Acute Mastoiditis

Acute mastoiditis is a suppurative infection of the mastoid air cells, usually a complication of acute otitis media, with periosteal involvement behind the ear, and it can spread to the intracranial space.

• It is commonest in children under 2 years.
• Streptococcus pneumoniae is the commonest organism, followed by Streptococcus pyogenes, Haemophilus influenzae, Staphylococcus aureus and Pseudomonas aeruginosa.
• The infection leads to mucosal swelling, blocked drainage and coalescent breakdown of the bony septa, forming a subperiosteal abscess.
• Complications include intracranial extension: meningitis, epidural abscess, subdural empyema, brain abscess, sigmoid sinus thrombosis; facial nerve palsy, labyrinthitis, and petrositis.
• Bezold abscess is spread into the neck below the sternocleidomastoid.

Postauricular signs follow an ear infection.

• Persisting ear pain, fever and otorrhoea in a child with recent otitis media.
• Postauricular erythema, tenderness, swelling and fluctuance, with the pinna pushed forward and downward (protruding ear).
• Sagging of the posterosuperior canal wall; bulging, red or perforated drum.
• Fever, irritability, lethargy, poor feeding.
• Headache, vomiting, neck stiffness, drowsiness, or seizures suggest intracranial extension. Spiking fever suggests sigmoid sinus thrombosis. Facial weakness, vertigo or deafness suggest labyrinthine or facial nerve involvement.
• Differential diagnosis: postauricular lymphadenitis, otitis externa, furuncle, cellulitis, parotitis, cholesteatoma with infection, Langerhans cell histiocytosis, mastoid tumours and lymphoma.
• Complications: subperiosteal abscess, Bezold abscess, facial palsy, labyrinthitis, meningitis, epidural or subdural abscess, brain abscess, sigmoid sinus thrombosis, petrous apicitis and hearing loss.

Diagnosis is clinical; imaging confirms the extent.

• Full blood count (leucocytosis), C-reactive protein, blood culture, and culture of ear discharge or pus (tympanocentesis).
• Computed tomography of the temporal bone with contrast: opacified mastoid, coalescence, subperiosteal abscess, and intracranial complications. MRI with venography for suspected venous sinus thrombosis or intracranial abscess.
• Lumbar puncture only after imaging when meningitis is suspected and no mass effect.
• Audiometry once recovered.

Intravenous antibiotics, with surgery for failure or complications.

• Supportive: admit, intravenous fluids, analgesia, antipyretic, and neurological observation.
• Pharmacological: intravenous ceftriaxone 50 to 100 mg/kg once daily (adults 2 g) with metronidazole 7.5 mg/kg every 8 hours (adults 500 mg), or ampicillin-sulbactam 50 mg/kg every 6 hours (adults 3 g every 6 hours). Add vancomycin 15 mg/kg every 6 hours if penicillin-resistant pneumococcus or MRSA is suspected. Use ceftazidime 50 mg/kg every 8 hours for suspected Pseudomonas.
• Continue intravenous therapy until afebrile and improving for 48 hours, then oral amoxicillin-clavulanate for a total of 2 to 3 weeks (longer for intracranial complications).
• Procedures: myringotomy with or without grommet for drainage and culture. Cortical mastoidectomy for subperiosteal abscess, coalescent mastoiditis, failure of medical treatment in 48 hours, or intracranial complications. Needle aspiration of subperiosteal abscess in selected children. Neurosurgical drainage for brain abscess or empyema.
• Sigmoid sinus thrombosis: anticoagulation with low molecular weight heparin (enoxaparin 1 mg/kg twice daily) under specialist advice, plus surgery.
• Special groups: infants and immunocompromised patients need closer monitoring. For suspected meningitis, give dexamethasone 0.15 mg/kg every 6 hours for 4 days, started with or just before the first antibiotic dose.
• Red flags: postauricular swelling, protruding ear, headache, vomiting, neck stiffness, drowsiness, seizure, facial palsy, vertigo, spiking fever and failure to improve at 48 hours.
• Follow-up: audiometry after recovery, review at 2 to 4 weeks and at 3 months. Check for residual effusion, cholesteatoma and hearing loss.