Meniere's disease (also known as endolymphatic hydrops) in detail - this is a technical article.
- Endolymph: Potassium-rich fluid in the middle portion of the inner ear.
- Endolymphatic sac: Dilated portion of the endolymphatic duct responsible for regulating endolymph flow within the membranous labyrinth.
- Cochlear Meniere’s Disease: Classification of Meniere’s disease with solely auditory symptoms (i.e., aural fullness, tinnitus, fluctuating hearing loss) lacking vertiginous episodes.
- Vestibular Meniere’s Disease: Classification of Meniere’s disease with solely vertiginous episodes, lacking auditory complaints.
- Vertigo: Symptom complaint of rotary movement involving patient complaints of either internal or external perception of movement.
Meniere’s disease has been described as an idiopathic form of endolymphatic hydrops. Meniere’s disease is a debilitating disorder that is characterized by episodic attacks of vertigo, hearing loss, tinnitus, and aural fullness (Gelfand 2009). Meniere’s disease can be classified as cochlear Meniere’s disease or vestibular Meniere’s disease. The cochlear classification includes the triad of auditory symptoms (aural fullness, fluctuating hearing loss, tinnitus) without the episodic vertigo, whereas the vestibular classification is reserved for cases of episodic vertigo without reported or measured hearing loss (Gelfand 2009). Although these descriptions are sometimes used, the presence of both cochlear and vestibular symptoms is referred to as Meniere’s disease; patients with only cochlear or only vestibular Meniere’s disease will develop the full spectrum of Meniere’s disease with time.
Meniere’s disease has been established for over a century as diagnosis for patients with dizziness and balance disorders; however, the etiology of this disorder remains a medical mystery. Once termed, “apoplectiform cerebral congestion” (Andrews and Honrubia 1996), Meniere’s disease was first described by Prosper Meniere in 1861; however, due to the controversial diagnosis, it was not until the 1900s that the initial work on this disease became accepted. In 1927, Guild was the first to discover the flow of endolymph in the cochlea to the endolymphatic sac and reabsorption of endolymph in the inner ear (Andrews and Honrubia 1996).
Subsequently, George Portman (1927) described the disease to be analogous to glaucoma. He devised a procedure to decompress the endolymphatic sac in the inner ear, with initial animal research. An important finding by Hallpike and Carns in 1938 involved photographic dilation of the membranous labyrinth due to excessive endolymph; this work led to the discovery of an endolymphatic flow theory to explain excessive endolymph within the membranous labyrinth (endolymphatic hydrops) (Andrews and Honrubia 1996).
Animal research tested this theory; however, the ability to develop endolymphatic hydrops is dependent on species. With the exception of rare cases, animals do not develop vestibular dysfunction typical of Meniere’s disease. Kimura and Schuknecht (1965) reported that cochlear hydrops can occur in guinea pigs with artificial hydrops, sparing the vestibular membranous labyrinth, thus supporting the theory of primary structural changes within the cochlea. Additional histopathology findings included: atrophy of the outer and inner hair cells, spiral ganglion, and stria vascularis, especially in the more apical region of the cochlea (Andrews and Honrubia 1996). Vestibular changes were subtle and included distortion of the membranous labyrinth in the region of the saccule and the horizontal canal ampulla.
Currently, there is still much debate on the correlation and sequence of disease progression between Meniere’s disease and endolymphatic hydrops. Symptoms of Meniere’s are hypothesized to result from excess production of endolymph fluid or problems with endolymph fluid absorption within the labyrinth (AAO-HNS 2010; NIDCD 2010). The excess fluid (endolymphatic hydrops) expands the endolymphatic space, disturbing the natural homeostasis of the labyrinth. This results in alterations to the hearing and balance organs’ physiologic function of transferring signals to the brain (NIDCD 2010). As supported by animal research, the cochlea and the saccule are the first labyrinthine structures affected by the endolymphatic hydrops (Kimura and Schuknecht 1965).
Specifically, the endolymphatic hydrops cause a distention of the saccule and displacement of Reissner’s membrane toward the scala vestibule. As the disease progresses, it can also distort the utricle and the semicircular canals (Weber 2008). Endolymphatic changes can result in bulging of the utricle into the semicircular canals space, severing the cupulae from attachment to the ampulla roof (Weber 2008). Ultimately, the structure distention leads to labyrinthine ruptures, resulting in potassium-rich endolymphatic fluid mixing with perilymph fluid surrounding the basal surfaces of the hair cells and eighth cranial nerve (Weber 2008). Prolonged episodes of this abnormal contact of fluid lead to a natural labyrinthectomy of the affected ear (Weber 2008).
In patients with Meniere’s disease, endolymphatic hydrops have been confirmed postmortem in human temporal bone histopathologic sections; however, similar structural changes (cellular density changes) to the cochlea and saccule have been observed in ears with endolymphatic hydrops without the characteristic symptoms of Meniere’s disease (Andrews and Honrubia 1996; Schwaber 2007; Weber 2008).
Recent evidence at the cellular level suggests an autoimmune dysfunction occurring in patients with Meniere’s disease, giving rise to the changes within the endolymphatic structures in the labyrinth. This suggests an overlap between autoimmune inner ear disease and bilateral Meniere’s disease (Rawal et al. 2010). Roland (2000) suggested that the endolymphatic sac is an “immunocompetent structure,” capable of processing antigen and synthesizing antibodies. It is speculated that in the presence of Meniere’s disease, there is an overactive immune response, leading to production of antibodies against the inner ear. Animal testing has confirmed antibodies to the inner ear proteins including 68 Kd, which corresponds to the heat-shock stress protein (HSP)-70 (Boulassel et al. 2001). Fuse et al. (2003) also observed abnormalities in the helper T-cell balance (TH1/TH2) and increased natural killer cell activity in patients with Meniere’s disease.
Prevalence of Meniere’s disease is difficult to determine based on the complexity in diagnosis. Approximately 45,000 new cases are diagnosed each year; at present over 600,000 people have the diagnosis of Meniere’s disease in the United States (NIDCD 2010). Meniere’s disease is most common in middle age, but can develop in all ages (NIDCD 2010). This is based on the assumption that Meniere’s disease is an idiopathic form of endolymphatic hydrops, requiring an extensive period of time to develop and change the structures within the inner ear. Although rare, reports of Meniere’s disease have been reported in children (Weber 2008). Familial presence of Meniere’s disease has been observed with a mutation of the coagulation factor C homology (COCH gene) (Weber 2008).
Meniere’s attacks may occur at any time, with initial symptoms being episodic (AAO-HNS 2010). Course of Meniere’s disease varies among patients; some experience episodes for only a few months after which the symptoms completely dissolve. Others experience continuous periodic events and remissions, and some reach a plateau phase with only continuous tinnitus and imbalance. Meniere’s disease has been categorized into two prominent stages: early and late (Andrews and Honrubia 1996). Symptoms in the earliest stage are typically episodic in nature, only affecting one ear. Vertigo is the primary crisis event, due to its unpredictable onset, symptom duration (20 min to 1 day), and associated visceral sensations. In addition, some patients may experience “drop attacks,” or unexpected loss of balance often resulting in a fall (NIDCD 2010). The vertigo may occur after onset of tinnitus or reduced hearing (NIDCD 2010). After the Meniere’s spell, the patient may be left with residual sensations of nausea, imbalance, and extreme fatigue. Consequently, the late stage may present with chronic symptom complaints, and may include bilateral involvement with progression of the disease over many years (Andrews and Honrubia 1996).
The hearing loss associated with Meniere’s disease is often intermittent, typically occurring simultaneously with attacks of vertigo (Brandt 2003). Hearing loss is noted in the lower pitches initially, but over time all pitches will likely be affected, ultimately resulting in permanent hearing loss (AAO-HNS 2010). Sensations of fluctuating hearing loss may last for minutes to hours (in the early stage); however, as the disease progresses, hearing fluctuations may last for days to weeks or become a permanent, severe stable sensorineural hearing impairment (Andrews and Honrubia 1996). Lamoise syndrome is a term used to describe a sudden improvement in hearing following an attack (Weber 2008).
Aural fullness can precede symptoms of vertigo and often it is accompanied by a “roaring” tinnitus; however, some patients never experience the fullness sensation, while others report the sensation as very similar to Eustachian tube dysfunction (Andrews and Honrubia 1996). Tinnitus may be present in all stages of the disease; however, it is most prominent in the late stage (Weber 2008). Often patients will report an intensity increase in their tinnitus just prior to the onset of vertigo.
Certain diagnosis of Meniere’s disease can only be inferred from histopathologic evidence; however, definite diagnosis stems from history and audiometric findings. The Committee on Hearing and Equilibrium, American Academy of Otolaryngology-Head and Neck Foundation (1995), developed the diagnostic criteria for Meniere’s disease (Table 1).
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.
One definitive episode of vertigo; documented hearing loss on at least one occasion; tinnitus or aural fullness in the treated ear; other causes excluded.
Two or more definitive spontaneous episodes of vertigo 20 minutes or longer; documented hearing loss on at least one occasion; tinnitus or aural fullness in the treated ear; other cases excluded.
Diagnosis of definite Meniere’s disease with histopathologic confirmation.
Collecting a thorough and accurate medical history is the first critical step in diagnosing the disease. Pertinent case history information includes asking questions regarding frequency, duration, description of attacks, associated auditory complaints, and the presence of tinnitus (AAO-HNS 2010).
Audiometric (pure-tone) evaluation serves as a documentation of hearing fluctuations and severity changes over time. It is recommended that if an individual is suspected of having Meniere’s disease, based on case history, frequent repeat audiograms are ordered to document disease progression and aid in confirmation of the suspected diagnosis of Meniere’s disease. Clinical audiometric presentation of Meniere’s disease presents with an initially low frequency, mild sensorineural hearing loss at 250 Hz in the earliest stage of the disease (see Picture 1).
As the disease progresses, threshold decreases at 500–1,000 Hz are observed (Andrews and Honrubia 1996). Fluctuations in hearing sensitivity are a common symptom complaint and can be documented via the repeat audiometric evaluations. Return to near-normal hearing sensitivity in between Meniere’s episodes is a common characteristic for early-stage disease.
In later stage Meniere’s, hearing loss becomes more permanent (see Picture 2); however, fluctuations in hearing may still occur at later stages but thresholds will not return to near-normal levels (Andrews and Honrubia 1996).
In the later stage ofMeniere’s disease, it is also common for the high frequencies to become affected, resulting in a flat, sensorineural hearing loss ranging from moderate to profound. The American Academy of Otolaryngology and Head and Neck Surgery developed a staging system of hearing loss in definite Meniere’s based on four-tone average hearing impairment (Table 2).
|Stage||Hearing loss (dB)|
|2.||26 - 40|
|3.||41 - 70|
Speech discrimination is relatively poor at this stage. It is not uncommon to have poorer speech discrimination results than expected, given the overall distortion of hearing due to the disease progression (Andrews and Honrubia 1996).
Vestibular assessment is recommended to confirm diagnostic suspicions from case history and audiometric findings, document disease progression, or treatment outcomes. These evaluations include traditional siteof- lesion examinations (electronystagmography, electrocochleography, rotational chair, and vestibular evokedmyogenic potentials). Test results will vary depending on stage of disease and whether the patient is in recovery from aMeniere’s attack. Direct examination and laboratory assessment may provide clinical signs of peripheral involvement, with absence of central signs.
Electrocochleography (ECoG) is a measurement of electrical activity close to the cochlea, and is reported as an objective means for classifying endolymphatic hydrops. Through the use of our noninvasive (wick electrode or gold foil tiptrode) electrodes placed into the outer ear canal, near the tympanic membrane, or invasive (trans-tympanic) electrode placed into the ear drum, the cochlear electrical activity in response to an external stimulus (high intensity click or tone burst) can be measured. ECoG is a modification of brainstem auditory evoked response testing; specifically, the results measure the action potential (AP; analogous to wave 1 of ABR) and a preceding wave known as the summating potential (SP). Measurements of the SP and AP are reported as a ratio. Normal ratio response is indicated by a SP/AP ratio <0.3 (see Picture 3).
Whereas an abnormal ratio is indicated by a SP/ AP ratio >0.3 suggesting endolymphatic hydrops (Weber 2008) (see Fig. 4).
Picture 4: Abnormal Electrocochleography (ECoG) results; SP/AP ratio >0.3. (Note: BL baseline measurement, SP summating potential, AP action potential)
Some controversy sounds the clinical utility of this test as sensitivity is fair for Meniere’s disease, and it cannot be used for late-stage Meniere’s disease given the severity of hearing sensitivity; however, it may serve as a tool to determine the side involved.
Electronystagmography, or more commonly known today as videonystagmography, is an objective measure of the peripheral and central vestibular system. During the evaluation, a patient will either wear electrodes or video goggles to capture physiologic or abnormal eye movement responses (nystagmus). Spontaneous nystagmus may be observed in patients with Meniere’s disease, with the fast phase (beat) of the nystagmus toward the diseased ear (irritative or recovery nystagmus). Results obtained from the bithermal caloric irrigation subtest may help in determining the side of involvement; however, caloric irrigation results vary depending on the stage of Meniere’s. In the early stage, bithermal caloric results may be symmetrical and strong; however, as the disease progresses, reduced vestibular response is observed on the affected side. As the disease progresses, bilateral reduced vestibular response can result.
Rotational chair assessment is recommended to further investigation of the peripheral vestibular system such as in the event of a bilateral weakness on caloric irrigations. Sinusoidal harmonic acceleration (SHA) results may indicate an increased phase lead at 0.01 Hz, or gain asymmetries, further suggesting peripheral vestibular involvement (Andrews and Honrubia 1996). Step velocity test may indicate a shortened time constant, also suggesting site-oflesion specific results localizing to the peripheral vestibular system (Weber 2008).
Vestibular Evoked Myogenic Potentials
Vestibular evoked myogenic potentials (VEMPs) are a relatively new assessment technique for quantifying changes within the peripheral vestibular system. VEMPs are short latency electromyograms (EMGs), evoked by a high intensity acoustic stimulus (click or tone burst), and recorded from the tonically contracted sternocleidomastoid muscle (cervical VEMP) or the recently discovered inferior oblique muscle (ocular VEMP). Cervical VEMPs are the traditional approach to VEMP testing, and results provide an objective assessment of the saccule and inferior division of the vestibular nerve. Normal cervical VEMP results yield a biphasic wave with an initial positive peak (located at approximately 13 ms), followed by a negative trough (located at approximately 23 ms). In addition to latency, cervical VEMPs are quantified by their amplitude, which is used to calculate an asymmetry ratio between ears. Abnormal amplitudes or interaural amplitude difference ratio (difference of peak to peak amplitudes on the right and left divided by the sum; R-L/R + L) has shown a significant correlation with Meniere’s disease staging (Young et al. 2003). Increased VEMP thresholds and altered frequency tuning (1,000 Hz as opposed to 500 Hz) have been exhibited in Meniere’s patients (Rauch et al. 2004; Timmer et al. 2006).
Magnetic Resonance Imaging (MRI)
MRI is a medical evaluation used to rule out retrocochlear pathology such as acoustic neuroma and multiple sclerosis, as these differential diagnoses can present with symptoms of true vertigo or unsteadiness, common symptoms in Meniere’s disease. Anatomical changes with the endolymphatic duct or sac may be observed with high-resolution MRI (Weber 2008).
Symptom complaints of sudden hearing loss and tinnitus, with or without vertigo, may be associated with a vast number of disorders including, but not limited to, autoimmune inner ear disease, labyrinthitis, migraine-associated dizziness, vestibular neuritis, perilymphatic fistula, and vascular events (See Table 3). Given the commonality between disorders, a thorough case history emphasizing the temporal characteristics including onset, duration, and associated auditory complaints is imperative.
|Disorder||Symptom characteristics||Temporal characteristics|
|Autoimmune inner ear disease||
Typically bilateral, rapidly progressive hearing loss with or without vestibular impairment
Progressive weeks to months or sudden hours to days
Vestibular and auditory crisis event; sudden onset of vertigo and unilateral sensorineural hearing loss, followed by head movement provoked symptoms
Days (1–3); followed by head movement provoked symptoms
Spontaneous onset of vertigo, with fluctuating hearing loss, aural fullness, and tinnitus
|Episodic; 20 min <24 h|
Vestibular aura associated with migraine headache; exacerbation of symptoms in complex visual environments
|Variable; seconds to hours <24|
Vestibular crisis event: sudden onset of vertigo without auditory symptoms, followed by head movement provoked symptoms
Days (1–3); followed by head movement provoked symptoms
|Perilymphatic fistula||Sudden onset, pressure-induced symptoms of vertigo, imbalance||Seconds to minutes|
|Vascular event (AICA or PICA stroke)||
Vestibular crisis event: sudden onset of vertigo with associated hearing loss and other neurological symptoms/signs
Days (1–3); followed by head movement provoked symptoms
Given the uncertain etiology of Meniere’s disease, there are little to no preventative measures that can be taken at this time to prevent acquiring the disease. However, for those individuals diagnosed with the disorder, reduction in frequency and onset of symptoms may occur following dietary restrictions and stress reduction.
Currently, there is no cure for Meniere’s disease; however, medical management can achieve successful symptom relief in most patients. Treatment categories include conservative, medial management (dietary, sodium restrictions) or more invasive forms of nondestructive (Meniett® device; endolymphatic sac decompression) and destructive (Intratympanic injection; vestibular nerve section) management. Physicians typically first recommend noninvasive treatment methods; however, multiple interventions or combinations of treatment are used to alleviate the symptoms. All management decisions are contingent upon hearing status, stage of disease, and patient values.
Meniere’s episodes may follow a high-sodium meal. Therefore, moderate sodium restrictions (1,500– 2,000 mg/ day of sodium) or strict sodium restrictions (no consumption of salt) are commonly recommended for patients (Weber 2008). Reduction of additional triggers such as caffeine intake, stress, nicotine, and dehydration may also alleviate symptoms. Traditionally used to treat glaucoma, diuretic control has been used for symptom control and to reduce excessive fluid within the membranous labyrinth (Andrews and Honrubia 1996). Allergy-avoidance behaviors or histamine treatments may benefit patients with high correlation of Meniere’s attacks and seasonal allergies. Also, due to a high association, treatment with migraine management in the form of medication or dietary restrictions may alleviate both migraines and Meniere’s symptoms (Weber 2008).
Nondestructive Options (Endolymphatic Sac Decompression & Meniett Device)
Endolymphatic sac surgery is a nondestructive procedure, preserving hearing and balance function, however, highly controversial. Pressure within the endolymphatic sac is decompressed by removing a piece of bone from the inner ear or shunting the fluid into the subarachnoid space or into the mastoid bone (Weber 2008). While this appears to be a viable surgery option, problems may arise with the drainage device becoming encased in fibrous tissue and the location of the sac decompression surgery is more distal (extraosseous region) to area with excessive fluid (Weber 2008).
The Meniett® device has recently been made available to eliminate symptoms while maintaining hearing. Pressure pulses are delivered to the inner ear via a tympanostomy tube to stimulate endolymph flow. In a recent clinical trial, the Meniett® device was 67% successful at improving symptoms in patients with classic, unilateral Meniere’s disease who did not benefit from traditional treatment approach (Gates et al. 2006).
Destructive Options (Intratympanic Injections, Vestibular Nerve Section, Labyrinthectomy)
Natural central nervous system compensation will not occur in patients with spontaneous Meniere’s events. Therefore, chemical or surgical ablation is recommended to stabilize the ear to facilitate the natural compensation process; however, consideration for the contralateral ear is necessary, as preservation of hearing is difficult with these options (Weber 2008). Destructive options are often viewed as a last line of treatment for Meniere’s disease.
While there is little evidence to support the use of oral steroids to treat Meniere’s, intratympanic steroid injections are gaining popularity to control symptoms. Typically, gentamicin is infused into the middle ear space, in low doses (titration regimen) (Cohen-Kerem et al. 2004). The method has been supported by the AAO-HNS guidelines as a highly successful method for controlling vertigo; however, hearing loss is possible (Silverstein et al. 2010). In the most severe cases with minimal usable hearing on the affected side, vestibular nerve section (vestibular neuronectomy) or labyrinthectomy (removal of diseased labyrinth) is recommended.
In addition to the aforementioned medical and surgical options, vestibular rehabilitation, a specialized form of physical therapy, may be beneficial for patients who are no longer experiencing acute attacks of spontaneous vertigo, but report imbalance or movement provoked symptoms, or have residual symptoms in between the spontaneous episodes.
Meniere’s disease is one of the most common causes for vertigo; however, the underlying basis of the disorder remains uncertain. Patient case history and audiometric evaluation remain the most sensitive diagnostic tools and determining factors for management. Effective treatment options and detection of genetic trends and autoimmune traits are emerging with advances in basic and applied research resulting in favorable prognosis for patients afflicted with the disorder and holding promise to one day discovering a cure.
American Academy of Otolaryngology-Head and Neck Surgery, Dec 2010.
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