Meniere's Disease

Introduction

Meniere’s disease is characterized by fluctuations in hearing, episodes of dizziness, tinnitus and a feeling of pressure in the ear. The classical type has attacks of dizziness lasting for minutes to hours, but there are several other forms that have fluctuating hearing loss, tinnitus and/or pressure but no dizziness, or just attacks of dizziness alone.
There are some associated and characteristic findings that help make the diagnosis. These include a typical sensorineural (nerve-type) deafness seen on audiometry, and often an ear that, despite the hearing loss, perceives sounds as being too loud and quite annoying. Some patients sense that there is a slight ache in or behind the ear. Patients with severe Meniere’s disease may have repeated spells of vertigo that may come frequently and without warning. Balance disorders can also make a patient lack concentration, have trouble focusing, and find it difficult to navigate through a supermarket or a shopping mall. The unpredictability of the vertigo spells can be dangerous, particularly when driving or working at any heights where precise balance is required. In severe cases, the incapacitating nature of this disorder and its unpredictability can create stress and some neurotic behavior that develops as a coping mechanism.
Over time, the severe cases gradually burn out; however, the price for this is usually good hearing. It may, however, take many years before the attacks eventually disappear. It is rare for this disease to be hereditary (less than 10%). Up to 40% of the cases will eventually become bilateral; however, if bilateral disease has not occurred within the first five years, the chances of occurrence in the other ear drops significantly.
Cause
There are many forms of Meniere’s disease and several possible causes. It is generally thought that the majority of cases are idiopathic, that is, that no specific cause will be identified. Some cases can be caused by head or ear trauma, some by middle ear infection, some by autoimmune or allergic problems, some by inner ear syphilis and, on occasion, by a virus. It is known that the end result is that the inner ear cannot get rid of the inner ear fluid (endolymph) that is constantly being produced, somewhat akin to glaucoma developing in the eye. The normal site within the inner ear that resorbs fluid is the endolymphatic sac that lies under the mastoid bone and up against the brain covering known as dura mater. Because fluid overload of the inner ear is present, factors that affect the retention of fluid in the body will have an adverse effect on this disease. Total body salt content is very important, as the more salt one has in the tissues, the more water that is retained. Similarly, in women, hormone shifts can cause fluid retention and aggravate the problem. In fact, some women will have exacerbations premenstrually, when they take birth control pills or estrogen replacement hormones.
Diagnosis<STRONG)DIAGNOSIS< strong>
It is important to make sure that there is nothing seriously wrong that may be causing the symptoms of inner ear disease. In order to do this, a hearing test and some blood work will be ordered. Additionally, depending upon the results, several other tests may be ordered, such as BERA (brainstem evoked response audiometry), to look at the functioning of the auditory nerve and brain; an ENG (electronystagmography), to assess possible damage to the inner ear balance system; an ECoG (elecrocochleography) to determine if the inner ear has an overabundance of fluid; and an MRI to visualize the nerves and brain.
Not all tests will be needed and each is ordered when the specific information that it produces is helpful in confirming the cause, delineating the amount of damage, and, in some cases, to determine which ear is affected by the illness.
The ear will look normal in Meniere’s disease and there will be no evidence of middle ear or Eustachian tube problems. Unfortunately, it is common for an untrained observer to conclude that ear infections are present, and antibiotics and decongestants are often prescribed to be on the “safe side.”
Medical Treatment
The mainstay of treatment for Meniere’s disease involves drugs to reduce the dizziness and drugs to reduce the fluid overload of the inner ear. When dizziness is occurring, vestibular sedatives such as Compazine, Dramamine, Antivert (meclizine), Phenergan, and Valium (diazepam) are prescribed. Since these provide symptomatic relief, they usually are needed only when dizziness is present. Some patients who are having multiple spells on a daily basis find that a low dose of these medications, taken around the clock, help them considerably. They do cause some drowsiness, however.
In order to treat the disease, we prescribe diuretics and a low salt diet. The diuretics alone will not help if a liberal salt intake is occurring, so we recommend a 1200-1500mg low salt diet. The diuretics that are most commonly prescribed are hydrochlorothiazide (HCTZ), Maxzide, aldactone, Lasix (furosemide), or Diamox (acetazolamide). Some diuretics also cause potassium to be lost in the urine, so potassium replacement is a must. Eating fresh bananas and oranges helps but is not usually sufficient to keep up with the potassium depletion. How long should the diuretics be continued? We recommend that diuretics be continued until no symptoms remain in the ear, exclusive of tinnitus, which may never completely resolve. Once the dizziness ceases and inner ear pressure and hearing loss improve, a slow withdrawal of the medication can begin. Usually we suggest that if twice a day diuretics are prescribed, then they be cut back to once a day for several weeks. If that is well tolerated, then they should be reduced to every other day. At that point, they can be stopped altogether and used on an as-needed basis, being guided by pressure, lightheadedness, or hearing loss.
On occasion, we find in our blood work that there is an abnormality suggesting the possibility that an autoimmune disorder may underlie the disease. If so, a short course of steroids (Medrol or prednisone) may be recommended. The side effects of prolonged steroid use are significant, so they must be used carefully. However, when an immune cause is identified, steroids plus diuretics may be the only effective treatment and the disease can be put into remission by such a regimen.
What about alcohol and coffee? The information about their effects on Meniere's disease is spotty and anecdotal at best. However, you might wish to experiment by avoiding them for a period of time to see if they particularly affect you.
With close follow-up and the aforementioned medical therapy, approximately 80-85% of patients with Meniere's disease will be controlled. Occasional spells of dizziness may occur, but with medication they can be minimized. Most experts feel that once a patient has developed classical spells, their ears will remain “prone” to relapses, even if they have been well-controlled by medication. As a result, one needs to be vigilant about diet, etc.
Surgical Treatment
Only a minority of patients need surgery; however, when medical treatment fails and there are incapacitating symptoms, patients and doctors then need to consider this next level of treatment. No patient should ever have to suffer from continued severe vertigo in this disease, as it can always be remedied. The types of therapy depend upon how good the hearing is. There are destructive procedures and more physiologic ones which will now be described.
Endolymphatic Sac Surgery
This is an ear operation that is done to drain and open the endolymphatic sac, the site that is responsible for resorbing inner ear fluid. This is a mastoid operation that takes approximately 1-2 hours. It is done under general anesthesia and the patient may stay overnight or, if doing well, may go home that afternoon. This operation will usually not cause hearing loss, but carries with it the risks associated with any ear operation: hearing loss, dizziness, and facial nerve weakness. This surgery has a success rate of 60-70% in control of vertigo. We usually do not perform this surgery solely for hearing loss, as it is impossible to predict if hearing will improve with time following the surgery. Sometimes there will be dramatic hearing improvement; however tinnitus is rarely affected. Why doesn’t this surgery work every time? Since this site of drainage for the inner ear is at the end of the drainage system, it requires that the ducts (tubes) that carry the fluid be open all the way to it, for the surgery to be successful. If the ducts are blocked upstream, then opening the sac will not have the desired effect. Unfortunately, there is no way to determine this preoperatively. This is a conservative, nondestructive procedure that is often recommended as a first step in attempting to control the illness.
Vestibular Nerve Sectioning
This procedure is done with a neurosurgeon, and is an intracranial approach. The procedure takes approximately 1-2 hours and requires a three-to-five-day hospital stay. In this microsurgery, the facial nerve is first positively identified by electrical stimulation, and then the eight nerve is exposed and the balance portion is identified and cut. The hearing nerve is spared. Sometimes the separation between the hearing and vestibular nerves is not distinct. In this case, the surgeon must estimate the percentage of the nerve that is balance and perform the neurectomy without exact knowledge of how much of the nerve carries hearing fibers and how much carries balance. Since vertigo is the compelling reason for doing the surgery, we usually recommend that we err on the side of taking more of the nerve rather than less, in order to ensure relief from vertigo, even at the expense of some hearing. The risks of the surgery include deafness, persistent dizziness, facial nerve weakness, meningitis, cerebrospinal fluid leakage, stroke and bleeding. While these risks are exceedingly small, they nevertheless need to be considered.
This operation is reserved for patients who have good hearing but severe vertigo, and who either have failed the endolymphatic sac procedure or only wish to undergo one, definitive operation. The success rate for relief of attacks of vertigo is 90-95%. Since the balance nerve has been cut and no information gets to the brain from the diseased labyrinth, some unsteadiness, particularly in the dark or with quick turns, can remain permanently.
Cochleosacculotomy
This is a procedure that attempts to drain fluid and create a fistula upstream rather than down at the endolymphatic sac. It is a procedure that can be performed in thirty minutes under local anesthesia and as an outpatient. It does not destroy balance function but tries to restore normal physiological function. It is a good choice for patients with severe dizziness and relatively poor hearing, especially if they are elderly and might have a hard time compensating after destruction of their balance system. The major drawback to this procedure is that there may be significant hearing loss from it (especially at high frequencies) and, over time, symptoms might return due to closure of the internal fistula. The success rate is approximately 65-70%.
Labyrinthectomy
This is an excellent, safe, definitive destructive procedure in which the balance organs are systematically drilled away under general anesthesia. Hospital stay is usually three to five days. Hearing will be lost from the procedure, so it is recommended for patients with severe vertigo and poor hearing. This has a high cure rate for vertigo (90-95%), but in elderly people with poor vision or any preexistent brain dysfunction, there can be a problem adjusting to the loss of balance function. Risks include persistent dizziness; definite, profound deafness in the operated ear; tinnitus; and facial nerve weakness.
Gentamicin Chemical Labyrinthectomy
This is an outpatient procedure that capitalizes on the known toxicity of this antibiotic to the inner ear. This drug, in drop preparation, is instilled on a daily basis into the ear canal or through a catheter into the middle ear through a small hole made in the eardrum.
Over time, enough of the antibiotic will be absorbed into the inner ear to cause a destructive effect on the balance system. Unfortunately, the drops also have a potential to destroy hearing and cause tinnitus, so it must be used with great caution in hearing ears. Because absorption of the drops is unpredictable and susceptibility varies, the end result will vary from patient to patient. Therefore, patients may still have instability because of the incomplete “labyrinthectomy.” This is a good technique in patients too ill to undergo surgery or who have poor hearing, but it is still a destructive procedure, and compensation issues raised above pertain to this procedure, as well.
Comment

Each of these techniques is designed to alleviate the symptoms of a patient with intractable Meniere's disease. This discussion is to allow you to reiterate what your doctor has told you and should not be substituted for a frank discussion about your own personal case.