Ménière’s Disease (Endolymphatic Hydrops)
High-Yield Revision Notes for NEET PG / NEXT
Ménière’s disease is an inner ear disorder pathologically characterized by endolymphatic hydrops—an abnormal distension of the endolymphatic system due to increased fluid pressure. This results from a mismatch between endolymph secretion (by the stria vascularis) and absorption (by the endolymphatic sac).
The Classic Diagnostic Tetrad
Diagnosis is fundamentally clinical and requires the documentation of a distinct symptom complex:
- Episodic Vertigo: Paroxysmal, spontaneous attacks of rotatory vertigo lasting anywhere from **20 minutes to several hours** (rarely exceeding 24 hours), accompanied by nausea and vomiting.
- Fluctuating Hearing Loss: Sensory hearing impairment that characteristically **affects low frequencies** early in the disease course, fluctuating in intensity before becoming permanently progressive.
- Tinnitus: Classically described as a low-pitched, subjective, roaring or seashell sound that often worsens during or immediately preceding an acute vertigo spike.
- Aural Fullness: A sensation of deep pressure or plugging within the affected ear cavity.
Named Clinical Variants & Pathognomonic Eponyms
| Variant / Phenomenon | Diagnostic Features & Mechanism |
|---|---|
| Lermoyez Syndrome | A paradoxical presentation where the order of symptoms is reversed. Hearing drops and tinnitus peaks first, followed by a vertigo attack that **paradoxically improves or restores the hearing profile** immediately afterward. |
| Tumarkin’s Otolithic Crisis (Drop Attacks) |
Sudden, catastrophic drop attacks without warnings or loss of consciousness. Driven by direct mechanical distortion of the otolithic organs (utricle/saccule), causing abrupt shifts in vestibular spatial orientation. |
| Lermoyez’s Variant Types | Cochlear Hydrops: Isolated fluctuating low-frequency hearing loss, tinnitus, and fullness without vertigo. Vestibular Hydrops: Isolated episodic vertigo episodes and fullness without auditory deficits. |
| Hennebert’s Sign | Nystagmus or vertigo elicited by manual digital compression of the external auditory canal or tragus **in the presence of an intact tympanic membrane**. Indicates fibrous adhesions between the stapes footplate and the membranous labyrinth. |
Diagnostic Workup & Audiometric Markers
- Pure Tone Audiometry (PTA): Confirms a sensorineural hearing loss. Early stages show a characteristically ascending curve due to selective **low-frequency loss** (peaking around 250–500 Hz). Advanced chronic stages transition to a flat or down-sloping configuration across all frequencies.
- Speech Audiometry: Demonstrates marked **recruitment** (an abnormal growth in the perception of loudness). Speech discrimination scores remain surprisingly good in early phases but deteriorate rapidly during late stages.
- Glycerol Dehydration Test: Baseline audiometry is followed by oral intake of dehydrating glycerol (1.2 mL/kg). A subsequent improvement in speech discrimination (greater than 12%) or pure tone thresholds (greater than 10 dB) serves as definitive evidence of underlying reversible endolymphatic hydrops.
- Electrocochleography (ECoG): Evaluates cellular potentials. A pathognomonic finding is an **elevated Summation Potential to Action Potential (SP/AP) ratio** (typically **greater than 0.35**), reflecting distortion of the basilar membrane.
- Cervical VEMP (Vestibular Evoked Myogenic Potentials): Used to evaluate saccular and inferior vestibular nerve integrity; demonstrates altered thresholds or absent responses in advanced disease tracking.
Management Protocol
1. Management of Acute Attacks
- Vestibular Suppressants: Intramuscular or oral H1-antagonists / benzodiazepines (e.g., Prochlorperazine, Promethazine, or **Diazepam**) to abort violent acute rotatory spells.
- Anti-emetics: Targeted medications like Ondansetron to control severe vegetative visceral symptoms.
2. Prophylactic Maintenance Therapy (Long-Term Control)
- Dietary Restriction: Strict **low-salt diet** (less than 1.5–2 grams/day) combined with the complete elimination of trigger substances like caffeine, nicotine, and alcohol to minimize systemic fluid shifts.
- Betahistine: A weak H1 agonist and strong H3 antagonist. It increases microvascular blood flow to the stria vascularis, aiding endolymphatic clearing and reducing attack frequencies.
- Diuretics: Long-term low-dose **Thiazides** or Acetazolamide to biochemically reduce total endolymphatic volume and control hydrostatic pressures.
3. Interventional & Surgical Cascades (Medical Refractory Cases)
- Intratympanic Dexamethasone Injections: Non-destructive chemical therapy aimed at stabilizing local inner ear microvessels and controlling active local inflammatory changes.
- Intratympanic Gentamicin Injections (Chemical Labyrinthrectomy): Gentamicin is selectively **vestibulotoxic**. Diffusing it into the middle ear selectively ablates the vestibular hair cells to stop vertigo, carrying a calculated risk of permanent cochlear hearing damage.
- Endolymphatic Sac Decompression (ESD) / Shunting: A conservative, non-destructive surgical strategy indicated for patients with useful residual hearing. The bone over the endolymphatic sac is exenterated via a cortical mastoidectomy to relieve fluid tension.
- Surgical Labyrinthrectomy / Vestibular Nerve Section: Destructive surgical options reserved exclusively as a final measure. Labyrinthrectomy provides absolute vertigo control but results in a complete **dead ear**, making it acceptable only when baseline hearing is completely non-serviceable.