Introduction

Mastoiditis is an infection and inflammation of the mastoid air cells in the ear, spreading to the mastoid bone: it is an extremely destructive disease, which in rare cases can lead to destruction of the mastoid process. There is a risk of extradural brain abscess and lateral sinus thrombosis.  It can occur in an acute form, as a direct complication of otitis media, or in a chronic form resulting from incomplete treatment of otitis media. The chronic form is often subclinical.

Aetiology of mastoiditis

Acute mastoiditis

The causative organisms of acute mastoiditis include:

• Streptococcus spp.
  • Streptococcus pneumoniae
  • Beta-haemolytic Streptococcus spp. Group A
• Haemophilus influenzae
• Moraxella catarrhalis
• Staphylococcus aureus
• Rarely, mycobacteria.

Chronic mastoiditis

In chronic mastoiditis the causative organisms are more likely to be a mixed flora including Pseudomonas spp., Streptococcus spp., Staphylococcus spp, Escherichia coli and anaerobes.

Diagnosis of mastoiditis

Clinical

Mastoiditis presents up to two weeks after the start of untreated otitis media, with:

• Inflammation and tenderness over the mastoid process
• Discharge from the ear
• Forward displacement of the pinna due to subperiosteal abscess
• Otalgia
• Fever and malaise
• Bulging or perforated tympanic membrane, leading to rupture and discharge
• Deafness.

Microbiology

Microbiological investigation of material taken from the mastoid cavity is the most useful technique:

• Gram stain and acid-fast stain should be performed
• Culture is often sterile if there has been previous antibiotic treatment, eg. for otitis media.

Management of mastoiditis

In acute mastoiditis antibiotic therapy can generally be used to control the infection. Intravenous antibiotics should be given for up to 24 hours and if there is no improvement by this time, the patient should be considered for surgery.  Surgery is often required in chronic mastoiditis.

Antibiotic rationale

The antibiotics chosen should be able to penetrate into bone and should have activity against both aerobes and anaerobes. A beta-lactamase stable antibiotic is desirable.

The second-generation cephalosporin, cefuroxime, is a suitable agent, being beta-lactamase resistant and having good activity against Haemophilus influenzae and Gram-positive organisms.

Empirical therapy

Acute mastoiditis

Suitable antibiotic regimens include:

First-line

• Cefuroxime plus metronidazole.

Second-line or in penicillin-allergic patients:

• Chloramphenicol or minocycline or a fluoroquinolone, such as ciprofloxacin, plus clindamycin.

Once culture and sensitivity results have been obtained, antibiotic therapy may be amended as required.

If medical treatment fails a cortical mastoidectomy is performed.  If cholesteatoma is the underlying cause a modified radical mastoidectomy is required, usually at a later date.

Chronic mastoiditis

The choice of antibiotic should be based on culture results. A minimum of 2 weeks' treatment with oral antibiotics or 3 weeks or more with antibiotic drops will be required. Following treatment the patients should be observed for a period to monitor for signs of recurrence. If after 3 months post-treatment there are no signs of recurrence then no further treatment will be required.

If recurrence occurs then CT visualisation and surgery will be required to prevent further recurrence. If cholesteatoma is present, surgery will be required unless the patient's condition contraindicates it.