Ménière's Disease — Endolymphatic Hydrops, Diagnostic Criteria, Glycerol Test and Management

Ménière's disease is a chronic inner-ear disorder characterised by recurrent spontaneous vertigo, fluctuating sensorineural hearing loss (typically low- to mid-frequency), tinnitus and aural fullness. It affects roughly 50 to 200 per 100,000 adults and most often starts between 40 and 60 years. The classic histopathological correlate is endolymphatic hydrops — excess endolymph in the membranous labyrinth — although the exact cause is still incompletely understood.

The course is variable and unpredictable, averaging 6 to 11 episodes a year, with remissions that can last months to years. Vertigo attacks usually become less frequent over time and about 34% of patients remit spontaneously, but hearing loss and balance dysfunction tend to progress in the first 5 to 10 years. Bilateral disease becomes more likely with time — up to 35% at 10 years and 47% at 20 years.

Endolymph is produced mainly by the stria vascularis and absorbed in the endolymphatic sac. In the classic model, impaired absorption in the endolymphatic duct and sac leads to progressive accumulation of endolymph and distension of the scala media with displacement of Reissner's membrane. Hydrops was first described in 1938 by Hallpike and Cairns and is found in about 97% of temporal bones from patients with Ménière's disease. It also occurs in some people with no symptoms, so it may be a downstream marker rather than the only trigger.

• Cochlear effect — enlargement of the scala media deflects the basilar membrane toward the scala tympani; this is thought to produce low-frequency hearing loss that fluctuates.
• Vestibular effect — abrupt shifts of endolymph can provoke vertigo; later in the disease, valve of Bast incompetence has been proposed to underlie drop attacks (Tumarkin otolithic crises).
• Tumarkin crisis — a sudden, unexpected fall without loss of consciousness; it occurs in about 34% of patients and is highly specific for Ménière's disease.
• Contributing factors — genetic susceptibility (familial disease in about 6–10%, usually autosomal dominant with incomplete penetrance), autoimmune and autoinflammatory mechanisms, and disturbed ion and fluid homeostasis including vasopressin regulation.

Ménière's disease is a clinical diagnosis classified as definite or probable (American Academy of Otolaryngology–Head and Neck Surgery, as summarised in StatPearls). Symptom clustering is the key: vertigo, hearing loss, tinnitus and fullness occurring together or close in time strongly supports the diagnosis, whereas isolated vertigo or isolated hearing loss should prompt a search for another cause.

When taking the history, define the onset, frequency and duration of each attack and ask whether hearing loss, tinnitus and fullness wax and wane, and whether there are symptom-free intervals — these separate Ménière's disease from chronic vestibular disorders. Triggers worth asking about are dietary salt, caffeine, alcohol, stress, fatigue and emotional upset. Ask about migraine (the commonest mimic) and about autoimmune disease, because autoimmune inner ear disease can cause rapidly progressive bilateral hearing loss. Attacks can cause anxiety and depression and significant functional impairment, which is why quality of life is a treatment goal.

Pure-tone audiometry is the key test: early disease shows a low- to mid-frequency sensorineural loss that fluctuates and later becomes flat or pan-frequency. The AAO-HNS guideline recommends against routine vestibular function testing or electronystagmography to establish the diagnosis. Where the picture is uncertain, adjuncts are available but none is pathognomonic: cervical VEMP is abnormal in about 76% and ocular VEMP in about 70% of definite cases; electrocochleography (ECochG) is abnormal in roughly 55% to 68%.

MRI has two jobs: to exclude retrocochlear lesions such as vestibular schwannoma, and — using delayed gadolinium-enhanced 3D FLAIR sequences — to visualise hydrops directly. Gadolinium enters the perilymph but not the endolymph, so hydrops appears as expansion of the endolymphatic space. Sensitivity is low (about 26%) in early disease and hydrops can also be seen in asymptomatic ears. Routine laboratory tests have little diagnostic value because no specific biomarker exists; they are used mainly to exclude other causes.

The glycerol test is an audiometric provocation test. Pure-tone thresholds are measured at baseline and then at hourly intervals after oral glycerol; an improvement in thresholds counts as a positive test. In a published analysis of 356 ears with suspected Ménière's disease, improvement was greatest in the low- and mid-frequency bands and most apparent 3 to 4 hours after administration. A small study found the glycerol test positive in only about 38% of patients with definite disease, compared with 62% for ECochG — so it is an extra tool, not a requirement for the diagnosis.

The AAO-HNS recommends a stepwise approach: conservative dietary changes, then medical therapy, then intratympanic injections and finally surgery for refractory disease. The goals are to control vertigo and improve quality of life. Evidence for most oral treatments is of low or very low certainty (2023 Cochrane review).

• Vestibular rehabilitation and hearing aids are non-invasive adjuncts for balance and hearing loss.
• Intratympanic gentamicin has strong cytotoxic effects on vestibular cells and is ototoxic — the reason for low-dose, limited use.
• A drop attack (Tumarkin crisis) is a safety issue; ask about falls, driving and work.

• Pathology → endolymphatic hydrops (distended scala media, bulging Reissner's membrane).
• Symptoms → episodic vertigo (20 min to 12 h), fluctuating low-frequency sensorineural loss, tinnitus, aural fullness.
• Drop attacks → Tumarkin otolithic crisis.
• Audiogram → low-frequency sensorineural hearing loss early on; flat later.
• Glycerol test → positive if hearing thresholds improve after oral glycerol.
• First step → low-salt diet, then diuretics/betahistine; refractory → intratympanic gentamicin or surgery.