Meniere's Disease: |
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GLENN W. KNOX, M.D. |
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Meniere's disease may be the underlying cause of dizziness, which is a common presenting complaint. This disease is differentiated from other causes of dizziness by its classic constellation of four symptoms: dizziness characterized as episodic spinning or whirling vertigo; fluctuating, low frequency sensorineural hearing loss; tinnitus, and a sensation of fullness in the ear. Because these symptoms may or may not develop or occur simultaneously, a careful history and a complete physical examination are necessary for diagnosis. If Meniere's is present but untreated for 10 or more years, hearing may deteriorate as the vertiginous episodes gradually subside. Medical management includes sodium restriction and the avoidance of caffeine and alcohol. Diuretics, antiemetics, antidepressants and vestibular suppressants may be prescribed, and surgery may be considered in severe, unresponsive cases. Meniere's disease is characterized four distinct symptoms: fluctuating sensorineural hearing loss, classically involving the low frequencies; vertiginous episodes; aural pressure, and tinnitus that is most frequently described as roaring. Any one of these symptoms may precede the others, but they characteristically appear together. Meniere's disease occurs fairly equally in men and women, with symptoms usually developing n the fifth decade of life. Rarely, the disease id diagnosed in children. Approximately 30 percent of patients with Meniere's disease have bilateral involvement. Because of the inconsistency in establishing the diagnosis, the true incidence of the disease is unknown. However, it is estimated that 300,000 new cases develop each year. |
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Clinical Presentation |
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| Early in the course of Meniere's disease, the primary complaint is an episodic vertigo that lasts from minutes to hours and is associated with nausea and vomiting. Most commonly, aural pressure, fluctuating tinnitus and fluctuating hearing loss accompany the vertiginous episodes. The dizziness or vertigo is most often described as a sensation of whirling or of the room spinning. During the active phase of Meniere's disease, patients can have more than 30 attacks of vertigo a year. In the later phase of the disease, the autometric pattern is flat but slightly worse for the very low and high frequencies, and there is no fluctuation n audiometric findings and/or subjecting hearing. | |
Differential Diagnosis |
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| When Meniere's disease presents with isolated auditory (cochlear) or
vertiginous (vestibular) components, the differential diagnosis becomes very important,
since dizziness is the presenting complaint in a number of disorders. In addition to
Meniere's disease, the most common diagnoses related to dizziness include benign
paroxysmal positional vertigo, vestibular neuronitis, vertebrobasilar insufficiency,
atherosclerosis, presbystasis, acoustic neuroma, vertiginous or basilar artery migraine,
and head trauma syndrome (Refer to Table I here or
below) Dizziness is a symptom of various other medical problems, including
(but not limited to) syphilis, impaired thyroid function, hypoglycemia anemia, cardiogenic
disorders and incompletely treated Lyme disease. Other central nervous system causes
of dizziness include brain tumors, demyelinating disorders and cerebellar infarcts. The
patient's description of the dizziness is extremely important. Lightheadedness or
wooziness is distinct from spinning vertigo, although both may be described as
dizziness. |
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Dizziness Characterized as Spinning or Whirling Vertigo: |
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Benign Paroxysmal Positional Vertigo: |
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| This condition is characterized by whirling vertigo without other aural symptoms. Dix-Hallpike or positional testing, which is used to diagnose this condition, can be performed in the office. In classic benign paroxysmal positional vertigo, dizziness is elicited by turning or hanging the head to the affected side. It is theorized that the dizziness associated with this condition is caused by the displacement of crystals (i.e., otoliths) from the utricle. The canalith repositioning procedure is used to realign the crystals and to treat the dizziness. | |
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Vestibular Neuronitis: |
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| An upper respiratory tract infection usually precedes vestibular neuronitis. The etiology is thought to be viral. In its acute phase, vestibular neuronitis is associated with severe vertigo that lasts for hours to days. The vertigo then resolved to constant imbalance or lightheadedness, which can persist for months in some cases. Daily quality of life is severely affected. No other aural symptoms occur. In intractable cases, benzodiazepines or antihistamines are sometimes used. | |
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Viral Labyrinthitis: |
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| This disorder mimics vestibular neuronitis, but hearing loss also occurs. Viral labyrinthitis, like vestibular neuronitis, resolves slowly over weeks to months. Some resolution of hearing occurs concomitantly with the resolution in dizziness. | |
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Vertebrobasilar Insufficiency and Atherosclerosis: |
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| These conditions can also cause dizziness. Vertebrobasilar insufficiency is suspected when a patient has dizziness while leaning the head backward, possibly reducing blood flow to the brainstem. The diagnosis of vertebrobasilar insufficiency and/or atherosclerosis can be difficult and often depends on the exclusion of other disorders. The diagnosis can be supported by a history of atherosclerosis in other vessels, as well as compatible findings on imaging studies, such as magnetic resonance angiography or ultrasonography of the neck vessels. | |
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Vertiginous Migraine: |
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| This disorder is characterized by vertigo in combination with either a
classic or atypical migraine pattern. In basilar artery migraine, transient
reduction of basilar artery blood flow produces a variety of symptoms, including ataxia,
vertigo, tinnitus, nausea and headache. Basilar artery migraine may also produce
diploma, dysarthria, paresthesias or a throbbing occipital headache. In addition,
fluctuating fullness and hearing loss may occur, but tinnitus is rare. Like all
migraines, those involving the basilar artery are associated with a strong familial
tendency and tend to occur more frequently in females. For any of the disorders that have a peripheral vestibular component, a course of physical therapy with an emphasis on vestibular rehabilitation may be helpful. |
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Dizziness Characterized As Light-headedness: |
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| A patient may characterize the symptom of dizziness as lightheadedness rather than true vertigo. The disorders associated with this type of dizziness are presbystasis, acoustic neuroma and, in some cases, head trauma syndrome. | |
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Presbystasis: |
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| A degeneration of the vestibular system that occurs with aging, presbystasis should not be confused with orthostasis of aging, which may be accompanied by lightheadedness with standing or walking. Imbalance and slight gait disturbance are common symptoms of presbystasis. Presbystasis may or may not be accompanied by degenerative hearing loss. Physical therapy is the treatment of choice, especially when gait disturbance predominates. | |
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Acoustic Neuroma: |
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| This benign tumor of the eighth cranial nerve typically causes gradually progressive imbalance and hearing loss on the affected side. Asymmetric hearing loss would be considered suspicious and should be evaluated with either a brainstem auditory evoked response test or magnetic resonance imaging (MRI) for the purpose of ruling out a tumor. | |
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Head Trauma Syndrome: |
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| In this syndrome, dizziness develops weeks to months after head
injury. Head trauma syndrome, which is very common after motor vehicle accidents is
thought to be the result of diffuse axonal damage. In addition to dizziness, patient
complaints commonly include tinnitus, slightly impaired cognitive ability (especially
visual and auditory memory and tasking) and headache. The symptoms persist for a
considerable period. Occupational and physical therapies are the most effective
treatments. Head injury with or without fracture of the temporal bone may result in a dramatic loss of equilibrium. It is becoming increasingly evident that much of the vertigo that occurs after head injury may have its origin outside of the labyrinth. Marked ecchymosis and edema of the brainstem, cerebral cortex and cerebellar cortical areas may be present. While Meniere's disease may occur following head trauma, such patients commonly have a mixed type of vertigo with both central and peripheral components. Surgery is less effective in these patients, as it only addresses the peripheral component. Hence, surgery should only be undertaken in cases in which the peripheral component predominates. |
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Idiopathic Meniere's Disease: |
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| Most cases of Meniere's disease are classified as idiopathic, and the diagnosis in based on the exclusion of other pathologies. The appropriate evaluation includes a history, a head, neck and neuro-otologic evaluation, audiometry, a vestibular evaluation that includes caloric testing, certain laboratory blood tests and a radiographic evaluation Metabolic tests often include serum electrolyte levels, a serologic test for syphilis, thyroid function tests, allergy testing and a lipid profile, and MRI may be indicated to rule out acoustic neuroma in selected cases. In recent years, electrocochleography has been used extensively in the diagnosis of Meniere's disease. The chief electrocochleographic finding is the ratio of the summating potential to the action potential. The ratio is increased in Meniere's disease. | |
Medical Treatment: |
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| Meniere's disease is difficult to treat. Since few controlled
studies have been performed, therapy is largely empiric. Nutritional therapy, which
is often tried initially, includes restrictions on the use of sodium, caffeine and
alcohol. Drug therapy is used to relieve the nausea and vomiting that accompany acute vertiginous episodes, as well as to control or arrest the disease process. Along with sodium restriction, medical therapy usually includes a diuretic such as trimterene (Dyazide, Maxzide) or a carbonic anhydrase inhibitor such as acetazolamide (Diamox). Benzodiazepines, such as lorazepam (Ativan) and diazepam (Valium), and antihistamines, such as meclizine (Antivert, Bonine), are commonly used. During acute attacks, antivertiginous medications are used to relive vertigo. Promethazine (Phenergan) is sometimes used to quell the nausea and vomiting in vertiginous episodes. Tricycle antidepressants can be tried in resistant cases. |
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Surgical Treatment: |
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| Although controversial, surgical treatment can be considered in patients
with severe, refractory Meniere's disease. Endolymphatic sac procedures attempt to
reestablish the function of the sac as the absorptive organ for the endolymph of the
middle ear. In all procedures, a mastoidectomy is performed. The sac can be
merely decompressed, or it can be opened. Silastic sheeting or another shunt device
is then inserted into the lumen of the endolymphatic sac and allowed to drape into the
mastoid cavity. The endolymph that is drained by the shunt is reabsorbed by the
mucous membranes of the mastoid cavity. Endolymphatic sac surgery is, however, highly controversial. The fluid spaces involved are minuscule, and it is doubtful that mechanical means can improve the function of the sac. In 1984, one group reported the results of 405 endolymphatic sac procedures. Overall, 65 percent of patients had complete control of vertigo at three years, but only 50 percent of patients had complete control at 10 years. One double-blind study examined the placebo effect in the reporting of sac surgery results by comparing 15 patients who underwent endolymphatic-mastoid shunt placement with 15 control subjects who had a simple mastoidectomy. Control of vertigo was reported by 70 percent of the persons in each group. A long-term follow-up report showed that the patients in both groups maintained 70 to 80 percent control of vertigo at six years, with no difference in hearing between the two groups. Based on these findings, the authors concluded that there was an indisputable placebo effect in patients' subjective reporting of vertigo following an operation designed to control vertigo. Another study compared endolymphatic sac decompression with mastoid shunt surgery for the control of vertigo. In this study, 53 patients with Meniere's disease were randomly divided into three groups. Endolymphatic sac decompression was performed in the first group, incision of the sac was performed in the second group, and Teflon film was inserted in the endolymphatic sac in the third group. Drainage of the sac did not affect vertigo control. A more recent study compared the effects of decompression and complete excision of the endolymphatic sac. No significant difference was found between the results of this procedure and the results of endolymphatic decompression. Because of the uncertain efficacy of endolymphatic sac surgery, all patients with serviceable hearing must be evaluated individually to determine f they are likely to benefit froth procedure. Labyrinthectomy is indicated in patients without serviceable hearing in the diseased ear, as well as in elderly or infirm patients who are unable to tolerate a more extensive neuro-otologic procedure. In transmastoid labyrinthectomy, all neuroepithelial elements of the vestibular end organ are removed, resulting in total hearing loss on the operative side. Several studies show complete or marked relief of vertigo in over 90 percent of cases. Vestibular neurectomy or labyrinthectomy should completely relieve vertiginous attacks, because each of these procedures totally eliminates vestibular input from the operative ear. The loss of all vestibular function on one side can easily be compensated for by an intact labyrinth on the opposite side. When the hearing is worth preserving (i.e., a speech reception threshold greater than 60 dB and a speech discrimination greater than 40 percent), the procedure of choice is vestibular neurectomy via the middle fossa or the posterior fossa. Recovery after middle fossa craniotomy is prompt. Unless significant vestibular symptoms are present, patients are usually out of bed and walking the day after surgery. While cerebrospinal fluid leakage is unlikely to occur following this procedure, patients should be checked for both external leakage and leakage down the Eustachian tube into the nasopharynx. |
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Prognosis: |
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| Meniere's disease is not a fatal illness, and affected persons can expect to have a normal life span. However, the debilitating symptoms of the disease may adversely affect the quality of life and may be frustrating for both patients and health care providers. The severe disability that can occur in patients with bilateral Meniere's disease can have an enormous impact on the lives of these patients and their families. | |
Please Refer to Table I |
