Middle Ear Pressure; A New Method for Continuous Direct Measurements
Abstract: Disturbances in the pressure homeostasis of the middle ear (ME) system cause a pressure gradient across the tympanic membrane lessen the effectiveness of sound transmission and may be associated to development of chronic ME disease. An equipment for continuous direct pressure measurements was developed and was found to be accurate, base-line stabile and portable. Long term pressure measurements and tubal function tests were performed on a normal group and subjects with PET (patulous Eustachian tube). During the 24-h pressure measurements sleep was the most important factor affecting the ME pressure. In normal subjects a ME pressure rise occurred during sleep compared to the erect position. A significantly higher pressure was demonstrated during sleep compared to the recumbent position while resting awake. Our results indicate that the state of sleep induce a ME pressure rise, not the recumbent position. These findings support the significance of a two directional gas diffusion for the regulation of the ME pressure. The ME pressure demonstrated a greater individual variation among subjects with PET than seen among normal subjects. The PET group had a negative ME pressure during sleep, and there was no pressure difference between sleep and erect position. We found that the clinical diagnosis PET does not imply a static state of an open ET, and function changed over time between a closed and an open state. None of the subjects investigated had any signs of sniffing behaviour. Our study shows that it is possible to perform long-term pressure measurement during normal every-day activity with the method developed. By describing the pressure fluctuations in healthy and pathologic ears during every-day conditions, a relevant physiologically evaluation of a ME pressure situation seems possible. Future studies with the method described could improve the understanding of the development of chronic ME disease, PET and SOM.
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