What is the Eustachian tube?
The Eustachian tube originates in the rear of the nose adjacent to the soft palate, runs a slightly uphill course, and ends in the middle ear space. The middle ear space is the hollowed out portion of the skull bone that contains the hearing apparatus and is covered on one side by the eardrum. In adults, the Eustachian tube is approximately 35mm long and approximately 3mm in diameter. Cartilage provides the supporting structure for the first two-thirds of the Eustachian tube, with the last third being made of bone.
The tissue that lines the Eustachian tube is similar to that inside the nasal cavity and may respond the same way (swelling) when presented with similar stimuli.
What are the functions of the Eustachian tube?
The primary function of the Eustachian tube is to ventilate the middle ear space, ensuring that its pressure remains at near normal environmental air pressure. The secondary function of the Eustachian tube is to drain any accumulated secretions, infection, or debris from the middle ear space. Several small muscles located in the back of the throat and palate control the opening and closing of the tube. Swallowing and yawning cause contractions of these muscles located in the back of the throat and help regulate Eustachian tube function. If it were not for this tube, the middle ear cavity would be an isolated air pocket inside the head that would be vulnerable to every change in air pressure and lead to unhealthy middle ear space function.
Normally, the Eustachian tube is closed, which helps prevent the inadvertent contamination of the middle ear space by the normal secretions found in the back of the nose. A dysfunctional Eustachian tube that is always open is called a “patulous” Eustachian tube. Patients with this rare condition are plagued by chronic ear infections. A much more common problem is a failure of the Eustachian tube to effectively regulate air pressure. Partial or complete blockage of the Eustachian tube can cause sensations of popping, clicking, and ear fullness and occasionally moderate to severe ear pain. Such intense pain is most frequently experienced during take-off and landing. Young children may describe the popping sensation as “a tickle in my ear”.
As Eustachian tube function worsens, air pressure in the middle ear falls, and the ear feels full and sounds are perceived as muffled. Eventually, a vacuum is created which can then cause fluid to be drawn into the middle ear space (termed serous otitis media). If the fluid becomes infected, the common ear infection (suppurative otitis media) develops.
What can cause Eustachian tube blockage?
The Eustachian tube can be blocked, or obstructed, for a variety of reasons:
- The most common cause is the common cold or upper respiratory infection.
- Sinus infections and allergies may also cause swelling of the tissue lining the Eustachian tube. Simply put, a stuffy nose leads to stuffy ears.
- Children are particularly prone to Eustachian tube blockage because their tubes are narrower in diameter, more horizontal in orientation, and closer at the nasal opening of the Eustachian tube to the adenoid.
- The possibility of an enlarged adenoid obstructing the opening of the Eustachian tube is the reason that adenoid removal is frequently recommended in children with chronic ear infections.
- Rarely, masses or tumours in skull base or nasopharynx can lead to Eustachian tube obstruction
Eustachian tube problems and the associated ear infections are among the most common problems seen by doctors. Many people have chronic problems regulating middle ear pressure. Causes range from allergies to excessively small Eustachian tubes. These patients often notice intermittent ear fullness, ear popping or cracking, mild hearing loss, ringing in the ear, and/or occasional poor balance. Smoking is associated with damage to the cilia that sweep along mucus and debris from the middle ear space to the back of the nose where it may be expelled.
How do changes in altitude or air travel affect Eustachian tube problems?
A rapid change in altitude, and thus air pressure is equalised across the eardrum by a normally functioning Eustachian tube. A healthy tube opens frequently and widely enough to equalise these changes in air pressure. With altitude changes during the descent of an airplane, air pressure increases as the plane lowers. The air pressure change pushes the eardrum inwards. Persons with Eustachian tube blockage can develop fullness of the ear, dulled hearing and possibly pain when his occurs. Those with poorly functioning Eustachian tubes may experience similar symptoms when riding in elevators, driving through the mountains, or diving to the bottom of a pool. Scuba divers learn tricks to equalise their ear pressures.
How is Eustachian tube blockage treated?
Several manoeuvres may be done to improve Eustachian tube function and thus aid in equalisation of air pressure.
- The simple act of swallowing activates the muscles in the back of the throat that help open the Eustachian tube. Any activity that promotes swallowing can help open the Eustachian tube, for example, chewing gum, drinking or eating.
- Yawning is even more effective because it is a stronger muscle activator.
- If the ears still feel full, the person can try to forcibly open the Eustachian tube by taking a deep breath and blowing while pinching your nostrils and closing the mouth. When a pop is felt, you know you have succeeded. If problems persist despite trying to forcibly open the tubes you may need to seek medical attention. If you feel dizzy performing this manoeuvre, then stop and discuss this with your doctor.
- If you have a cold, sinus infection, ear infection or suffering from allergies, it may be advisable to postpone air travel.
- Similarly, individuals with Eustachian tube problems may find such sports as scuba diving painful, and in some situations quite dangerous.
- Babies travelling on airplanes cannot intentionally pop their ears, but may do so if they are sucking on a bottle or pacifier. Crying, similar in function to yawning, will also enable equalisation of air pressure.
Many individuals who travel with Eustachian tube problems use a decongestant pill or nasal spray an hour prior to take off, and if necessary, prior to descent. The decongestant acts to shrink the membranes lining the nose and throat, allowing the ears to equalise more easily. Similarly, patients experiencing chronic daily problems with Eustachian tube dysfunction can benefit by aggressive control of allergies (with antihistamines, decongests, and prescription nasal sprays). Allergy evaluation can be helpful. In severe situations, a “pressure equalisation tube” can be surgically placed in the ear drum, replacing the role of a functioning Eustachian tube, and thus guaranteeing equalisation of the middle ear pressure.
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