What is otitis media?

What is Otitis Media

Otitis media (OM) is inflammation of the middle ear—the space behind the eardrum containing the ossicles—and represents a spectrum of diseases including acute otitis media (AOM), otitis media with effusion (OME), and chronic suppurative otitis media (CSOM). 1

Core Definition and Disease Spectrum

Otitis media is an umbrella term for any condition involving middle ear inflammation, without reference to specific cause or mechanism. 1 The disease manifests in three primary forms:

• Acute Otitis Media (AOM): Rapid onset of signs and symptoms of middle ear inflammation, characterized by fluid in the middle ear (middle ear effusion) with acute symptoms like ear pain, fever, and irritability 1
• Otitis Media with Effusion (OME): Fluid in the middle ear without signs or symptoms of acute infection, often called "glue ear" 1
• Chronic Suppurative Otitis Media (CSOM): Chronic middle ear and mastoid inflammation with a perforated tympanic membrane and persistent ear discharge 1

Epidemiology and Clinical Significance

OM is among the most common diseases in young children worldwide, with 50-85% of children experiencing at least one episode by age three years. 2 The highest rates occur in children 1-4 years of age, with 61 new episodes per 100 children annually. 3

In high-income countries, OM remains a leading cause for medical consultation, antibiotic prescription, and surgery in children. 1 In developing countries, CSOM represents a leading cause of hearing loss. 1

Pathophysiology and Causative Organisms

AOM is always preceded by viral upper respiratory tract infection (the "common cold") affecting the nasopharyngeal and Eustachian tube epithelium. 1, 3 This viral infection causes Eustachian tube dysfunction, allowing viruses and bacteria from the nasopharynx to ascend into the middle ear. 3

Microbial Etiology:

• Bacterial pathogens: Streptococcus pneumoniae, non-typeable Haemophilus influenzae, and Moraxella catarrhalis are the most common organisms 1, 3, 4
• Viral pathogens: Respiratory syncytial virus, rhinovirus, adenovirus, parainfluenza, and coronavirus 5
• Mixed infections: Bacteria and viruses can be detected in middle ear fluid in up to 96% of AOM cases (66% bacteria and viruses together, 27% bacteria alone, 4% virus alone) 3
• Approximately 5% of middle ear effusions contain only viruses 1

Biofilm Formation:

Bacterial biofilms—bacteria embedded in extracellular matrix adherent to surfaces—have been demonstrated in middle ears of patients with CSOM, persistent OME, and treatment-failure cases. 1, 3 These biofilms protect bacteria against antibiotics and immune responses, making infections more difficult to eradicate. 3

Clinical Manifestations

Acute Otitis Media:

• Sudden onset of ear pain (otalgia), fever, irritability 1, 2
• Otorrhea (ear discharge) 1, 2
• In young children: rubbing, tugging, or holding the ear; anorexia; vomiting or lethargy 2
• Physical findings: moderate-to-severe bulging of the tympanic membrane, intense erythema, or acute ear discharge not from otitis externa 1, 2

Otitis Media with Effusion:

• Often asymptomatic 5
• Hearing loss is the primary symptom 1
• Reduced tympanic membrane mobility on examination 1

Chronic Suppurative Otitis Media:

• Persistent ear discharge through a perforated tympanic membrane 1
• Chronic inflammation lasting weeks to months 1

Complications and Long-term Sequelae

Although OM may resolve spontaneously without complications, it can be associated with significant morbidity. 1 Hearing loss is the most common complication, with potential for life-long sequelae affecting speech, language development, and learning capabilities in children. 1, 6

Serious complications requiring imaging include subperiosteal abscess, labyrinthitis, meningitis, intracranial abscess, subdural empyema, and dural venous sinus thrombosis. 1 These occur when infection extends beyond the middle ear to involve the skull base, cranial nerves, or intracranial structures. 1

Anatomical Context

The middle ear comprises the middle ear cavity and ossicles (malleus, incus, and stapes) attached to the tympanic membrane (eardrum), which separates the outer ear from the middle ear. 1 The middle ear cavity connects to the nasopharynx via the Eustachian tube, which is the primary route for pathogen entry during upper respiratory infections. 1, 3