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Dr T Balasubramanian MS DLO

Meniere’s Disease

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Definition

Meniere’s disease is defined as a symptom complex associated with:1. Roaring tinnitus2. Sensorineural hearing loss (Low frequency)3. Vertigo (episodic)4. Fullness of the ear5. These symptoms are associated with dilated membranous

labyrinth filled with endolymph

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History

1. 1747 – Antonio Scarpa described anatomy of membranous labyrinth2. 1861 – Prosper Meniere described the classic features of Meniere’s

disease & attributed it to labyrinthine causes3. 1871 – Knappin theorized that dilated membranous labyrinth to be

the cause of this disorder4. 1927 – Guild described endolymphatic ciruclation5. 1938 – Hallpike and Portmann described pathology of Meniere’s

disease by studying temporal bones.

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Where do we stand?

1. 150 years have passed since this syndrome was described2. Amount of literature accumulated has virtually doubled3. Only consensus reached so far is that its cause is multifactorial4. Not all individuals with histological features of Meniere’s disease

manifested the classic clinical features (? Unknown factors protecting the individuals)

5. Surgical destruction of sac ameliorates symptoms. (? What role does sac play exactly in endolymphatic circulation)

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Physiology of inner ear fluids

1. Inner ear contains two types of fluids (perilyimph and endolymph separated by membranous labyrinth.

2. Perilymph is similar in composition to CSF (Containing high Na and low K ions)

3. Endolymph similar in composition to intracellular fluid (Containing low Na and high K concentration). It is secreted by stria vascularis

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Anatomy of Sac

Duct begins at ductus reuniens Duct is a single lumen tube

about 2 mm long The duct narrows at the isthmus

which lies at the level of vestibular aqueduct

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Functions of sac

1. Secretory function2. Absorptive function3. Immune / defense function

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Secretions from the sac

1. Aquaporins2. Glycoproteins like Saccain3. Endolymph4. Glycoproteins act as a driving force

for longitudinal flow

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Endolymphatic fluid circulation

1. Longitudinal flow2. Radial flow3. Dynamic flow

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Longitudinal flow

1. Was first proposed by Guild2. Striavascularis is the principal source3. This is a slow process4. Elimination occurs at the endolymphatic

sac level

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Dynamic flow

1. First proposed by Lawrence2. This is a combination of both

longitudinal and radial flow patterns

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Radial flow

1. This is active process (energy consuming)2. Production occurs from dark vestibular cells &

planum semilunatum3. Absorption occurs at the striavestibularis

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Endolymphatic sinus

1. This is a small membranous bulb located where the endolymphatic duct enters the vestibule

2. This is where the volume of circulating endolymph is monitored3. Monitoring the volume of endolymph is not possible by sac

because it will be interfered by CSF pressure and pressure exerted by lateral sinus

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How endolymphatic sinus monitors

endolymph volume

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Salt’s findings on endolymphatic flow

1. Composition of endolymph is maintained by stria vascularis by controlling the influx of water

2. Normally endolymph is a biological puddle with very little radial / longitudinal flow

3. Only under exceptional circumstances like increased endolymphatic fluid volumes does radial / longitudinal movement towards sac occurs

4. Under normal circumstances radial flow alone is sufficient to maintain endolymph fluid balance and the longitudinal flow due to saccmechanics is not necessary

5. The longitudinal flow is restricted by the isthmus portion of the duct which acts like the constriction seen in the hour glass

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Mechanism of Meniere’s disease

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Lake pond hypothesis

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Drainage theory

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Drainage theory (contd)

1. Small amounts of excess endolymph can be cleared by radial flow2. Larger volumes need longitudinal flow for their clearance3. Endolymphatic sinus temporarily accommodates excess endolymph till

the sac is ready for it4. Endolymphatic valve of Bast isolates pars superior and prevents

endolymph from draining out of the utricle

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Causes

1. Genetic causes2. Infection3. Otosclerosis4. Trauma (physical / acoustic)5. Syphilis6. Miscellaneous – Allergy, tumors, leukemia and autoimmune disorders

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Types of Meniere's disease

1. Classical Meniere’s disease2. Vestibular Meniere’s disease – vestibular symptoms and aural pressure3. Cochlear Meniere’s disease – cochlear symptoms and aural pressure4. Lermoyez syndrome – Reverse Meniere’s5. Tumarkin’s crisis – Utricular Meniere’s

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Lermoyez syndrome

This is a variant of Meniere’s disease. It is characterized by sudden sensori neural hearing loss which improves during or immediately after the attack of vertigo.

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Tumarkin’s drop attacks

This variant is characterized by abrupt falling attacks of brief duration without loss of consciousness. This is caused due to an enlarging utricle due to excess endolymphatic volume. Utricular crisis is used to indicate this condition.In the later disease stages the valve of Bast remaining patent may cause sudden drainage of endolymph from the utricle due to longitudinal flow resulting in these drop attacks

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Incidence

Roughly 1 in 1000 individuals are affected Constitutes 10% of all patients attending vertigo clinic Female preponderance Rare in children under the age of 10 Commonly begins between 4th and 5th decades of life Bilateral Meniere’s syndrome is seen in 5% of these patients

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Pathophysiology

1. Endolymphatic hydrops causes distortion of membranous labyrinth2. Pressure building up in the scala media may cause mirco ruptures of

membranous labyrinth3. This would account for the episodic nature of the attacks4. Healing of these ruptures causes resolution of the disorder

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Clinical manifestations

1. Episodic vertigo rotatory in nature2. Ipsilateral hearing loss3. Aural fullness4. Roaring tinnitus5. Diplacusis

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Stages

1. Stage I – Patient has solely cochlear symptoms2. Stages II – IV – Patients have progressively more cochlear and

vestibular symptoms3. Stage V – End stage Meniere’s disease (dead ear)

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Direction of nystagmus

1. Irritative nystagmus during the first 20 mins of attack2. Paralytic nystagmus follows3. Later recovery nystagmus starts

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Diagnostic criteria

Possible Meniere’s disease: Episodic vertigo of Meniere’s type without documented hearing loss Fluctuating hearing loss with disequilibrium but without definite episodes Probable Meniere’s disease: One definitive episode of vertigo Audiometrically documented hearing loss at least during one attack Definitive Meniere’s disease Two or more definitive episodes of spontaneous vertigo one atleast lasting for 20 mins. Audiometrically documented hearing loss at least on one occasion Tinnitus and aural fullness in the treated ear

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Groningen criteria of diagnosis

Sensori neural hearing loss combined with: Tinnitus now / in the past Vertigo attacks (at least two present now or in the past) Exclusion of other pathology following Groningen protocol Hearing loss: Sensori neural in nature No demonstrable conductive element Hearing loss of 20 dB or more at one of the usually measured audiometric thresholds Vertigo: Paroxysmal rotatory dizziness, accompanied by nausea / vomiting At least two episodes should be reported during a course of illness. One of the attack should last at least for 5 mins In between attacks there may be periods of unsteadiness

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Hearing loss

1. Sensori neural in nature2. Fluctuating and progressive3. Affects low frequencies4. Mild low frequency conductive hearing loss (rare)5. Profound sensori neural hearing loss (End stage)

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Tinnitus

Roaring in nature Could be continuous / intermittent Non pulsatile in nature Frequency of tinnitus corresponds to the region of cochlea which has suffered

the maximum damage

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Loudness recruitment

1. This is abnormal growth in the perceived intensity of sound2. This is usually positive in patients with Meniere’s disease3. ABLB is the test used to look for the presence of recruitment4. This test is really time consuming

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Electro cochleography

1. Increased summating potential / action potential ratio. 1:3 is normal2. Widened summating potential / action potential complex. A widening of

greater than 2 ms is significant3. Small distorted cochlear microphonics

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Vestibular tests

1. Not mandatory for diagnosis of Meniere’s disease2. Caloric test is still performed3. It is low frequency stimulation (0.003 Hz) of lateral canal4. Caloric asymmetry will point to the diseased ear5. 20% difference between the two ears (Jongkee’s formula) is significant

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VEMP

1. Vestibular evoked myogenic potential2. Measures the relaxation of sternomastoid muscle in response to ipsilateral click

stimulus3. Brief high intensity ipsilateral clicks produce large short latency inhibitory

potentials (VEMP) in the toncially contracted Ipsilateral sternomastoid muscle4. This test is due to the presence of vestibulo collic reflex5. Afferent arises from sound responsive cells in the saccule, conducted via the

inferior vestibular nerve.6. Efferent is via vestibulo spinal tract7. Normal responses are composed of biphasic (positive-negative) waves8. VEMP reveals saccular dysfunction

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Dehydration tests

1. Glycerol2. Frusemide3. Isosorbide4. Tests are positive if there is pure tone improvement of 10dB or more

at two / more frequencies between 200-2000Hz

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Glycerol test

1. First introduced by Klockhoff and Lindblom – 19662. Glycerol is administered in doses of 1.5 mg/kg body wt in empty stomach3. Serum osmolality should increase at least by 10 mos/kg4. Side effects include Headache, Nausea, vomiting, drowsiness5. PTA is performed 2-3 hours after administration6. False positivity is rare7. Positivity depends on the phase of the disease

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Medical Management

1. Dietary management2. Physiotherapy3. Psychological support4. Pharmacological intervention

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Treatment of acute exacerbation

1. Intravenous fluids – dehydration2. Vestibular suppressants – May delay recovery / rehabilitation process3. Corticosteroids – May help if tinnitus and deafness are debilitating

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Low salt diet

1. Frustenberg diet2. 2 grams / 24 hours (restricted salt intake)3. Life style modification

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Role of diuretics

1. Diuretics play a vital role in alleviating acute symptoms2. This has been in use since 1930’s3. Thiazide group of drugs are commonly used4. Frusemide may be used to alleviate acute symptoms5. Clear scientific evidence is lacking regarding the usefulness of diuretics

(cochrane review)

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Betahistine

1. Cochlear vascular insufficiency has been proposed as one of the mechanism of Meniere's disease

2. Betahistine is supposed to cause vasodilatation of cochlear blood vessels

3. Betahistine has weak H1 agonistic property and considerable H3 antagonist properties

4. It reduces the frequency & intensity of vertigo. Has minimal effect on tinnitus

5. Doesn’t help much with hearing loss (Cochrane review)

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Intratympanic steroids

1. Immune modulating effects2. Improves fluid dynamics of inner ear due to mineralocorticoid effects3. Vertigo was controlled on an immediate basis4. Methylprednisolone has the best effect as it penetrates the round window

better5. Silverstein microwick can be used for intratympanic drug administration

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Miscellaneous drugs

1. Isordil2. ϒ – globulin3. Urea4. Glycerol5. Lithium6. Anticholinergics – Glycopyrrolate 1-2 mg /day7. Antidopaminergics – Droperidol 2.5 – 10 mg orally / day8. Leuprolide acetate – Blocks normal sex hormone production9. Innovar – A combination of droperidol and fentanyl can be used to

suppress vestibular symptoms (can replace endolymphatic sac surgery)10. Hyperbaric oxygen therapy

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Other treatment modalities (ancillary)

1. Stress reduction2. Patient education3. Hearing aids – can be used to suppress troublesome tinnitus4. Tinnitus retraining

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Vibrator therapy

1. Meniett Device 2. Low pressure pulse generator3. Vibrations are transmitted via external

auditory canal4. Vibrations alter inner ear fluid dynamics by

their effects on the oval and round windows

5. Exact mechanism of action is not known6. It is totally non invasive7. This device is portable

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Vibrator therapy steps

1. Diagnosis should be confirmed2. Ventilation tube should be inserted3. Patient should be trained for self administration of the treatment4. Usually administered thrice a day about 5 mins each time5. Treatment lasts for 5 weeks

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Indications for vibrator therapy

1. Classic unilateral Meniere’s disease2. Intense vestibular / cochlear symptoms3. Failed medical therapy4. Over 65 years of age5. Imbalance / aural fullness / tinnitus after gentamycin treatment

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Contraindications for vibrator therapy

1. Perilymph fistula2. Acoustic neuroma / brain tumor3. Retrocochlear damage4. Low pressure hydrocephalus

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Role of aminoglycosides

1. Vestibulotoxic effects are put to therapeutic use.2. Sensation of vertigo reduced while hearing is preserved3. Streptomycin / gentamycin are predominantly Vestibulotoxic4. Intratympanic administration is preferred

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Intratympanic gentamycin

1. Fixed dose protocol is used2. 40 mg/ml gentamycin is buffered with soda bicarb (pH6.4) final concentration

26.7mg/ml.3. T tube grommet inserted into the postero inferior quadrant of ear drum. A

mcirocatheter is inserted through the grommet4. 1ml of gentamycin solution is injected into the middle ear cavity via the

microcatheter5. Three injections are given per day in outpatient setting6. Injections are given for 4 days7. After injection patient should lie supine with the infiltrated ear up for 30 mins8. Vertigo usually develops between 2-4 days after cessation of treatment

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Surgical management

1. Sac enhancement procedure2. Sac decompression procedure3. Labyrinthine ablative procedures

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Shunt procedure

1. External shunts – Drains the sac into mastoid cavity / subarachnoid space2. Internal shunts – Drains excessive endolymph into the perilymphatic space

(cochleosacculotomy / labyrinthotomy)

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Sac identification

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Cochleosacculotomy / Labyrinthotomy

1. Helpful in treating debilitated patients2. Involves disruption of osseous spiral lamina3. Angular pick introduced via round window towards oval window. It will

accommodate 3 mm long pick4. After perforation the pick is withdrawn and the round window is sealed by

fat

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Ablative procedures

1. Labyrinthectomy2. Translabyrinthine vestibular neurectomy3. Retrolabyrinthine vestibular neurinectomy4. Retrosigmoid vestibular neurinectomy5. Middle cranial fossa vestibular neurinectomy