Impedance Audiometry in Serous Otitis Media Daniel J. Orchik, PhD;

\s=b\ The relationship between the results of impedance audiometry and middle ear effusion in serous otitis media was examined in 76 ears immediately prior to myringotomy. Tympanometry and acoustic reflex threshold showed the highest correlation with the operative findings relative to middle ear effusion. The combination of tympanometry and acoustic reflex threshold was superior to the use of either component alone. Results are discussed in terms of clinical implications with specific consideration of hearing screen-

ing programs. (Arch Otolaryngol 104:409-412, 1978)

The

most

of hearing preschool- and levels is serous

common cause

loss in children of

elementary school-age

otitis media.1 In recent years, impe¬ dance audiometry has been advocated as a more efficient means of screen¬ ing for serous otitis media in children when compared with conventional pure-tone methods.-'1 In most applica¬ tions of impedance audiometry to screening, tympanometry has been the major component of the hearing conservation program designed to detect serous otitis media.1"' Assessing the validity of impedance screening has traditionally followed one of two approaches. Either the findings of impedance audiometry are compared with otoscopie findings,1 or the impedance results are compared with postoperative findings at myrin-

Accepted

for publication Feb 29, 1978. From the Department of Audiology and Speech Pathology, Memphis State University (Dr Orchik), and the East Texas Rehabilitation Center, Kilgore (Ms Morff). Dr Dunn is in private practice in Denton, Tex. Reprint requests to Department of Audiology and Speech Pathology, Memphis State University, 807 Jefferson Ave, Memphis, TN 38105 (Dr

Orchik).

Rosemary Morff, MS; James

W.

gotomy.- Recent evidence suggests that agreement between tympanome¬ try and otoscopy is not as strong as

thought.6 When postoperative data have been employed, the results of tympanome¬ try are usually evaluated on the basis of the ability to predict the presence

Dunn, MD months to 14 years, with

absence of effusion in the middle ear.-7-9 Although the presence or absence of effusion is not the only clinically significant finding from the viewpoint of the otolaryngologist, it is a relatively objective finding when compared with routine otoscopie ex¬ amination. The relationship between the re¬ sults of tympanometry and the pres¬ ence of middle ear effusion has been examined by a number of research¬ ers.-81" Although certain tympano¬ metric types, ie, type as described by Jerger et al," have been shown to indicate a high probability of middle sufficient variability ear effusion, exists to suggest that single tympa¬ nometric screening may not be the most efficient means of predicting middle ear effusion common to serous otitis media.1"12 Our investigation was designed to assess whether any combination of components in the impedance audiom¬

etry

static

test

battery (tympanometry,

compliance, acoustic reflex test¬ ing) might prove to be a better indica¬ tor of significant middle ear effusion. If the sensitivity could be so en¬ hanced, the efficiency of impedance screening might be likewise im¬ proved. METHOD

Subjects sample for this investigation includ¬ ears of patients who underwent myringotomy for suspected serous otitis media. Subjects ranged in age from 6 The ed 76

of 4Vè

Experimental Procedure

once

or

a mean

years.

Each subject was brought to the operat¬ ing room area approximately 30 minutes prior to surgery. The patient's transport bed was placed in a position adjacent to a cart that contained

an

electroacoustic

impedance bridge (Madsen 70-72), which was used to gather the impedance data. The following information was obtained for each ear: 1. A tympanogram was plotted from + 200 to -400 mm/ , in 100 mm/H.,0 steps, including the point of maximum compliance. In addition, the points at ±50 mm/ , , in reference to the point of maximum compliance, were plotted. 2. The measurement of static com¬ pliance was obtained for the middle ear. 3. The acoustic reflex threshold was examined at 500 through 4,000 Hz. Tympanograms were classified as either type A, B, or C since the use of these

symbols was thought to represent an easilyrecognized classification system.11 In addi¬

tion, type C tympanograms were further subdivided into three categories on the basis of the magnitude of negative pres¬ sure. A C, classification was applied to

whose point of maximum within the negative pres¬ sure range of -100 to -150 mm/H,0. The point of maximum compliance for a C2 tympanogram fell between -151 and -200 mm/H.,0. Those tympanograms with a point of maxmium compliance greater than -200 mm/rLO were classified as C3 curves. In this manner, tympanograms could be rated on a five-point scale from normal through increasing abnormality. The type A indicated normal function while a type represented the opposite extreme. Types C,, C2, and C, described the intermediate points on the scale. Static compliance was recorded in cubic centimeters by subtracting the volume measure that was obtained with a positive pressure of 200 mm/H.,0 from the volume measure that was obtained at the point of maximum compliance." The acoustic reflex those

curves

compliance fell

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threshold was taken at the lowest level in decibels of the hearing threshold level (HTL) (ANSI-1969), where a consistent deflection of the balance meter could be observed. For the purpose of this analysis, acoustic reflex thresholds were recorded for the probe ear so that they could be

analyzed with the tympanometric and stat¬ ic compliance data for the same ear. The patient was then taken to the oper¬ ating room where the myringotomy was performed. The surgeon (J.W.D.) had no prior knowledge of the impedance data. During the surgery, data relative to the status of effusion in the middle

displays the

ears

then

subjected

No effusion or an insignificant was found in 37 ears. Twentyfour of those ears (65%) showed type A tympanograms, 11 ears (30%) showed type C curves, and two ears (5%) showed type tympanograms. As noted earlier, the 26 type C tympanograms were further differenamount

Table 1— Correlation Coefficients for Tympanometry, Static Compliance, Acoustic Reflex Threshold, and Status of Effusion in Middle Ear at

ear were

Myringotomy Reflex

Threshold, Hz

Middle Ear Effusion .66" -.37* .61* .62* .62* .52*

Static

Variable

Compliance

Tympanogram Static compliance

500 .39s -.11

-.44*

Significant

2,000

1,000 42« 91*

-

4,000 38s

.45* .13 .91s .95*

12

Reflex threshold, 500 Hz Reflex threshold, 1,000 Hz Reflex threshold, 2,000 Hz Reflex threshold, 4,000 Hz Middle ear effusion

10 48:!

51 ' 54 s

at the .01 level.

Table 2—Status of Effusion in Middle Ear

as

Function of

Tympanogram Type

No. (%) of Ears

Tympanogram Type

previous investigation." were

15 ears (38%) were type C tympanograms, and three ears (8%) were type A tympanograms.

to tym¬ amount of

fluid present in the middle ear. With the use of the designations of "moderate" and "impacted" as indica¬ tive of significantly abnormal find¬ ings at myringotomy," 39 ears dis¬ played significant amounts of middle ear effusion. Twenty-one (54%) of those with significant fluid exhibited type tympanograms. Of those

recorded by a second observer, as noted by the operating physician. The presence or absence of effusion was rated by the operating physician on a four-point scale as none, minimal, moder¬ ate, or impaction. A rating of no effusion indicated that the middle ear was dry on examination after myringotomy, whereas a rating of impaction indicated that the middle ear space was completely filled with effusion. The ratings of minimal and moderate were somewhat more subjective but were used to establish a boundary for significant effusion. A rating of minimal was employed to indicate an ear where a very slight amount of fluid was found, while a rating of moderate was used to indicate an ear with a significant amount of effusion but some remaining air space in the middle ear. The operating physician was satisfied with this four-point-rating scale since it provided a means of differen¬ tiating to a somewhat greater degree the status of effusion in the middle ear. The same rating scale had been used in a

The data

remaining,

according

type and the

panogram

Insignificant

Significant

Effusion

Effusion

None

Minimal

14(52) 5(19) 2(9)

10(37) 6(23)

Moderate

Total 27 26 23

Impacted 3(11) 11 (42) 18(78)

4(15) 3(13)

to a

computer analysis that yielded Pearson's

Table 3.—Status of Effusion

multiple correlations (R's) between components of the impedance battery and the status of middle ear effusion at myrin¬ r's and

Function of Magnitude of in Middle Ear

(%)

No.

gotomy.

C3

*C, =

5(56)

Moderate

3(33) 3(23)

negative pressure of 100 to 150 negative pressure of 200 mm H20. =

as

Significant

Minimal

None

C,

mm

Negative Pressure

of Ears

Insignificant Effusion

Tympanogram Type*

RESULTS Tympanometry and Middle Ear Effusion

Of the 76 ears that were examined, 55 were found to have fluid present in the middle ear at myringotomy. Of these, 32 ears were impacted, and seven ears were judged to have moderate amounts of fluid in the middle ear. The remaining 16 ears displayed minimal amounts of middle ear effusion. As shown in Table 1, a significant correlation (r .66, < .01) was found between the tym¬ panogram type and the amount of effusion in the middle ear. Table 2

as

2(15) 2(50)

H„0; C,

negative

Effusion

Impacted 1(11) 8(62) 2(50)

pressure of 151 to 200

mm

Table 4.—Status of Middle Ear Effusion Function of Measured Static Compliance No. of Ears

Insignificant Effusion

=

Static Compliance Normal (> 0.28 cc) Reduced (< 0.28 cc)

None

Minimal

12

10

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Significant Effusion Moderate

Impacted 29

H20;

tiated into three categories according to the amount of negative middle ear air pressure. Table 3 presents a break¬ down of the type C tympanograms as a function of the amount of effusion present in the middle ear at myringo¬

tomy.

Fifteen type C tympanograms dis¬ played significant amounts of effu¬ sion. Of these, one ear (6%) was a C, curve, ten

and four

(67%) were C2 curves, (27%) were C, curves.

ears

ears

Static Compliance and Middle Ear Effusion A small yet significant negative correlation was shown to exist be¬ tween the static compliance measure¬ ment and the amount of middle ear effusion, ie, as the amount of effusion increased, static compliance decreased (r -.37, < .01). Table 4 presents the relationship between the static compliance value and the amount of effusion present in the middle ear. It is apparent that the relationship is not as strong as that found between the results of tympanometry and the amount of middle ear effusion. As shown in Table 4, of the 76 ears that were examined, 19 had static compliance values within the normal range (0.28 to 1.72 cc), as specified by Brooks.14 Of these, 15 (78%) exhibited insignificant effusion at myringoto¬ my. However, significant effusion was discovered in four (21%) of the ears with normal static compliance. Reduced static compliance values (

Impedance audiometry in serous otitis media.

Impedance Audiometry in Serous Otitis Media Daniel J. Orchik, PhD; \s=b\ The relationship between the results of impedance audiometry and middle ear...
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