The ear is divided into three parts; the external ear, middle ear and inner ear. Each part performs an important function in hearing and/or maintenance of balance.
Sound waves pass through the ear canal of the external ear and vibrate the tympanic membrane (ear drum). The tympanic membrane separates the external and middle ear. There are three small bones of hearing (hammer or malleus, anvil or incus, stirrup or stapes) in the middle ear which act as a transformer to transmit the energy of sound vibrations to the inner ear fluids. The inner ear (labyrinth) contains two fluid systems, one suspended inside the other, separated by a thin membrane. This system contains a delicately balanced fluid which bathes nerve endings responsible for hearing and balance. The nerve endings generate electrical impulses in the hearing center (cochlea) which are then transmitted through the hearing nerve to the brain where they are interpreted as sound. Movement of fluid in the balance portion of the inner ear (vestibule and semicircular canals) results in electrical impulses which are sent through the balance nerve to the brain where they are interpreted as motion. The inner ear senses posture, rotation, acceleration and deceleration.
Meniere's disease is a problem with the fluid balance regulating system in the inner ear. The exact cause of the disease remains unknown. It is defined as the symptom complex of; episodic vertigo (vertigo being the sensation of spinning or whirling), tinnitus (hissing, ringing or roaring usually in one ear), fluctuating hearing loss (usually in the ear with tinnitus) and aural pressure (feeling of fullness or pressure in the involved ear). All these symptoms form a pattern which makes up "Classical Meniere's Disease". This pattern is usually a sensation of pressure build up in one ear with increasing tinnitus and a drop in hearing. Then the vertigo comes, often quite suddenly, and may last for hours or days. The severe vertigo subsides and balance may takes weeks to return to normal. Once the vertigo attack is over, hearing often improves.
The current theory is that Meniere's Disease symptoms are caused by an imbalance in fluid pressure between two inner ear fluid chambers. The endolymphatic chamber is believed to build up excess fluid and pressure causing the feeling of pressure, increased tinnitus and worsened hearing. Once the pressure has reached a critical level, the thin membrane separating the endolymphatic and perilymphatic chambers ruptures, causing a mixture of the fluids from the two chambers. These fluids are chemically different and their mixture causes a "short-circuiting' of the inner ear. This results in the severe vertigo of the Meniere's attack. Once the pressure has been released, this membrane heals and the fluid chemistries return to normal. It is thought that when this healing occurs the hearing recovers, although not always completely. This fluid pressure build up can reoccur causing the symptoms to return. It is important to remember that this is all theory supported by the appearance of microscopically examined inner ears from deceased patients who had Meniere's Disease during their lifetime.
No one knows for certain, but there are several theories surrounding this issue. Some researchers feel it is a defect in the reabsorption of endolymphatic fluid in the endolymphatic sac (part of the endolymphatic chamber felt to remove excess fluid). Others feel that too much fluid is made causing a pressure build up. yet others feel there may be scarring in the endolymph system blocking the flow of fluid. Whatever theory, or combinations of theories may be correct, microscopic evaluation of inner ears from Meniere's patients show the endolymphatic chamber to be dilated. Many factors can affect how often symptoms appear and how severe they may be. Minimizing salt intake in the diet is critically important. Americans consume excessive amounts of salt. This excessive salt intake can make Meniere's disease worse by causing extra fluid retention in the endolymphatic chamber. Therefore, limited salt intake to 1,500 mg per day can have a favorable impact on Meniere's Disease. Other factors can influence Meniere's such as caffeine and tobacco use which worsen symptoms. Along with limiting salt, caffeine and tobacco consumption, stress reduction can also decrease Meniere's symptoms. Stress at home, work place or school can set off or worsen Meniere's symptoms. Biofeedback training is very effective in helping control the effects of stress on the body.
This questions is difficult to answer satisfactorily because individual cases are extremely variable. Some patients will have only one attack, never to be bothered again. Another group of patients will have their initial episode which is followed by a symptom-free period which may last many years. Symptoms then return and can be quite sporadic.
The more typical history of Meniere's Disease is one of repeated bouts of vertigo, tinnitus, and hearing loss. These attacks can vary in frequency from once to several times per year. There can be considerable variation in the symptom-free intervals. In addition, the symptoms can vary in their intensity and duration from one attack to another. The disease can continue in this unpredictable fashion for several years and will often "burn out" after a period of 8-10 years. In the process of "burning out", vertigo will tend to become less severe and less frequent. At the same time, hearing will have a tendency to recover less and less after each attack until, unfortunately, many patients become deaf in the affected ear. In 70% of Meniere's patients, vertigo will resolve under medical treatment alone in 8-10 years.
In some patients, Meniere's Disease takes a more debilitating course. This group of patients will suffer frequent, severe bouts of vertigo, tinnitus and hearing loss. So much so that they cannot work, drive an automobile, or even walk about without fear of falling. These severe symptoms can persist in spite of aggressive medical therapy, including diet modification. It is these patients that most often undergo surgery to control their vertigo symptoms.
So far we have discussed unilateral Classical Meniere's Disease (only one ear affected). Meniere's Disease can have atypical forms in which balance alone may be affected (vestibular hydrops). Another type is cochlear hydrops in which the symptoms of tinnitus and fluctuating hearing loss occur without vertigo. Common to both is the sensation of aural fullness. There are studies which show that 20-30% of patients with Meniere's will develop the disease in their previously unaffected ear. This situation is serious, since there is potential for complete deafness. It is also challenging to treat, since symptoms can come from either ear. In patients who have bilateral Meniere's (both ears affected) with severe symptoms, surgery is an absolute last resort since one is not certain about which ear to operate on.
Medical treatment of Meniere's Disease is aimed at decreasing the amount of fluid in the inner ear. This is accomplished by following a low salt diet and taking a diuretic (water pill).
Salt (sodium chloride) causes water to be retained by the body; therefore, by reducing the amount of salt in the diet less fluid will be retained. A diuretic is taken on a routine basis to further reduce the amount of fluid in the body. The above treatments are aimed at controlling the disease process and can be used for many months or years.
In addition to the low sodium diet and diuretic, a vestibular suppressant, such as Antivert, Centrax, Phenergan, Robinal or Valium, may be prescribed for symptomatic relief of dizziness. Basically, these medications tell the brain not to pay attention to the abnormal impulses coming from the ear.
Surgical intervention is considered only if medical treatment has failed and the patient is suffering from incapacitating vertigo. Every effort is made to conserve hearing; therefore, the type of surgery depends on the amount of hearing loss in the affected ear. Although hearing may be worse after surgery, it usually remains the same. Tinnitus may or may not be improved.
Depending on the type of surgery, there is an excellent chance of controlling the attacks of dizziness. These attacks may be replaced by a feeling of unsteadiness or lightheadedness for a period of six to twelve months until the brain and opposite ear take over balance function.
The following is a description of the types of surgery that are available. Your physician will discuss with you in detail the type of surgery best suited for you.
This surgery is designed to preserve hearing. An incision is made behind the affected ear and the mastoid air cells are removed to gain exposure to the inner ear. A small incision is made in the endolymphatic sac to allow excess fluid to drain into the mastoid area.
The success of the surgery cannot be predicated immediately because the reaction of the ear to the stimulation will differ from patient to patient. In some patients, there may be an immediate noticeable improvement in ear pressure and tinnitus, while in others there will be no improvement at all. Since the surgery causes irritation to the ear, dizziness and ear symptoms may continue for several months; therefore, the success of surgery often cannot be predicted for at least several months.
Overall, there is a 60% chance of controlling the attacks of vertigo, a 20% chance that the attacks will remain the same, and a 20% chance that the attacks will be worse. Hearing may stabilize but rarely improves and tinnitus may be unaltered. There is a 2% chance of total deafness in the operated ear. Even if hearing is lost, dizziness often still improves.
Because the nerve of facial movement (facial nerve) lies next to the inner ear, there also is a small chance that a temporary weakness of the face could occur for several days or weeks after surgery. This generally recovers completely, but not always.
This procedure is performed when there is no useful hearing in the ear. It sacrifices all remaining hearing in that ear.
The surgery requires general anesthesia and a three to four day hospitalization. An incision is made behind the ear and the mastoid air cells are removed. Once the inner ear (labyrinth) is identified, the entire bony inner ear is surgically removed.
Postoperatively, the patient may be quite dizzy for several days, may need some assistance with bathing for another week at home, and may require several months before feeling completely well. If the symptoms are severe during the immediate postoperative period, intravenous fluids and medications are given to control the dizziness.
With this operation, there is an excellent chance of controlling dizziness. Total deafness in the affected ear is the expected result of the surgery. Temporary facial weakness can occur as in all operations for dizziness.
This surgery requires general anesthesia and a one week hospitalization. An incision is made behind the ear, the mastoid air cells removed and the inner ear structure surgically removed. The dura (brain covering) of the internal auditory canal is then located. An incision is made in the dura to expose the balance and hearing nerves. The nerves are divided. Then a small piece of fat taken from the abdomen is placed over the dura opening to prevent a spinal fluid leak.
The postoperative course is like that of a labyrinthectomy. (see "Labyrinthectomy" for more details)
There is an excellent chance of controlling the vertigo. There is a 50% chance of improving tinnitus.
Due to the close proximity of the hearing and balance nerve to the facial nerve, again there is a chance of developing a transient facial weakness or paralysis postoperatively. There is also the chance of developing a spinal fluid leak and meningitis.
Total deafness in the affected ear is the expected result of surgery.
This surgery is designed to preserve hearing. This procedure requires general anesthesia and a one week hospitalization. An incision is made behind the ear and the mastoid air cells removed. An opening is made in the posterior fossa dura (brain covering) and the eighth cranial nerve (hearing and balance) is identified behind the inner ear. The balance portion of the nerve is identified and selectively cut.
The immediate postoperative period is similar to a labyrinthectomy. (see "Labyrinthectomy" for more details)
There is a chance of developing a spinal fluid leak or meningitis. There is a 5% chance of total deafness in the affected ear. Temporary facial weakness or paralysis is rare but may last for several days, weeks or even months. It generally resolves completely.
There is approximately an 85% chance of controlling the dizziness.
There is a Chronic Ear Disease Support Group located in the Metro area. If you would like to talk to someone you can call 339-2120.
One option for patients with Meniere's disease is physical therapy assessment and treatment for the symptoms of dizziness and balance problems that may occur. Vestibular rehabilitation is an exercise approach to the remediation of disequilibrium and dizziness. Although exercise cannot cure Meniere's disease, it offers the patient a program to manage the symptoms of the disease. Specific exercises are designed to 1) decrease dizziness; 2) increase balance function; and 3) increase general activity levels. The exercise program is designed to promote the ability of the brain to compensate for inner ear deficits. The assessment usually takes 1.5 hours and patients are given a home program. Follow-up is by telephone or 1-2 additional physical therapy sessions, as needed. This program is offered through the Human Performance Laboratory, Program in Physical Therapy, and is coordinated by Patricia Montgomery, Ph.D., P.T.