Definition and Overview
Meniere's disease is a chronic inner ear disorder characterized by episodic vertigo, fluctuating sensorineural hearing loss, tinnitus, and aural fullness (pressure sensation in the ear). Endolymphatic hydrops (excess fluid accumulation in the endolymphatic space) is the pathological hallmark [1].
Prevalence is approximately 50-200 per 100,000, typically presenting between ages 40-60. Most cases are unilateral at onset, with bilateral involvement developing in 15-40% over time [2].
Pathophysiology
Endolymphatic hydrops results from an imbalance between endolymph production and absorption. Proposed mechanisms include impaired endolymphatic sac absorption, increased endolymph production, and altered ion homeostasis [1].
Hydrops causes distension of the membranous labyrinth, and rupture of Reissner's membrane may allow potassium-rich endolymph to contact perilymph, temporarily disrupting vestibular and cochlear function and triggering attacks.
Symptoms
The four cardinal symptoms of Meniere's disease [2]:
- Vertigo: spontaneous rotational vertigo lasting 20 minutes to 12 hours, accompanied by nausea and vomiting
- Hearing loss: fluctuating low-frequency sensorineural hearing loss, progressive over time
- Tinnitus: typically low-pitched roaring or buzzing, often worsening before attacks
- Aural fullness: pressure or stuffiness sensation in the affected ear
Attacks are unpredictable and cluster in episodes of weeks to months (active phases) separated by remission periods. Drop attacks (Tumarkin crises) with sudden falls without loss of consciousness occur in advanced disease.
Diagnosis
Definite Meniere's disease requires [3]:
- Two or more spontaneous vertigo episodes lasting 20 minutes to 12 hours
- Audiometrically documented fluctuating low-to-medium frequency sensorineural hearing loss 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 vestibular diagnosis
Audiometry documents characteristic low-frequency hearing loss. Electrocochleography (ECoG) shows elevated SP/AP ratio. MRI with intratympanic gadolinium can visualize endolymphatic hydrops.
Treatment
Lifestyle Modifications
Low-sodium diet (<2g/day) is the foundation of management, reducing endolymphatic fluid accumulation. Caffeine, alcohol, and tobacco avoidance are recommended. Stress management is important as stress can trigger attacks.
Pharmacotherapy
Diuretics (hydrochlorothiazide) reduce endolymphatic volume. Betahistine increases inner ear blood flow and is widely used outside the US [4]. Acute attacks are managed with vestibular suppressants (meclizine, diazepam) and antiemetics.
Procedures
Intratympanic dexamethasone injection reduces attack frequency. Intratympanic gentamicin selectively ablates vestibular function for refractory cases. Endolymphatic sac surgery aims to improve drainage [5].
Differences from BPPV
BPPV: brief vertigo (seconds), triggered by head position changes, no hearing loss. Meniere's: prolonged vertigo (minutes to hours), spontaneous onset, associated hearing loss and tinnitus.