Type B Tympanogram Full Chapter URL

If the ear canal volume is abnormally small and a Type B tympanogram is observed, this is suggestive of blockage of the ear canal because of cerumen impaction.

From: Mandell, Douglas, and Bennetts Principles and Practice of Infectious Diseases (Eighth Edition), 2015 Related terms: Clinician Effusion Middle Ear Pressure Barotrauma Audiometry Hearing Impairment Acoustic Reflex Conduction Deafness Secretory Otitis Media Acute Otitis Media View all Topics Download as PDF Set alert About this page Earache Brittany Player, in Nelson Pediatric Symptom-Based Diagnosis, 2018 Tympanometry (See Nelson Textbook of Pediatrics, p.

Tympanometry is an objective, painless method for detecting the presence of middle ear effusion by providing information about tympanic membrane compliance.

A soft plastic probe is inserted into the external auditory canal in order to obtain an airtight seal.

The tympanometer measures the flow of sound energy into the middle ear under conditions of changing air pressure.

When the air pressure is equal on both sides of an intact eardrum, with the drum in neutral position, the transmission of sound energy through the tympanic membrane is at its maximum.

The peak on the tympanogram represents the pressure at which the flow of sound energy is maximal.

For example, in a normal air-filled middle ear cavity, the peak occurs at ambient atmospheric pressure ( Fig.

C ). With middle ear effusion, the sound energy flow into the middle ear is reduced, which produces a flat tympanogram ( Fig.

B ). A flat tympanogram may also result from cerumen, foreign body, or from occlusion of the opening of the probe by the wall of the external auditory canal.

In a perforated eardrum, the sound energy is readily transmitted through the hole in the drum throughout the entire pressure range, resulting in a flat tympanogram.

The use of tympanometry can be limited by patient age and cooperation with testing, cerumen impaction, and the skill of the individual performing the testing.

When performed by experts, tympanometry and pneumatic otoscopy have equivalent sensitivity (approximately 90) and specificity (70-80).

Tympanometry is neither more accurate nor more convenient than is properly performed pneumatic otoscopy.

Some tympanometers do not perform well in infants younger than 6 months of age.

Tympanometry is advantageous if the clinician is unsure of the otoscopic findings.

Tympanometry can only indicate middle ear effusion, but cannot distinguish between AOM and OME.

Type B Tympanogram Full Chapter URL

View chapter Purchase book Read full chapter URL: Behavior and Development Mark F.

Ditmar MD, in Pediatric Secrets (Fifth Edition), 2011 93 What causes flat tympanograms Tympanometry is an objective measurement of the compliance of the tympanic membrane and the middle ear compartment that involves varying the air pressure in the external ear canal from about 200 to 400 mm H 2 O while measuring the reflected energy of a simultaneous acoustic tone.

A normal tracing looks like an inverted V, with the peak occurring at an air pressure of 0 mm H 2 O; this indicates a functionally normal external canal, an intact tympanic membrane, and a lack of excess of middle ear fluid.

Flat tympanograms occur with perforation of the tympanic membrane, occlusion of the tympanometry probe against the wall of the canal, obstruction of the canal by a foreign body or impaction by cerumen, or large middle ear effusion.

Flat tympanograms due to middle ear effusion are usually associated with a 20- to 30-dB conductive hearing loss, although in occasional instances, the loss may be as great as 50 dB.

View chapter Purchase book Read full chapter URL: Auditory, Vestibular, and Visual Impairments Ding-Hao Liu, in Braddoms Rehabilitation Care: A Clinical Handbook, 2018 Immittance Audiometry Tympanometry measures the mobility of the tympanic membrane and the middle ear pressure, but it does not measure perceptual hearing.

The results from tympanometry are plotted as a graph called a tympanogram (eSlide 50.5).

There are three main types of tympanograms: A, B, and C.

Reduced mobility of the tympanic membrane caused by a stiffened middle ear system can cause a shallow peak on the tympanogram, called a Type A s tympanogram.

A Type B tympanogram shows no clear peak pressure and is relatively flat.

If the ear canal volume is normal, the Type B tympanogram may be reflective of an advanced stage of otosclerosis or a middle ear filled with an effusion (possibly caused by an ear infection).