Effects of consecutive wideband tympanometry trials on energy absorbance measures of the middle ear

Improving the Differential Diagnosis of Otitis Media With Effusion Using Wideband Acoustic Immittance

OBJECTIVES

The objective of this work is to determine whether there is a systematic effect of middle ear effusion volume on wideband acoustic immittance in children with surgically confirmed otitis media with effusion.

DESIGN

Wideband acoustic immittance was measured in 49 ears from children (9 months to 11 years) who had a diagnosis of otitis media with effusion and compared to 14 ears from children (10 months to 10 years) without a recent history of otitis media. For children with otitis media with effusion, wideband acoustic immittance testing took place in the child's preoperative waiting room before surgical placement of tympanostomy tubes. Testing was completed in a pressurized condition (wideband tympanometry) for all ears as well as in an ambient condition in a subset of ears. Intraoperative findings regarding effusion volume were reported by the surgeons immediately before tube placement and confirmed following myringotomy. This classified the volume of effusion as compared to middle ear volume categorically as either full, partial, or clear of effusion. The type of wideband acoustic immittance explored in this work was absorbance. Absorbance responses were grouped based on effusion volume into one of four groups: full effusions, partial effusions, ears clear of effusion at the time of surgery, and normal control ears. Standard tympanometry was also completed on all ears.

RESULTS

Absorbance is systematically reduced as the volume of the middle ear effusion increases. This reduction is present at most frequencies but is greatest in the frequency range from 1 to 5 kHz. A multivariate logistic regression approach was utilized to classify ears based on effusion volume. The regression approach classified ears as effusion present (full and partial ears) or absent (clear ears and normal control ears) with 100% accuracy, ears with effusion present as either partial or full with 100% accuracy, and ears without effusion as either normal control ears or ears clear of effusion with 75% accuracy. Regression performance was also explored when the dataset was split into a training set (70% of the data) and a validation test set (30% of the data) to simulate how this approach would perform on unseen data in a clinical setting. Accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve are reported. Overall, this approach demonstrates high sensitivity and specificity for classifying ears as effusion being present or absent and as present effusions being full or partial with areas under the curve ranging from 1 to 0.944. Despite the lack of effusion present in both clear ears and normal control ears, this approach was able to distinguish between these ears, but with a more moderate sensitivity and specificity. No systematic effect of effusion volume was found on standard tympanometry.

CONCLUSIONS

Wideband acoustic immittance, and more specifically, absorbance, is a strong and sensitive indicator of the volume of a middle ear effusion in children with otitis media with effusion.

Wideband acoustic immitance - Absorbance measurements in ears after stapes surgery

OBJECTIVES

The study aimed to thoroughly assess absorbance in ears after stapes surgery (stapedotomy/stapedectomy) and how stapes surgery affects wideband acoustic immittance (WAI) metrics.

METHODS

Eighty-three otosclerotic ears were analyzed pre- and postoperatively. The analysis comprised: air-bone gap (ABG) and WAI which included absorbance measurements, resonance frequency assessment, low frequency tympanometry and metrics derived from these measures.

RESULTS

Absorbance after stapes surgery changed considerably compared to otosclerotic ears before surgery and also differed from normal ears. Absorbance after stapes surgery revealed two significantly different plot types: single-low-frequency-peak absorbance and two-peaks absorbance. Stapes surgery reduced resonance frequency in majority of operated ears and increased static compliance in low frequency tympanometry. Static compliance difference was directly proportional to ABG improvement at low frequencies. Postoperative ABG at 250 Hz and 500 Hz was most commonly correlated with postoperative WAI parameters. ABG improvement at 3000 Hz and 4000 Hz was directly proportional to absorbance difference at ~3000 Hz and 4000 Hz. It influenced the width of the postoperative absorbance by shifting both sides of the plot (negative values shift the points of the plot toward lower frequencies) with the correlation being more pronounced in postoperative two-peaks absorbance type ears.

CONCLUSIONS

Absorbance by itself is not sufficient for assessment of changes to middle function following stapes surgery, and should be complemented with other measures. WAI measurements including absorbance, resonance frequency assessment, low frequency tympanometry, and metrics derived from these measures combined with air-bone gap provide insight into mechano-acoustic changes in the middle-ear system as a result of stapes surgery.

Wideband tympanometry and absorbance measurements in otosclerotic ears

OBJECTIVES

This study aimed to assess absorbance using a thorough analysis of individual points of its plot in ears with intraoperatively confirmed otosclerosis. To the best of our knowledge, until recently no analyses have been performed that concerned the shape of an absorbance plot and a detailed analysis of its individual points. This study is the first to undertake such an issue.

METHODS

A total of 77 otosclerotic ears were included in the study. Pure tone audiometry, low frequency tympanometry, and wide band tympanometry including absorbance were performed preoperatively. The average patients' age in the group was 43.49 years (standard deviation = 10.44). Individual points of absorbance plot were thoroughly analyzed. Parameters were analyzed, such as resonance frequency; number of peaks; maximum absorbance (Height); and plot Width at the following Heights: 1/3, 1/2, and 2/3 (Width1/3, Width1/2, Width2/3, respectively), as well as associated absorbance parameters and frequencies.

RESULTS

Data analysis revealed five different types of absorbance plots. Numerous statistically significant differences regarding the parameters of individual points of the plots were found among the distinguished types.

CONCLUSIONS

There are five types of absorbance plots in otosclerotic ears: type I, characterized by two distinct peaks, closely resembling normal ear absorbance plot; type II with a single distinct peak reaching high values of absorbance; type III with reduced absorbance for frequencies <2000 Hz; type IV with reduced absorbance for all frequencies; and type V with reduced absorbance for frequencies >2000 Hz. Absorbance measurements may play an important role in the diagnostics of otosclerosis; however, further research is necessary in this area.

LEVELS OF EVIDENCE

4 Laryngoscope, 129:E365-E376, 2019.

Wideband Acoustic Immittance: Normative Study and Test-Retest Reliability of Tympanometric Measurements in Adults

PURPOSE

The purpose of this study was to present normative data of tympanometric measurements of wideband acoustic immittance and to characterize wideband tympanograms.

METHOD

Data were collected in 84 young adults with strictly defined normal hearing and middle ear status. Energy absorbance (EA) was measured using clicks for 1/12-octave frequencies (0.236 to 8 kHz), with the ear canal air pressure systematically varied (+200 to -300 daPa). In 40 ears, 7 consecutive trials and a trial of clinical 226-Hz acoustic admittance (Ya) tympanometry followed. A cavity test was also conducted.

RESULTS

From the wideband EA tympanogram, several EA spectrums and EA tympanograms were derived. Descriptive statistics were performed, and population parameters were estimated. The immediate test-retest reliability was excellent. Effects of ear canal air pressure on EA were examined comprehensively. Differences in EA between tympanometric and ambient-pressure measurements were significant. Single-frequency EA tympanograms exemplified for half-octave frequencies were contrasted. The bandpass EA tympanogram, 0.236- and 1-kHz EA and Ya tympanograms, and 226-Hz Ya tympanogram were compared in 9 variables.

CONCLUSIONS

This study established a database of wideband tympanograms in healthy adults. The data analyses will promote our understanding of the middle ear transfer function. These data will serve as a reference for further studies in clinical populations.