Conditions: Eustachian tube dysfunction
This page describes the Eustachian tube, including anatomy, function, dysfunction, and assessment. See also treatment of Eustachian tube dysfunction, and ear infection.
what is the eustachian tube and how does it work?
Click to enlarge.
The Eustachian tube is a narrow channel — about 35 mm (1.4 inches) long in an adult — that connects the back of the nose and throat (the nasopharynx) to the air-filled space behind the eardrum (the middle ear). The two-thirds of the tube closest to the nose is made of cartilage and soft tissue and is the flexible, working part; the one-third closest to the ear is a bony tunnel inside the skull.
The Eustachian tube has three main jobs:
Balancing air pressure. It keeps the air pressure in the middle ear equal to the pressure of the outside world.
Drainage. It clears fluid and mucus from the middle ear down to the throat, helped by tiny hair-like cells (cilia) that sweep secretions toward the nose.
Protection. When closed, it shields the middle ear from germs, secretions, and loud sound coming from the nose and throat.
When middle-ear pressure equals the pressure outside, the eardrum (tympanic membrane) sits in a neutral position and transmits sound vibrations efficiently to the small bones of the middle ear (the ossicles) and on to the inner ear.
The Eustachian tube is normally closed (collapsed) at rest and opens only briefly — most often when you swallow, yawn, or chew. The muscle that actively pulls it open is the tensor veli palatini, a small palate muscle. The lining of the middle ear and the neighboring mastoid air cells constantly absorbs air, which slowly lowers the pressure behind the eardrum. To make up for this, air must be periodically resupplied each time the tube briefly opens and lets air pass from the throat into the middle ear.
An occasional "popping" of the ears, sometimes with a brief sense of a pressure change, is normal and healthy Eustachian tube function. When a pocket of air moves quickly in or out of the middle ear, the eardrum shifts position. Because the eardrum is attached to the middle-ear bones, which connect to the inner ear, this movement is registered by the brain as sound. The eardrum can also sense touch, so its stretch and relaxation add to the physical feeling of the ear popping.
Endoscopic view of the right Eustachian tube orifice. The arrow indicates the orifice, in its usual closed configuration. The arch-shaped raised surface around the orifice demonstrates the torus tubarius, which is the cartilage of the Eustachian tube. When the surface tissue (called mucosa) becomes swollen, the orifice becomes less able to open periodically.
What is Eustachian tube dysfunction?
Eustachian tube dysfunction (ETD) is a condition in which the tube fails to do its jobs — most often failing to keep middle-ear pressure balanced and to drain fluid to the throat. It is common, affecting an estimated 1–5% of adults, and is even more frequent in children.
Doctors group ETD into three main types:
Obstructive (dilatory) ETD — the most common type. The tube does not open as fully or as often as it should. Because the anatomy lets air escape out of the middle ear more easily than it lets air in, a persistent imbalance almost always means the pressure in the middle ear is lower than in the ear canal and the outside world. This negative pressure tends to pull fluid into the middle ear and the nearby mastoid cells — a condition called otitis media with effusion, or serous otitis media ("glue ear"). Symptoms include a feeling of fullness or pressure, popping or crackling, ear discomfort, muffled hearing, and sometimes ringing (tinnitus).
Baro-challenge-induced ETD. This may be considered a mild form of obstructive ETD. The tube cannot keep up with rapid changes in outside pressure — typically during airplane descent or scuba diving. People are often completely normal at ground level, and examination between episodes may be entirely normal, so the diagnosis rests mainly on the history. Severe pressure changes can occasionally cause fluid or even bleeding behind the eardrum.
Patulous Eustachian tube — the least common type. Here the tube is stuck open instead of closed. Because the tube stays open, sound travels up it from the throat to the eardrum, producing an unpleasant, echoing awareness of one's own voice (called autophony) and of one's own breathing. Symptoms often improve when lying down or during a head cold and worsen with exercise; many people habitually sniff to briefly close the tube. The best-established cause is significant weight loss, which thins the fat pad (Ostmann's fat pad) that normally helps keep the tube shut, though in most cases no clear trigger is found.
Visualization of the eardrum (tympanic membrane)
Assessing ETD relies heavily on physical examination, which usually includes looking at the eardrum through the ear canal[18]. Retraction of the eardrum — as though it has been suctioned inward — is a common sign of obstructive ETD and reflects the negative pressure behind it.
Examination of the ear with a microscope.
View of a normal right eardrum (tympanic membrane). The tympanic membrane is partially translucent, demonstrates normal blood vessels, color, and light reflectivity, Photo attribution to Michael Hawke MD.
What causes Eustachian tube dysfunction?
Both children and adults can develop ETD, but the reasons differ somewhat by age.
Children are especially prone to ETD because their Eustachian tubes are shorter, wider, floppier, and more horizontal than an adult's — roughly 13 mm long and only about 10 degrees from horizontal at birth, versus about 35 mm and 45 degrees in adults. These features make it easier for germs and secretions from the nose and throat to reach the middle ear and harder for the tube to drain and ventilate properly. The tube gradually lengthens and tilts downward as the skull grows, reaching adult shape by early adolescence.
Genetics and host factors also play a role. Family history, male sex, and inherited differences in immune and mucosal proteins can make some people more susceptible to middle-ear disease and Eustachian tube problems.
Common contributing causes include:
Colds and other upper respiratory infections, the most frequent trigger for short-term ETD, because they swell the lining around the tube's opening.
Allergic rhinitis and sinus inflammation (including from sinusitis), which spread swelling and mucus to the tube's opening in the nose.
Enlarged or chronically infected adenoids in children, which sit right next to the tube's opening and can block it or act as a reservoir for bacteria.
Laryngopharyngeal reflux — stomach contents refluxing up to the throat and irritating the tube.
Surface irritants such as tobacco smoke.
Scar tissue in the tube, which can follow repeated infections or radiation therapy to the head and neck.
In adults, one-sided ETD that persists deserves special attention. Uncommonly, a tumor in the back of the nose — such as nasopharyngeal carcinoma — can block one Eustachian tube. For this reason, persistent one-sided ETD or unexplained one-sided fluid behind the eardrum in an adult will often prompt examination of the nasopharynx with an endoscope to rule out a growth.
As noted above, at the opposite end of the spectrum is the patulous (stuck-open) tube, which tends to occur in older adults and in people who have lost a significant amount of weight.
How is Eustachian tube dysfunction identified and what problems can it cause?
Symptoms alone are often enough to recognize ETD. For example, most people feel fullness and muffled hearing with a change in altitude; if those symptoms fail to clear within an hour or so at a steady altitude, that suggests at least mild ETD. When the tube cannot equalize pressure, the eardrum bulges outward or retracts inward until the pressure balances, usually causing mild, temporary hearing loss. If the imbalance persists, fluid can collect behind the eardrum, causing moderate but usually reversible hearing loss (serous otitis media). Frequent or long-standing fluid can go on to become a middle-ear infection.
To confirm the diagnosis and find the cause, an evaluation may include several tools:
Otoscopy or otomicroscopy — looking at the eardrum for retraction, fluid, or (in a patulous tube) movement of the eardrum in time with breathing.
Tympanometry — a quick test in which a small probe changes the pressure in the ear canal and graphs how well the eardrum moves. It is the most widely used objective test for the middle ear. A "type C" tracing points to negative middle-ear pressure and a "type B" (flat) tracing suggests fluid — both consistent with ETD.
Hearing tests (tuning-fork tests or a formal audiogram) to measure any hearing loss.
Nasal endoscopy (nasopharyngoscopy) to view the tube's opening and, importantly, to rule out a blockage or tumor.
A symptom questionnaire such as the ETDQ-7, which is useful for tracking symptoms over time but is not accurate enough to diagnose ETD on its own.
Imaging (CT or MRI) in selected cases, which can show fluid in the middle ear or mastoid, or other conditions linked to ETD such as a cholesteatoma.
It is worth knowing that there is no single "gold-standard" test for ETD; the diagnosis is made by combining the history, the examination, and these tests.
Why it matters: when negative middle-ear pressure persists over months, it can lead to a chain of problems — a retracted eardrum and retraction pockets, ongoing fluid (glue ear), collapse (atelectasis) of the eardrum onto the middle-ear bones, and, in some cases, a skin cyst called a cholesteatoma that can erode the bones of hearing. Treating ETD aims to interrupt this cascade and restore normal middle-ear ventilation.
Examples of otomicroscopic findings of ETD:
View of a right tympanic membrane with middle ear fluid (serous otitis media) seen through the tympanic membrane. This resulted from Eustachian tube dysfunction.
Severe retraction of the eardrum (tympanic membrane) as a result of Eustachian tube dysfunction.
View of a tympanic membrane with acute otitis media. Redness, thickening, bulging, and obscured landmarks of the eardrum (tympanic membrane) are evident. Photo attribution: B. Welleschik
When to seek care
Consider seeing a clinician if ear fullness, pressure, muffled hearing, or ear pain last more than a few weeks, keep coming back, affect only one ear and do not resolve, or are accompanied by drainage, significant hearing loss, dizziness, or a nosebleed. Prompt evaluation is especially important for persistent one-sided symptoms in an adult.
how to get the most from your appointment for hearing
Appointment time is valuable. Here are some suggestions to make the most of your appointment. This preparation will help you and your doctor maximize efficiency and accuracy, freeing up time for questions and answers.
• Click here to prepare for your hearing loss appointment (adult)
This page