Tinnitus

Tinnitus

Ringing in the Ears or Tinnitus

Ringing in the ears is common.  It may be intermittent or constant, mild or severe, and may vary from a high-pitched sound to a low roar.  It is usually subjective (audible only to the patient) but can occasionally be objective (audible to others).  It may or may not be associated with hearing loss.

Tinnitus should be thought of as a symptom, not a disease.  Just as pain in the arm or leg is a symptom and not a disease.  That said, the challenge with tinnitus is that the cause may not be apparent.

Tinnitus may or may not be accompanied by a hearing impairment.  Hearing is measured in decibels (dB).  A hearing level of 0 to 25 dB is considered normal.

Hearing Mechanism

In order to understand the possible causes of tinnitus, you must have some knowledge of the hearing mechanism.  This mechanism is made up of five main divisions: the external ear, the middle ear, the inner ear, the nerve pathways, and the brain.

The External Ear

The external ear consists of the auricle and the external ear canal.  These structures collect the sound waves and transmit them to the ear drum.

The Middle Ear

The middle ear is the space between the ear drum and the inner ear.  The air filled space contains the three ossicles: the malleus, the incus, and the stapes (or hammer, anvil, and stapes).  Vibrations of the ear drum are transmitted across the middle ear space by these three small ear bones.  Movement of the third bone (the stapes or stirrup) results in fluid wave in the inner ear.

The middle ear chamber is lined by a membrane similar to the lining of the nose and contains secreting glands and blood vessels.  This chamber is connected to the back of the nose through the eustachian tube.

The eustachian tube serves to equalize the pressure between the middle ear chamber and the outside atmosphere.  Air passing through the eustachian tube is responsible for the popping sensation noted during altitude changes.

Inner Ear

The inner ear is enclosed in the densest bone in the body (the otic capsule).  It contains fluid and delicate membranes, hearing cells, and microscopic blood vessels.  On those delicate membranes there are hair cells.  As the fluid wave moves through the inner ear it causes movement of the membranes and deflection o the hair cells.  When the hair cells are deflected they generate an electrical signal.

Nerve Pathways

The electrical impulses created in the inner ear are transmitted to the brain by the hearing nerve.  The passes through the skull enroute to the brain through a small bony canal, called the internal auditory canal.  It is joined in the canal by the balance nerves and the facial nerve (the nerve that moves the muscles of the face).

Brain

The hearing nerve pathways divide as they reach the brain into an extremely complex network.  The impulses are transformed by the brain into recognizable sound.

Objective Tinnitus

Most tinnitus is audible only to the patient, this is called subjective tinnitus.  Tinnitus audible to both the patient and others is called objective tinnitus and is uncommon.

Objective tinnitus may be due to muscle spasms in the middle ear or eustachian tube or be due to abnormalities in the blood vessels surrounding the ear.

Muscular Tinnitus

There are two muscles attached to the hearing bones.  The stapedius attaches to the stapes (stirrup) and the tensor tympani attaches to the malleus (hammer).  These muscles normally contract in response to loud impulse sounds and act to stabilize the hearing bones and decrease the amount of sound transmitted to the inner ear. 

However, for no apparent reason, one or both of these muscles may begin to contact rhythmically for brief periods of time.  Because the muscles are attached to one of the hearing bones these contractions may result in a repetitious sound in the ear.  The clicking, although annoying, is harmless and usually subsides without treatment.

Should the muscle spasms continue, medical treatment (muscle relaxants) or surgery (cutting the spastic muscle) may be necessary.  Muscular tinnitus resulting from spasm of one of the two muscles that attach to the eustachian tube is uncommon but can also result in episodes of rhythmic clicking in the ear.  This is called palatal myoclonus and usually responds to muscle relaxants.

Vascular Tinnitus

There are two large blood vessels intimately associated with the middle and inner ear: the jugular vein and the carotid artery.  These are the major blood vessels supplying the brain.

It is not uncommon to hear one’s heart beat or the hear the blood circulating through these large vessels.  This may be noticeable when an individual has a fever, a middle ear infection, or after engaging in strenuous exercise.  This circulation increase is temporary and usually subsides when the exertion or fever are reduced.  It is not audible to others.  On occasion the sound of blood circulation will become audible to others.  This can be due to thickening of the blood vessel wall (a normal occurrence as one grows older), a kink in the vessel or an abnormal growth on the vessel wall.  Further testing may be necessary to determine the cause and treatment indicated in these uncommon cases.

External Ear Tinnitus

Obstruction of the external ear canal by wax, foreign bodies or swelling may produce a hearing impairment or pressure on the ear drum.  This frequently results in a pulsating type of tinnitus.

Middle Ear Tinnitus

Disturbances of function of the middle ear may result from allergy, infections, injury, scar tissue or impaired motion of the three middle ear bones.  These disturbances often result in hearing impairment and may lead to ringing.  But there is no relationship between the degree of hearing loss and the intensity of the tinnitus.

Inner Ear Tinnitus

Any condition which disturbs the fluid pressure in the inner ear may produce ringing.  This may be due to infections, allergy, hydrops (too much inner ear fluid), or circulatory disturbances which produce changes not only in the fluid but also in the encasing membranes of the inner ear.

Nerve Pathway Tinnitus

The nerve pathways are the most delicate structures of the hearing mechanisms.  The small hair cells which serve to transform fluid waves into nerve impulses are analogous to the cells of the eye retina which transform light waves in to nerve impulses.  The slightest swelling or interference with these delicate cells from any cause readily produces impairment of function and irritation.  This may occur from a variety of causes: infection, allergic swelling, systemic diseases, sudden exposure to a blast of sound or prolonged exposure to high noise levels, certain drugs to which the patient may be sensitive, and minute changes in the blood supply may all potentially cause damage.  The list is long and varied.  These can be either acute or chronic.

Unfortunately, due to the small size and the location within dense bone it is not possible to visualize the hair cells.  No imaging study (CT scan or MRI) can show the hair cells. As a result, most of the time, we have no way of knowing what is actually causing the tinnitus.

Brain Tinnitus

There are patients who have, for various reasons, had the inner ear surgically removed or the hearing nerve divided.  On occasion, these patients will still have tinnitus in the affected ear.  Therefore, there must be centers in the brain which are capable of generating sound.

Hearing Impairment

Ringing in the ears may or may not be associated with hearing loss.  Most people with tinnitus do not have hearing loss.  Conversely, most people with hearing loss have tinnitus.  Oftentimes, improving the hearing may help reduce the ringing.  The level of the ringing has not particular correlation with the level of hearing loss.  Many persons with tinnitus have the erroneous fear they are going to lose their hearing.  This is an unnecessary fear.

Stress and Depression

Stress in present in everyone life periodically.  There are five stress factors that may cause or aggravate stress: Chemical stress, Acoustic stress, Physical stress, Pathological stress and Emotional stress.  Examples of chemical stress include aspirin in high doses, caffeine, or some drugs used for chemotherapy.  There are many examples of very loud sounds in our everyday lives that may increase tinnitus.  Fatigue often contributes to the perception of tinnitus.  As a result, tinnitus is often louder at the of the day or after physical exertion.

In some, the ringing is chronic and can result in symptoms or lead to depression.  At times the tinnitus may lead to depression and this can make the tinnitus more bothersome: a vicious cycle develops.  Knowing this, we may recommend that a patient with severe tinnitus be treated with antidepressants or antianxiety medications.  Patients in this situation are also the ones who are most likely to benefit from biofeedback therapy (also known as Tinnitus Retraining Therapy).

Treatment

If the examination reveals a medical cause that may be causing the tinnitus, it will be addressed.  Even then, there are no medical or surgical therapies that are guaranteed to eliminate tinnitus.

General Measures

  1. Avoid all forms of loud sound.  If you must be exposed, use ear protectors such as ear plugs or ear muffs.  If you are exposed to certain sounds which increase the ringing, make it a point not to repeat that experience.
  2. Make every effort to avoid nervous anxiety, for this only stimulates an already tense auditory system.
  3. Make every attempt to obtain adequate rest and avoid over fatigue.
  4. The use of nerve stimulants is to be avoided.  Therefore, excessive amounts of coffee (caffeine) and smoking (nicotine)should be avoided. 
  5. Learn as quickly as possible to accept the existence of the ringing as an annoying reality and then promptly and completely ignore it.
  6. Tinnitus will not cause you to go deaf, will not result in you losing your mind, or cause your death.  You have been evaluated and we are confident that there is nothing waiting to take your life.
  7. Tinnitus is usually more marked after one goes to bed and the surroundings become quiet.  Any noise in the room, such as a fan or a radio or a sound generator, will serve to mask irritating ringing and make them less noticeable. 
  8. If one sleeps in an elevated position with one or two pillows, less congestion in the head will result and the tinnitus may be less noticeable.
  9. Sedatives of various types may be used occasionally for temporary relief.
  10. More often than not, having the reassurance of a thorough evaluation and implementing the above suggestions will be enough to manage the tinnitus.  In a small subset, the noise is too irritating and they are not able to focus on anything else.  In this group of patients, we may try a benzodiazepine or anti-depressant to help.

Hearing Aid

When the tinnitus is associated with a hearing loss, even a mild one, the use of a hearing aid in the involved ear is frequently very effective in reducing the awareness of the ringing by “masking out” the tinnitus.  It also possible for the audiologist to program the hearing aid to introduce a “white noise” in the background to help with the masking.

Tinnitus Masking

As mentioned before, in patients with hearing loss well fitted hearing aids are often the most effective treatment.  For individuals who have normal hearing but are severely distracted by their tinnitus, a tinnitus masker may be effective.  The tinnitus masker is essentially a hearing aid that generates a noise which is intended to prevent the wearer from hearing his own head noise.

Biofeedback Training

Treatment consists of biofeedback exercises in hourly sessions, in which the patient learns to control circulation to certain parts of the body and relax muscle groups.  It helps them to disassociate the stress and anxiety from the ringing.  Then the patient is able to accomplish this type of relaxation tinnitus often subsides.  An attempt is made to identify the pitch of the tinnitus.  We then recommend or program a masker matching this frequency as closely as possible.

Tinnitus Retraining Therapy (TRT)

This technique is based on the idea that the brain is flexible and can adapt to different situations, which is referred to as habituation.  TRT consists of two components: direct counseling and education to learn more effective coping techniques, and sound therapy.  The premise behind TRT is that with proper counseling, education, and understanding, the brain is able to habituate or get used to the sound pattern in order to both reduce the anxiety and allow one to focus their attention away from the tinnitus.  It is felt that the negative reaction to tinnitus is largely a conditioned response that may be altered with intervention.

For the sound therapy component, the patient wears a hearing aid type of device that presents a soft sound.  This is combined with adaptation techniques that are taught during the counseling sessions, allowing the brain to de-emphasize the importance of the tinnitus.  The actual counseling techniques are taught on a regular basis by an audiologist or professional who has received special training in this area.

Conclusions

The auditory (hearing) pathway is one of the most delicate and sensitive mechanisms of the human body.  Since it is directly associated with the general nervous system, its responses are in direct proportion to the anxiety state of the person involved. 

In order for any treatment of tinnitus to be successful, it is imperative that the patient have a thorough understanding of this distressing symptom complex.

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