Middle Ear, Eustachian Tube, Inflammation/Infection Workup

Updated: May 03, 2017
  • Author: Robert B Meek, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Workup

Laboratory Studies

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  • Lab studies are seldom necessary unless the patient is being evaluated for a complication of otitis media (OM).
    • In rare instances, tympanocentesis is performed, the specimen is cultured, and sensitivity tests are performed. These instances include refractory cases of acute otitis media (AOM), neonates with severe otitis media (OM), immunocompromised patients, and very ill children with otitis media (OM).
    • A CBC count may be useful in a patient who appears toxic, and a lumbar puncture is useful if concerns of meningitis secondary to otitis media (OM) have arisen.
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Imaging Studies

Imaging studies are not typically applicable in cases of otitis media (OM). A computed tomography (CT) scan of the temporal bones is useful to evaluate the temporal bone for extracranial complications of otitis media (OM). A magnetic resonance imaging (MRI) study is useful to evaluate for intracranial complications of otitis media (OM).

A prospective study by Tarabichi and Najmi indicated that in most persons with healthy ears, temporal bone CT scans performed during the Valsalva maneuver can visualize the distal third of the eustachian tube lumen, suggesting that this imaging strategy could help to localize disorders in patients with symptoms of eustachian tube obstruction. The study was performed on 38 patients (76 ears), with the distal third of the lumen visualized in 71 ears (93%) and the entire lumen visualized in 27 ears (36%). [8]

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Other Tests

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  • An impedance measurement (tympanogram) is an indirect measurement of eustachian tube and middle ear function that suggests the presence or absence of effusion or pressure in the middle ear space.
    • Type A tympanogram with little negative pressure suggests normal middle ear and eustachian tube function.
    • Type B tympanogram with low volume suggests middle ear fluid.
    • Type B tympanogram with a large volume suggests a patent tube or perforation. Small volume with visible perforation on examination suggests eustachian tube edema. Volume of 4-5 mL suggests a patent eustachian tube.
    • Type C tympanogram with high negative pressure suggests eustachian tube inflammation and dysfunction.
    • Type D tympanogram suggests a flaccid tympanogram with high negative pressure or ossicular discontinuity.
  • Audiometry is critical in determining any temporary effects that middle ear fluid may have on hearing sensitivities.
    • The method of audiological examination depends on the patient's age. Infants younger than 6 months typically undergo behavioral observation audiometry, while children aged 6 months to 2.5 years typically undergo visual reinforcement audiology. Children older than 2.5 years undergo play audiometry, while older children are evaluated using standard testing with hand raising.
    • Middle ear effusions can produce mild-to-moderate levels of conductive hearing loss, although threshold testing may be normal. Children with middle ear effusions may demonstrate problems with auditory processing despite normal thresholds.
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Procedures

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  • Myringotomy with tube placement is the primary treatment for persistent middle ear effusion. A tympanocentesis is useful for refractory cases of acute otitis media (AOM) and for research purposes.
    • Second-line surgical treatment of persistent OME involves adenoidectomy without tonsillectomy. Consider adenoidectomy in patients requiring a second set of ventilation tubes.
    • Mastoidectomy and tympanoplasty are also used to treat eustachian tube abnormalities and otitis media (OM).
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Histologic Findings

A bony and cartilaginous structure separated by a tubal isthmus forms the eustachian tube. The isthmus is smaller in children (about 2.4 mm x 0.8 mm) than in adults (about 4.3 mm x 1.7 mm). Analysis of human eustachian tube mucosa reveals that it is similar to respiratory epithelium, which is found elsewhere. The cartilaginous portion contains many seromucoid glands.

The middle ear mucosa consists of tall columnar cells near the tube and hypotympanum and cuboidal and simple squamous mucosal cells throughout the remainder of the middle ear. Collagen fibers, blood and lymph capillaries, and nerve fibers predominantly form the subepithelial space. A relative paucity of immunocompetent and seromucoid glands are found in the noninfected middle ear.

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