A
GUIDE TO TYMPANOMETRY FOR PEDIATRICIANS
Steven
D. Smith, Au.D., F-AAA, Neuro-Audiologist
Introduction
The clinical
value of measuring middle ear function with aural impedance techniques
dates back to Otto Metz in 1946, however, the advent of clinical
instrumentation through the 1960s and 1970s led to many observations
of the effects of specific pathological conditions on tympanograms.
The wide variety of tympanometric patterns was not understood well
until a group of physicists at the University of Antwerp took an
interest in understanding the relations between tympanometric patterns
and the physics of the middle ear. The result was the Vanhuyse model,
which is the single most important contribution to the understanding
of tympanometry. This is the basis for which the clinical interpretation
of tympanograms is derived. Since the 1970s Immittance Audiometry,
especially tympanometry measurements has been the topic much research.
Immittance measures include not only tympanometry, but also acoustic
reflex testing which helps differentiate sensory versus neural auditory
dysfunction. Tympanometry has become the single most utilized clinical
test in audiology.
A tympanogram,
is one test that can be utilized in "Immittance Audiometry."
Immittance testing utilized a device to quantify the impedance (resistance
to movement) of the conductive mechanism of the ear by producing
a probe tone that is in essence bounced off the tympanic membrane
and measures the proportion of reflected sound. Tympanometry is
a graphic representation of the relationship of external auditory
canal air pressure to impedance. Pressure in the external auditory
canal is varied from -200 daPa through +200 daPa while monitoring
impedance. Impedance is lowest (maximal compliance) when pressure
in the canal equals pressure contained within the middle ear space.
There are typically three major groups on the basis of the configuration
of the tympanogram. These are:
1.
Type A:
The peak compliance occurs at or near atmospheric pressure indicating
normal pressure within the middle ear. Three subcategories:
 |
 |
A: Normal
shape reflects a normal middle ear mechanism |
|
AD: A
deep curse with a tall peak indicates an abnormally compliant
middle ear system, as typically seen with ossicular chain
dislocation or loss of elastic fibers in the tympanic membrane. |
| |
|
AS: A
shallow curve indicative of a stiff system, as seen in otosclerosis
or thickened tympanic membrane. |
2.
Type B: No
sharpe peak, little or no variation in impedance over a wide sweep
range, usually secondary to non-compressible fluid within the middle
ear space (otitis media), tympanic membrane perforation, or debris
within the external ear canal (cerumen).
3.
Type C:
Peak compliance is significantly below zero, indicating negative
pressure (sub-atmospheric) within the middle ear space. This finding
is suggestive of Eustachian tube dysfunction or middle ear fluid.
The test is performed
after appropriate otoscopic examination is performed. Any debris,
such as cerumen, should be removed from the external ear canal prior
to the performance of the test. A soft tip is placed on a probe
and inserted into the ear canal. The device will sweep from a negative
to positive air pressure fashion and measure the impedance of the
ear. The tympanogram is a non-invasive, fast, and accurate test.
Typical test for both ears is less than 2 minutes. The information
derived from the tympanogram provides the physician with the additional
information regarding the patient's middle ear function. In a pediatric
population this is typically to document or rule out the presence
of otitis media, tympanic membrane perforation or Eustachian tube
dysfunction.
What are the clinical uses for tympanometry?
Tympanometry is utilized in a clinical setting for the evaluation
of middle ear function. The test can provide excellent information
regarding the function of the middle ear. It can assist with the
visual otoscopic evaluation in evaluating the middle ear for otitis
media, tympanic membrane perforation, and Eustachian tube dysfunction.
Depending on the type of device a facility has it can be performed
on newborns to adults.
How much does equipment cost?
As with many of the devices currently in use today, these
devices have become economically viable for all facilities. There
are currently many different devices ranging from handheld to full
clinically diagnostic units. The costs vary from manufacturer to
manufacturer but the range is $2,000.00 to $ 8,500.00 depending
on the type of device. This equipment is very reliable and provides
excellent diagnostic information.
How do I bill for Tympanometry and what
is the average reimbursement?
The Current Procedural Terminology (CPT) code for tympanometry
allows for full reimbursement for this test. To date this test has
an established history of diagnostic value and utilization. The
CPT code for this procedure is as follows:
1.
CPT Code #92567: Tympanometry
(Impedance testing).
REFERENCE:
Current Procedural Terminology, CPT 2001, Professional Edition,
American Medical Association, AMA Press, ISBN: 1-57947-108-0 (SPIRAL
NOTEBOOK) OR ISBN: 1-57947-109-9 (BINDER NOTEBOOK)
In a recent survey among offices performing tympanometry the
average office charge range $18.00 to $34.00 per test with the average
reimbursement (depending on the insurance carrier) ranging from
$15.00 to $24.00 per test.
This equipment typically will pay for itself in 3 to 6 months. A
practice should average 30 to 60 tympanograms per month. If an average
of 45 tympanograms is used with the average reimbursement charge
of $18.00 per test the income derived from these tests per month
would be approximately $810.00 per month and $9,720.00 per year.
This is only an estimate, however, most facilities perform over
45 tympanograms per month.
In addition, it must be stated that a correct diagnosis code must
be utilized in conjunction with the test. The following diagnosis
codes are provided:
COMMON AUDIOLOGICAL DIAGNOSIS CODES
REFERENCE:
INTERNATIONAL CLASSIFICATION OF DISEASES, 9TH REVISION, CLINICAL
MODIFICATION, ICD-9-CM 2001, VOLUMES 1 AND 2, AMERICAN MEDICAL ASSOICATION,
AMA PRESS. ISBN: 1-57947-150-1
| 380.40 |
CERUMEN
IMPACTION |
| 381.0 |
OTITIS
MEDIA, WITH EFFUSION |
| 381.02 |
OTITIS
MEDIA, SEROMUCINOUS |
| 381.03 |
OTITIS
MEDIA, HEMORRHAGIC |
| 381.04 |
OTITIS MEDIA, SEROUS |
| 381.05 |
OTITIS
MEDIA, MUCOID |
| 381.06 |
OTITIS
MEDIA, ACUTE, ALLERIC HEMORRHAGIC |
| 381.81 |
UNSPECIFIED
EUSTACHIAN TUBE DISORDER |
| 382.01 |
OTITIS
MEDIA, WITH TM RUPTURE |
| 385.23 |
OSSICLES,
DISCONTINUITY/DISLOCATION |
| 384.20 |
PERFORATION,
UNSPECIFIED |
| 384.21 |
PERFORATION,
CENTRAL |
| 384.22 |
PERFORATION, ATTIC |
| 384.23 |
PERFORATION,
MARGINAL, OTHER |
| 384.24 |
PERFORATION,
MULTIPLE |
| 384.25 |
PERFORATION,
TOTAL |
| 387.0 |
OTOSCLEROSIS,
OVAL WINDOW, NONOBLITERATIVE |
| 387.10 |
OTOSCLEROSIS,
OBLITERATIVE |
| 387.90 |
OTOSCLEROSIS,
UNSPECIFIED |
| 388.01 |
PRESBYACUSIS |
| 388.02 |
TRANSIENT
ISCHEMIC DEAFNESS |
| 388.10 |
NOISE EFFECTS ON INNER EAR |
| 388.11 |
ACOUSTIC
TRAUMA (EXPOSIVE) TO EAR |
| 388.12 |
NOISE-INDUCED HEARING LOSS |
| 388.20 |
SUDDEN HEARING LOSS, UNSPECIFIED |
| 388.30 |
TINNITUS,
UNSPECIFIED |
| 388.31 |
SUBJECTIVE TINNITUS |
| 388.32 |
OBJECTIVE
TINNITUS |
| 388.40 |
ABNORMAL
AUDITORY PERCEPTION |
| 388.41 |
DIPLACUSIS |
| 388.42 |
HYPERACUSIS |
| 388.43 |
IMPAIRMENT OF AUDITORY DISCRIMINATION |
| 388.44 |
RECRUITMENT |
| 388.50 |
DISORDERS
OF ACOUSTIC NERVE |
| 388.0 |
CONDUCTIVE
HEARING LOSS, UNSPECIFIED |
| 388.01 |
CONDUCTIVE
HEARING LOSS, EXTERNAL |
| 388.02 |
CONDUCTIVE
HEARING LOSS, TYMPANIC |
| 388.03 |
CONDUCTIVE
HEARING LOSS, MIDDLE EAR |
| 388.04 |
CONDUCTIVE HEARING LOSS, INNER EAR |
| 388.08 |
CONDUCTIVE HEARING LOSS, COMBINED |
| 389.10 |
SENSORINEURAL HEARING LOSS, UNSPECIFIED |
| 389.11 |
SENSORY HEARING LOSS |
| 389.12 |
NEURAL HEARING LOSS |
| 389.14 |
CENTRAL
HEARING LOSS |
| 389.18 |
SENSORINEURAL
HEAIRNG LOSS, COMBINED TYPES |
| 389.20 |
MIXED
CONDUCTIVE AND SENSORINEURAL |
| 389.70 |
DEAF MUTISM |
| 389.80 |
OTHER
SPECIFIED FORMS OF HEARING LOSS |
| 389.90 |
UNSPECIFIED
HEARING LOSS |
Conclusion:
The
cost effectiveness and diagnostic utilization of tympanometry can
provide the pediatrician with an excellent method of assisting in
the identification of middle ear pathology. The objective information
derived from this test modality will ensure that the middle ear
function of a particular patient has been fully evaluated. The utilization
of handheld devices offers a fast, non-invasive, and cost effective
method to assess the integrity and function of the middle ear. This
equipment typically is the most utilized device in any audiology
or otology facility. The ability to objectively measure and document
middle ear function is vital in today's health care environment.
Most
will find that the incorporation of this type of testing into their
office protocol will not only pay for itself in 3 to 6 months and
generate additional revenue, but also provide a level of diagnostic
objectivity that was not previously available.
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