Acute Otitis Media

Question 1

What is acute otitis media?

Answer 1

• infection of middle ear
• common in 6-12month olds
• infants predisposed due to short, horizontal and poorly functional eustachian tubes
• RFs → day-care attendance, older siblings, young age, FHx, absence of breast feeding, immunological deficiency
• Ddx → otitis media w/ effusion, myringitis, mastoiditis

Question 2

What are the signs and symptoms of acute otitis media?

Answer 2

• conductive hearing loss
• otalgia
• fever, malaise, N+V
• otorrhoea in perforation
• often preceding viral URTI
• TM examination → dilatation of blood vessels, reddened membrane which is thickened + bulging, may be perforated w/ discharge
• tenderness of mastoid process

Question 3

What is the aetiology of AOM?

Answer 3

• viruses → RSV, rhinovirus
• bacterial → strep pneumoniae (40%), haem influenzae (30%) + moraxella catarrhalis (15%)

Question 4

What is the pathophysiology of AOM?

Answer 4

• under normal conditions, the mucociliary action + ventilator function of Eustachian tube clears the nasopharyngeal flora that enter middle ear
• however, upper resp viruses can infect the nasal passage, Eustachian tube + middle ear
• causes inflammation, oedema, exudate + pus
• oedema closes Eustachian tube preventing drainage
• pressure from pus rises causing tympanic membrane to bulge + perforate
• most cases resolve spontaneously but complications may occur

Question 5

Usually no tests are necessary for AOM, condition is diagnosed on clinical examination.

What is the management?

Answer 5

• analgesia → paracetamol, NSAIDs, calpol
• antibiotics → amoxicillin 5-days, IF:
  
  • symptoms lasting >4days + not improving
  • systemically unwell, but not requiring admission
  • immunocompromised
  • younger than 2yrs w/ bilateral otitis media
  • otitis media w/ perforation and/or dischage in canal
• surgical management rare → occasionally myringotomy (surgical perforation of TM) or insertion of ventilation tube

Once analgesia and/or antibiotics are initiated, most patients improve quickly over course of 2-3 days

Question 6

Serious complications of AOM are rare but up to 50% of children will develop otitis media w/ effusion (OME) - “glue ear”.

What are the intra-temporal complications?

Answer 6

• OME → fluid builds up in middle ear behind TM, dx → required fluid to be present for at least 3months; non-infective; common in those w/ inefficienct Eustachian tube (eg. large adenoids or cleft palate); usually present w/ insidious loss of hearing + maybe development delay; O/E - ear drum grey + retracted
• hearing loss → direct damage to cochlear
• dizziness
• facial nerve paralysis → occasionally facial nerve passes through mid ear rather than being coated in bone, temporary
• mastoiditis +/- petrositis

Question 7

What are the extra-temporal complications of acute otitis media?

Answer 7

• neck abscess
• intracranial complications → abscess, subdural or extradural collections, meningitis

Question 8

Some children are particularly susceptible to repeated attacks of AOM. This tends to resolve as child gets older. Repeated attacks can be partially prevented by reduced exposure to passive smoke + by breastfeeding.

What are the risk factors for recurrence?

Answer 8

• Abnormal Eustachian drainage → large adenoids (removal reduces recurrence), cleft palate
• Down’s syndrome
• Immunodeficiency

Question 9

Mastoiditis is an extension of AOM into the mastoid air cells w/ suppuration and necrosis.

What are the clinical features and management of mastoiditis?

Answer 9

• symptoms → pain (persistent + throbbing), otorrhoea, increasing deafness
• signs → fever, post-auricular swelling + antero-inferior displacement of ear, mastoid tenderness
• Rx → IV abx: amoxicillin and metronidazole
• surgery → pus drained under GA

Question 10

A brain abscess is a particularly morbid complication of AOM. Otogenic abscesses usually occur in the cerebellum or temporal bone and spread occurs via the vasculature or direct extension through bone + meninges. Abscesses may develop rapidly or over several months. Mortality is about 25% (up to 70% if cerebellar).

What is the clinical presentation and treatment?

Answer 10

Symptoms caused by:

• infection → malaise + pyrexia
• raised ICP → headache, drowsiness, confusion, reduced GCS, papilloedema
• focal neurological signs → depending on where lesion is

Treatment directed at drainage of abscess. This should take priority over all other conditions. Drainage is via a burr hole, or excised via craniotomy. Vigorous antibiotic follow-up is required.