Bullous Myringitis

Bullous myringitis is an acute inflammation of the tympanic membrane with haemorrhagic or serous blisters (bullae) on the outer layer of the drum. It causes sudden severe ear pain and is usually a variant of acute otitis media.

It accounts for a small share of acute otitis media, is seen in children and young adults, and often follows an upper respiratory tract infection. Both viral and bacterial causes occur (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Mycoplasma pneumoniae, which was once thought to be the main cause).

Pathophysiology.

Infection of the outer epithelial layer and the middle ear produces fluid collections between the epithelium and the fibrous layer. The blisters rupture, releasing blood stained fluid, and pain falls quickly afterwards.

Abrupt severe otalgia, a feeling of fullness, mild conductive hearing loss, blood stained discharge on rupture and fever in some. Sensorineural hearing loss and tinnitus are reported.

Red flags.

• Sensorineural hearing loss.
• Vertigo or facial weakness.
• Mastoid swelling or tenderness.
• Fever with severe headache or neck stiffness.

Otoscopy shows one or several tense, red or purple blisters on the tympanic membrane and the adjacent canal wall, with a red, bulging drum. Diagnosis is clinical. Pure tone audiometry is done if hearing loss persists beyond 2 weeks or is sensorineural. Swab any discharge for culture.

Differential diagnosis.

• Acute otitis media without bullae.
• Herpes zoster oticus (Ramsay Hunt syndrome).
• Acute otitis externa.
• Haemorrhagic otitis media from trauma.
• Cholesteatoma with infection.

Give analgesia first. Antibiotics are given for bacterial acute otitis media and when the patient is unwell, is under 2 years, or has bilateral disease. Do not puncture the blisters routinely, since they rupture on their own and pain settles quickly.

• Paracetamol: 1 g orally every 6 hours; maximum 4 g daily (3 g daily if weight under 50 kg or chronic liver disease); for 3 to 5 days; monitor liver tests with prolonged use; children 15 mg/kg every 6 hours, maximum 60 mg/kg daily.
• Ibuprofen: 400 mg orally three times daily with food for 3 to 5 days; maximum 1.2 g daily without supervision; monitor for dyspepsia and renal function; avoid in peptic ulcer, renal impairment and late pregnancy; children 10 mg/kg every 8 hours, maximum 30 mg/kg daily.
• Amoxicillin: 500 mg orally three times daily for 5 to 7 days; maximum 3 g daily; monitor for rash and diarrhoea; reduce to 500 mg every 12 hours when creatinine clearance is 10 to 30 mL/min; children 40 mg/kg daily in three divided doses.
• Azithromycin (penicillin allergy, or suspected Mycoplasma): 500 mg orally once daily for 3 days; maximum 500 mg daily; monitor QT interval and liver tests; avoid with other QT-prolonging drugs; children 10 mg/kg once daily for 3 days, maximum 500 mg.

Monitoring. Review at 2 to 4 weeks, with audiometry if hearing loss continues.

Referral and escalation. ENT if there is sensorineural hearing loss, vertigo, facial weakness or no improvement in 72 hours.

Special groups. Children under 2 years with bilateral disease need antibiotics. Pregnancy: use paracetamol and amoxicillin, and avoid ibuprofen in the third trimester.