Meniere's Disease

Meniere's disease is an idiopathic inner-ear disorder defined by endolymphatic hydrops — over-accumulation of endolymph in the membranous labyrinth. It is a clinical favourite for NEET PG because of its crisp clinical triad, the elegant audiometric signature, and a stepladder of management options that examiners love to test from diet right up to ablative surgery.

Definition and the classic triad

Meniere's disease is a chronic, episodic disorder of the membranous labyrinth characterised by the classic triad:

1. Episodic vertigo (rotatory, lasting 20 minutes to 24 hours — typically a few hours)
2. Fluctuating sensorineural hearing loss (initially low-frequency)
3. Tinnitus (often low-pitched, "roaring," ipsilateral)

A frequently quoted fourth symptom is aural fullness / pressure in the affected ear — the modern diagnostic criteria explicitly include it.

High-yield: The vertigo of Meniere's lasts minutes to hours (classically 20 min–24 h). Contrast this with BPPV (seconds), vestibular neuritis (days), and migraine-associated vertigo (variable). The duration of vertigo is the single most discriminating examination point.

When all features of the triad are not yet present, terminology matters:

Term	What it means
Cochlear hydrops	Only auditory symptoms (hearing loss, tinnitus, fullness), no vertigo yet
Vestibular hydrops	Only vertigo, no auditory component yet
Classic Meniere's	Full triad/tetrad present
Lermoyez syndrome	Variant where hearing improves as vertigo appears ("vertigo that hears")
Tumarkin otolithic crisis	Sudden drop attacks without warning or LOC, from utricle/saccule dysfunction

High-yield: Lermoyez syndrome = hearing improves during the vertigo attack. Tumarkin's otolithic crisis / drop attacks = patient suddenly falls ("pushed to the ground") without losing consciousness — a marker of advanced disease and a strong surgical indication.

Etiology and pathophysiology

Meniere's disease is idiopathic by definition; the same clinical picture from a known cause (syphilis, trauma, post-viral, autoimmune) is termed Meniere's syndrome / secondary hydrops.

The unifying pathology is endolymphatic hydrops — distension of the endolymphatic system. Proposed mechanisms:

• Defective endolymph absorption by the endolymphatic sac (the leading theory) — under-resorption rather than over-production.
• Longitudinal flow obstruction in the endolymphatic duct.
• Possible roles of genetic predisposition, autoimmunity, viral injury, vascular factors, and allergy.

Pathophysiology of an attack (membrane rupture theory):

Endolymph accumulates → Reissner's membrane distends → membrane ruptures → potassium-rich endolymph mixes with perilymph → potassium intoxication of vestibular and cochlear nerve fibres → acute vertigo + worsened hearing → membrane heals → symptoms settle until the next cycle.

Repeated rupture–heal cycles cause progressive, cumulative damage, explaining why hearing loss becomes permanent and high-frequency over years, even though early on it fluctuates and is low-frequency.

High-yield: The earliest and most characteristic site of hydrops is the cochlear duct and the saccule (pars inferior of the labyrinth). This is why low-frequency (apical cochlea) hearing loss appears first.

Clinical features

• Vertigo: Sudden, rotatory, severe, with nausea/vomiting; often preceded by an aura of aural fullness and increased tinnitus. Patient lies still during attacks. Between attacks, the patient may be symptom-free initially.
• Hearing loss: Fluctuating, sensorineural, low-frequency in early disease; becomes flat/high-frequency and permanent as disease advances. Diplacusis (same tone heard at different pitch in the two ears) and distortion of sound are characteristic.
• Tinnitus: Low-pitched, roaring/sea-shell, usually worse before/during an attack.
• Aural fullness/pressure.
• Recruitment positive (abnormal loudness growth) — points to a cochlear (end-organ) lesion, distinguishing it from retrocochlear pathology.
• Usually unilateral at onset; bilateral involvement develops in a significant minority (roughly 30–50% over years).

High-yield: Positive recruitment + low-frequency SNHL + episodic vertigo = cochlear hydrops pattern. Recruitment positivity localises the lesion to the cochlea (hair cells), not the nerve.

Diagnosis and investigation of choice

Diagnosis is clinical, supported by audiometry. The 2015 Bárány Society / AAO-HNS criteria are the reference standard.

Definite Meniere's disease:

• ≥2 spontaneous vertigo episodes, each 20 minutes to 12 hours
• Audiometrically documented low-to-medium frequency SNHL in the affected ear on at least one occasion
• Fluctuating aural symptoms (hearing, tinnitus, fullness) in the affected ear
• Not better accounted for by another diagnosis

Probable Meniere's disease: episodic vestibular symptoms 20 min–24 h + fluctuating aural symptoms, but without documented audiometric loss.

Investigations

Test	Finding in Meniere's	Exam pearl
Pure-tone audiometry	Rising (low-frequency) SNHL early; later flat/peaked at 2 kHz ("peak/tent" curve) or downsloping	Investigation of first choice; document fluctuation
Speech audiometry	Reduced discrimination, roll-over may occur	Discrimination poorer than pure-tone predicts in advanced cases
Recruitment tests (SISI, ABLB)	Positive recruitment, high SISI score	Confirms cochlear site
Glycerol dehydration test	≥10 dB improvement / ≥10% speech gain after oral glycerol	Confirms a reversible hydrops component
Electrocochleography (ECochG)	↑ SP/AP ratio (>0.3–0.5)	Most useful objective test of hydrops
Caloric test (electronystagmography)	Canal paresis (reduced response) on affected side	Quantifies vestibular hypofunction
MRI (gadolinium, IAC)	Normal — done to exclude acoustic neuroma/retrocochlear lesion	Mandatory in unilateral SNHL

High-yield: Electrocochleography (ECochG) is the classic objective investigation — an elevated summating potential to action potential (SP/AP) ratio (>0.3, often quoted >0.4–0.5) supports endolymphatic hydrops. This is the single most repeated lab fact in PG papers.

High-yield: The glycerol dehydration test: oral glycerol (an osmotic diuretic, ~1.5 mL/kg with water/lemon) transiently reduces endolymph; a hearing improvement of ≥10 dB (or ≥10% speech discrimination gain) at 1–2 hours is positive and predicts a good response to medical (dehydrating) therapy.

Stepwise diagnostic approach:

Episodic vertigo + ear symptoms → audiometry (low-frequency SNHL?) → confirm recruitment / cochlear localisation → ECochG (SP/AP↑) and/or glycerol test → MRI IAC to rule out acoustic neuroma → apply Bárány/AAO-HNS criteria → label Definite vs Probable.

Management and drug of choice

Management is staged — most patients are controlled medically; only a refractory minority need surgery. The goals are to abort acute attacks, reduce attack frequency (long-term), and preserve hearing.

1. Acute attack (vestibular sedation)

• Vestibular sedatives: prochlorperazine (drug commonly used), promethazine, or antihistaminics (cinnarizine, dimenhydrinate, meclizine).
• Antiemetics (ondansetron, metoclopramide) and IV fluids if vomiting is severe.
• A short course of benzodiazepine (diazepam) may help severe attacks.

High-yield: Prochlorperazine is the typical acute vestibular sedative/antiemetic. Avoid using sedatives long-term as they delay central vestibular compensation.

2. Long-term / prophylactic medical therapy

• Lifestyle: Low-salt diet (<1.5–2 g sodium/day), caffeine restriction, avoidance of alcohol, nicotine, and stress; adequate hydration.
• Diuretics: hydrochlorothiazide (+ triamterene) or acetazolamide — reduce endolymph volume. Considered first-line maintenance in many texts.
• Betahistine — a histamine H1 agonist/H3 antagonist that improves cochlear microcirculation; widely used in maintenance (especially outside the USA).

High-yield: First-line long-term therapy = low-salt diet + diuretic (HCTZ + triamterene) ± betahistine. The cornerstone non-drug measure most quoted in NEET PG is salt restriction.

3. Intratympanic therapy (intermediate, for refractory cases)

Agent	Mechanism	Effect on hearing	When used
Intratympanic steroid (dexamethasone/methylprednisolone)	Anti-inflammatory, reduces hydrops	Hearing-preserving	Preferred when hearing is still serviceable
Intratympanic gentamicin	Chemical labyrinthectomy — ablates vestibular hair cells (vestibulotoxic > cochleotoxic)	Risk of hearing loss	Disabling vertigo with already poor hearing

High-yield: Intratympanic gentamicin = chemical/medical labyrinthectomy. Gentamicin is preferentially vestibulotoxic, so it controls vertigo while relatively sparing (but still risking) hearing. Choose intratympanic steroids when you want to preserve hearing.

4. Surgery

Reserved for intractable vertigo failing medical therapy:

Procedure	Vertigo control	Hearing	Type
Endolymphatic sac decompression / shunt	Good	Conservative — preserves hearing	Conservative
Vestibular neurectomy (section of vestibular nerve)	Excellent (>90%)	Preserves hearing	Hearing-conservation, destructive to balance nerve
Labyrinthectomy	Excellent	Destroys hearing	For dead/non-serviceable ear

High-yield: Endolymphatic sac surgery is the most conservative procedure (hearing-preserving). Vestibular neurectomy gives the best vertigo control while preserving hearing. Labyrinthectomy is used only when there is no serviceable hearing because it sacrifices the cochlea.

Treatment ladder mnemonic flow:

Diet + diuretic → betahistine → intratympanic steroid → intratympanic gentamicin → endolymphatic sac surgery → vestibular neurectomy → labyrinthectomy.

Mnemonic for the management staircase: "Don't Be In Great Spirits, Vertigo Lingers" — Diet, Betahistine, Intratympanic steroid, Gentamicin, Sac surgery, Vestibular neurectomy, Labyrinthectomy.

Complications and natural history

• Progressive, permanent SNHL — fluctuation gives way to fixed loss; speech discrimination declines.
• Bilateral disease in a substantial minority over years.
• Tumarkin's otolithic crises (drop attacks) — injury risk; a surgical indication.
• Chronic disequilibrium between acute attacks once vestibular function is depleted.
• "Burnt-out" Meniere's — vertigo eventually subsides as the labyrinth fails, but hearing is severely and permanently impaired.
• Psychosocial morbidity — anxiety, depression, loss of livelihood from unpredictable vertigo.

Key differential diagnosis

Condition	Vertigo duration	Hearing	Distinguishing feature
Meniere's disease	20 min–24 h, episodic	Fluctuating low-freq SNHL	Aural fullness + tinnitus; ECochG SP/AP↑
BPPV	Seconds (<1 min), positional	Normal	Dix–Hallpike positive; fatigable rotatory nystagmus
Vestibular neuritis	Days, single severe episode	Normal	Recent viral illness; no auditory symptoms
Labyrinthitis	Days	SNHL present	Vertigo + hearing loss after infection
Acoustic neuroma (vestibular schwannoma)	Usually disequilibrium, not true spells	Progressive unilateral SNHL, poor discrimination	MRI IAC; absent recruitment, abnormal ABR
Vestibular migraine	Minutes–hours	Usually normal	Headache/photophobia; migraine history
Perilymph fistula	Variable	Fluctuating SNHL	Trauma/barotrauma; positive fistula test

High-yield: Any unilateral SNHL with poor speech discrimination and absent recruitment should raise suspicion of acoustic neuroma — order an MRI of the internal acoustic canal before settling on Meniere's. Recruitment is positive in Meniere's (cochlear) and absent in acoustic neuroma (retrocochlear).

High-yield: Fistula test / Hennebert's sign (nystagmus/vertigo on pressing the tragus or pressure change) can be positive in Meniere's due to hydrops as well as in perilymph fistula.

Recently asked / exam angle

• "Vertigo lasting minutes to hours with fluctuating low-frequency hearing loss" — the stem points to Meniere's; pick duration as the differentiator from BPPV (seconds) and neuritis (days).
• Investigation of choice for endolymphatic hydrops → Electrocochleography, look for raised SP/AP ratio (>0.3–0.5).
• Glycerol test — knows the osmotic-diuretic principle and the ≥10 dB improvement cut-off.
• Intratympanic gentamicin = chemical labyrinthectomy, preferentially vestibulotoxic — a recurring single-line MCQ.
• Drop attacks without LOC = Tumarkin otolithic crisis; hearing improves with vertigo = Lermoyez syndrome — classic eponym matches.
• Earliest part of labyrinth involved = cochlear duct/saccule (pars inferior) → low-frequency loss first.
• Surgery that preserves hearing AND best controls vertigo = vestibular neurectomy; most conservative = endolymphatic sac decompression; needs dead ear = labyrinthectomy.
• Recruitment positive localises lesion to the cochlea, helping separate Meniere's from acoustic neuroma.
• Membrane rupture / potassium intoxication theory explains the episodic nature — a favourite pathophysiology one-liner.

Rapid revision

1. Meniere's = idiopathic endolymphatic hydrops; "syndrome" if cause is known (syphilis, trauma).
2. Triad: episodic vertigo + fluctuating low-frequency SNHL + tinnitus; tetrad adds aural fullness.
3. Vertigo lasts 20 min–24 h (key against BPPV seconds, neuritis days).
4. Earliest hydrops in cochlear duct + saccule (pars inferior) → low-frequency loss first.
5. Recruitment positive = cochlear lesion; helps exclude acoustic neuroma.
6. ECochG: SP/AP ratio >0.3–0.5 is the objective marker of hydrops.
7. Glycerol test: ≥10 dB hearing gain = positive, predicts medical response.
8. MRI IAC mandatory to rule out vestibular schwannoma in unilateral SNHL.
9. Long-term medical: low-salt diet + diuretic (HCTZ/triamterene) ± betahistine; acute: prochlorperazine/antihistaminics.
10. Intratympanic gentamicin = chemical labyrinthectomy (vestibulotoxic); intratympanic steroid preserves hearing.
11. Surgery: sac decompression (most conservative) → vestibular neurectomy (best hearing-preserving vertigo control) → labyrinthectomy (dead ear only).
12. Eponyms: Lermoyez (hearing improves with vertigo), Tumarkin (drop attacks, no LOC), Hennebert's sign / fistula test positive.