Problem Addressed: The sonotubometric assessment of eustachian tube (ET) function is usually performed with 8kHz pure-tone signals. Reliability of these measurements can be significantly reduced by various factors. The authors present a novel approach by applying perfect sequences (PS).
Methods and Measures: PS are periodically repeated noise signals commonly used in mobile phone communication. These signals cover a broad band spectrum and allow the detection of changes in a spectrum up to 16kHz. The application of PS allows extraction of additional information about spatial changes in a lumen. For the first time PS was used for an evaluation of ET dynamics. PS were applied with a custom-made device in 22 healthy probands. All individuals were measured during swallowing, yawning, and Valsalva maneuver with both PS and 8kHz signals. To control the tubal activity, only openings that were realized in the patient`s own perception were included.
Results: ET openings were detected with both methods in all patients but not in all maneuvers. PS detected in 19% maneuvers an opening where 8kHz signals failed (p< 0.05). The quality of the measurements was 47% better with PS. In 3% the result was worse as compared to 8kHz signals. PS demonstrated that signals at 2 and 4kHz also contain valuable information about the tube activity. The application of PS allowed first online insights about the spatial changes in the ET opening.
Conclusions: The application of PS is more sensitive and reliable than any other sonotubometric approach. The visualization of luminal changes can add information about the localization of an ET pathology. PS represent a promising new approach for the recording of Eustachian tube activity.
Clinical Significance of Study: This new approach can contribute to a better understanding of ET physiology and improves clinical evaluation of the dynamic ET function.