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Meniere's Disease or Syndrome
ALTERNATIVE NAMES: Endolymphatic hydrops, recurrent episodic vertigo, cochlear hydrops.
DEFINITION: Meniere's syndrome is a result of a build-up of fluid pressure inside the inner of two fluid-filled compartments in the inner ear, the endolymphatic system. The term Meniere's syndrome is used if an identifiable cause of this increased pressure is present, such as syphilis, autoimmune inner ear disease, hypothyroidism, allergies, etc. The term Meniere's disease is used if there is no identifiable cause.
WHAT IS GOING ON IN MY BODY? The inner ear has two separate components. The first component, the cochlea, is a snail-shaped structure involved in hearing. The labyrinth consists of three semi-circular canals arising from a fluid-filled compartment termed the vestibule. Within the cochlea and the labyrinth are two fluid-filled compartments which are completely separate. The outer compartment is filled with perilymph, the chemical composition of which is very similar to that of spinal fluid and actually communicates through the periductal aqueduct. The inner compartment is filled with endolymph, which is chemically similar to that seen inside cells. The endolymphatic system drains through the endolymphatic duct into the endolymphatic sac. The separateness of these two fluid-filled compartments is vital for the creation of the initial electrical signal generated by the nerves for hearing or the nerve structures for balance. It is the movement of the fluid in the balance portion of the inner ear which deflects the sensors used to pick up head rotation and assist in the brain perceiving rotation.
In Meniere's disease or syndrome, there is poor drainage of the endolymphatic fluid compartment. As a result, these membranes are stretched as the fluid pressure increases. Because the endolymphatic system is common to both the hearing and balance components of the inner ear, in classic Meniere's disease or syndrome there are, therefore, effects upon both hearing and balance. The main distinction between Meniere's syndrome and disease is that in the disease there is no identifiable cause.
WHAT ARE THE SIGNS AND SYMPTOMS? In a classic Meniere's attack, the initial sign is a build-up of fluid pressure in the ear. As the fluid pressure builds up in the endolymphatic system, the patient will initially start to complain of a feeling as if their ear is plugged. Along with this plugging sensation, there is an identifiable real, usually temporary, decline in low-frequency hearing. Along with this decline in low-frequency hearing, a roaring-like sound in the ear (tinnitus) then occurs. With the ear symptoms, discomfort to loud sound may present, and individuals may comment that sounds are distorted in the affected ear just as if they are hearing through a broken speaker. With this increased pressure of fluid in the inner ear, diplacusis results. Diplacusis is defined as a perceived difference from one ear to the other of a single pitch. For example, in a patient with increasing endolymphatic fluid pressure, the same note on a piano will be heard as different notes between the two ears. Along with the hearing symptoms, there is the sudden onset of true vertigo, which patients describe as a spinning sensation. This is often so violent that nausea and vomiting ensue. Typically the vertigo lasts anywhere from 30 minutes up to 24 hours. On examination of an individual during an acute attack the eardrum and middle ear space are normal. They will often have diminished hearing in the affected ear. Using the tuning fork and asking them to determine whether or not it is the same pitch from one ear to the other looking for diplacusis is quite common. During the acute attack, nystagmus may also be present. Nystagmus is an abnormal eye movement caused by an acute dysfunction in the inner ear. Nystagmus is a back-and-forth or rotational back-and-forth eye movement that consists of a fast phase and a slow phase. The fast phase is in the direction of the normally functioning ear, whereas in the slow phase recovery its direction is toward the affected ear. A hearing test when the ear feels plugged will often demonstrate a decline in low-frequency hearing in the affected ear.
Typically when the acute attack resolves, the hearing comes back to normal; but Meniere's syndrome or disease can clearly cause a sudden, irreversible hearing loss.
Meniere's can also present with just the hearing symptoms, such as fullness, low-frequency hearing loss, tinnitus, loud sound discomfort and sound distortion, or episodic vertigo lasting hours. Ultimately individuals with these variations of Meniere's go on to form the full-blown symptom complex, whereby hearing and balance are both affected.
WHAT ARE THE CAUSES AND RISKS? In most patients who have Meniere's disease, the cause is never identified. The best evidence at present is that this is an inflammatory process affecting the endolymphatic sac so that it does not drain the endolymph appropriately. What causes the inflammation is not completely clear, but the most current data seems to suggest that it is an individual's immune system that can be attacking the endolymphatic sac. Herpes viruses have also been implicated as inflammatory agents of the endolymphatic system. Other diseases can also cause Meniere's-like symptoms. There are clearly some individuals in whom an allergic component may exist. These people may have a Meniere's attack after the ingestion of certain foods or at certain times of the year, the latter of which usually coincides with allergic eye and nose symptoms. Other causes have been suggested, such as hypothyroidism, elevated blood lipids, excessive salt loads, and caffeine intake. Syphilis affecting the central nervous system can also cause symptoms very characteristic of Meniere's, although typically syphilis or autoimmune attacks on the endolymphatic system usually affect both ears at some point. Approximately 50% of patients with Meniere's have it bilaterally.
The main risk from Meniere's, should it continue to occur, is a gradual worsening of a low-frequency hearing loss and chronic balance dysfunction. The vertiginous attacks can be quite debilitating, and if they do not respond to medical management, then procedures to destroy the balance component of the inner ear may be necessary.
HOW TO PREVENT THE DISEASE: Since most cases of Meniere's do not have a clear cause, prevention may not always be possible. For the individual who has it as a consequence of allergic processes, then avoidance of that to which the patient is allergic is important, or aggressive treatment with antihistamines and possibly allergy desensitization. Since autoimmune causes are a result of defective function of the immune system, this is not really preventable. In those individuals in whom it might be a result of elevated blood lipids, appropriate diet and cholesterol or triglyceride-lowering medications may be useful. It is quite obvious how syphilis might be prevented.
HOW IS IT DIAGNOSED? The main method of diagnosis is the history. It is also very beneficial to obtain a hearing test during and between acute attacks looking for the classical fluctuation in low-frequency nerve hearing. A special type of hearing test termed electrocochleography can also be performed. Meniere's patients have a characteristic change in the electrical currents in the inner ear which can be picked up with electrocochleography.
WHAT ARE THE LONG-TERM EFFECTS? Recurrent increases in pressure of the endolymphatic system can ultimately lead to progressive hearing loss and loss of balance function in the affected ear with resultant deafness and imbalance respectively.
AM I PUTTING OTHERS AT RISK? Individuals who have very frequent Meniere's attacks could be putting others at risk, particularly if they were to have a vertiginous attack while driving or working with machinery.
WHAT ARE THE TREATMENTS? The treatment will depend upon the cause of the Meniere's syndrome. If it is allergic, then aggressive avoidance, medical management, or desensitization may be useful. For those individuals with hypothyroidism, correction of their blood thyroid levels should help. Individuals with elevated cholesterol and lipids should have these controlled by diet and/or medication. For those patients whose Meniere's syndrome is caused by syphilis, long-term Penicillin therapy or other effective antibiotics is required. For the individual with very infrequent attacks, chronic medications may be excessive. Therefore, it may be best just to aggressively treat the acute dizzy attacks with antivertigo medications (Meclizine, Antivert, Valium derivatives, particularly Klonopin) and other medications that control the nausea. For individuals with more frequent attacks, daily diuretic therapy can often be useful. Avoiding caffeine and salt intake can also be helpful in some individuals. The addition of small blood vessel dilators, such as Papaverine, is often beneficial. In those who may have an immune system attack on the endolymphatic sac, steroids frequently will interrupt the dizziness attack and also temporarily reduce their frequency. There are some exciting and promising forms of steroid management which entail placing high dose steroids behind the eardrum concomitant with IV steroid infusions. After this initial three-day IV and steroid ointment treatment, the individual is placed on a small dose of steroids over the next month. Preliminary results indicate that 85% of patients with early forms of Meniere's have their disease process stabilize. For those individuals suffering from frequent, intractable episodes of vertigo, destructive procedures are often beneficial. These procedures take the form of surgery or medications. There are certain antibiotics, such as Gentamycin and Streptomycin, which are toxic to the inner ear and when placed in high dose concentration behind the eardrum can actually destroy the nerve elements of the hearing and balance portions of the inner ear. These individuals make a trade-off between deafness and a certain amount of permanent imbalance with the acute vertiginous attacks. Other forms of inner ear destruction, such as labyrinthectomy where the whole inner ear is surgically removed, can be helpful, particularly in individuals who have no residual hearing. The balance nerve itself can be cut, which may be employed in those individuals who still have reasonable levels of hearing.
WHAT ARE THE SIDE EFFECTS TO THE TREATMENTS? The side effects to the treatments would be specific to the various medications employed. The side effects to antibiotic destruction of the inner ear structures would be a certain degree of low-level permanent imbalance and possibly deafness. Low-level permanent imbalance and deafness certainly result from labyrinthectomy. A small amount of permanent imbalance would also be expected after cutting the balance nerves.
WHAT HAPPENS AFTER TREATMENT? Ideally for those individuals suffering from fairly frequent attacks, appropriate dietary avoidance combined with diuretics and possibly small blood vessel dilators will have a reduction in the frequency and severity of their attacks. As mentioned above, there are some early promising data for those individuals getting the steroid form of treatment. The greatest morbidity occurs with labyrinthectomy, where the patient becomes permanently deaf and has chronic imbalance.
HOW DO I MONITOR THE DISEASE? The disease is basically monitored by the frequency of the attacks and whether or not permanent injuries are beginning, such as hearing loss. If fluctuating attacks are severe enough to affect an individual's function and safety, then medical management must be obtained.
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