• Nalaka de Silva

Acute Otitis Media

Updated: Jun 16, 2019

Please note that the following is a general guideline only.



Definitions

-AOM is defined as acute inflammation of the middle ear

-OME is middle ear effusion without signs or symptoms of an acute infection

-Recurrent AOM which requires grommets: 4 or more episodes in one year or three or more episodes in one 6 month period



Epidemiology

age: 6-11 months declines around 18-20 months

Incidence: 70% experience one or more attacks before 2 years of age

Race: higher incidence in indigenous (95% of Aboriginal children by 2 months)

Familial-higher predisposition if in siblings or parental history

peaks in winter months which correspond to the peak in respiratory infect



Aetiology


Bacterial (50-70%)

Streptococcus p, HI, Moraxella Catarrhalis, Group A streptococcus > S. aureus, E. coli, Klebsiella, Pseudomonas aeruginosa

Resistance- 100% M. catarrhalis B-lactamase producers


Pneumococcal vaccinated with severe OM have 2x more gram negatives

50% S. pneumoniae decrease in penicillin binding proteins



Virus (20%- causative or co pathogenic)

Peak incidence 2-4 days after URTI, most develop within 2 weeks of URTITypes same as URTI -RSV / rhinovirus/ influenza virus/ adenovirus, enterovirus / parainfleunza virus




Pathophysiology- Viral


1 URTI → oedema and narrowing of the ET → increase in negative ME pressure and decreased clearance → influx of bacteria when open → inflammatory response elicited in the ME → mucosal oedema, capillary engorgement and infiltration of neutrophils


2 URTI- directly inflaming the middle ear. The result is usually serous OME; secondary bacterial infection may occur




Pathophysiology Bacterial


Acute suppurative otitis media typically progresses in four stages: hyperemia, exudation, suppuration, coalescence and resolution

1 Hyperemia

Initial infection by bacteria results in simple hyperemia, causing otalgia

The otologic examination demonstrates injection of the vessels of the tympanic membrane

The drum is edematous, although landmarks can still be distinguished



2 Exudation

After 12 to 24 hours tympanomastoid compartment becomes filled with exudate under pressure.

Manifestations -increased otalgia and fever, conductive hearing loss.

Otoscopy, the tympanic membrane is red, thickened, and bulging.

The drum may appear pale instead of red

may have mastoid tenderness






Bulging TM, loss of landmarks













3 coalescence



When the infection is severe and persists beyond 2 weeks

Pus is under pressure



Destroy septa of the mastoid bone - coalescence of the mastoid

Symptomatology, in comparison to the stage of exudation, is deceptively mild.

It is the timing of the symptomatology rather than its severity that is critical to the correct diagnosis

4 Suppuration

may drain naturally via a perforated tympanic membrane


4 Complicated AOM

Develops Mastoiditis with subperiosteal abscess formation

An abscess can extend to the neck along the facial planes or intracranial

Other complications include sigmoid sinus thrombosis/ labyrinthitis/ facial nerve palsy







Note the subperiosteal abscess, pain is over the high mastoid-the antrum















Symptoms & Signs



Clinical Presentation

Initially acute ear ache/hearing loss/ fever

Temporal course of bacterial infection is as above

Drum may perforate and discharge

Mastoiditis take up to two weeks to develop

Tenderness in mastoiditis occurs over the antrum (high-up posterior) NOT over the tip (more likely a lymph node)





Examination

Tympanic membrane- hyperemia ---Budging--- perforation

Suspect mastoiditis if postauricular swelling due to subperiosteal abscess




Investigations

Imaging (CT +/- MRI) only if signs of complication (intratemporal and extratemporal)

tympanocentesis and myringotomy: if non-resolving/ mastoiditis



Note the destruction of septa on the left side leading to coalescence









Treatment


1 Observation

if uncomplicated

reassess at 48-72 hours

analgesia


2 Antimicrobials

Benefit

decrease treatment failure and rate of effusion

short term benefit → more rapid resolution of symptoms AOM

late benefit → more rapid resolution of MEE

antibiotics reduce risk of bacteraemia and may prevent focal infections i.e. mastoiditis


When to prescribe

younger children < 2y more risk of complications → prescribe from the onset

Others if no improvement in 3-4 days


Type of antibiotics

amoxicillin for uncomplicated AOM-if not working day 3 change



3 Surgical Treatment

A Myringotomy (if pus under pressure) and not settling

Therapeutic and obtains fluid for culture

low risk but TM heals within 3 days → insufficient time for mucosal recovery → high likelihood of recurrent OME


B Grommets-Indications

for recurrent AOM > 3 in 3 months or > 4 in 1 yr

failure of medical therapy and significant symptoms

suppurative complications (Mastoiditis/ facial nerve palsy- initial treatment along with IV abs)

immunocompromised patients after failure of medical therapy with 48-72 hours



C Adenoidectomy

recommended removal (irrespective of size) during placement of the second set of tympanostomy tubes

addition of tonsillectomy as little, if any, benefit and is not recommended

D Mastoidectomy

Suppurative complications/ not responded to grommet and IV ABS




4 Prevention


Antimicrobial prophylaxis: reduces 1 episode of AOM per 9 month treatment of antibiotics per child.





Allergy control: may help if a specific allergen can be identified

Vaccination-Prevenar: pneumococcal vaccine

use of the hepavalent (7 strains) conjugate pneumococcal vaccine-decrease in invasive pneumococcal infection

Only 6-7% decrease in episodes of AOM

reduced efficacy, as other pathogens causing AOM

reduces the URTI that predisposes to AOM


influenza vaccine

some studies -32% decrease in AOM others have shown only placebo

Changing environmental contributors: feeding methods, daycare, passive smoke exposure and allergen exposure


Natural History and Prognosis


60-70% resolve MEE by 30 days follow up

up to 90% in 3 months

younger children less likely to resolve a MEE and more likely to have an effusion that persists for > 12 weeks





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