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Meniere’s Disease: A Challenging and Relentless Disorder
Clinical Vignette
A.S. was a 34-year-old healthy female, without significant past medical history, who presented to the otology clinic 10 years ago for evaluation of a 3-day complaint of a “blocked” right ear: muffled hearing, aural fullness, and a low-pitched “oceanlike” sound. She denied vertigo or significant disequilibrium. She denied any recent viral illnesses. The otoscopic examination was normal. She had a similar episode 8 months earlier that spontaneously resolved. She denied a history of migraine, photophobia, phonophobia, or visual aura associated with her hearing changes. An audiogram performed 10 years ago during the first event is shown in Fig. 13.1A , which demonstrated right-sided low-frequency sensorineural hearing loss (SNHL) rising to normal with an excellent word discrimination score (WDS). Her tympanogram and stapedial reflexes (not shown) were normal. A follow-up audiogram, performed 3 weeks following the initial presentation ( Fig. 13.1B ), showed normal hearing thresholds bilaterally.
An audiogram performed during our next clinic visit ( Fig. 13.1C ) revealed moderate rising to mild low-frequency SNHL for the right ear with a WDS of 84%. The Stenger test was negative.
Additional testing was performed to aid in diagnosis. A gadolinium-enhanced magnetic resonance imaging (gadolinium-MRI) centered on the internal auditory canals was normal. Electrocochleography (ECoG) showed an elevated summating potential/action potential ( SP/AP) ratio of 0.64/0.74 on the right side ( Fig. 13.2 ), with the contralateral ear showing a normal ratio (<0.4—not shown). The presumed diagnosis was cochlear hydrops (CH). She completed a 10-day course of prednisone, and instructions were given for a low-salt diet. Her hearing returned to normal.
Six months later the patient developed a recurrence of her right-sided hearing loss, aural fullness, roaring right-sided tinnitus, and a vertigo spell that lasted approximately 3 hours and was associated with nausea and vomiting. She also described a sensation of falling backward. On examination, she had right-beating horizontal nystagmus with a slight torsional component, increasing in amplitude on right lateral gaze. The audiogram showed moderate rising to mild SNHL in the right ear ( Fig. 13.1D ) , with a WDS of 76%. A vestibular-evoked myogenic potential (VEMP) showed an increased threshold on the right side ( Fig. 13.3 ) . She was treated with a course of steroids and started on hydrochlorothiazide and triamterene. The patient’s symptoms were consistent with the diagnosis of right-sided probable Meniere’s disease.
Introduction
Meniere’s disease (MD) is characterized by episodic vertigo, fluctuating hearing loss, aural pressure, and tinnitus, usually in one ear. Since its description by Prosper Meniere in the Gazette médicale de Paris in 1861, the pathophysiology and management of MD has been a controversial topic. Depending on the geographic location, the incidence of MD varies between 4.3 and 15.3 per 100,000. Affected individuals are usually between the third and seventh decades of life with a female to male ratio of 1.3:1.
There have been several classification schemes to define MD. Most recently, the Barany Society, in conjunction with numerous other international groups, including the American Academy of Otolaryngology–Head and Neck Surgery, proposed a simplified classification scheme ( Table 13.1 ). This scheme identifies two groups: definite and probable MD. Alternatively, staging systems have been proposed that are based on the residual hearing and residual vertigo after treatment ( Tables 13.2 and 13.3 ). These staging systems may be used to assess the degree of disability and help quantify treatment efficacy. Furthermore, the staging systems allow for uniform reporting of outcomes for various treatment modalities.
TABLE 13.1
Definition of Meniere’s Disease According to the 2015 Barany Society Consensus Statement
| Definition | Symptoms |
|---|---|
| Definite Meniere’s disease |
|
| Probable Meniere’s disease |
|
TABLE 13.2
Staging of Meniere’s Disease According to the 1995 Guidelines of the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology and Head and Neck Surgery
| Stage | Four-Tone Average (dB) |
|---|---|
| 1 | ≤25 |
| 2 | 26–40 |
| 3 | 41–70 |
| 4 | >70 |
TABLE 13.3
American Academy of Otolaryngology (AAO) Disability Class Associated With Meniere’s Disease
| Numerical Value | Class |
|---|---|
| 0 | A |
| 1–40 | B |
| 41–80 | C |
| 81–120 | D |
| >120 | E |
| Secondary treatment initiated due to disability from vertigo | F |
Reporting guidelines according to the 1995 guidelines of the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology and Head & Neck Surgery. Numerical value = (X/Y) × 100. X is the average number of definitive spells per month for the 18–24 months after therapy and Y is the average number definitive spells per month for the 6 months before therapy.
The diagnosis of MD, an idiopathic condition, is made after excluding other causes that may mimic the disorder. These conditions can be infectious (e.g., otosyphilis), neurologic (e.g., migraine), autoimmune (e.g., Cogan’s syndrome, autoimmune inner ear disease), and neoplastic (e.g., intralabyrinthine or vestibular schwannomas, endolymphatic sac [ELS] tumors) ( Table 13.4 ).
TABLE 13.4
Differential Diagnosis of Meniere’s Disease
| Neoplastic | Vestibular schwannoma |
| Endolymphatic sac tumor | |
| Meningioma | |
| Genetic | Autosomal dominant sensorineural hearing loss type 9 (DFNA9) caused by COCH gene |
| Autosomal dominant sensorineural hearing loss type 6/14 (DFNA6/14) caused by WSF1 gene | |
| Autoimmune | Cogan’s syndrome |
| Autoimmune inner ear disease | |
| Susac’s syndrome | |
| Vogt-Koyanagi-Harada syndrome | |
| Infectious | Otosyphilis |
| Neuroborreliosis | |
| Neurologic | Vestibular migraine |
| Cerebrovascular events/transient ischemic attack/stroke | |
| Vestibular paroxysmia (neurovascular compression syndrome) | |
| Anatomic | Third window syndromes including superior canal dehiscence, enlarged vestibular aqueduct, perilymphatic fistula |
In this chapter, we present a clinical vignette of a patient with MD who ultimately displays the full spectrum of the disease, and we discuss the clinical presentation, the diagnostic evaluation, and the different therapeutic modalities available to patients with this challenging disease.
What Are the Diagnostic Criteria for Meniere’s Disease?
The current consensus guidelines published in 2015 by the Barany Society after collaboration with an international group of experts identify two diagnostic categories for MD summarized as follows: definite and probable MD. The criteria for definite MD are “(1) two or more spontaneous episodes of vertigo each lasting 20 minutes to 12 hours; (2) audiometrically documented low- to medium-frequency SNHL in the affected ear on at least one occasion before, during, or after one of the episodes of vertigo; (3) fluctuating aural symptoms including hearing, tinnitus, or aural fullness in the affected ear; and (4) not better accounted for by another vestibular diagnosis.” According to these criteria, there may be nonsimultaneous onset of vertigo and hearing loss. In some patients, the hearing loss may precede the onset of vertigo by several months or years. Alternatively, episodic vertigo may precede the onset of hearing loss by weeks to months, although vestibular symptoms are usually accompanied by tinnitus and aural fullness. Some patients experience an increase in tinnitus intensity or aural fullness associated with the episodes of vertigo.
Probable MD is noted to include one or two episodes of vertigo or dizziness lasting 20 minutes to 24 hours. Patients can also experience fluctuating aural symptoms including hearing loss, tinnitus, and aural fullness in the affected ear. Patients with probable MD do not have documented low-frequency hearing loss or do not describe true vertigo symptoms.
Differential Diagnosis of Meniere’s Disease—Migraine and Meniere’s Disease
The diagnosis of MD is one of exclusion. The practitioner must confirm that no other etiology is the likely cause of symptoms. Approximately 1% of the population suffers from vestibular migraine (see Chapter 11 ). Early in the course of MD, before the patient manifests all symptoms of the disease, MD may be very difficult to be distinguished from vestibular migraine, as these disorders share many similar symptoms. Although patients with vestibular migraine may have fluctuating hearing, tinnitus, and aural fullness with each episode, the hearing loss usually does not progress to the levels seen in MD. Furthermore, many migraine patients report that vestibular symptoms can last up to 72 hours, which is highly unusual in MD. Some patients may manifest symptoms consistent with both disorders. Diagnosis of migraine is more common in patients with a definitive diagnosis of MD.
What Is the Role of Adjunctive Tests in the Diagnosis of Meniere’s Disease?
A national survey showed that depending on the region (West, Midwest, Northeast, New England, and Atlantic coast), 26.9%–46.7% of treating otolaryngologists relied on history, physical examination, and audiometry only to establish the diagnosis of MD. Others obtained adjunctive tests to support their diagnosis.
Electrophysiologic studies
In recent years, several diagnostic tests have been proposed to study the presence of endolymphatic hydrops (ELH) and complement the diagnosis of CH or MD. Two electrophysiologic tests merit mention: ECoG and cervical and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP).
ECoG is recorded in response to condensation and rarefaction click or tone-burst stimuli. The SP and AP of the eighth nerve are recorded via ear canal or transtympanic electrodes. An elevated SP/AP ratio (>0.4) and/or a widened AP width (>3 ms) are considered to be indicative of ELH. The alteration of SP and AP morphology in the hydropic ear is thought to result from a mechanical asymmetry in the basilar membrane (i.e., nonlinear basilar membrane vibration). Reports in the literature regarding sensitivity and specificity of ECoG vary widely. Ge X et al. reviewed 1549 patients with MD and found an elevated SP/AP ratio in 71.6%. They also showed that the sensitivity of ECoG increased with duration and severity of the disease. The sensitivity increases from 71% in stage 1 disease to 90% in stage 4 disease and from 43% in MD of less than 1 year duration to 100% when MD has been present for over 30 years. Others have reported combining the SP amplitude, SP area, SP/AP area ratio, and total SP/AP area to improve diagnostic accuracy. Abnormal ECoG findings for MD will be present when the disease is active; if the disease is not active, ECoG results may be normal; therefore, a negative ECoG study does not rule out MD (false negative).
The cVEMP is a short latency (8 ms) inhibitory potential of the ipsilateral sternocleidomastoid muscle evoked by brief and loud (>85 dB) click or tone-burst stimuli. The cVEMP is thought to be a recording of vestibulocollic reflex activity generated in the saccule and carried via the inferior vestibular nerve. Results of cVEMP testing in patients with MD are somewhat contradictory. MD patients may have elevated or absent VEMP thresholds compared with controls. These findings are more common in MD patients with Tumarkin’s crisis and are seen in 27% of the contralateral asymptomatic ears of affected individuals. Other studies have shown no difference between MD patients and control patients with regard to either VEMP amplitude or threshold. The sensitivity of cVEMP for a diagnosis of MD ranges from 50% to 63%. However, the cVEMP peak to peak amplitude may be a useful measure to monitor the progression of MD, as this value decreases over time.
The oVEMP reflex arc involves the contralateral orbicularis oculi and may be mediated partially by the utricle. oVEMPs are less frequently abnormal in patients with MD, particularly in early stages of the disease. Chen et al. found that only 16% of subjects had abnormal oVEMP responses, and the majority of these abnormalities were seen in patients with long-standing MD.
We feel that both cVEMP and ECoG can be used to complement the clinical picture but should not be the sole basis for or against diagnosis.
Caloric testing and head thrust testing
The role of videonystagmography (VNG) in the diagnosis of MD is somewhat limited. Significant caloric weakness is present in 42%–73% of patients with MD. Complete loss of function is seen in 6%–11%. Approximately 23%–29% of patients will have an abnormal angular vestibulo-ocular reflex on head thrust testing with gain asymmetry and phase lead being the most common findings.
We feel that caloric testing is useful in the (1) assessment of contralateral function before an ablative procedure, (2) assessment of residual function after an ablative procedure, and (3) assessment of ipsilateral function—if residual function is good, we favor a nondestructive procedure.
Retrocochlear studies
When surveyed for workup of retrocochlear pathology, 57.7%–93.3% of otologists obtained retrocochlear studies. One of the diagnostic criteria of MD is that other causes have been ruled out; therefore, we obtain a gadolinium-enhanced MRI of the internal auditory canals on all of our MD patients.
What Is Cochlear Hydrops? What Is Its Significance?
The term “cochlear hydrops” has been used to describe fluctuating hearing loss without associated vertigo. This may represent an earlier phase of a continuum ranging from mild cochlear involvement to full cochleovestibular dysfunction seen in MD.
House et al. studied the relationship of CH and MD. In their retrospective review of 950 “hydropic” ears, 71% were diagnosed with unilateral MD and 29% were labeled as unilateral CH. Bilateral MD (BMD) at presentation was seen in 11% with another 14% of unilateral MD becoming BMD. Of patients initially diagnosed as having unilateral CH, 33% developed MD over an average of 7.6 years of follow-up.
What Is the Pathophysiology of Cochlear Hydrops and Meniere’s Disease?
Although ELH is felt to be the underlying histopathologic finding in MD, to date no histopathologic study has confirmed the presence of ELH in patients with CH. Despite the lack of direct evidence of this association, electrophysiologic studies demonstrating elevated SP/AP ratio suggest ELH.
The pathophysiology of hydrops remains unknown. Several intrinsic (genetic, anatomical, autoimmune, or vascular) and extrinsic (allergy, viral, neoplastic, or trauma) causes can result in the disturbance of mechanisms involved in the regulation of endolymphatic fluid homeostasis.
Work to identify an underlying pathophysiology of ELH has identified several possible gene products for the disorder. Abnormal distribution of aquaporin 4 and 6, transmembrane water channels, may be the underlying cause of the ELH seen in MD patients. Genetic polymorphisms have been identified in these genes in MD patients. Other histochemical abnormalities noted in MD patients include abnormally thickened basement membranes and loss of the neuroepithelium in the saccule and semicircular canals. Whether this disturbance causes a predominant alteration in the longitudinal versus radial flow of the endolymph has been long debated. On the other hand, it remains unclear whether the subsequent hydrops is the result of a cytochemical abnormality or an anatomical anomaly.
In fact, the relationship of ELH to the symptoms of MD has also been questioned, raising debate as to whether the observed ELH is the direct pathologic initiator of cochleovestibular dysfunction or “epiphenomena” of subtler biochemical perturbations. In a review of their temporal bone registry, Merchant et al. found that all 28 patients with Meniere syndrome had evidence of ELH. However, of the 79 patients with ELH only 51 had Meniere’s symptoms. Classic symptoms were absent in 9 of the 35 patients with “idiopathic hydrops” and in 42 of the 44 patients with “secondary hydrops.”
In an effort to identify ELH with more certainty in vivo, Nakishima et al. described visualization of ELH in MD patients using intratympanic gadolinium and delayed high-resolution (3T) MRI; however, intratympanic gadolinium administration is off-label; therefore an intravenous (IV) gadolinium protocol has been developed. This MRI technique has subsequently shown higher rates of ELH in patients with MD compared with control patients, with sensitivity for diagnosis of 85%, and has significant promise in diagnosing hydrops and confirming the diagnosis of MD.
During the following year, our patient had a total of five episodes of severe vertigo associated with aural fullness, fluctuating hearing, and tinnitus. Over the course of that year, she developed a progression of her hearing loss. The audiogram showed moderate low-frequency SNHL in the right ear, with a WDS of 72% ( Fig. 13.1E ) . Three of the spells responded to a steroid taper and a regimen of antiemetics. Two episodes were treated with intratympanic injections of dexamethasone (IT-Dex) that gave temporary relief of vertigo. Her hearing remained unchanged, and she acquired a hearing aid for hearing assistance.
Nine months later, she developed a recurrence of vertigo spells occurring weekly. These spells did not respond to a combination of oral and intratympanic steroids. A Meniett (Norcross, GA) device was used without success. Her audiogram was unchanged, and she continued to use her hearing aid.
At that time, destructive and nondestructive options were discussed owing to the weekly vertigo spells. She underwent ELS decompression with placement of a shunt (endolymphatic sac surgery [ESS]). The sigmoid was noted to be far-forward requiring decompression. The sac was hypoplastic and inferiorly displaced. This resulted in the complete resolution of her vertigo spells. Her hearing remained stable. Nevertheless, she continued to complain of moderate to severe roaring tinnitus and a constant sensation of aural fullness.
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