1

IN THE UNITED STATES COURT OF APPEALS FOR VETERANS CLAIMS

KENNETH J. CLAPP, ) Appellant, ) ) vs. ) Vet. App. No. 17-0776 ) DENIS MCDONOUGH, ) Secretary of Veterans Affairs, ) Appellee. )

APPELLANT’S SUPPLEMENTAL MEMORANDUM OF LAW

In response to the Court’s January 21, 2021 Order, Appellant submits this

supplemental memorandum of law discussing Long v. Wilkie, -- Vet.App. --, 2020 WL

7757076 (Vet.App. Dec. 30, 2020), and its application to this case. He asserts that the

Court’s decisions in Long, 2020 WL 7757076 and Morgan v. Wilkie, 31 Vet.App. 162

(2019) provide further support for remand here because Mr. Clapp’s abnormal acoustic

reflexes are not contemplated by the hearing loss rating criteria, and the Board failed to

provide this analysis in the first instance.

The Board erred when it failed to analyze the Veteran’s abnormal

ipsilateral and contralateral acoustic reflexes. See R-670. Acoustic reflexes do not

measure hearing thresholds; rather, they measure reflected energy, which is a function

of stapedius muscle contraction and allows an examiner to assess the middle ear.

Jackie L. Clark, Open Access Guide to Audiology and Hearing Aids for Otolaryngologists,

available at https://vula.uct.ac.za/access/content/group/27b5cb1b-1b65-4280-9437-

2

a9898ddd4c40/Acoustic%20_stapedius_%20reflexes.pdf (last accessed Feb. 22,

2021)1; see Appellant’s Br. at 6 n. 1, Appendix 1. Sensorineural hearing loss, such as

Mr. Clapp’s, R-670, obstructs transmissions of signals within the ear and causes

reduced or absent acoustic reflexes. See Clark, Open Access Guide to Audiology and

Hearing Aids for Otolaryngologists at 3.

Whether the Veteran’s abnormal acoustic reflexes meet the first step of the

extraschedular framework is a factual determination that the Board must make in the

first instance. See Hensley v. West, 212 F. 3d 1255, 1263 (Fed. Cir. 2000). But in

evaluating the Veteran’s disability picture, the Board did not discuss the Veteran’s

non-auditory symptoms of abnormal ipsilateral and contralateral acoustic reflexes. See

R-2-9; R-670. In Long, the Court reaffirmed its long-standing extraschedular

framework requiring the Board to assess “the veteran’s disability picture as a whole” to

determine whether he or she “presents an impairment that is so exceptional that the

rating schedule is not capable of assessing it in the first instance.” 2020 WL 7757076

at *3 (emphasis added). While the Board need not in engage in “a line-item

accounting of each symptoms and effect,” it must make a “reasoned assessment of

both the veteran’s full disability picture and the capacity of the rating schedule to

evaluate such.” Id. This holding is consistent with the Court’s previous decision in

Morgan, which held that VA’s duty to maximize benefits requires the Board to

1 For the Court’s convenience, a copy of this article is attached in the appendix.

3

examine “all possible rating methods in search of the highest possible level of

established compensation as a schedular matter before resorting to the extraschedular

referral process.” 31 Vet. App. at 168. When read together, Morgan and Long require

the Board to determine whether a veteran’s disability picture is fully contemplated by

the assigned rating. If it is not, the Board must first consider the available schedular

rating tools before resorting, in the truly exceptional case, to extraschedular referral.

In this case, the Board failed to conduct the analysis required by Morgan and

Long. This was prejudicial because the record raised the theory of entitlement to

either a schedular alternative or extraschedular consideration. See Long, 2020 WL

7757076 at *5. Mr. Clapp raised the theory that his non-compensable schedular rating

did not adequately compensate him for his full disability picture and requested a 50%

disability rating. R-61; see also R-387-88; R-423-24.

Although the Veteran pointed to difficulties communicating, his pleadings did

not relieve the Board of its duty to assess his full disability picture, which included his

abnormal acoustic reflexes. See Long, 2020 WL 7757076 at *3. The Federal Circuit

recently found that this Court’s holding in Clemons v. Shinseki, 23 Vet.App. 1 (2009)

“provides valuable guidance as to how the VA should interpret filings from a

veteran.” Murphy v. Wilkie, 983 F. 3d 1313, 1318 (Fed. Cir. 2020). Specifically,

interpreting a veteran’s filings “is best accomplished by looking to the veteran’s

reasonable expectations in filing the claim and the evidence developed in processing

that claim.” Id.

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Here, the record makes clear the Mr. Clapp reasonably expected VA to provide

proper consideration to his claim and believed that a minimum rating of 50% was

appropriate. R-61. In the process of developing the Veteran’s claim, VA obtained

evidence of abnormal acoustic reflexes. R-670. These abnormalities were diagnosed

during the Veteran’s VA hearing loss examination and are therefore clearly related to

his service-connected hearing loss. See Long, 2020 WL 7757076 at *5. Thus, where

the Board only considered the Veteran’s hearing and communication impairment, it

failed to analyze his complete disability picture. Moreover, the Board’s incomplete

analysis of the first step resulted in its failure to assess the second step, despite

evidence that Mr. Clapp experienced interference with work. See Appellant’s Br. at 8-

10; R-314-15; R-672; see also Yancy v. McDonald, 27 Vet.App. 484, 495 n. 5 (2016).

In order to establish that remand is warranted under Morgan, a veteran must

simply show that he or she has symptoms or complications related to a service-

connected disability, but which are not compensated by his or her assigned schedular

rating. See Morgan, 31 Vet.App. at 168. It is the Board’s duty to maximize benefits

based on the availability of schedular rating tools when those “schedular alternatives

for rating a disability are either raised by the claimant or reasonably raised by the

record.” See id. This Court’s recent decision in Bailey v. Wilkie, --Vet.App. --, 2021

WL 45679 (Vet. App. Jan. 6, 2021), reaffirmed the Board’s duty to maximize benefits

by considering schedular alternatives to compensate complications of a service-

connected disability. Similar to its holding in Long, the Court held that there must be

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some “causal or aggravative relationship” between the primary service-connected

disability and the disability for which a schedular alternative is sought. Bailey, 2021

WL 45679 at *9.

Such a relationship exists here. As discussed above, the Veteran’s acoustic

reflexes were noted during a VA hearing loss examination. R-670. And sensorineural

hearing loss causes reduced or absent acoustic reflexes. See Clark, Open Access Guide to

Audiology and Hearing Aids for Otolaryngologists, supra. Therefore, there exists a causal

relationship between the Veteran’s hearing loss and his abnormal acoustic reflexes.

See Bailey, at *9.

Had the Board found that the Veteran’s hearing loss rating did not adequately

contemplate his acoustic reflexes, it might have determined that they warranted a

separate rating under an alternative diagnostic code, pursuant to its duty to maximize

benefits. The Veteran’s abnormal acoustic reflexes were noted in the

“(Tympanometry) Findings” section of his examination. R-670. Tympanometry

measures the pressure, presence of fluid, and mobility in the middle ear. Claude

Laurent, “Tympanometry,” Open Access Guide to Audiology and Hearing Aids for

Otolaryngologists, https://vula.uct.ac.za/access/content/group/27b5cb1b-1b65-4280-

9437-a9898ddd4c40/Tympanometry.pdf (last accessed Feb. 22, 2021)2. These

2 For the Court’s convenience, a copy of this article is attached in the appendix.

6

measurements can evaluate otitis media, which is a compensable disability under 38

C.F.R. § 4.87, Diagnostic Code 6200. See id.

This Court’s holdings in Long and Morgan demonstrate that remand is required

because the Board failed to analyze the Veteran’s complete disability picture when it

did not determine whether his hearing loss rating contemplated his abnormal acoustic

reflexes. The Board needs to assess the Veteran’s entitlement to maximized

benefits—either via a schedular alternative or via extraschedular consideration—in the

first instance. See Wagner v. United States, 365 F.3d 1358, 1365 (Fed. Cir. 2004)

(“Where the effect of an error on the outcome of a proceeding is unquantifiable,

however, we will not speculate as to what the outcome might have been had the error

not occurred.”).

Respectfully submitted,

/s/Alec Saxe ALEC SAXE CHISHOLM CHISHOLM & KILPATRICK 321 S Main St #200 Providence, RI 02903 (401) 331-6300 Telephone (401) 421-3185 Facsimile Attorneys for Appellant

APPENDIX

OPEN ACCESS GUIDE TO AUDIOLOGY AND HEARING

AIDS FOR OTOLARYNGOLOGISTS

ACOUSTIC (STAPEDIUS) REFLEXES Jackie L. Clark

The acoustic reflex, also known as the

stapedius reflex refers to an involuntary

muscle contraction of the stapedius muscle

in response to a high-intensity sound sti-

mulus. Due to ease of administration and

information yielded, the acoustic reflex is

considered one of the most powerful

differential diagnostic audiological proce-

dures.

The acoustic reflex and the tympanogram

(see tympanometry chapter) are commonly

used to assess middle ear function and are

considered best practice. Each test yields

invaluable information based on the

delivery of acoustic energy (sound) to the

ear canal. Thanks to microprocessors, the

instruments used are now capable of rapid

middle ear function assessment (typically

<1min/ear).

Acoustic reflexes do not measure hearing

threshold. Rather, they measure reflected

energy which is a function of stapedius

muscle contraction; it allows one to indi-

rectly assess the middle ear, cochlea and

neural innervation of the stapedius muscle.

As the acoustic reflex is involuntary and

bilateral, it is replicable and provides

valuable diagnostic information when

comparing the amount of reflected energy

according to signal intensity, as well as the

presence of ipsilateral and bilateral acous-

tic reflexes.

Premise behind instrumentation

An acoustic stimulus is presented to the

external auditory canal; energy is transfer-

red from the ear canal through the middle

ear, some of which is reflected and some

absorbed by the tympanic membrane and

external ear structures.

The premise behind the immittance

instrumentation used to measure the

acoustic reflex is the ability to accurately

measure changes in reflected energy

occurring from stiffening of the tympanic

membrane as a result of contraction of the

stapedius muscle (For the premise behind

tympanometry see tympanometry chapter).

The amount of reflected and absorbed

energy varies depending on the admit-

tance/impedance (flow/resistance) of ener-

gy within the system and the complex

interaction between the ear structures.

The presence of reflexes within normal

intensity limits is consistent with normal

middle ear and brainstem function and

suggests that auditory sensitivity is not

significantly impaired. An elevated or ab-

sent acoustic reflex threshold is consistent

with a middle ear disorder, hearing loss in

the stimulated ear, and/or interruption of

neural innervation of the stapedius muscle.

Anatomy & Physiology

Neural mechanisms mediate the acoustic

reflex that results in involuntary stapedius

muscle contraction stiffening the stapes

within the middle ear. It is presumed that

the physiologic reason for the reflex is that

it serves as an inhibitory response to re-

duce the sound intensities reaching the in-

ner ear by as much as 20 dB evoked when

individuals vocalise (Møller, 2000).

As is illustrated in Figure 1, once a high

intensity auditory stimulus is initiated and

reaches the cochleae, neural impulses from

the auditory nerves (CN VIII) ascend from

both cochleae to each ipsilateral ventral

cochlear nucleus (VCN). From VCN the

reflex has two main neural pathways: one

passes from the VCN directly to the ipsi-

lateral facial motor nucleus (CN VII) that

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directly innervates the stapedius muscle

via the facial nerve and its stapedius

branch; the other passes from the VCN to

the superior olivary complex (SOC) before

the impulses cross at the brainstem to

innervate both ipsilateral and contralateral

facial motor nuclei.

Figure 1: Schematic of the acoustic reflex neural

pathways. CNVII (facial/seventh cranial nerve);

CNVIII (auditory/eighth cranial nerve); MNVII

(motor nucleus of seventh cranial nerve); SOC

(superior olivary complex); VCN (ventral cochlear

nucleus). Dashed lines represent the contralateral

pathway and solid lines represent ipsilateral path-

way of acoustic reflex

Contraction of the stapedius muscle

stiffens the middle ear ossicles and tilts the

stapes in the oval window of the cochlea;

this effectively decreases the vibrational

energy transmitted to the cochlea. Stape-

dius muscle contraction is clinically appa-

rent by a marked change in the impedance

properties of the middle ear.

It is important to realize that a bilateral

acoustic reflex occurs i.e. stimulating one

ear (ipsilateral ear) elicits an acoustic re-

flex in both the ipsilateral and contralateral

ears.

Acoustic Threshold

An acoustic reflex threshold is the lowest

intensity level at which an acoustic reflex

is elicited at each frequency for each ear.

Stapedius muscle contraction increases as

the stimulus intensity is increased; it is

therefore possible to determine acoustic

reflex thresholds by incrementally increas-

ing the stimulus by 5 dB steps, beginning

at 80 dB HL, until a contraction occurs

(Figure 2). With a normally functioning

middle ear and cochlea, an acoustic reflex

is elicited contralaterally at four frequen-

cies (500, 1000, 2000, 4000 Hz), and

ipsilaterally at two frequencies (1000, 2000

Hz) when stimulus intensities of 85-90 dB

HL (hearing level) are delivered to the ear

canal.

Figure 2: Example (right ear) of acoustic reflex

threshold obtained from an immittance instrument.

Results shown would indicate 85 & 90 dB HL

thresholds for 1000 and 2000 Hz respectively,

which would be expected for a normal ear

In a normal ear, after an initial contraction

the strength increases with each sequential

increase of signal intensity until a plateau

is reached. Threshold is defined as the

lowest acoustic stimulus intensity elicited

with a deflection magnitude of at least

0.03ml. As seen in the magnitude of

deflections in Figure 2, thresholds for both

frequencies assessed clearly fall within the

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criteria of at least 0.03ml deflection. To

identify a threshold it is advisable to

confirm the magnitude of the deflection

with a repeat presentation. Once a thres-

hold has been established at one frequency,

the intensity is recorded, and the other

frequencies are then assessed. During

quick screening it is not unusual to assess

an acoustic reflex threshold at only one

frequency and a single set intensity (~95 or

100 dB HL. An ipsilateral acoustic reflex

threshold tends to be attained at a slightly

lower intensity stimulus than an acoustic

reflex threshold elicited by a contralateral

stimulus.

Factors affecting acoustic reflexes

• Ipsilateral conductive hearing loss:

Anything that obstructs transmission of

a sound signal to the cochlea in the

stimulated ear results in reduced or

absent contraction of the stapedius

muscles. Middle ear disorders therefore

easily mask an acoustic reflex. Forty

percent of patients with conductive

hearing loss of >20 dB HL do not have

an acoustic reflex. Once conductive

hearing loss reaches 40 dB HL, about

80% of patients do not have a reflex

(Jerger, Anthony, Jerger and Mauldin,

1974)

• Ipsilateral sensorineural hearing loss:

This may obstruct transmission of a

signal beyond the cochlea of the stimu-

lated ear and usually causes reduced or

absent contraction of the stapedius

muscles. However, because of recruit-

ment of loudness in cochlear sensori-

neural hearing loss, acoustic reflexes

may occur even within the expected

normal or partially elevated intensity

range in the presence of mild or

moderate-to-severe sensorineural hear-

ing loss.

• Stapes fixation: The stapes footplate is

more-or-less fixed to the surrounding

bone with otosclerosis (and sometimes

with tympanosclerosis). This may in-

terfere with the acoustic reflex in two

ways: it causes a conductive hearing

loss; and reduced mobility of the stapes

prevents stiffening of the tympanic

membrane when the stapedius muscle

contracts

• Ossicular disarticulation: As with

otosclerosis, it causes a conductive

hearing loss, and if located lateral to

the stapes, prevents stiffening of the

ossicles and tympanic membrane when

the stapedius muscle contracts

• Middle ear effusion: This causes a

conductive hearing loss, and reduces

compliance of the tympanic membrane

and middle ear structures and may

mask the presence of an acoustic reflex

• Tympanic membrane perforation:

This causes a conductive hearing loss.

Furthermore, due to the perforation,

changes in compliance caused by con-

traction of the stapedius muscle cannot

be measured

• Negative/abnormal middle ear pres-

sure: To maximize the likelihood that a

reflex will be detected, the pressure on

either side of the tympanic membrane

has to be equal for the tympanic mem-

brane to be at or near the point of

maximum compliance (see tympano-

metry chapter for further explanation).

This necessitates one to match the peak

pressure of the tympanogram to the

actual middle ear pressure so that valid

acoustic reflex threshold values may be

obtained

• Facial nerve dysfunction: The stape-

dius muscle is innervated by the facial

nerve. Contraction of the stapedius

muscle has to occur for both ipsi- and

contralateral acoustic reflexes.

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Interpretation of acoustic reflexes

Acoustic reflexes may be reported as:

• Ipsilateral: Reflex recorded in ear to

which auditory stimulus is presented

• Contralateral: Reflex recorded in ear

contralateral to which auditory stimu-

lus is presented

• Partially present: Reflex present at

some frequencies and absent at others

• Elevated threshold: Reflex thresholds

elicited >100 dB HL

• Absent reflex: No reflex elicited

Partial or elevated reflex thresholds may

indicate the presence of hearing loss at the

frequencies where they are specifically

absent.

Absent reflexes have also been observed in

individuals with normal or near-normal

hearing, which may then indicate middle

ear disease or neurological involvement of

the 8th cranial nerve, such as in pontine

angle tumours and auditory neuropathy

(see below), or neurological involvement

of the 7th cranial nerve. With facial nerve

paralysis, the absence of acoustic reflexes

in the presence of normal middle ear

function suggests a lesion in the neural

pathway proximal to the stapedius nerve,

whereas the presence of an acoustic reflex

in patients with facial nerve paralysis sug-

gests that the lesion is distal to the origin

of the nerve. A very small percentage of

people will have normal auditory sensiti-

vity and absent acoustic reflexes across all

frequencies without other identifiable pa-

thology.

Interruption of Neural Transmission

As is illustrated in Figure 1, both ipsi- and

contralateral acoustic reflex pathways pass

through the SOC of the lower brainstem

before proceeding to the facial nerve. Con-

sequently, brainstem lesions can interrupt

transduction of neural impulses resulting in

an absence or reduction of acoustic reflex-

es elicited with ipsi- and/or contralateral

stimulation.

Table 1: Six patterns of acoustic reflex thresholds

based on presence or absence of each ipsilateral

and contralateral reflexes, based on Jerger &

Jerger (1977). This example depicts left sided

involvement.

Table 1 is a system to classify acoustic

reflex thresholds according to the presence

or absence of ipsilateral and contralateral

reflexes; it has great diagnostic value

(Jerger and Jerger, 1977). The system

categorises acoustic reflex thresholds into

six distinct patterns based on presence or

absence of ipsilateral and contralateral

reflexes. Cochlear, CN VII, CN VIII, or

brainstem sites of lesion are represented by

vertical, diagonal, inverted L-shape, hori-

zontal, and unibox patterns.

Reflex Pattern

Reflex Probe Right

Probe Left

Description Interpretation

Normal Contra

Normal Normal Ipsi

Vertical

Contra Abnormal whenever

probe in

affected ear

Mild middle ear

disorder (left ear)

Ipsi

CN VII (facial

nerve) disorder (left side)

Diagonal

Contra Abnormal

with sound to the

affected ear

Right nerve disorder (left side)

Ipsi Severe cochlear

loss (left ear)

Inverted L-shape

Contra

Crossed stimulation

abnormal in

both ears; uncrossed

stimulation

abnormal in affected ear

Unilateral middle

ear disorder (left ear)

Ipsi

Intra-axial

brainstem disorder

eccentric to one side (left side)

Horizon-

tal

Contra

Abnormal

to crossed stimulation

on both

ears

Extra-axial and/or intra-axial

brainstem disorder Ipsi

Unibox

Contra

Abnormal

with sound

to affected ear on cros-

sed stimu-

lation only

Extra-axial and/or

intra-axial

brainstem disorder Ipsi

Red box = Absent reflex

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Wideband reflectance technique

This is a newer measuring technique (Fee-

ney, Douglas and Sanford, 2004) to assess

acoustic stapedius reflex thresholds by

using complex wideband (125 - 10,000 Hz

range) reflectance with a stimulus

resembling “chirplike” sounds instead of a

single probe tone frequency. The wideband

reflectance technique reportedly yields

more reliable results than the single probe

tone technique, and appears to hold

promise as a clinical procedure for

measuring acoustic reflexes for normal-

hearing subjects who fail to demonstrate

reflexes with the standard clinical proce-

dure.

Acoustic Reflex Decay

This is another powerful differential diag-

nostic test and has a high degree of sensi-

tivity to identify retrocochlear pathology

due to e.g. tumours of the cerebellopontine

angle. However magnetic resonance

imaging is considered the examination of

choice to identify retrocochlear pathology.

In order to examine acoustic reflex decay,

an extended duration signal (>10 seconds)

is presented, using low-frequency stimuli

(500, 1000 and 2000 Hz) contralateral to

the probe (test) ear. Muscle contraction of

the acoustic reflex is sustained in the

normal ear at maximum or near-maximum

amplitude throughout the entire duration of

the stimulus.

The standard procedure is to present the

stimulus contralaterally at 10 dB SL

(threshold of acoustic reflex of test ear), or

between 90 and 105 dB HL for 10 seconds.

Abnormal reflex decay is evidenced by an

inability of the stapedius muscle to

maintain full contraction (amplitude) for

the duration of the stimulus signal. When

reflex decay occurs within 5 seconds or at

frequencies less than 1000 Hz, it is

suggestive of 8th nerve dysfunction.

Figure 4: (A) Normal and (B) abnormal

findings on acoustic reflex decay test

Concerns have recently been raised about

causing temporary or permanent auditory

threshold shifts as a consequence of

presenting acoustic stimuli for extended

periods of time at exceptionally high

intensities. For this reason, clinicians are

cautioned to administer acoustic reflex

decay tests judiciously and never to exceed

105 dB HL presentation levels at any

frequency.

Caveats with acoustic reflex measures

It is important to recognize that there are

some limitations with acoustic reflex

measures.

• Correct probe placement may become

challenging for those patients with

external auditory meatal openings

being larger than the available probe

tips (as seen in the elderly)

• Conversely, the very small canal

openings (as seen in infants) may not

be compatible with any of the available

probes

• In addition, care must be taken that the

patient is capable of sitting quietly.

Any jaw movements that occur during

A.

B.

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coughing, crying, talking, swallowing,

or jaw clenching will result in artifact

and provide fallacious results.

• Reportedly, collapsed canals due to

placement of supra-aural headphones

on the pinna of the contralateral ear

may also result in fallacious findings

Concluding remarks

Despite the few limitations with acoustic

reflex threshold testing, the advantages far

overshadow those limitations. Although

few new discoveries have been made with

acoustic reflex threshold testing, it is still

considered one of the most powerful

differential diagnostic tools that should be

within the standard battery of tests

attempted with all patients. Within a very

brief time period it allows one to identify

middle ear pathology; cochlear or retro-

cochlear pathology; evaluate neural trans-

mission efficiency; while providing a

general indicator of magnitude of hearing

loss.

References

• Feeney MP, Douglas HK, & Sanford

CA (2004). Wideband reflectance

measures of the ipsilateral acoustic

stapedium reflex threshold. Ear

Hearing, 25: 421-30

• Jerger S & Jerger J (1977). Diagnostic

value of cross vs. uncrossed acoustic

reflexes: Eighth nerve and brain stem

disorders. Arch Otolaryngol, 103: 445-

53

• Jerger J, Anthony L, Jerger S, and

Mauldin L. (1974). Studies in impe-

dance audiometry. III. Middle ear dis-

orders. Arch Otolaryngol, 99: 165-71

• Møller A. (2000). Hearing: Its physio-

logy and pathophysiology. Academic

Press.181-90

Author

Jackie L. Clark, PhD/CCC-A; F-AAA

Clinical Associate Professor

School of Behavioral & Brain Sciences,

UT Dallas/Callier Center

Research Scholar; Univ Witwatersrand,

Johannesburg, South Africa

Managing Editor International Journal of

Audiology

jclark@utdallas.edu

http://www.utdallas.edu/~jclark

Editors

Claude Laurent, MD, PhD

Professor in ENT

ENT Unit, Department of Clinical Science

University of Umeå

Umeå, Sweden

claude.laurent@ent.umu.se

De Wet Swanepoel PhD

Associate Professor

Department of Communication Pathology

University of Pretoria

Pretoria, South Africa

dewet.swanepoel@up.ac.za

Johan Fagan MBChB, FCS(ORL), MMed

Professor and Chairman

Division of Otolaryngology

University of Cape Town

Cape Town, South Africa

johannes.fagan@uct.ac.za

OPEN ACCESS GUIDE TO

AUDIOLOGY & HEARING AIDS

FOR OTOLARYNGOLOGISTS

http://www.entdev.uct.ac.za

Open Access Guide to Audiology & Hearing Aids for

Otolaryngologists by Johan Fagan (Editor)

johannes.fagan@uct.ac.za is licensed under a Creative

Commons Attribution - Non-Commercial 3.0 Unported

License

OPEN ACCESS GUIDE TO AUDIOLOGY AND HEARING

AIDS FOR OTOLARYNGOLOGISTS

TYMPANOMETRY Claude Laurent

Tympanometry is not a test of a patient’s

hearing. It objectively provides an indi-

cation of the status of the middle ear and

the mobility of the ear drum. It does this

by measuring the degree to which sound

transmission through the eardrum and

middle ear is modified when there is a

change in air pressure applied to the

eardrum. Tympanometry provides useful

information about:

• Pressure in the middle ear space

• Presence of fluid in the middle ear

space

• Mobility of the middle ear system

• Volume of the ear canal

Indications for tympanometry

Not all patients with ear pathology require

tympanometry.

1. Suspected middle ear effusion (OME)

Tympanometry is recommended main-ly to

evaluate suspected OME/secre-tory otitis

media (SOM). It is done in conjunction

with information obtained from the history,

appearance and mobility of the eardrum.

Otoscopic and otomicroscopic evidence of

OME may include yellowness, redness,

hypervascularity, bulging or retraction of

the ear-drum, visible air-fluid levels, and

diminished mobility on pneumatic

otoscopy. Otomicroscopic and pneu-matic

otoscopy have been reported to have a high

accuracy for diagnosing OME in children1.

Yet it is uncertain what degree of training

and expertise is required to obtain high

accuracy 1. Tympanometry however requi-

res minimal training, is quick and simple to

perform, and provides objective

information.

2. Patency of tympanostomy/ventilation

tubes/grommets

3. Whether there is a perforation in the

eardrum

4. Mobility of the eardrum

5. Mobility of the ossicular chain

Principles of tympanometry

Tympanometry provides a measurement

of impedance of the middle ear system

including the eardrum. It allows one to

determine how much resistance the

middle ear system renders to passage of

sound to the inner ear.

Impedance of the middle ear is increased

if:

• The middle ear is filled with fluid,

especially with thick secretion

• There is increased stiffness of the

ossicular chain, for example when

there is a fixation of the malleus or

stapes (hammer or stirrup). In oto-

sclerosis the stapes becomes progress-

sively fixed in the oval window; due to

this the impedance increases in later

stages of the disease.

Impedance of the middle ear is reduced

if:

• The eardrum is overly mobile or flac-

cid

• There is a disruption of the ossicular

chain

How does tympanometry work?

A constant low-pitch sound (~220Hz) is

introduced into the ear through an opening

in the head (tip) of the tympanometer that

is tightly introduced into the external ear

canal using a plastic or foam rubber collar

(Figure 1). In the same tip there is another

opening that leads to a microphone that

continuously registers the sound reflected

2

from the ear drum; a third opening in the

tip is connected to an air pump that can

change the air pressure applied to the

eardrum from positive to low pressures.

Figure 1: Tympanometer probe tip in the

ear canal

Between the tip of the tympanometer and

the eardrum a small “chamber” is thus

created in the deep ear canal in which the

sound level is constantly measured while

the pump alters the air pressure in this

“chamber”. The least amount of sound is

reflected when the eardrum is in a normal

and relaxed position since most of the

sound passes through the eardrum and

middle ear. When the eardrum is however

pressed outwards or retracted inwards it

becomes stiffer and more sound is

reflected back from its surface into the

“chamber”.

Tympanogram

The tympanometer displays the reflected

sound in the ear canal “chamber” relative

to changes in stiffness of the eardrum

(achieved by changes in ear canal pressure

produced by the tympanometer) as a

tympanogram. The tympanogram curve is

plotted upside-down - the inverted reflec-

ted sound level is called “compliance”.

The pressure is expressed along the X-axis

in deca-Pascal (daPa) and the compliance

along the Y-axis in “volume of air in cm3”

required putting the system “under

pressure”. The resulting curve is called a

tympanogram (Figure 2). Tympanometry

is thus an acoustic method that indirectly

measures the compliance of the tympanic

membrane and middle ear.

Figure 2: A: Normal type-A tympano-

grams; AD: hypermobile; AS: restricted

Types of tympanogram readings

The reflected sound has its lowest value

when the eardrum is in its most relaxed

and normal position. Tympanogram

tracings are classified as type A (normal),

type B (flat, clearly abnormal indicating

fluid in the middle ear or a perforation), or

type C (indicating a significantly negative

pressure in the middle ear (< -200 daPa).

(Figure 3)

What can “tympanometry” tell us?

1. Pressure in the middle ear: A

negative pressure of < -200 daPa

(Type C curve) is considered patho-

logic (Figure 3). To have an idea what

this means, you may think of it as the

pressure of a 20cm column of water.

2. Is the middle ear fluid-filled? One

then sees a flat tympanogram (Type

Bcurve) with a normal ear canal

volume (Figure 3)

3

Figure 3: Typical tympanogram tracings

3. If the eardrum has a perforation or an

open tympanostomy/ventilation tube

/grommet one also sees a flat tym-

panogram (Type B curve), but with a

big ear canal volume (>3cm3)

4. If the eardrum or middle ear system is

overly mobile, one then obtains a high

tympanogram curve (Type-AD) with

high compliance of >1.5cm3 (Figures

2 and 3)

5. If the eardrum or middle ear system

has restricted mobility, one sees a very

low tympanogram curve (Type-AS)

with a small volume, (low compliance

<0.3cm3) (Figures 2 and 3)

6. The stapedial reflex measurement

allows one to assess facial nerve

function in the examined ear and

mobility of the ossicular chain (inclu-

ding the stapes) in the same ear. Note

that in otosclerosis the stapedial re-

flexes are already changed or absent at

an early stage of the disease even

when the shape of the tympanogram is

still fairly normal

How does one perform tympanometry?

It only takes a few seconds to record a

tympanogram. Figures 4 & 5 show typical

4

examples of tympanometers. Tympanome-

ters found in developing countries are

usually automatic screening tympano-

meters that automatically start to record

when the tip is tightly introduced into the

ear canal to create an airtight seal; the

pump that alters the pressure in the ear

canal is automatically activated when the

tip of the instrument is tightly fitted into

the ear. It is important that it is kept tightly

fitted during the whole recording process

to ensure the airtight seal is not interrupted

during testing. The tympanometer

produces a tympanometric curve that

represents the compliance of the middle

ear system, including the ear drum, as a

function of the pressure applied to the

eardrum (Figure 2). From the shape of the

curve or the figures, one can also read the

volume between the tip of the

tympanometer and the eardrum and

determine the compliance of the middle ear

system. Many screening tympanometers

also have a function to automatically

measure the ipsilateral (same side)

stapedial reflex at 1-3 supraliminal sound

stimuli (90-100 dB).

Advantages of tympanometry

It is an objective audiometric method

because it does not depend on information

that the patient gives us but rather

measures something without subjective

feedback from the patient. The patient then

becomes the object and does not have to

say whether he or she has heard or

experienced anything.

It also does not require clinical expertise

to diagnose middle ear effusions.

Pitfalls of tympanometry

• An undiagnosed, perforated eardrum or

an inadequate seal between the tip of

the tympanometer and the ear canal

will produce a Type B tympanogram

which may be misconstrued as a

middle ear effusion

• Diagnosis of a middle ear effusion per

se is not an indication for insertion of

ventilation tubes; it must be

accompanied by clinically significant

and persistent conductive hearing loss

• Although a conventional probe tone of

220 Hz is sufficient for tympanometry

in almost all populations it is not

effective for evaluating infants younger

than 7 months. For these young infants

a higher frequency probe tone of 1000

Hz is recommended.

Figure 4: Microtympanometer with

printout of tympanogram on right side

Figure 5: Tympanometer

5

References

1. Takata GS et al. Evidence assessment

of the accuracy of methods of

diagnosing middle ear effusion in

children with otitis media with

effusion. Pediatrics. 2003;112(6 Pt

1):1379-87

Author and Editor

Claude Laurent, MD, PhD

Professor in ENT

ENT Unit

Department of Clinical Science

University of Umeå

Umeå

Sweden

claude.laurent@ent.umu.se

Editor

De Wet Swanepoel PhD

Associate Professor

Department of Communication Pathology

University of Pretoria

Pretoria

South Africa

dewet.swanepoel@up.ac.za

Editor

Johan Fagan MBChB, FCS(ORL), MMed

Professor and Chairman

Division of Otolaryngology

University of Cape Town

Cape Town

South Africa

johannes.fagan@uct.ac.za

OPEN ACCESS GUIDE TO

AUDIOLOGY & HEARING AIDS

FOR OTOLARYNGOLOGISTS www.entdev.uct.ac.za

The Open Access Atlas of Otolaryngology, Head & Neck Operative Surgery by Johan Fagan (Editor) johannes.fagan@uct.ac.za is licensed under a Creative Commons Attribution - Non-Commercial 3.0 Unported License