Tympanometry refers to the measurement of middle ear pressure using a special device. It is thus used to diagnose changes in the sound-conducting ability of the middle ear. This examination method is one of the standard methods in otolaryngology.
Indications (areas of application)
- Tubal middle ear catarrh (inflammation of the mucous membrane of the ear trumpet (tube) resulting in constriction and consequent inadequate middle ear ventilation).
- Tympanic effusion (synonym: seromucotympanum) – accumulation of fluid in the middle ear (tympanum).
- Luxation (displacement) of the ossicles.
- Otosclerosis – disease associated with ossification of an ossicle (stapes) and cochlea (cochlea), respectively.
- Tinnitus (ringing in the ears)
- Glomus tumor (very rare!) – benign tumor in the area of the middle ear and / or mastoid process and the tip of the temporal bone.
The procedure
Tympanometry is a simple and quick to perform method in which a pressure variation is created in the ear canal with a positive pressure followed by a negative pressure. These pressure changes are reflected by the eardrum and can then be measured with a probe. This examination is well suited to study the condition of the eardrum.
Tympanometry thus measures the acoustic resistance, more correctly its reciprocal (the so-called conductance (admittance)), at the eardrum and thus indirectly infers the pressure present in the middle ear. Six graphical curves of the compliance of the tympanic membrane as a function of the applied air pressure difference to the ambient air pressure in the external auditory canal can thus be distinguished (see below “Measurement results and interpretation”).
Standard tympanometry is performed as low-frequency tympanometry (= single-frequency tympanometry at 226 Hz or 220 Hz).
Newer methods use multifrequency tympanometry. This expands the possibilities for differential diagnosis of diseases of the tympanic membrane-middle ear apparatus. For example, detection of otosclerosis can be made more confidently using this procedure.
Tympanometry is often combined with testing of the stapedius reflex.
Measurement results and interpretation
| Type | Pressure-dependent compliance of the tympanic membrane | Typical diagnosis |
| A | Normal summit altitude, approximately at 0 decapascals (daPa) pressure difference. | Normal middle ear |
| AD | Greatly increased peak height, approximately at 0 daPa pressure difference. | Scarred tympanic membrane or interruption of the ossicular chain |
| AS | Greatly reduced peak height, approximately at 0 daPa pressure difference. | Otosclerosis |
| B | Flat tympanogram with no discernible apex | Tympanic effusion or cerumen obturans (obstruction by earwax) |
| C | Normal peak altitude, but in negative or positive pressure range | Tube dysfunction |
| D | Double peak | Indication of severely decreased resonant frequency(rarely used for diagnosis) |
Benefit
Tympanometry is a simple and rapid diagnostic procedure for examining the tympanic membrane and middle ear.
