Treating the Structure & Function of the Ear
Ear care, or otology, specifically treats the structure and function of the ear. Ear conditions include hearing and balance disorders, damage or disease of the ear, tumors, and others (see below). Our specialists treat both adult and pediatric patients. Patients are also seen by neurotology specialists, who specifically care for the nerves that connect the ear and brain in surgery.
We treat many ear conditions that include the following:
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How Does My Ear Hear Sounds?
The ear is divided into three parts: the external ear, the middle ear, and the inner ear. Each part performs an important function in the process of hearing. Sound waves pass through the canal of the external ear and vibrate the eardrum, which separates the external ear from the middle ear. The three small bones in the middle ear (hammer or malleus, anvil or incus, and stirrup or stapes) act as a transformer to transmit energy of the sound vibrations to the fluids of the inner ear. Vibrations in this fluid stimulate the delicate nerve fibers. The hearing nerve then carries the sound impulses to the brain where they are interpreted as understandable sound.
What Are the Different Types of Hearing Loss?
The external ear and the middle ear conduct sound; the inner ear receives it. If there is some difficulty in the external or middle ear, a conductive hearing loss occurs. If the trouble lies in the inner ear, a sensorineural (SNHL) or nerve hearing loss is the result. When there is some difficulty in both the middle and inner ear, a combination of conductive and sensorineural impairment exists, called a mixed hearing loss.
- Conductive Hearing Losses - Any disease affecting the ear canal (external ear), ear drum, middle ear space, or the three small ear bones may cause a conductive hearing loss by interfering with the transmission of sound to the inner ear. Such a conductive hearing impairment may be due to a perforation (hole) in the ear drum, partial destruction or fixation of one or all of the three little ear bones, or scar tissue around the ear bones or in the ear drum. Other causes of conductive hearing losses include wax in the ear canal, middle ear fluid or infection, or any other process that would prevent sound from reaching the inner ear.
- Sensorineural Hearing Loss (inner ear hearing loss) - As described above, sensorineural hearing loss is an inner ear hearing loss. The inner ear loss can occur in the cochlea, the cochlear or auditory nerve, the brainstem, or the auditory cortex. The auditory cortex is the region of the brain in which sound is heard. For most cases of sensorineural hearing loss, including sudden SNHL, the abnormality is within the cochlea itself. For most case of SNHL, including sudden SNHL, the external ear canal and the middle ear are normal.
What Is Sudden Sensorineural Hearing Loss?
Sudden sensorineural hearing loss (SSNHL) is defined as a decline in hearing greater than or equal to 20 dB over three days or less without any identifiable cause.
Sensorineural Hearing Loss Symptoms
Very few symptoms are usually experienced in patients with sudden SNHL. Obviously hearing loss (the vast majority in one ear only) is the major symptom. The patient may also experience tinnitus or ringing in the ear. Occasionally, fullness in the involved ear is encountered. Pain is rarely associated. In some cases imbalance, or true spinning (vertigo) can be associated with sudden SNHL.
Is it common to suddenly lose your hearing?
Approximately 4,000 cases of sudden SNHL occur annually in the United States. Hearing loss from aging (presbycusus) and noise exposure are relatively common. There types of losses occur gradually over many years. Sudden hearing losses that are sensorineural in nature (inner ear) are relatively uncommon. Sudden losses of a conductive type (see above) are much more common than sudden inner ear losses. Examples of sudden conductive hearing losses include wax in the ear canal, fluid or infection in the middle ear space, chronic infections of the ear, or middle ear bone abnormalities.
Causes of Sudden SNHL
By definition the exact cause of sudden SNHL is literally unknown cause. Current research is underway to determine the cause of sudden hearing loss as well as potential cures. Some of the proposed causes are listed below. The most commonly proposed causes of sudden SNHL include:
- viral infection of the inner ear,
- blood flow abnormalities to the inner ear, and
- problems with the fluid mechanics of the inner ear which leads to tears in the fine membranes of the cochlea.
Perhaps the most common theory to explain sudden hearing loss is a viral infection. Evidence of viral infections have been found by researchers in patients who have had sudden SNHL, which is why viral infection is suspected. A viral infection can cause inflammation of the inner ear or auditory nerve. This inflammation of the inner ear structure and associated blood vessels can cause hearing loss. No pain, fever, muscle cramps, or other signs of a viral illness are usually encountered. Occasionally, signs of an upper respiratory infection may precede the onset of sudden SNHL.
Cochlear Membrane Tears
The cochlea or inner ear is made of fine, delicate membranes that contain fluid-filled spaces. It is the movement of the fluid in these spaces that creates sound. Particular electrolytes are in these fluid filled spaces. This active storage of electrolytes creates different charges (+ or -) in these fluid-filled spaces separated by the fine membranes. This charge difference, or potential, between the spaces allows for the generation of a nerve impulse much in the same way a battery with its positive and negative poles can induce electricity.
A tear in the fine delicate membranes can lead to a mixing of the fluid, a loss in the potential, and an inability to generate a nerve impulse. This inability to generate a nerve impulse leads to a hearing loss. Tears in the membrane can occur from pre-existing defects (probably hereditary) and from excessive fluid in the spaces such as Meniere’s disease (see Meniere’s disease section).
Blood Flow Abnormalities
Another potential cause for hearing loss is abnormal blood flow to the cochlea. Severe hypertension may lead to bleeding in the inner ear with resulting hearing loss. Poor blood flow from arteriosclerosis may lead to inadequate perfusion or flow of blood into the cochlea. These mechanisms may be described as a stroke of the inner ear. This cause is more commonly found in the elderly, but may also be associated with the use of birth control pills in the younger population.
Intra-Cochlear Membrane Tears
A tear in one of the fine membranes that makes up the inner ear. May be the cause of hearing loss in Meniere’s disease.
Other Potential Causes of Sudden SNHL
- Bacterial infection, such as Otitis media, syphilis
- Vascular occlusion (from stroke)
- Vasculitis or inflammation of the blood vessels
- Meniere’s disease or inner ear fluid build up
- Labyrinthitis, (viral or bacterial inner ear infection)
- Meningitis (viral or bacterial infection of brain lining)
- Medical disorders, such as diabetes, hypo- or hyperthyroidism
- Hereditary disorders, such as inner ear hereditary hearing loss, Usher’s syndrome, Waardenburg’s syndrome
- Low levels of oxygen (hypoxia) (from stroke)
- Medications, such as antibiotics, (termed ototoxic medications)
- Malignant neoplasm (tumors or cancer of the ear)
- Benign neoplasms (tumors), such as acoustic neuroma, meningioma
- Autoimmune hearing loss: immune system disorder that can affect the inner ear as rheumatoid arthritis is an immune system disorder that affects the joints
- Cholesteatoma or chronic middle ear infection can also cause an inner ear loss in advanced cases
- Otosclerosis or fixation of hearing bones, can also cause an inner ear loss
- Hypertension, which may cause bleeding in the inner ear or brain
Treatment for Hearing Loss
The standard evaluation of a patient who comes to the office with the complaint of a hearing loss is to obtain a formal hearing test. As part of this evaluation, we perform an extensive history and physical examination to determine if a cause can be found to direct the evaluation and therapy. The first test we do is a formal hearing test to determine the type and degree of hearing loss. If a sensorineural loss is confirmed, we may get a MRI scan of the head. The primary purpose of this is to rule out other causes of sudden hearing loss (tumors, strokes).
The most common medications used are steroids (like prednisone), which are powerful anti-inflammatory agents. It is usually given orally but, in some cases may be injected directly into the middle ear. Vasodilator medications may also be prescribed. Often multiple medications may be given to treat the proposed causes over a short period of time. The earlier treatment is started, the better the potential for hearing improvement.
Prednisone is the mainstay in the treatment of sudden SNHL. Prednisone is usually given over a 10–14 day period as a tapering (decreasing) dose. Like all medications, steroids have certain potential side effects that include mood elevation, insomnia, bone and hip problems, and stomach irritation.
Middle ear steroid injection
The dexamethasone perfusion is a relatively straightforward procedure performed in the office setting. Essentially a steroid solution is injected directly into the middle ear space through the eardrum of the affected ear. Initial studies have demonstrated that transtympanic therapy may have a positive role in treating patients with sudden hearing loss. Several physicians across the country are currently studying the potential beneficial effect on steroid perfusion to restore hearing. The effect is currently unknown.
Hearing aid placement
Hearing aids, such as a CROS or bone-anchored hearing aid (BAHA) may be placed.
Cochlear implants may be used in the event of a bilateral SNHL.
The patient may opt to do nothing further.
Hearing Loss Recovery
Recovery rates range from 5–90%, but the overall accepted recovery is about 60 percent (two-thirds of patients are expected to recover hearing to some degree). In some patients, the hearing loss will recover spontaneously without therapy.