Definition & Overview
The ability to hear is often taken for granted. Many don’t realize that hearing is actually a complex process that can easily be lost due to injuries or diseases of the ears. In fact, millions of people around the world suffer from a certain degree of deafness. While there are those that were born with the condition, many more experience a sudden or gradual loss of their hearing abilities.
Sounds are vibrations in the air that originate from a source. The process of converting sound into something that the brain understands is called hearing. Hearing takes place only if all the components of the ears are functioning normally. Failure of one or more of the components will result in a reduction or total loss of a person’s hearing abilities.
The ear is divided into three parts: the outer, middle, and inner ear.
The outer ear serves as the main passageway for sound vibrations. The earflaps, called the pinna, are responsible for capturing sound waves and directing them to the middle ear via the ear canal.
The middle ear, made up of the eardrum, tympanic membrane, ossicles, stirrup footplate, and Eustachian tube, amplifies the sound waves and transfer them to the inner ear.
The inner ear contains the stirrup footplate, cochlea, and acoustic nerve. These components convert the amplified sound waves into nerve impulses that are transmitted to the brain for translation, thus completing the hearing process.
Hearing can be impaired because of damage to any of the components of the inner, middle, or outer ears. However, hearing can also be lost due to problems with the brain’s ability to translate the electrical signals produced by the ears. Such problems are often a result of a brain tumor.
Cause of Condition
One of the primary causes of hearing loss is an ear injury due to sudden blows, loud noises, pressure, or foreign objects inserted into the ear canal. It’s important to remember that the components of the ear are extremely sensitive and easily prone to damage.
A good example is the tympanic membrane, also known as the eardrum, which is a thin tissue that separates the outer and middle ear. Loud noises, pressure, and foreign objects can easily create a hole in the membrane resulting in a condition called a ruptured eardrum, which is a common cause of hearing loss. It can also result in an ear infection (otitis media) that needs to be treated promptly. If not, the infection will likely spread to the inner ear and cause further damage. Although rare, such infection can even spread to the brain and damage nerves and tissue. Other types of ear infections include swimmer’s ear and vestibular neuritis.
Certain diseases can also damage the ears. Some of the most common are otosclerosis, cholesteatoma, Meniere’s disease, Herpes Zoster Otitis, and acoustic neuroma. * Otosclerosis affects the middle ear and prevents the ossicles from functioning correctly. This results in conductive hearing loss. If the disease progresses to the inner ear, it is referred to as cochlear otosclerosis, which would then result in a condition called permanent sensorineural hearing impairment.
Cholesteatoma is a condition characterized by the growth of skin cells in the middle ear. As the condition progresses, it destroys or affects the components of the middle and inner ear, causing hearing loss, in the process. If not treated promptly, the condition can result in severe ear damage.
Meniere’s disease occurs when the fluids in the inner ear are not balanced, which then results in ringing in the ear (tinnitus) and excessive pressure. This requires prompt treatment as it could lead to total deafness.
Herpes zoster otitis is a viral infection that usually affects the facial nerves. However, there is a possibility of the infection affecting the nerves located in the inner ears as well. Not only will someone affected with this disease experience diminished hearing, he or she may also begin hearing abnormal sounds.
Acoustic neuroma is a tumor that grows in the inner ear and the brain as well. Its growth is usually very slow and the tumor is benign, meaning that it is non-cancerous. However, as it continues to grow, it can damage the nearby components causing a variety of symptoms, such as vertigo and loss of hearing. The tumor needs to be surgically removed, but this decision will depend on the patient’s age and the size of the tumor.
Although the primary function of the ears is hearing, they are also responsible for a person’s ability to balance. As such, a person with a damaged ear due to an injury or disease, will likely experience dizziness (vertigo) and nausea in addition to a certain degree of hearing loss. Other symptoms can include fever, a malformed outer ear, blocked ear canal, foul smelling ear discharge, and even facial paralysis.
Who to See & Types of Treatment Available
Any problems with the ears should be brought to the attention of an ear, nose, and throat (ENT) specialist or an otolaryngologist.
A consultation with an ENT specialist will typically begin with a short interview where the patient will be asked about his symptoms, their severity, when they started, and any medications that were taken to treat the condition. The interview is typically followed by a physical examination of the affected ear for obvious signs of infection. The eardrums will also be checked for any perforations.
The patient’s hearing abilities will then be assessed using a simple tuning fork. In some cases, an ENT refers a patient to an audiologist to obtain a more precise assessment.
Once the condition has been identified, the doctor will present all available treatment options. Depending on the ear condition and its severity, options may include medications, eardrops, or surgery.
- Haddad J Jr. Congenital malformations. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 630.