Ear infections are medical problems caused by viral or bacterial infections somewhere in the ear. Most commonly, the term refers to middle ear infections, but any part of the ear can be involved. While most ear infections clear up and leave no residual effects, they can cause temporary hearing loss, and in some cases, they are linked to permanent changes in hearing ability. This article will discuss the types and causes of ear infections, as well as the reasons that permanent hearing loss can result from an infection.
Types of ear infections
The ear is divided into three sections: the outer ear (including the pinna and the canal as far as the eardrum), the middle ear (the space between the eardrum and the cochlea, including the three bones called the ossicles), and the inner ear (the cochlea and labyrinth, and all structures contained within). Outer ear infections are infections of the ear canal. The most common type is swimmer’s ear, which is caused by excessive moisture in the canal which allows bacteria to grow.
Other outer ear infections can be caused by fungal growth, or trauma to the skin of the ear canal and an infection in that wound – this is one of the reasons we advise people to avoid Q-tips! Outer ear infections can result in pain, drainage, and swelling in the ear canal. If the swelling is significant enough, or if the infection results in buildup of material in the canal, short-term hearing loss is possible. Outer ear infections generally don’t lead to permanent hearing problems.
Middle ear infections very often begin with an upper respiratory infection such as a cold or flu, or with seasonal allergies that cause you to feel stuffy. The reason is a tiny tube that runs from your middle ear to the nasopharynx (the very back of your nose where it connects to your throat), called the Eustachian tube. Under normal circumstances, this tube opens on its own dozens of time a day when you swallow, yawn, or chew, and this allows the middle ear space to equalize with outside air pressure. When the tube swells shut due to inflammation from a cold or allergies, it can’t open, and that pressure can’t equalize.
Meanwhile, the tissues in the middle ear are constantly absorbing oxygen. When the Eustachian tube swells shut and can’t replenish that air, the middle ear space becomes a vacuum, which then sucks fluid out of those middle ear tissues and causes the middle ear to be filled with fluid. If that fluid becomes infected, this is a middle ear infection. Typical symptoms are a feeling of pressure or fullness in the ear, possible pain, and a decrease in hearing in the affected ear. At first, this hearing loss is simply caused by the fluid in the middle ear space preventing sound from being effectively transmitted to the inner ear. If the infection goes on too long, however, it can lead to permanent hearing issues, which will be discussed in the next section.
Inner ear infections are less common than outer or middle ear infections, for the simple reason that the inner ear is very tightly sealed from the outside world and it’s hard for viruses or bacteria to get in. It isn’t impossible, though, and inner ear infections do occur. Because the inner ear includes the labyrinth, or semicircular canals, which are partially responsible for your sense of balance, inner ear infections often come with severe dizziness in addition to hearing loss and tinnitus. Most inner ear infections are viral rather than bacterial, although they can be associated with bacterial meningitis. Inner ear infections can also lead to permanent hearing loss, particularly if not treated right away.
Middle ear infections and permanent hearing loss
How can a middle ear infection lead to permanent hearing problems? In adults, the reasons are generally mechanical in nature. The presence of infectious material in the middle ear can eventually erode the ossicles, which are those tiny bones that conduct sound waves from the eardrum to the inner ear, and make them less effective. An eardrum can burst from the pressure of the fluid behind it, and if it scars badly or doesn’t heal at all, it too will transmit sound waves less effectively. And in some cases, the fluid itself lingers so long that it thickens into a glue-like substance which is very difficult to remove; this condition is called “glue ear” and can become chronic.
In children, it’s more complicated because they’re still developing. Middle ear infections are much more common in small children (under the age of 6) because their Eustachian tubes are shorter and more horizontal than those of older kids and adults, making it more difficult for their ears to drain appropriately and easier for bacteria to get from the nose into the middle ear. Additionally, their immune systems are less developed, so they aren’t able to fight off infections as easily. When children get fluid buildup in their middle ears, they experience a mild hearing loss due to the ineffective transmission of sound waves to the inner ear. These infections usually clear up when treated, but that temporary hearing loss can affect the development of the child’s auditory system in critical ways. Studies have shown that measures of central auditory processing ability, such as separating competing sounds (think background noise, or two people talking at once), can register as abnormal long after a middle ear infection subsides. Chronic middle ear infections are associated with auditory processing disorder (APD), a condition that can affect a child’s academic performance and result in lifelong reduction in earning potential and socioeconomic status.
Chronic middle ear infections are also associated with speech and language delays in small children. If a child can’t hear language accurately and consistently, they will have a harder time learning to speak.
This is why children so often get pressure equalization (PE) tubes placed in their eardrums: not because the fluid won’t eventually clear on its own, but because inconsistent auditory input during those critical developing years can be so harmful. Tubes allow the middle ear space to maintain equal pressure with the outside air in situations where the Eustachian tubes can’t do it, preventing the formation of a vacuum and the accumulation of fluids. Adults can get tubes as well if their Eustachian tube dysfunction becomes chronic and middle ear infections become problematic, but in adults, there isn’t the same concern for speech and language development or long-term central auditory processing difficulties.
Inner ear infections and permanent hearing loss
Certain types of inner ear infections can cause you to lose the hearing in one or (less commonly) both ears very quickly – it can come on within minutes, or you can wake up one morning and not be able to hear. When this happens, it’s called a “sudden sensorineural hearing loss” or SSNHL, and the best chance of recovering some hearing is to see an ENT (ear, nose and throat physician) within the first day or two for steroid treatment.
When this type of hearing loss does end up being permanent, it can often come with tinnitus in that ear, and many times the residual hearing is not clear; things can sound muffled or distorted compared to the good ear.
Conclusions
Ear infections can occur at any stage of life, and in any part of the ear. However, the risk of permanent hearing loss varies with the specifics of the infection. If you or your child experience signs of an infection – particularly sudden hearing loss in one ear – it is advisable to seek medical attention.