MENIERE'S SYNDROME INTRODUCTION

by Dr Mark J Levenson MD, FACS

Meniere's Disease is a very disturbing illness, presenting patients with hearing loss, pressure in the ear, tinnitus, severe imbalance and vertigo.

• Vertigo is the most dramatic and distressing symptom of Meniere's; it is described as a sudden loss of normal balance or equilibrium. The room may suddenly begin to spin and rotate at high speed. Focusing is difficult, and if the vertigo continues, nausea and vomiting may occur. Vertigo is commonnly caused by acute labyrinthitis (a viral inflammation of the inner ear), benign positional vertigo (a condition due to abnormally floating crystals in the inner ear that stimulate the nerve endings of the inner ear), delayed symptom of head injury, or result of cervical spine problems.
• Hearing loss typically fluctuates with hearing being worse some days than others. The hearing loss in Meniere's may lead to severe permanent hearing loss and deafness in the affected ear.
• People with Meniere's Disease report that tinnitus may be variable and often worsen before an attack of vertigo. Tinnitus is often described as a motor-like whirring noise present only in the ear with the hearing loss.
• Pressure or a sense of fullness in the affected ear are also common.

Meniere's Disease rarely occurs in children. In most cases, it begins in both men and women in the thirties or early middle age. Also, Meniere's is rarely noted for the first time in older people. Ear surgeons see many patients with dizziness. Very few of these patients actually have Meniere's Disease.

Symptoms

Symptoms of Meniere's Disease come in cycles. The patient suffers multiple episodes lasting several months at a time; then, it generally subsides. In some individuals, the symptoms seem to be more severe in spring, fall or when under extra emotional stress.

The most unpredictable and frightening symptom of Meniere's Disease is vertigo. The vertigo in Meniere's Disease is thought to result from an accumulation of excessive fluid in the inner ear. The fluid pressure stretches the membranes, that divide the compartments of the inner ear. As the membranes of the inner ear stretch, hearing diminishes and tinnitus worsens. When the membranes are severely stretched, the fluids of the inner ear may rupture them. This results in mixing of the fluids, one rich in sodium, the other rich in potassium. The mixture of these fluids is thought to bring on the vertigo.

After the membranes rupture, they eventually heal, but some hearing is usually lost. Surprisingly, with salt restriction, careful dietary planning and a mild diuretic, the symptoms of Meniere's Disease will often subside. In some cases, hearing can return to normal.

Classic symptoms of Meniere's aren't always present. Sometimes, hearing loss will precede episodes of vertigo by several years. Tinnitus alone, without associated hearing loss or vertigo, is rarely caused by Meniere's Disease. The only symptom in very early cases of Meniere's may be a sense of fullness or pressure in one ear.

Diagnosing Meniere Disease

Other conditions can produce the same symptoms as Meniere's Disease and, thus, have to be ruled out or excluded in order to develop an accurate diagnosis.

For instance, infections of the inner ear, including syphilis and Lyme's Disease, may produce episodes of vertigo and hearing loss quite indistinguishable from Meniere's; these symptoms usually occur in both ears. Tumors of the inner ear nerve (the eighth nerve), especially acoustic neuromas, can also produce similar symptoms. These tumors grow slowly and compress the nerve. Thus, the hearing loss doesn't have periods of improvement. Also, the patient usually experiences imbalance rather than vertigo.

Ten to 15 percent of cases resembling Meniere's Disease may be the result of an immune disorder of the body, the system producing antibodies which attack the inner ear. Cholesteatomas (cystic growths) and other infections of the middle ear can also produce symptoms similar to Meniere's.

How we diagnose

Initial evaluation is based on a very careful history given to the ear surgeon, as well as an examination of the ears under the operating microscope to rule out obvious infections or visible growths. Then, a comprehensive hearing test (audiogram) is taken. A low frequency upsloping hearing loss of the neural type noted on the hearing test is typical of Meniere's.

Additional testing is performed:

• electronystagmography, or balance test (ENG),
• electrocochleography (ECOG),
• brainstem evoked response audiometry (BSER),
• Magnetic Resonance Imaging (MRI) with a contrast dye called Gadolinium can rule out an acoustic neuroma or other brain tumor as a possible source of symptoms
• lab tests should include examination for inner ear immune related infections or conditions.

Once testing is completed, the ear surgeon can evaluate the results, rule out extraneous conditions and confirm the diagnosis of Meniere's Disease. Even after this extensive testing, the test results may not be conclusive.

What the tests reveal

ENG (electronystagmography) measures the nerve of balance. Over time, this nerve will lose function in Meniere's Disease. Most patients with Meniere's have a reduced response to stimulation with cold and warm water or air which is used in this test.

Electrocholeography (ECOG) measures the excess fluid accumulation in the inner ear; in Meniere's, this test will also confirm increased pressure due to excess fluids in the inner ear.

The Brain Stem auditory evoked responses (BSER) will usually be normal despite the hearing loss, unless a central disorder is present.

What the other tests show

The MRI with Gadolinium specifically visualizes the eighth nerve (acoustic and balance nerve). Some older scanners can miss a small acoustic neuroma (tumor). Newer MRIs can actually visualize the structures of the inner ear including the cochlea and semicircular canals. This is most helpful. The eighth nerve can be clearly identified on MRI scan. A nerve that does not show enhancement (increase in brightness), when the dye is given, rules out an acoustic neuroma from the diagnosis.

Laboratory tests are geared to identify other conditions that may be responsible for Meniere's. Syphilis can involve the inner ear even twenty to thirty years after the original infection. Lyme Disease can also produce Meniere's-like symptoms, and symptoms can surface months after the original infection.

Individuals with certain auto immune disorders such as Lupus and severe rheumatoid arthritis, or who suffer from thyroid disorders such as Grave's Disease and Hashimoto's thyroiditis may be at higher risk for developing Meniere's Disease. This sub-group with their potential auto immune cause for the Meniere's can often be successfully treated with medications which slow the immune system's responses: cortisone-containing medications such as Decadron or Prednisone.

Treatment

When the diagnosis of Meniere's Disease is eventually confirmed, treatment is directed at ending or markedly reducing the frequency and severity of attacks. Treatment includes modification of personal habits, diet, stress reduction and regular exercise -- all extremely important in the overall treatment of Meniere's Disease. Medications will be recommended; evaluation of all treatments must be carefully annotated.

Dietary

Dietary restriction of salt intake is primary. Most Americans consume over 10 grams of salt daily. Under normal conditions, the body requires 2 grams or less. The taste for salting food is an acquired one. Most individuals who restrict their salt intake become keenly aware of excess salt added to their food. Over time, salt restriction results in decreased fluid accumulation in the inner ear, reducing excess pressure on the nerve endings of balance and hearing. A daily diuretic, typically Hydrochlorthiazide (combined with Triamterene to retain potassium) help the body to further reduce fluid retention.

Other lifestyle modifications

Smoking must stop immediately. Smoking constricts and reduces blood flow to the tiny blood vessels which nourish the inner ear nerve endings. Caffeine in coffee, tea and colas, as well as chocolate, must also be eliminated from the diet since caffeine excessively stimulates nerve endings. Reasonable exercise such as a daily brisk walk will stimulate circulation and help blood flow. A regular exercise program is also helpful.

Vertigo medications

Valium (Diazepam) and other Benzodiazepines have a direct effect on the nerve controlling balance and its central connections to the brain. When Valium is given at the onset of a vertigo attack, it can prevent the attack from continuing. (N.B. Valium and similar medications should not be taken daily, because they may be habit forming.)

Eating pros and cons

Diets can include fresh meats, poultry, vegetables and fruits. Processed meats, canned products, monosodium glutamate, table salt and "Lite salt" should be avoided totally. Olives, pickled foods, chips and some cheeses are also very high in sodium and should be avoided. Flavor can be added by using natural herbs and other spices NOT mixed with salt. Many individuals with Meniere's follow a typical low salt diet, similar to those diets used to control high blood pressure. Dieticians, pamphlets, and diet books are sources of further information.

Younger patients

Young patients may have symptoms which are more severe and resistant to treatment. When recurring bouts of vertigo begin to interfere with daily activities, surgical options are often discussed. Generally, surgery is not to be considered unless attacks of vertigo are severe and do not respond to treatment. Often, patients with Meniere's have consulted a number of physicians who used the aforementioned treatments without success. Combining Cortisone-type medications with diuretics should be tried once again. Dyazide, combined with oral Decadron or Prednisone (cortisone) given over a period of 2 to 3 weeks will be helpful in gauging some form of medical response. If combined cortisone and diuretics plus diet are not effectice in improving clinical symptoms, then surgery is advised.

Surgery: Endolymphatic sac decompression

The actual cause of the fluid accumulation in the inner ear, the condition which sets off the whole process to begin with in Meniere's Disease, is not known. In animals, experiments have been done which show that if the sac that drains fluids from the inner ear is tied off, fluid will build up in the inner ear and cause changes comparable to those in humans. Because of the observation of fluid build up in the inner ear of animals, the most commonly performed operation in the past involved drainage of the endolymphatic sac in patients with Meniere's.

The endolymphatic sac decompression operation is performed by making an incision behind the involved ear and exposing the mastoid bone. The mastoid is opened, and the facial nerve is identified in its course through the mastoid. The bone over the endolymphatic sac is then exposed and once identified, the sac is opened. A non-reactive sheet of silastic or a valve is inserted into the sac to allow for future drainage, when fluid reforms. The operation takes about an hour.

In theory, the endolymphatic sac operation should decompress the excessive fluid within the inner ear chambers and allow the inner ear to re-equilibrate, taking pressure off the nerve endings of hearing and balance. Studies have shown little positive effect on hearing from drainage of the endolymphatic sac. ESD often does NOT cure Meniere's sufferers. Vertigo subsides after surgery in about 70 percent of Meniere's cases, but vertigo symptoms recurr with the same severity as before in a significant number of individuals within three years of surgery.

Surgery: Labyrinthectomy

Historically, ear surgeons have tried many procedures to cure vertigo. In individuals with complete or near complete hearing loss in one ear due to Meniere's, a surgical procedure termed a labyrinthectomy is usually curative. Using the same approach through the mastoid bone as the older procedure, the endolymphatic sac operation, the inner ear balance organ (the labyrinth) is exposed. The semicircular canals are then carefully drilled away, exposing the nerve of balance which is completely removed.

Following surgery, there is often severe vertigo for a day or two. This can be controlled with medication. After a week, the patient experiences a period of moderate imbalance without vertigo while the opposite ear takes over the command of the entire balance function and assumes full control. This period can last six to eight weeks. The more active an individual is after surgery, the more rapid the recovery of balance function will be.

The two inner ear balance centers can be thought of as gyroscopes. The gyroscope of each ear helps to control balance by sending signals of the position we are in to the brain. If one gyroscope is faulty, as is the case in Meniere's, the brain has trouble adapting, since it is intermittently getting wrong signals mixed with correct ones. However, if the inner ear balance nerve is completely shut off on one side and the "faulty gyroscope" removed, the brain will adapt to this new situation, since it now receives only correct signals from the one remaining gyroscope (inner ear) which will control the entire balance function. This is the reason labyrinthectomy is successful.

Labyrinthectomy does not spare any residual hearing. In a young individual, surgery that conserves the remaining hearing in the ear affected by Meniere's is most important. A certain percentage of young people with Meniere's may also develop the illness in their opposite ear later in their lifetime: 10 to 20 percent.

Surgery: Vestibular neurectomy

If there is substantial hearing present, vestibular neurectomy may be a prefered surgical option which can cure vertigo and preserve hearing.

Vestibular neurectomy involves the discrete sectioning of the nerve of balance near where it comes out of the brain. The hearing portion of the nerve is thus preserved. Ninety to 95 percent of vestibular neurectomies will result in cure of vertigo.

Hearing is preserved at the level experienced before surgery in most cases. The operation is a team effort performed by an ear surgeon and a neurosurgeon. Since the nerve must be identified as it exits the brain, the vestibular neurectomy is an intracranial operation.

Recovery from a vestibular neurectomy is similar to that of a labyrinthectomy. However, because it is an intracranial (brain) operation, closer post-operative monitoring will be the order of the day. Younger people (those who are less than 60) who are in good health are offered this operation as the most definitive operation both to cure vertigo from Meniere's and preserve hearing. This minimally invasive operation takes less than two hours. A hospital stay of three or four days is usually necessary...

Other surgical procedures have been attempted over the years to treat Meniere's Disease. Although the endolymphatic sac operation seems appealing from a physiologic point of view, the operation fails in many cases. This failure is probably due to the fact that the canal leading to the endolymphatic sac from the inner ear may be obstructed or clogged. Draining the sac can remove the excess fluid within it, but does not allow continuous drainage of fluid from the inner ear to the sac.

Chemical labyrinthectomy

In the past several years, studies have been conducted placing specific antibiotics into the inners ear to treat Meniere's Disease. It has been known for over forty years that streptomycin, an antibiotic rarely used today, is toxic to the nerve of balance. This information has been used by researchers who give very small doses of streptomycin (or more recently, gentamicin) directly into the ear. The intent of this treatment is to deliver sufficient medication to stabilize or partially destroy the nerve endings of balance while sparing the nerves of hearing. Further research is underway. There is one significant exception.

In cases of Meniere's Disease affecting both ears simultaneously, the administration of streptomycin intramuscularly (injection into the muscle of the arm or buttocks) can cure vertigo attacks and hearing may also be spared.

Treatment, of course, affects both inner ears, and leaves the individual with complete absence of balance nerve function, both gyroscopes having been stilled. Most people can adjust to this loss of balance, although they often complain of a "bouncing up and down feeling" when walking. The horizon may also seem to move up and down with their steps. This sensation is called Ossiculopsia. For this reason, the streptomycin injections are only recommended for Bilateral Meniere's.

Other factors: Lifestyle modification

Meniere's Disease is an episodic illness. Attacks come in cycles followed by symptom-free intervals. Studies measuring the results of treatment must be carried out over periods of years to be of scientific value. Many treatments have been advocated at one time or another for Meniere's, only to have them abandoned a few years later when studies proved them to be ineffective.

Stress, emotional or physical, also seems to play a significant role in precipitating attacks. Some researchers have considered Meniere's a psychosomatic illness (an illness that has a psychological root). This is certainly not true in all cases of Meniere's.

There is no doubt that stress is often associated with attacks, but whether stress causes or is the result of the attack, is not clear. The vertigo attacks, when they occur, may be so frightening and unpleasant that apprehension exists constantly. The patient fears that an attack may interrupt life at any time. This can result in added fears and stresses, worsening the condition.

It is important for the individual with Meniere's to gain control again over the illness and be able to prevent attacks. This can often be achieved by medical therapy and rehabilitated lifestyle. In those cases where medical treatment and lifestyle modification are not successful (usually less than one-third), surgical treatment is often the curative solution.