How to assess the tympanic membrane?

Tympanic Membrane Assessment

The most effective assessment of the tympanic membrane should be performed using pneumatic otoscopy, which allows visualization of the membrane and evaluation of its mobility through the application of positive and negative pressure.1

Examination Techniques

Primary Assessment Methods

• Pneumatic otoscopy is the gold standard for tympanic membrane examination, creating an air-tight seal in the ear canal and using a rubber bulb to change pressure to assess membrane mobility 1
• A normal tympanic membrane moves briskly with applied pressure, while movement is minimal or sluggish when middle ear fluid is present 1
• Careful examination should specifically search for retraction pockets, ossicular erosion, and areas of atelectasis and atrophy 1

Advanced Assessment Methods

• Otomicroscopy provides a magnified binocular view with good depth perception when there is uncertainty about normal structures 1
• Tympanometry offers objective measurement of middle ear function by creating graphs showing how energy is reflected while canal pressure varies from negative to positive 1, 2
• Standard tympanometry uses a 226 Hz probe tone for adults and children over 6 months, while 1,000 Hz is more appropriate for infants under 6 months due to their naturally stiffer tympanic membranes 2

Normal Tympanic Membrane Characteristics

• The normal tympanic membrane appears pearly gray, translucent, and has good mobility when assessed with pneumatic otoscopy 1, 3
• Normal mobility is a key distinguishing feature from conditions like acute otitis media where mobility is limited or absent 3
• The resonance frequency of a normal tympanic membrane typically ranges from 226 Hz to 1,000 Hz 2

Pathological Findings

Acute Otitis Media

• A bulging tympanic membrane is most useful for diagnosing acute otitis media 1
• In acute otitis media, the tympanic membrane appears distinctly erythematous, bulging, and cloudy with limited or absent mobility 3

Otitis Media with Effusion

• An opaque or cloudy tympanic membrane is most useful for diagnosing otitis media with effusion 1
• Tympanometry typically shows a flat tracing (Type B) in otitis media with effusion 3
• Children with chronic otitis media with effusion are at risk for structural changes of the tympanic membrane due to inflammatory mediators 1

Swimmer's Ear (Acute Otitis Externa)

• The tympanic membrane maintains good mobility when assessed with pneumatic otoscopy, distinguishing it from acute otitis media 3
• The membrane may show some erythema extending from ear canal inflammation, potentially causing confusion with acute otitis media 3
• Tympanometry typically shows a normal peaked curve (Type A) in swimmer's ear 3

Documentation Recommendations

• Record the status of the tympanic membrane separately from ear canal findings 3
• Document whether the tympanic membrane is fully visualized, partially visualized, or not visualized due to canal edema 3
• Note the mobility of the tympanic membrane if pneumatic otoscopy was performed 3
• For perforations, document size, site, and location as these factors influence healing outcomes 4

Common Pitfalls and Caveats

• Visualization of the tympanic membrane may be difficult due to ear canal edema and discharge, potentially requiring gentle cleaning before adequate assessment 3
• Complete otoscopic examination may not be possible on the first visit for some patients, requiring anti-inflammatory medications or otic flushing to visualize the entire ear canal and tympanic membrane 5
• Increased stiffness of the tympanic membrane can lead to conductive hearing loss by impeding sound energy transmission to the middle ear ossicles 2
• Factors associated with poor healing of traumatic perforations include postero-superior location, large size, and penetrating injuries 4