Middle Ear

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

Otitis Media

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 2^nd or 3^rd 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 2^nd 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

Other Middle Ear Conditions

·        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, ­in 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