Otitis media

Introduction

Otitis media is an inflammation of the middle ear and is one of the most common infections in children. It can cause ear pain, hearing loss, and occasionally systemic symptoms such as fever. Prompt recognition and management are important to prevent complications and chronic disease.

Anatomy of the Ear Relevant to Otitis Media

External ear

The external ear consists of the pinna and the external auditory canal, which collect and channel sound waves to the tympanic membrane.

Middle ear

The middle ear is an air-filled cavity that houses the ossicles and connects to the nasopharynx via the Eustachian tube:

• Tympanic membrane: Separates the external ear from the middle ear and vibrates in response to sound.
• Ossicles: The malleus, incus, and stapes transmit sound vibrations to the inner ear.
• Eustachian tube: Maintains pressure equilibrium between the middle ear and nasopharynx; dysfunction contributes to fluid accumulation.
• Middle ear mucosa: Lining that can become inflamed and produce effusion during infection.

Inner ear (brief overview)

The inner ear contains the cochlea, responsible for hearing, and the vestibular apparatus, which maintains balance. Although not primarily affected in otitis media, severe infections can occasionally involve the inner ear structures.

Classification of Otitis Media

Acute Otitis Media (AOM)

Acute otitis media is characterized by rapid onset of signs and symptoms of middle ear inflammation. It often occurs following a viral upper respiratory infection and is typically associated with bacterial infection.

• Definition: Rapid onset ear pain, fever, and possible hearing loss.
• Common causative organisms: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis.

Otitis Media with Effusion (OME)

Otitis media with effusion involves the presence of fluid in the middle ear without acute signs of infection. It may be asymptomatic or cause mild discomfort and hearing loss.

• Definition: Non-infected fluid accumulation in the middle ear.
• Asymptomatic versus symptomatic cases: Some children may have subtle hearing difficulties or delayed speech development.

Chronic Otitis Media (COM)

Chronic otitis media is a persistent infection or inflammation of the middle ear, often associated with tympanic membrane perforation or cholesteatoma formation.

• Persistent infection and tympanic membrane perforation
• Cholesteatoma formation: Abnormal skin growth in the middle ear leading to chronic infection and potential complications.

Etiology

Infectious causes

Otitis media is commonly caused by bacterial or viral pathogens:

• Bacterial pathogens: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis.
• Viral infections: Respiratory syncytial virus (RSV), influenza virus, adenovirus, and other respiratory viruses.

Predisposing factors

Several factors increase susceptibility to otitis media:

• Eustachian tube dysfunction leading to poor ventilation of the middle ear
• Allergies and recurrent upper respiratory infections
• Environmental factors: Exposure to tobacco smoke, crowded daycare settings
• Anatomical variations: Cleft palate or other craniofacial abnormalities

Pathophysiology

Otitis media develops when the normal aeration of the middle ear is disrupted, leading to fluid accumulation and inflammation. The sequence of events typically involves Eustachian tube dysfunction, microbial infection, and an inflammatory response.

• Fluid accumulation: Impaired drainage through the Eustachian tube results in a sterile or infected effusion in the middle ear cavity.
• Inflammatory response: The middle ear mucosa becomes inflamed, leading to pain, erythema, and tympanic membrane bulging.
• Impact of Eustachian tube dysfunction: Negative middle ear pressure promotes bacterial growth and prolongs effusion, increasing the risk of chronic otitis media.

Clinical Features

Symptoms

Symptoms vary based on the type and severity of otitis media. Common presentations include:

• Ear pain (otalgia), often severe in acute infections
• Hearing loss due to fluid accumulation or tympanic membrane changes
• Fever and general malaise, particularly in children
• Irritability, poor feeding, or disturbed sleep in infants and young children
• Otorrhea in cases of tympanic membrane perforation or chronic infection

Signs

Physical examination may reveal characteristic findings on otoscopy:

• Tympanic membrane erythema and bulging
• Presence of fluid levels or air bubbles behind the tympanic membrane
• Reduced mobility of the tympanic membrane on pneumatic otoscopy

Red flag symptoms

Certain clinical features warrant urgent evaluation to rule out serious complications:

• Severe or rapidly progressing ear pain
• Neurological deficits such as facial weakness or vertigo
• Persistent high fever or signs of systemic infection

Diagnosis

Clinical evaluation

Diagnosis of otitis media is primarily clinical, based on patient history and physical examination:

• Detailed history including onset, duration, and nature of ear pain
• Assessment of associated symptoms such as fever, hearing loss, or irritability in children
• Physical examination using otoscopy to inspect the tympanic membrane for redness, bulging, or perforation
• Pneumatic otoscopy to evaluate tympanic membrane mobility
• Tuning fork tests (Weber and Rinne) to assess conductive hearing loss

Imaging

Imaging is generally reserved for complicated or chronic cases:

• CT scan to evaluate mastoid involvement or cholesteatoma
• MRI for soft tissue evaluation or intracranial complications

Laboratory tests

Laboratory investigations are not routinely required but may be indicated in severe or refractory infections:

• Cultures of middle ear fluid in chronic otorrhea or post-tympanostomy cases
• Blood tests such as complete blood count or inflammatory markers in systemic infection

Management

Conservative treatment

Initial management often involves supportive care, especially for mild cases:

• Analgesics and antipyretics to relieve pain and fever
• Observation or watchful waiting, particularly for otitis media with effusion
• Encouragement of adequate hydration and rest

Medical treatment

Pharmacological therapy is indicated for bacterial infections or persistent symptoms:

• Oral antibiotics targeting common bacterial pathogens in acute otitis media
• Topical antibiotic drops for otorrhea with tympanic membrane perforation
• Treatment of underlying conditions such as allergies or upper respiratory infections

Surgical treatment

Interventions may be required for recurrent, chronic, or complicated cases:

• Myringotomy with or without tympanostomy tube placement to drain effusions
• Management of cholesteatoma or chronic perforation to prevent structural damage
• Tonsillectomy or adenoidectomy when indicated to improve Eustachian tube function

Complications

Otitis media can lead to several local and systemic complications, especially if inadequately treated or in chronic cases:

• Tympanic membrane perforation, which may result in persistent otorrhea
• Hearing loss, typically conductive but occasionally sensorineural if inner ear is involved
• Mastoiditis, an infection of the mastoid air cells
• Intracranial complications such as meningitis, brain abscess, or lateral sinus thrombosis in severe cases
• Cholesteatoma formation, which can erode bone and lead to chronic infection

Prevention

Preventive strategies aim to reduce the incidence and recurrence of otitis media, particularly in children:

• Vaccination: Pneumococcal and influenza vaccines reduce the risk of bacterial and viral triggers
• Breastfeeding and proper nutrition to enhance immune function
• Avoidance of exposure to tobacco smoke and other environmental irritants
• Good hygiene practices, including handwashing and minimizing spread of respiratory infections in daycare settings

Prognosis

The prognosis of otitis media varies depending on the type, severity, and timeliness of treatment. Most acute cases resolve without long-term consequences, while chronic or recurrent infections may lead to persistent problems.

• Outcomes for acute versus chronic otitis media: Acute otitis media usually resolves within a few days to weeks with appropriate management; chronic otitis media may require long-term follow-up and intervention.
• Factors affecting recurrence and chronicity: Eustachian tube dysfunction, anatomical variations, frequent upper respiratory infections, and incomplete treatment can increase recurrence risk.
• Impact on hearing and development in children: Recurrent or prolonged otitis media can cause temporary or, rarely, permanent hearing loss, affecting speech and language development.

References

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