Middle Ear
·
Middle ear cleft = ear drum +
tympanum + eustachian tube
·
Ear drum:
o Should see malleous, top towards the back
o May see incus through the drum.
If internal jugular very high, may see it at bottom
o Main part called pars tensa, pars flaccida at top
Acute Otitis Media
·
= Infection of the middle ear
cleft
· Presentation:
o Eardrum opaque (not semitransparent), red, normal landmarks lost,
bulging. But if kid is screaming, ear will be red regardless
o Otalgia, otorrhoea, hearing loss
o Systemic signs: fever, irritability
o If it ruptures, child will be instantly better (but parents will panic!). Acutely ruptured eardrum will heal in 24 hours
·
Pathogens:
o S pneumoniae (30 – 50%)
o Non-typeable strains of H influenzae (20 – 30%)
o M Catarrhalis (10 – 20%)
o Viral (10 – 20%) especially RSV
o Mixed bacterial/viral infections account for 50% of antibiotic failures
·
Treatment:
o Without treatment, 70 –90% of infections resolve spontaneously
o Those least likely to respond are:
§ Aged < 2 years
§ Those with constitutional disturbance (eg > 39 C)
§ Where S pneumoniae is the pathogen
· Antibiotics:
o Should be directed against S pneumoniae: it is the most common pathogen, the least likely to resolve spontaneously, and the most commonly associated with mastoiditis. Amoxycillin for 7 – 10 days (?5 days just as good) is the treatment of choice, even when there are non-susceptible S pneumoniae isolates. Good penetration of middle ear. Erythromycin/cotrimoxazole if allergic. Main reason for antibiotics is to prevent rare complications
o For the 90 – 95% of otitis media that responds to antibiotics, 90% are
due to spontaneous resolution
o If < 2 years, constitutional disturbance and persistent symptoms >
48 hours:
§ Amoxycillin 15 – 30 mg/kg TID for 10 days (ie high dose).
§ If no improvement after 48 – 72 hours try Augmentin (cover H influenzae
and Moraxella)
§ Main aim is to reduce the very small chance of suppurative complications
o Treatment for Acute Otitis Media in children (NZ Guideline for Acute
Otitis Media):
§ Main benefit from antibiotics is less pain on the 2nd or 3rd day in 1 in 17 kids, and failure to spread to other side in 1 in 17. No effect on pain on first day, prevention of recurrence or build up of middle ear fluid
§ Side effects of skin rash, vomiting or diarrhoea are as common as benefits
§ Recommendation: use Paracetamol, return to doctor if symptoms persist beyond 48 hours, and have ears checked in a month for persisting fluid (common in first several weeks) – this occurs in about 1 in 10
o Oral cephalosporins and 2nd generation macrolides don‟t penetrate the middle ear and/or have poor
activity against S pneumoniae
·
Complications:
o Mastoiditis in 0.1%. Incidence is
not increased by delayed treatment
o Little evidence to suggest that untreated otitis media causes
mastoiditis
o Very rare: petrositis, labyrinthitis, facial palsy,
subdural/epidural/brain abscess
·
Cholesteatoma:
o Most commonly affects the attic (=epitympanum) and antrum of the mastoid
o Pars flaccida gets sucked in, expands, erodes surrounding tissue
o May present with:
§ Chronically discharging, smelly ear, resistant to treatment
§ Conductive hearing loss: ossicles eroded
§ Complication: brain or mastoid abscess
o Treatment: remove diseased bone
·
Otosclerosis:
o New bone formation fixes the footplate of stapes
o Conductive hearing loss but ear looks normal
o F > M, familial, Âin pregnancy, menopause
o 1:20 – 25,000K, can be bilateral
o Treatment: Stapendectomy (put in piston) or hearing aid
·
Tympanic sclerosis. White plaques on ear drum. No consequence
·
Barotrauma: from
flying/diving. Bleeding and bruising
around malleolus. Will settle
spontaneously
·
Haemotympanum: Blood in middle ear. ?Temporal bone fracture. Battle‟s Sign (of temporal
·
fracture): bruising behind the
pinna
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