What is the relationship between Eustachian Tube Dysfunction and tinnitus? Can it cause or accentuate tinnitus? And how can it be relieved?
The human Eustachian tube is of immense importance in regulating the cavity of the middle ear as well in contributing to voice modulation. The tensor tympani muscle, the muscle connecting the tympanic membrane with the upper end of the Eustachian tube, opens the normally-closed isthmus by yawning, swallowing, and less dependably by chewing. In terms of swallowing, the most common form of activation, it is estimated that about every third or fourth swallow causes the tensor tympani to open the isthmus area so that the otherwise air-tight middle ear cavity can equalize air-pressure to that of the external auditory canal (EAC) side of the tympanic membrane. At this point, there are two main tinnitus/Eustachian abnormalities that can occur here:
- If the Eustachian tube stays closed, as during inhalant allergy, head cold, or middle ear infection, the oxygen trapped in the middle ear cavity is soon absorbed into the mucosa, creating a vacuum. The ensuring vacuum causes the cavity to fill with mucous. If uninterrupted, it will continue to do so until the pressure can cause tympanic membrane perforation. It is that in-between state that presents varying types of possible objective tinnitus: roaring, buzzing, humming, heartbeat, and in some cases, spasm of the tensor tympani and/or venous hum (when the pressure on vascular structures and surrounding tissues become too great). All of this, of course, can be ascertained through tympanometry, otoscopy, and other diagnostic measures.
- If the Eustachian stays open (Patulous) as from physical abnormality, one will likely experience another type of objective tinnitus: described as an ocean roar or hollow effect, like a sea shell. In some cases, other palatal and middle ear structures may be involved, bringing even more complex descriptions of tinnitus.
Dr. Chartrand has served actively in the hearing health field for almost 32 years. His works are available in textbooks, hundreds of papers and articles, and on the Internet. He is Associate Professor of Behavioral Medicine at North Central University, and Director of Research at DigiCare Hearing Research & Rehabilitation. Contact: www.digicare.org.