the human ear.

The ear can be divided into three parts: the outer, middle and inner ear. The outer ear comprises the auricle (or pinna) and the ear canal. The tympanic membrane (eardrum), a thin cone-shaped membrane, separates the outer ear from the middle ear. The middle ear comprises the middle ear cavity and the ossicles (the malleus, incus and stapes), which are attached to the tympanic membrane. The oval window connects the middle ear with the inner ear, which includes the semicircular ducts and the cochlea. The middle ear cavity is connected to the nasopharynx by the Eustachian tube. PowerPoint slide

Figure 2. Global acute otitis media and chronic suppurative otitis media incidence.

a | Acute otitis media (AOM) incidence. Incidence rate estimates (per 100 people) in 2005 based on data from 39 papers conducted in six WHO regions. b | Chronic suppurative otitis media (CSOM) incidence. Incidence rate estimates (per 1,000 people) in 2005 based on data from 65 papers worldwide. Reproduced from Ref. . PowerPoint slide

Figure 3. Causal pathways for otitis media.

Otitis media is a multifactorial disease. Specific host and environmental factors put children at risk for otitis media through various mechanisms, as illustrated in this diagram. Reducing the burden of otitis media will therefore require attention to more than a single risk factor. Given the complex causal pathways for otitis media, public health interventions may need to be prioritized differently for various at-risk populations and geographical regions. URTI, upper respiratory tract infection. Data from Refs –. PowerPoint slide

Figure 4. Steps in the pathogenesis of virus-induced acute otitis media.

The child might have a pre-existing nasopharyngeal bacterial colonization, which does not cause symptoms. When the child contracts a common cold, the viral infection initiates inflammation of the nasopharynx and the Eustachian tube, leading to increased adherence and colonization of bacteria and other activating mechanisms. Eustachian tube dysfunction follows, leading to negative middle ear pressure, allowing bacteria and/or viruses in the nasopharynx to move into the middle ear causing infection and/or inflammation. PowerPoint slide

Figure 5. Otoscopical images.

a | Normal tympanic membrane. b | Red and bulging tympanic membrane indicative of acute otitis media. c | Otitis media with effusion. d | Presence of a ventilation tube in the tympanic membrane. Parts a, c and d reproduced with permission from Ref. , Springer. Part b courtesy of D. McCormick, University of Texas Medical Branch, Galveston, Texas, USA. PowerPoint slide

Figure 6. Tympanogram.

The tympanometric curve, or tracing, is categorized as type A, B or C based on middle ear pressure and the presence or absence of a discernable peak. a | The type A tympanogram curve has a sharp peak and normal middle ear pressure and therefore a low probability of middle ear effusion. b | The type B tympanogram curve has a flattened shape with no discernible peak pressure and has a high probability of middle ear effusion. A flat tympanogram with a normal equivalent ear canal volume usually indicates middle ear effusion. A flat tympanogram associated with a low equivalent ear canal volume indicates probe obstruction by cerumen (earwax) or contact with the ear canal. A flat tympanogram with a high volume indicates a patent ventilation tube or a tympanic membrane perforation. c | Type C tympanogram curve (intermediate probability of effusion) has negative middle ear pressure with a sharp (C1) or rounded (C2) peak. PowerPoint slide

Figure 7. Ventilation tubes.

Ventilation (tympanostomy) tubes are tiny plastic tubes put into the tympanic membrane (eardrum) during a short operation under general anaesthesia. The tubes usually stay in place for 6–12 months and fall out themselves. The main indications for this surgical procedure are the restoration of hearing in children with chronic otitis media with effusion (‘glue ear’) and the prevention of recurrences in children who have recurrent acute otitis media (AOM) by draining the fluid from the ear and improving its ventilation. In addition, by providing access to the middle ear, ventilation tubes may allow for local antibiotic treatment of AOM rather than systemic treatment. PowerPoint slide