Acute mastoiditis is a rare but serious complication of otitis media.
Refer patients with a suspected or definite retroauricular or neck abscess associated with otitis media to hospital as emergencies.
Epidemiology and symptoms
The incidence in children in the Western countries is 2-4 infections/100 000 person-years.
Purulent otitis media predisposes to mastoiditis.
The clinical picture consists of
high fever
marked pain and tenderness of the ear
swelling, redness, and tenderness on percussion of the retroauricular area
impaired general condition.
In children the auricle may be turned out- and downwards (lateral displacement).
If antibiotics are administered the disease may be milder but results in secretory or chronic otitis media with discharge.
Investigations
Laboratory findings
Leucocytosis
Increased ESR and CRP
The primary x-ray examination in acute mastoiditis is a CT scan showing the collection of fluid in the cavi of the mastoid bone, possible destructive bone changes as well as subperiostal abscesses. If an intracranial complication is suspected, an MRI study is indicated.
Differential diagnosis
Otitis externa with swelling of the outer auditory canal. The symptoms are not as severe as in mastoiditis, there is no tenderness or swelling behind the auricle, the results of the laboratory tests are only slightly abnormal, and the mastoid is radiologically normal.
If a patient has lymphadenitis of the neck, always examine the ears.
In otitis media, there is always some accumulation of fluid in the mastoid air cells but no bone destruction.
Treatment
Refer the patient to a specialist unit without delay. If treatment with intravenous antibiotics is not successful within 1-2 days, mastoidectomy should be performed. The operation consists of opening and cleansing of the middle ear and the mastoid air cells.
Tympanocentesis and, in most cases, insertion of a tympanostomy tube are indicated to evacuate infectious secretions, to relieve the pressure, to prevent necrosis of the tympanic membrane and to assess treatment response. At the same time, it is possible to obtain a sample for bacterial culture from the aspirate to identify the cause of infection.