Acute Otitis Media (AOM)
Acute otitis media is a bacterial infection of the mucosally lined air-containing spaces of the temporal bone. Purulent material forms not only within the middle ear cleft but also within the pneumatized mastoid air cells and petrous apex.
Acute otitis media is usually precipitated by a viral upper respiratory tract infection that causes eustachian tube obstruction. This results in accumulation of fluid and mucus, which becomes secondarily infected by bacteria. The most common pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and Streptococcus pyogenes.
In people with acute otitis media, the infected ear is painful, with a red, bulging eardrum. Many people have hearing loss. Infants may simply be cranky or have difficulty sleeping. Fever, nausea, vomiting, and diarrhea often occur in young children. The bulging eardrum sometimes ruptures, causing pus to drain from the ear.
Acute otitis media may occur at any age. Presenting symptoms and signs include otalgia, aural pressure, decreased hearing, and often fever. The typical physical findings are erythema and decreased mobility of the tympanic membrane.
Occasionally, bullae will appear on the tympanic membrane. Rarely, when middle ear empyema is severe, the tympanic membrane bulges outward. In such cases, tympanic membrane rupture is imminent. Rupture is accompanied by a sudden decrease in pain, followed by the onset of otorrhea. With appropriate therapy, spontaneous healing of the tympanic membrane occurs in most cases. When perforation persists, chronic otitis media may develop. Mastoid tenderness often accompanies acute otitis media and is due to the presence of pus within the mastoid air cells. This alone does not indicate suppurative (surgical) mastoiditis. Frank swelling over the mastoid bone or the association of cranial neuropathies or central findings indicates severe disease requiring urgent care.
The treatment of acute otitis media is specific antibiotic therapy, often combined with nasal decongestants. The first-choice oral antibiotic treatment is amoxicillin (80–90 mg/kg/day divided twice daily) (or erythromycin [50 mg/ kg/day]) plus sulfonamide (150 mg/kg/day) for 10 days. Alternatives useful in resistant cases are cefaclor (20–40 mg/kg/day) or amoxicillin-clavulanate (20–40 mg/kg/day).
Tympanocentesis for bacterial (aerobic and anaerobic) and fungal culture may be performed by any experienced physician. A 20-gauge spinal needle bent 90 degrees to the hub attached to a 3-mL syringe is inserted through the inferior portion of the tympanic membrane. Interposition of a pliable connecting tube between the needle and syringe permits an assistant to aspirate without inducing movement of the needle. Tympanocentesis is useful for otitis media in immunocompromised patients and when infection persists or recurs despite multiple courses of antibiotics.
Surgical drainage of the middle ear (myringotomy) is reserved for patients with severe otalgia or when complications of otitis (eg, mastoiditis, meningitis) have occurred.
Recurrent acute otitis media may be managed with long-term antibiotic prophylaxis. Single daily oral doses of sulfamethoxazole (500 mg) or amoxicillin (250 or 500 mg) are given over a period of 1–3 months. Failure of this regimen to control infection is an indication for insertion of ventilating tubes.
Tympanic membrane perforation
- AOM with TM perforation is common and results in otorrhoea and frequently, relief of pain
- Otorrhoea due to TM perforation should be distinguished from Otitis Externa
Acute Mastoiditis (AM)
Acute mastoiditis, although rare, is the most common suppurative complication of AOM and may be associated with intracranial complications
- The diagnosis of AM is based on post auricular inflammatory signs (erythema, oedema, tenderness or fluctuance), a protruding auricle often with external auditory canal oedema and signs of AOM (see image below)
- Requires prompt treatment with appropriate intravenous antibiotics (eg flucloxacillin plus 3rd generation cephalosporin)
- Consult ENT as may require surgical treatment
- Other suppurative complications including intracranial spread of infection are rare
- Facial nerve palsy secondary to AOM should be discussed with ENT
- Long-term non suppurative complications include atelectasis of the TM and cholesteatoma