MENIERE’S DISEASE

INTRODUCTION

• Ménière’s disease, also called endolymphatic hydrops,
• It is a disorder of the inner ear where the endolymphatic system is distended with endolymph.
• It is characterized by

(i) vertigo

(ii) sensorineural hearing loss

(iii) tinnitus

(iv) aural fullness.

PATHOLOGY

• The main pathology is distension of endolymphatic system, mainly affecting the cochlear duct (scala media) and the saccule, and to a lesser extent the utricle and semicircular canals.
• The dilatation of cochlear duct is such that it may completely fill the scala vestibuli, there is marked bulging of Reissner’s membrane, which may even herniate through the helicotrema into the apical part of scala tympani
• The distended saccule may come to lie against the stapes footplate. The utricle and saccule may show outpouchings into the semicircular canals.

AETIOLOGY

• This can result either from increased production of endolymph or its faulty absorption or both.
• Normally, endolymph is secreted by stria vascularis, fills the membranous labyrinth and is absorbed through the endolymphatic sac.

1.Defective absorption by endolymphatic sac.

2. Vasomotor disturbance:

There is sympathetic overactivity resulting in spasm of internal auditory artery and/or its branches, thus interfering with the function of cochlear or vestibular sensory neuroepithelium.

This is responsible for deafness and vertigo

3. Allergy:

The offending allergen may be a foodstuff or an inhalant. In these cases, inner ear acts as the “shock organ” producing excess of endolymph.

4. Sodium and water retention:

Excessive amounts of fluid are retained leading to endolymphatic hydrops.

5. Hypothyroidism:

About 3% of cases of Ménière’s disease are due to hypothyroidism. Such cases benefit from thyroid replacement therapy.

6. Autoimmune and viral aetiologies have also been suggested on the basis of experimental, laboratory and clinical observations.

• Commonly seen in the age group of 35–60 years.
• Males are affected more than females. Usually, disease is unilateral but the other ear may be affected after a few years.

Cardinal symptoms of Ménière’s disease are

• (i) episodic vertigo,
• (ii) fluctuating hearing loss,
• (iii) tinnitus
• (iv) sense of fullness or pressure in the involved ear

• Vertigo:

It comes in attacks.Sudden onset. Patient gets a feeling of rotation of himself or his environment. Sometimes, there is feeling of “to and fro” or “up and down” movement.

Attacks come in clusters, with periods of spontaneous remission lasting for weeks, months or years.

It is accompanied by nausea and vomiting with ataxia and nystagmus.

Tullio phenomenon:

• It is a condition where loud sounds or noise produce vertigo and is due to the distended saccule lying against the stapes footplate.
• This phenomenon is also seen when there are three functioning windows in the ear.(fenestration of horizontal canal in the presence of a mobile stapes)

Hearing loss:

• It usually accompanies vertigo or may precede it.
• Hearing improves after the attack and may be normal during the periods of remission. This fluctuating nature of hearing loss is quite characteristic of the disease.
• Distortion of sound
• Intolerance to loud sounds

3. Tinnitus:

It is low-pitched roaring type and is aggravated during acute attacks. Sometimes, it has a hissing character. It may persist during periods of remission.

4. Sense of fullness or pressure:

Like other symptoms, it also fluctuates. It may accompany or precede an attack of vertigo

EXAMINATION

1. Otoscopy: Normal TM.

2. Nystagmus. It is seen only during acute attack. The quick component of nystagmus is towards the unaffected ear.

3. Tuning fork tests:They indicate sensorineural hearing loss.

Rinne test is positive.

Absolute bone conduction is reduced in the affected ear.

Weber is lateralized to the better ear.

INVESTIGATIONS

Pure tone audiometry:

In early stages, lower frequencies are affected and the curve is of rising type.

When higher frequencies are involved curve becomes flat or a falling type.

Speech audiometry.

Discrimination score is usually 55–85% between the attacks but discrimination ability is much impaired during and immediately following an attack.

Special audiometry tests:

(a) Recruitment test is positive.

(b) SISI (short increment sensitivity index) test. SISI score is better than 70% in two-thirds of the patients (normal 15%).

(c) Tone decay test. Normally, there is decay of less than

20 dB.

Electrocochleography.:

It shows changes diagnostic of Ménière’s disease.

Normally, ratio of summating potential (SP) to action potential (AP) is 30%.

In Ménière’s disease, SP/AP ratio is greater than 30%.

5. Caloric test.:

It shows reduced response on the affected side in 75% of cases.

6Glycerol test.

Glycerol is a dehydrating agent. When given orally, it reduces endolymph pressure and thus causes an improvement in hearing.

PROCEDURE:

Patient is given glycerol (1.5 mL/kg) with an equal amount of water.

Audiogram and speech discrimination scores are recorded before and 1–2 h after ingestion of glycerol.

An improvement of 10 dB in two or more adjacent octaves or gain of 10% in discrimination score makes the test positive.

The test has a diagnostic and prognostic value.

MANAGEMENT

• GENERAL MEASURES

1. Reassurance..

2. Cessation of smoking..

3. Low salt diet.

4. Avoid excessive intake of water.

5. Avoid over-indulgence in coffee, tea and alcohol.

6. Avoid stress and bring a change in lifestyle.

7. Avoid activities requiring good body balance.

MANAGEMENT OF ACUTE ATTACK

1. Reassurance.

2. Bed rest.

3. Vestibular sedatives to relieve vertigo.

IM or IV, if vomiting precludes oral administration. Drugs useful in acute attack

• Dimenhydrinate (Dramamine),
• Promethazine theoclate (Avomine) or prochlorperazine (Stemetil).
• Diazepam (Valium or Calmpose) 5–10 mg may be given intravenously.

4. Vasodilators

(a)Inhalation of carbogen (5% CO2 with 95% O2):

It is a good cerebral vasodilator and improves labyrinthine circulation.

(b) Histamine drip:

Histamine diphosphate, 2.75 mg dissolved in 500 mL of glucose, given as i.v. drip at a slow rate is also a good vasodilator and helps to control acute attacks.

MANAGEMENT OF CHRONIC PHASE

1.Vestibular sedatives: Prochlorperazine (Stemetil) 10 mg, thrice a day, orally for two months and then reduced to 5 mg thrice a day for another month.

2. Vasodilators:

Nicotinic acid, 50 mg, is taken about an hour before meals thrice a day.

• Betahistine (Vertin) 8–16 mg, thrice a day, given orally, also increases labyrinthine blood flow by releasing histamine in the body.

3. Diuretics. Sometimes, diuretic furosemide, 40 mg tablet, taken on alternate days with potassium supplement helps to control recurrent attacks.

INTRATYMPANIC GENTAMICIN THERAPY (CHEMICAL LABYRINTHECTOMY)

• Gentamicin is mainly vestibulotoxic. It has been used in daily or biweekly injections into the middle ear.
• Drug is absorbed through the round window and causes destruction of the vestibular labyrinth. Total control of vertigo spells has been reported in 60–80% of patients with some relief from symptoms in others.
• Hearing loss, sometimes severe and profound, has been reported in 4–30% of patients treated with this mode of therapy.

SURGICAL TREATMENT

• 1. Conservative procedures : They are used in cases where vertigo is disabling but hearing is still useful and needs to be preserved. They are:
• (a) Decompression of endolymphatic sac.
• (b) Endolymphatic shunt operation. A tube is put, connecting endolymphatic sac with subarachnoid space, to drain excess endolymph.
• (c) Sacculotomy (Fick’s operation). It is puncturing the saccule
• with a needle through stapes footplate. A distended
• saccule lies close to stapes footplate and can be easily
• penetrated. Cody’s tack procedure consists of placing
• a stainless steel tack through the stapes footplate.

• Cochleosacculotomy is another similar procedure in which, instead of saccule, cochlear duct is punctured and drained into the perilymph (otic-periotic shunt). The procedure is performed with a curved needle pass through the round window to puncture cochlear duct.
• (d) Section of vestibular nerve. The nerve is exposed by retrosigmoid
• or middle cranial fossa approach and selectively
• sectioned. It controls vertigo but preserves hearing.
• (e) Ultrasonic destruction of vestibular labyrinth. Cochlear
• function is preserved.

2. Destructive procedures. They totally destroy cochlear and vestibular function and are thus used only when cochlear function is not serviceable.

• • Labyrinthectomy. Membranous labyrinth is completely destroyed either by opening through the lateral semicircular canal by transmastoid route or through the oval window by a transcanal approach. This gives relief from the attacks of vertigo.
• 3. Intermittent low-pressure pulse therapy [Meniett device therapy . It is observed that intermittent positive pressure delivered to inner ear fluids brings relief from the symptoms of Ménière’s disease.

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