Meniere’s Disease

7 Meniere’s Disease

Sujana S. Chandrasekhar

images Introduction

Meniere’s disease is a syndrome classically characterized by a quadrad of symptoms occurring episodically: aural fullness, fluctuating sensorineural hearing loss (SNHL), roaring tinnitus, and spinning vertigo, often accompanied by nausea and/or vomiting. This inner ear disorder’s pathological correlate is hydrops of the endolymphatic space.1 It is named for Prosper Meniere, the first individual to describe the symptom complex and who proposed its labyrinthine origin in 1861.2 The term was applied indiscriminately until the current definition of the disorder was published in 1938 by Hallpike and Cairns,3 and then in 1995 the American Academy of Otolaryngology–Head and Neck Surgery (AAO-HNS) published clear criteria enabling researchers to communicate coherently.4 For the purist, the idiopathic constellation of these findings is called Meniere’s syndrome, while when there is attribution to a specified cause, such as otosyphilis, it is called Meniere’s disease; however, it is exceedingly rare that a proper etiology is identified, and the terms are generally used interchangeably.

images Incidence

Vestibular dysfunction in the U.S. population, as estimated from the 2001–2004 National Health and Nutrition Examination Survey (NHANES), affects 35% of U.S. adults 40 years old and older, and 85% of those 80 years old and older.5 Meniere’s disease is a relatively unusual cause of vertigo among all patients with vertigo, as benign paroxysmal positional vertigo (BPPV) and migrainoid vertigo are far more common.6 The most common vestibular disorder is BPPV, with a cumulative lifetime incidence of 10% by age 89; vestibular migraine is the second most common cause of dizziness, with a lifetime prevalence of 0.98%.

The incidence of Meniere’s disease varies from 7.5 to 515 per 100,000 population in published studies from several countries.7 The most rigorous assessment in the United States, based on the U.S. Health Claims Database, shows 473,000 Meniere’s disease diagnoses out of 60 million claims, yielding a prevalence of 190 per 100,000 population.8 Females are slightly more likely than males to be affected (1.3:1), and although the peak ages affected are between the fourth and sixth decades, Meniere’s has been diagnosed in all age groups. Meniere’s disease generally presents in only one ear, and in early stages either vestibular or cochlear symptoms may occur in isolation. Only about one-third of cases present with the full quadrad of symptoms.9

The published incidence10 of bilateral involvement varies widely, between 9 and 50%, but is generally accepted to be around 30%. The enormous range appears to reflect a lack of consensus about diagnostic criteria and varying lengths of time of follow-up. A prospective study of 610 patients with disabling unilateral Meniere’s disease found only a 5% incidence of contralateral Meniere’s disease11; however, there was a 16% incidence of isolated hearing loss in the low frequencies in the contralateral ear. Other studies have suggested that there is an increased percentage of bilateral involvement over time.12,13 There is evidence of immune complexes and circulating complement level abnormalities in Meniere’s disease,14 although the evidence of causal association between allergy and Meniere’s disease is inconclusive.15 The natural course of the disease is variable; up to 60% of patients with severe disease show remission within 2 years of onset and up to 71% within 8 years,16 but there is a sizeable group of patients with progressive, unremitting disease.17

images Pathophysiology and Possible Causes

The pathologic basis of Meniere’s disease is thought to be distortion of the membranous labyrinth, which is characterized by endolymphatic hydrops. In this disorder, endolymph, the potassium-rich fluid in the middle portion of the inner ear, is either overabundantly produced or is inadequately absorbed. Either or both of these conditions results in expansion of the endolymphatic space. It is thought that when Reissner’s membrane ruptures due to endolymphatic overpressure, the admixture of endolymph and perilymph results in vertigo, and eventually normal pressures are re-established and the membrane heals. Evidence of both hydrops and healed Reissner’s membrane are seen in temporal bone specimens of Meniere’s patients. However, although we can produce histopathologic findings of Meniere’s disease in animals by disrupting the endolymphatic sac, these same animals do not display the characteristic symptoms of the disorder.18 There is also lack of specificity in the human temporal bone histopathologic findings, in that endolymphatic hydrops is also seen in patients without the clinical history.19 Cellular density changes in Reissner’s membrane have been described in ears with endolymphatic hydrops with and without Meniere’s disease.20

Endolymphatic hydrops is most consistently found in the pars inferior of the inner ear, that is, in the cochlea and saccule,21 as bowing of Reissner’s membrane out toward the scala vestibuli and distention of the saccule. When saccular distension is extensive, it can distort the utricle and semicircular canals in the vestibule and the saccular membrane can bulge out to contact the stapes footplate either directly or via fibrous adhesions.22 The Hennebert sign, described in idiopathic as well as otosyphilitic endolymphatic hydrops, is vertigo produced by pressure insufflation on an intact tympanic membrane, causing stapes footplate movement, and is thought to result from this severe saccular distension.23 Endolymphatic changes in the pars superior are infrequently seen and include herniation of the utricle into the common crus and displacement of semicircular canal cupulae from their ampullary roof attachment.24

Membranous ruptures in the labyrinth have been found in nearly all parts of the inner ear in Meniere’s disease.25 The ruptures appear to be significant in Meniere’s pathophysiology in that they allow leakage of the potassium-rich endolymph into the perilymph, bathing the eighth cranial nerve and basal surfaces of the hair cells. This causes direction-changing nystagmus, which is a result of initial excitation from a rise in perilymphatic potassium concentration followed by inhibition due to a blockade of transmitter release. Membrane healing allows restitution of the normal chemical milieu and termination of the vertiginous attack, with hearing improvement. Repeated exposure to potassium’s effects is presumably the cause of the chronic inner ear function deterioration that is seen in some cases of Meniere’s disease.

Evidence for autoimmune processes causing Meniere’s disease exists at the cellular level and, for bilateral disease, in clinical studies. The human endolymphatic sac appears to be the primary immunocompetent structure of the inner ear.26 It can process antigen, synthesize antibodies, and raise a cellular immune response; its stromal cells contain immunoglobulins A and G and secretory component, and the perisaccular tissues contain macrophages, lymphocytes, and plasma cells. An abnormality of the Thl/Th2 balance in acute low-tone hearing loss, as well as increased natural killer cell activity, has been demonstrated in patients with Meniere’s disease.27 Antibodies against bovine 68-kDa heat shock protein HSP-70, regarded as an indicator of autoimmune ear disease, are elevated in 50% of patients with bilateral Meniere’s disease.28 Additionally, based on the potential role of thrombogenic antiphospholipid antibodies, patients with bilateral Meniere’s disease may be more likely to have a systemic autoimmune process than those with unilateral disease.29

Other entities30 implicated in causation include viral infection,31 both acute and chronic, ischemia of the inner ear and sac,32 and vascular disease that accounts for the association between Meniere’s disease and migraine headaches.33 This multifactorial list reflects both our lack of complete understanding of the pathophysiology as well as the fact that it is a syndrome, or constellation of symptoms, that we treat, with several potential causes. Clinicians generally lump the disorder into the “hydrops group” or the “migraine group,” and management based on the causational belief ensues.

Genetic evaluation is of no value in patients without a suggestive history, as the data from various studies indicate only 5 to 15% heredity.34 However, a high prevalence of symptoms of Meniere’s disease has been described in families with a mutation in the coagulation factor C homology (COCH) gene, while no differences were found in the nucleotide sequences of exons 4 and 5 in the COCH gene in patients with sporadic Meniere’s disease compared with controls.35 Missense mutations in the COCH gene (14ql2-ql3) cause the disorder DFNA9, which is characterized by autosomal dominant SNHL with vestibular symptomatology. Individuals who are homozygous for the mutation appear to have earlier onset of symptoms.36

images Symptoms

The diagnosis of Meniere’s syndrome or disease is made clinically, based on the symptoms of aural fullness, fluctuating hearing loss, roaring tinnitus, and episodic vertigo. Classically, the patient experiences all of these symptoms in a single episode. However, in practice, symptoms are rarely “classic,” and, especially initially, the patient may present with only cochlear or only vestibular symptoms. Thirty percent of sudden “idiopathic” hearing loss patients, when followed over a year in one study, manifested Meniere’s disease.37 In an acute Meniere’s attack, the vertigo lasts several minutes to several hours, with most patients reporting a duration of 2 to 3 hours.38 After the rotatory vertigo subsides, the patient is unsteady for some period of time (minutes to hours). In general, the length of the postvertiginous disequilibrium is related to the duration of the vertigo; that is, the longer the episode of spinning lasts, the longer the post-episode unsteadiness lasts. The patient is classically symptom-free between episodes. Atypical Meniere’s disease includes cochlear hydrops, in which there is aural fullness, tinnitus, and fluctuating SNHL without vertigo, vestibular hydrops in which there is episodic vertigo alone, and attacks that occur without the typical “aura” of ear fullness and tinnitus. The variability of disease presentation contributes to the diagnostic and treatment inconsistencies.

The most debilitating symptom these patients face is episodic rotatory vertigo. When it occurs, it is exacerbated by head movements—the patient generally maintains a static position with the affected ear up to minimize the spinning—and may be accompanied by nausea, vomiting, diarrhea, and sweating. The vertigo causes patients to miss work and personal activities, and its unpredictability is the root of the anxiety seen in Meniere’s disease. Two to 6% of patients with Meniere’s disease may experience sudden, unexplained falls without vertigo or loss of consciousness,39 known as otolithic crises of Tumarkin (or drop attacks, which Tumarkin attributed to acute utriculosaccular dysfunction).40 Other diagnoses, such as vertebrobasilar insufficiency and migraine, must be ruled out before this diagnosis is made.

Low-frequency SNHL is the typical audiometric finding.41 The hearing loss in Meniere’s disease is typically fluctuating and can be progressive. Although high frequencies are initially preserved, with longer duration of disease, all frequencies may be affected. Hearing loss is effectively managed with hearing aids or, in more severe cases, cochlear implantation. Only 1 to 2% of patients will develop profound hearing loss. Lermoyez described what is frequently encountered in early Meniere’s disease, that is, improvement in hearing thresholds in some patients after the vertiginous attack.

Tinnitus is the first presenting symptom in only 5% of patients and is equally divided in early Meniere’s disease between mild (38%), moderate (32%), and severe (30%).42 Intense tinnitus is, however, common in late-stage Meniere’s disease. In the author’s clinical experience, patients with advanced Meniere’s disease are more overwhelmed and disabled by their tinnitus than is published and are willing to sacrifice any remaining hearing if only the tinnitus can be reduced or abolished.

Episodic vertigo is present in 96.2% of patients with Meniere’s disease, tinnitus in 91.1%, and ipsilateral hearing loss in 87.7%.43 Diagnosis and reporting on Meniere’s disease was standardized when the AAO-HNS published guidelines for making a diagnosis of “definite” Meniere’s disease. The criteria include two or more spontaneous episodes of vertigo, each lasting 20 minutes or longer; hearing loss documented at least once by audiometry; and tinnitus or aural fullness in the affected ear. The disease must be idiopathic, in that other causes have been excluded, typically with brain imaging. Symptoms need not be (and frequently are not) present simultaneously or in the same pattern, especially in the early phases of the disease.

Meniere’s disease causes a significant impairment in quality of life that is worse on days of vertiginous attacks.,44 Meniere’s patients also have higher incidences of depression and anxiety.45 A vicious circle of interaction exists between the organic symptoms of Meniere’s disease, particularly vertigo and tinnitus, and resultant psychological stress and anxiety.46,47 Fifty-seven percent of patients have spontaneous cessation of vertigo in 2 years; 71% after 8.3 years.48 However, there is an average pure-tone hearing loss of 50 dB, a mean speech discrimination score of 53%, and an average caloric response reduction of 50% in patients with long-standing Meniere’s disease.49 Attacks may be few and far between, separated by several months or years, or the patient may experience a months-to-years period of unrelenting, recurring attacks. Patients with Meniere’s disease of shorter than 10 years’ duration tend to experience less continuous vertigo than those in whom the disease is present for more than 20 years.50 In those with > 20-year histories, 36% still have attacks one to four times per week, and 75% still consider their attacks to be severe in nature.

Triggers of Meniere’s attacks include high salt intake, dehydration, high caffeine intake, and significant emotional stress. Emotional stress increases the risk of experiencing an attack of Meniere’s disease during the next hour, and the hazard period is possibly extended up to 3 hours.51

Distinction between Meniere’s Disease and Vestibular Migraine

Meniere’s disease and vestibular migraine share symptoms, and the clinician may confuse one with the other. Additionally, the same patient may have both disorders. Forty-five percent of patients with Meniere’s disease have at least one migrainous symptom during their vertiginous attacks as well as an increased lifetime prevalence of migraine.52 Vestibular migraine is often associated with motion sensitivity, and diagnostic criteria for basilar migraine include vertigo, tinnitus, and hypacusia in the aura symptoms.53 The categories of migraine accepted by the International Headache Society unfortunately do not reflect the complex presentations of patients suspected of having vestibular migraine, leading clinicians to expand criteria on their own, and that affects comparison of treatment outcomes.54 However, as vestibular migraine is much more prevalent than Meniere’s disease, and given that many of the symptoms overlap, some institutions treat all of Meniere’s disease as a cerebrovascular disorder.55

images Diagnosis

The diagnosis of Meniere’s disease is based on history and audiometric findings, as detailed in the AAO-HNS Guidelines, which are summarized here:

Certain Meniere’s disease:

• Definite Meniere’s disease plus histopathological confirmation

Definite Meniere’s disease:

• Two or more definitive spontaneous episodes of vertigo, each 20 minutes or longer

• Audiometrically documented hearing loss on at least one occasion

• Tinnitus or aural fullness in the treated ear

• Other causes excluded

Probable Meniere’s disease:

• One definitive episode of vertigo

• Audiometrically documented hearing loss on at least one occasion

• Tinnitus or aural fullness in the treated ear

• Other causes excluded

Possible Meniere’s disease:

• Episodic vertigo of the Meniere’s type without documented hearing loss; or

• Sensorineural hearing loss, fluctuating or fixed, with disequilibrium but without definitive episodes

• Other causes excluded

Despite the guidelines, a survey of neuro-otologists showed that only one-third relied solely on history, physical examination, and audiometry. Two-thirds used adjunctive tests, including electrocochleography, electronystagmography, rotary chair evaluation, vestibular evoked myogenic potentials, head thrust testing, glycerol and furosemide dehydration tests, posturography, auditory brainstem response testing, tympanometry, blood tests, and magnetic resonance imaging (MRI).56,57

Electrocochleography (ECoG) is frequently used as a diagnostic tool in Meniere’s disease; it is helpful when the results are positive, but a normal ECoG cannot rule out the presence of endolymphatic hydrops.58 Electrocochleography is based on the presence of a summating potential (SP) and an action potential (AP) generated by the cochlea in response to repeated presentations of sound. In Meniere’s disease, due to distension of the basilar membrane into the scala tympani causing increase in the (normal) asymmetry of its vibration, the SP is reported to be larger and more negative than in normal ears. A difference of > 45% SP/AP ratio is abnormal (Fig. 7.1).

The sensitivity of a basic ECoG test in evaluating the SP/AP amplitude ratio ranges from 20%59 to 70%.60 Modifying the test to measure the SP/AP area ratio is reported to significantly improve detection, to 83%.61 However, the test is not specific for Meniere’s disease, as an abnormal ECoG is characteristic of other disease entities, such as perilymphatic fistula and semicircular canal dehiscence.

Electronystagmography (ENG) or video-ENG (VNG) is a more exact test of vestibular function,62 and a significantly reduced vestibular response to caloric stimulation is seen in the affected ear in Meniere’s disease in 48 to 74% of patients. Additionally, absent caloric response in the affected ear is seen in 6 to 11% of patients.63 It is very difficult to obtain ENG or VNG evaluation during an acute Meniere’s attack, as patients are too ill for testing at that time, and they must be free of central nervous system sedative agents (typically used to “abort” the attacks) for 72 hours prior to the test. Findings are shown in Fig. 7.2 and include spontaneous nystagmus to the lesioned side and severely reduced caloric response from the affected ear. It is important to remember that a caloric response difference of 20 to 25% between ears is normal, depending upon the individual laboratory’s settings. Additionally, testing can be normal between episodes, particularly in early or very sporadic Meniere’s disease. ENG has only a 50% total positive rate response in patients with Meniere’s disease, indicating limited sensitivity for diagnosis. This modality is of great benefit, however, when deciding on ablation types of therapy for disabling Meniere’s disease, as it indicates not only the condition of the affected ear, but the vestibular reserve in the opposite ear, allowing for enhanced patient counseling. Vestibular evoked myogenic potential (VEMP) testing may be of benefit in an early Meniere’s diagnosis.64 VEMPs are auditory evoked potentials that measure small variations in neck muscle (cVEMP) or extraocular muscle (oVEMP) contractions that occur when a sudden burst of sound is introduced to the ear. The linear sensing parts of the saccule cause a brief relaxation of the muscles in the neck that function to keep the head erect. The VEMP, therefore, is an inferior vestibular nerve test. Studies have demonstrated that up to 67% of patients with Meniere’s attacks had abnormal VEMPs, indicating that the saccule participates in a Meniere’s attack; half of the abnormal VEMPs return to normal after 48 hours65 or after glycerol or furosemide dehydration. In Meniere’s disease, an abnormal VEMP test result is seen as a reduction in amplitude of > 40%, or greater than 3:1 ratio (Fig. 7.3).

The advantages of using VEMPs for a Meniere’s diagnosis are that they can confirm the side of the lesion, they can be used in patients with severe to profound hearing loss, where auditory brainstem response testing cannot, and they can help to distinguish atypical Meniere’s disease from superior semicircular canal dehiscence syndrome or perilymphatic fistula, in which VEMPs are present at abnormally low thresholds (lower than 80 dB) in the affected ear.

The Halmagyi head thrust test66 is a passive test of unilateral vestibulo-ocular reflex (VOR) gain in which the patient is instructed to view a distant object and to keep his visual focus on that object at all times. The examiner suddenly turns the patient’s head to the right or left rapidly through a small arc and then to the opposite side (Fig. 7.4). If the VOR gain is normal, or near normal, on the side of the direction of the movement, the eyes will remain on the visual target. However, if the patient exhibits saccadic corrections of the eye, reduced VOR gain on the side of the movement is suggested. Head thrust testing may be of limited benefit if there is less than 50% vestibular weakness.67

Osmotic diuretics are able to reduce endolymphatic pressure and volume and hence improve peripheral auditory and vestibular function. After baseline audiometric testing, a dose of glycerol, urea, furosemide, or other osmotic diuretic is administered. Repeat audiometric testing is performed at 3 hours (and sometimes at 1 and 2 hours) after ingestion. The test is considered positive if (1) there is a 10-dB or greater improvement at two or more frequencies (250 to 2000 Hz), or (2) there is a 12% or greater improvement in speech discrimination scores. Positive dehydration tests are found in 60 to 66% of patients with Meniere’s disease.68,69 The glycerol test is associated with several unpleasant side effects, including headache, nausea, thirst, diarrhea, emesis, diuresis, and dizziness; these are not seen with furosemide.70 Because dehydration tests are relatively specific for endolymphatic hydrops, they may be useful in confirming the presence of disease in patients with atypical presentations. However, because the tests are relatively insensitive, they are not useful to rule out endolymphatic hydrops or as screening tests for the disease. Tests are more likely negative very early and very late in the course of disease, although the stage of the disease is not predictable from the results of the dehydration testing.71

Rotary chair testing is of benefit in acute Meniere’s disease as well as in determining the level of residual deficit in poorly compensated but inactive disease. Findings include reduced response to the velocity step of rotation on the affected side and offset to that side during sinusoidal rotation. Some literature suggests that computerized dynamic posturography (CDP) evaluation can be of benefit in classifying Meniere’s disease patients as acute (recent post-attack), subacute (late post-attack), or inactive.72 The value of CDP, however, lies primarily in objective assessment of quality-of-life issues in the disease, such as balance dysfunction, which is seen in chronic or poorly compensated Meniere’s.

Auditory brainstem response (ABR) testing is primarily employed to rule out retrocochlear pathology in these patients; however, attempts have also been made to use ABR as an objective method to indicate endolymphatic hydrops.73 The traveling-wave velocity test, which uses derived ABRs, has been shown to be altered, reflecting endolymphatic hydrops in 27% of the asymptomatic (contralateral) ears of unilateral Meniere’s disease patients.74 Cochlear hydrops analysis masking procedures (CHAMPs) is an ABR test masked at different frequencies with high-pass noise masking. In Meniere’s patients CHAMPs show that the masking noise is insufficient, such that an undermasked wave V is still present similar to that with clicks alone. This is not true in non-Meniere’s ears.75 The CHAMPs test may prove to be of use in objectively distinguishing active Meniere’s disease and in tracking changes in severity of disease.76

Tympanometric evaluation of Meniere’s patients reveals reduced resonant frequency in the affected ear, with consistently increased width of conductance tympanograms at 2 kHz in these patients. In one study, while more than 95% of normal subjects had a negative test, 56.5% of affected ears and 45.8% of nonaffected ears of Meniere’s patients had a positive test.77 As detailed previously in this chapter, metabolic screening, including carbohydrate and lipid metabolism and thyroid function tests, has not proved useful in the diagnosis of Meniere’s disease, and the use of laboratory tests is generally limited to the treponemal antigen test for syphilis and suitable tests for patients in whom autoimmune disease is highly suspected.

Magnetic resonance imaging (MRI) is generally employed to rule out retrocochlear pathology as a cause for the symptoms; however, some studies have found smaller and shorter endolymph drainage systems or inflammatory changes in the endolymphatic sac in Meniere’s disease patients.78,79 High-resolution MRI can be used to image the endolymphatic duct and sac. One study correlated visible abnormalities and the lack of a visible endolymphatic duct and sac with the clinical course of Meniere’s disease.80 Intratympanic injection of gadolinium and 3D FLAIR MRI may be more conclusive for Meniere’s; in patients with clinically and ECoG-confirmed definitive Meniere’s disease,81 the degree of impairment of perilymph enhancement directly correlated with degree of otovestibular dysfunction, and in all normals there was no impairment of perilymph enhancement.82,83,84 However, the diagnosis of Meniere’s disease still cannot be made by MRI.85 Twenty-three patients with Meniere’s disease and 50 controls were evaluated by high-resolution computed tomography (HRCT) and MRI.86 The percentage of nonvisualized vestibular aqueduct on HRCT was significantly lower in the control group (3.4%) than in either the involved (27.8%) or uninvolved (22.2%) ears of the study group. There was no difference between diseased and nondiseased ears in the Meniere’s group. MRI showed the endolymphatic duct and sac system in 64.1% of controls and only 39.1% of subjects (p = 0.05). Computed tomography (CT) is not overly useful in confirming the diagnosis of Meniere’s disease, with the possible exception being that the vestibular aqueduct may be narrow in some cases, as shown in Fig. 7.5. MR images in Meniere’s disease are seen in Fig. 7.6.

images Treatment

To standardize result reporting for Meniere’s disease and therapy, the then-American Academy of Ophthalmology and Otolaryngology (AAOO) devised a system in 1972 that was later revised by the AAOHNS in 1985 and again in 1995.4 Because of the capriciousness of behavior and treatment response identified in the initial AAOO system, adherence to the 1995 guidelines, which demand 18- to 24-month follow-up and strict mathematical comparison of pre- and posttreatment vertigo (Table 7.1), would be very useful to enhance our understanding of this disorder. Unfortunately, only 50% of papers in peer-reviewed, English-language publications between January 1989 and December 1999 used the guidelines.87

The same study of neuro-otologists quoted above regarding diagnosis revealed the following about treatment. Conservative medical management is preferred; when this fails, the preferred initial invasive intervention is endolymphatic sac surgery in 50%, intratympanic gentamicin in 39%, local overpressure using the Meniett device in 9%, and vestibular nerve section in 2%. Over the last decade and a half, intratympanic steroid injection for Meniere’s disease has increased in popularity.88 Overall, clinicians continue to turn toward less invasive means to treat medically recalcitrant Meniere’s disease. The treatment of the disease continues to be one of palliation and support.

Apr 3, 2018 | Posted by in OTOLARYNGOLOGY | Comments Off on Meniere’s Disease

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