Wideband Tympanometry and Absorbance for Diagnosing Middle Ear Fluids in Otitis Media with Effusion

Abstract

Background: Surgical tympanostomy tube insertion is a standard procedure in Otitis media with effusion after proper follow-up. During the surgery, the presence of serous or mucoid fluids, atelectatic tympanic membrane, or empty ear may be observed, despite all patients having the same diagnosis. A better method based on a non-invasive approach can help avoid unnecessary surgery. This study aimed to compare surgically confirmed otitis media with effusion with wideband tympanometry and absorbance tests.

Methods: A total of 122 children diagnosed with otitis media with effusion were included. Eighty healthy children were included as controls. Ears were divided into 4 groups: serous, mucoid, atelectasis, and empty. Resonance frequency, 226 Hz and 1000 Hz compliance, wideband peak pressure, and absorbance data were used for comparison.

Results: The most practical tests were the average of 500, 1000, and 2000 Hz absorbance according to positive likelihood ratio (4.8) and model 2 according to negative likelihood ratio (0.11). It was better than the standard 226 Hz and 1000 Hz compliance tests. Although some statistically significant parameters were observed between serous fluid and empty ear, they were not sufficiently impactful for a differential diagnosis. No parameter could help us differentiate between serous and mucous fluids.

Conclusion: According to negative likelihood ratio (0.11), a person with normal middle ear is 9 times more likely to have negative test with the use of resonance frequency, wideband tympanometry, and average absorbance together. To differentiate serous fluid from the empty ear, using only 226 Hz or 1000 Hz compliance for surgical indication can potentially cause wrong decisions according to negative likelihood ratios.

Figure 1.

Frequency-specific absorbance values of all groups were plotted in the same graphic. Over every group label, frequencies 250-, 500-, 1000-, 2000-, 4000-, and 8000-Hz error bars were shown. Median, error bars, and extreme cases of all the groups were plotted also.

Figure 2.

The mean absorbance measurements of different patient groups are shown. It is noteworthy that the empty and atelectatic groups have very similar curves.

Figure 3.

Tympanic peak pressure of the groups.

Figure 4.

Receiver operating characteristic curve analysis of average absorbance parameter to distinguish patients from controls (area under the curve: 0.831, P < .01).

Figure 5.

We divided patients into 3 groups according to the convergence of the absorbance curves in Figure 2 and tried to find cut-off points between them for the average absorbance test. (Sens = sensitivity, Spec = specificity).