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