Monday, April 9, 2018

Acute Otitis Media (AOM)

AOM refers to the acute onset of signs and symptoms of middle ear inflammation. Otits Media and URTIs are one of the commonest diagnosis in children. The peak incidence of AOM is between 6 and 18 months of age. Most common bugs causing AOM are Streptococcus pneumoniae (49%), Haemophilus influenzae (29%), and Moraxella catarrhalis (28%), picornaviruses such as rhinovirus and enterovirus, respiratory syncytial virus, and parainfluenza virus. RIsk factors for AOM are:


  • Males
  • Day care attendees
  • Exposed to tobacco smoke
  • Craniofacial anomalies
  • Prone position sleepers
  • Pacifier users
  • Born with immunodeficiency syndromes

Breastfed infants have a lower incidence of AOM compared to infants who are formula-fed.


Middle Ear Anatomy



In the healthy state, middle ear is aerated and contains the auditory bones, which transmit sound to the inner ear. Compared with adults, the eustachian tube in children is shorter and more horizontally oriented. This orientation is the anatomic rationale for the increased incidence of middle ear disease seen in children. An upper respiratory tract infection can obstruct the eustachian tube and disrupt its function of aerating the middle ear, creating conditions favorable to the development of sterile or purulent effusions. 


Clinical Features
The classic presnetation of AOM is fever with rapid-onset ear pain with preciding history of  rhinorrhea, congestion, cough is common because an URTI creates conditions favorable to the development of AOM. Children may pull or rub the ear or be fussy and irritable. Older children may complain of decreased hearing due to con- ductive hearing loss of middle ear effusion. Complications of AOM are tympanic membrane perforation, mastoid- itis, encephalitis, abscess, sinus thrombosis, otitis hydrocephalus, facial or abducens nerve palsy, and labyrinthitis/acquired sensorineural hearing due to changes in the inner ear.


Diagnosis
Erythema of the tympanic membrane alone is insufficient fto diagnose AOM because erythema can be caused by middle ear inflammation, crying, or fever. When examining, look specifically for discharge in the ear canal, tympanic membrane’s position, color, degree of translucency. 

Treatment 
Most cases of AOM resolve spontaneously and without complications. Tympanic membrane perforation typically heals spontaneously after AOM resolution, but persistent perforations need ENT consultation. Mainstay of treatment is pain relief. Symptoms can last for up to a week but most children get better within 3 days without antibiotics. Antibiotics make little difference to the rates of common complications. 

Pain Relief: Rx with NSAIDs. Topical otic analgesic drops may be used in combination as they have a rapid onset of action. Topical analgesics are contraindicated in patients with perforation.


Need for Antibiotics?
Initial observation option is a reasonable startegy for select children with AOM and this approach is supported by numerous studies. Remember, when observation is used,  ensure fa way to follow-up and start of antibiotics if the child worsens or fails to improve. A wait-and-see antibiotic prescription can be provided at the initial visit with instructions for the caregiver to initiate antibiotics if the child worsens or fails to improve within 3-4 days. Indications for Abx are:

  • Bilateral AOM in <2 years
  • AOM with perforation/ear discharge
  • Recurrent AOM
  • Craniofacial abnormalitites
  • Immunocompromised
  • Systemically unwell
  • Infants <6/12 old
Amoxicillin for 5 to 10 days is the first-line treatment.  If amoxicillin fails, change to amoxicillin-clavulanate or ceftriaxone to provide coverage against β-lactamase–producing M. catarrhalis and nontypeable H. influenzae. If the second antibiotic regimen fails, treat with clindamycin and a third-general cephalosporin, or consult ear, nose, and throat for tympanocentesis and culture. For people who are allergic to penicillin, prescribe a 5-day course of erythromycin or clarithromycin.

References:

  1. Tintinalli textbook of EM - 8th edition
  2. https://cks.nice.org.uk/otitis-media-acute#!scenario



Posted by:


              
     Lakshay Chanana
     
     Speciality Doctor
     Northwick Park Hospital
     Department of Emergency Medicine
     England

     @EMDidactic

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