OTITIS MEDIA and other ear infections

Timothy C. Hain, MD Page last modified: July 2, 2008

UNDER CONSTRUCTION

Main Points:

• 1. Otitis media is a common infection of the middle ear
• 2. It is diagnosed by looking at the ear
• 3. Observation is sufficient for uncomplicated mild infections

DEFINITIONS

• Otitis media (OM) -- inflammation of the middle ear.
  • Acute otitis media (AOM)-- acute middle ear infection, generally bacterial.
• Serous otitis media (SOM)-- fluid without bacteria filling the middle ear. AKA middle ear effusion, AKA Otitis media with effusion (OME)
• Otitis externa - -infection of external ear canal (not otitis media per se, but can accompany OM).

GENERAL SIGNS AND SYMPTOMS:

Children with AOM (acute otitis media) usually present with a history of rapid onset of signs and symptoms such as ear pain and/or fever.

OTOLOGIC SIGNS AND SYMPTOMS

The presence of middle ear effusion (fluid) is indicated by fullness or bulging of the tympanic membrane, an air-fluid level behind the membrane, or fluid coming out of the ear (this means there is a perforation).

Otoscopic findings of a bulging tympanic membrane with impaired mobility is highly predictive of AOM. A red tympanic membrane is less predictive since the redness may be a flush that comes from crying. However, in an adult, a red TM is very helpful.

Both AOM and OME have fluid in the middle ear cavity. In AOM -- the fluid is infected and often pus. In OME, it is clear or straw colored fluid without an infection. Factors that help differentiate between AOM and OME are as follows:

Causes of Otitis Media

AOM is generally caused by one of three bacteria: streptococcus pneumoniae, hemophilus influenzae, and moraxella catarrhalis. About 40-50% of AOM is caused by strep, about 20-30 by hemophilus, and about 10-15 by M. Catarrhalis. Resistance of these bacteria to antibiotics are increasing and also there is a change in flora related to use of pneumococcal vaccine, with an increase in H influenzae to roughly 50-60%.

OME is not generally due to an infection but rather caused by eustachian tube blockage or other non-infective causes (e.g. radiation as an example).

Otitis externa is most commonly caused by

• staphylococcus (about 50%)
• MRSA (about 10%)
• pseudomonas (about 30%)

Fungi (otomycosis) are usually accompanying organisms, but can be the primary cause of otitis media or otitis externa.

TREATMENT of Otitis Media

Observation of otitis media without antibiotics but with pain control is an appropriate option for many children with uncomplicated AOM. Antibiotics are recommended in children under 6 months of age as well as patients with severe illness.

Drugs that are often used are as following:

• Amoxicillin (80-90 mg/kg/d) (twice/day)
• Amoxicillin/clavulinate (90 mg/kg/day of amoxicillin with 6.4 mg/kg/d of clavulinate)

Alternatives for persons with penicillin allergy

• Cefdinir (once/day)
• Cefurxime
• Cefpodoxime
• Azithromycin (once/day)
• Clarithromycin
• Ceftriaxone (once/day)

If treatment fails at 48-72 hours switch to higher dose of anbtibiotics, ceftriaxone or clindamycin

Treatment of Otitis Externa

Cultures of draining ears are recommended at the initial visit. However, the impact on management is uncertain.

• Ear drops are generally used to treat otitis externa.
  • Presently most patients are started on a drop that contains a floroquinolone, possibly with the addition of a steroid to reduce swelling.
• If ear drops fail, then systemic antibiotics follow.
  • Systemic antibiotics are not recommended as the first line of treatment (Hamerlynck et al., 2006).
• Because of the bacteriology of OE (staph, pseudomonas, MRSA, fungus), somewhat unusual systemic antibiotics may be used.
  • This may include high-dose trimethoprim sulfa (for MRSA).

Prevention measures for recurrence include the following (Sander, 2001)

• Avoid manipulation of ear canal (i.e. avoid putting things in the ear canal)
• Dry and clean ear
  • Dry ears with hair dryer
  • Clean ears in doctor's office with suction/microscope
• Acidification (2% acetic acid with hydrocortisone) -- Vosol is a brand name for this preparation.

When acidification fails, antifungal topical preparations are also commonly used. There are numerous of these agents used in animal medicine. None of these is presently FDA approved for human use and for this reason they are used "off-label" in humans. Several of these are available over-the-counter such as clotrimazole -- (Lotrimin AF) cream and tinactin solution. Use of these preparations should be under the supervision of a physician experienced in treating ear infections.

Mastoiditis

Right sided mastoiditis (white blotch on the left side of this image). On MRI films, the right side of the head is shown on the left side of the image.

Otitis media may be accompanied by mastoiditis - -an infection of the sinus which is attached to the middle ear. This can be seen on imaging studies (see above)

There are several types of Mastoiditis

• Noncoalescent mastoiditis
  • MRI findings of fluid in mastoid -- not necessarily infectious
  • AOM plus swollen or protruding ear
• Coalescent mastoiditis (destruction of bony trabeculae or cortex of temporal bone)

Severe mastoiditis is characterized by a swollen external auditory canal. Mild mastoiditis, may be silent, and only seen on imaging (as above).

There are several treatment approaches --

• Antibiotics
• Myringotomy -- means cutting a hole in the ear drum. This procedure may be done to drain pus from the middle ear, obtain material for culture, and aerate the middle ear.
• Mastoidectomy -- means opening up the mastoid sinus.
  • This is a procedure used for hospitalized patients whose otitis media dies not respond to IV antibiotics.
• PE tubes may be helpful in mild cases but they do not provide adequate drainage for severe cases of mastoiditis. PE tubes tend to be used in more chronic situations than myringotamy

Facial Paralysis

An acute lower motor neuron facial palsy is rare even though dehiscence of the facial canal is very common. When this happens, there should be a myringotamy with PE tube placement, Infectious disease consultation, intravenous antibiotics, and consideration of mastoidectomy. Once the infection resolves, facial nerve function usually recovers over several months.

Labyrinthitis

This comes in several stages.

• Serious labyrinthitis - -bacterial toxins enter the inner ear and cause vertigo and mild hearing loss.
• Purulent labyrinthitis occurs as bacteria enter the inner ear.
• Labyrinthitis ossificans -- occurs when the inner ear fills with scar tissue

In patients believed to have labyrinthitis associated with AOM, one should image the brain, obtain a lumbar puncture, place a PE tube, administer IV antibioitics, and consider mastoidectomy.

Gradenigo's syndrome (Petrous apicitis)

The symptoms of this include severe frontal headache, eye pain, diplopia, dizziness, nausea, and 6th nerve palsy. There should be otitis media seen on otoscopy. MRI shows inflammation of the petrous apex and mastoids. CT may show bone erosion in the petrous apex.

Treatment is with myringotomy with PE tube, culture-directed IV antibiotic therapy.

Mimickers of mastoidits

• Rhabdomyosacroma
• Langerhans cell histiocytosis

References

• Hamerlynck, J. V., P. P. van Benthem, et al. (2006). "[From the Cochrane Library: topical antibiotic treatment is more effective than systemic antibiotic treatment for chronic otitis media with eardrum perforation and purulent discharge]." Ned Tijdschr Geneeskd 150(37): 2033-5.
• Ramakrishnan, K., R. A. Sparks, et al. (2007). "Diagnosis and treatment of otitis media." Am Fam Physician 76(11): 1650-8.
• Sander, R. (2001). "Otitis externa: a practical guide to treatment and prevention." Am Fam Physician 63(5): 927-36, 941-2.