The Dizzy Patient with a Normal MRI
A 62-year-old woman presents with a 4-month history of episodic vertigo lasting 20 minutes to several hours, associated with left-sided hearing loss, tinnitus and a feeling of fullness in the left ear. She has had three episodes in the last month, each leaving her unsteady for a day. Between episodes she is well. Pure tone audiometry shows a left low-frequency sensorineural loss of 40 dB with normal high frequencies; the right ear is normal. MRI with contrast of the internal auditory meati is reported as normal. She is convinced she has a brain tumour and asks why the scan was normal if she is so dizzy.
1. What is the most likely diagnosis, and how do the audiometric findings support it?
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The diagnosis is Ménière's disease, based on the combination of:
- Episodic vertigo lasting 20 minutes to hours (the classic duration is 20 minutes to 24 hours).
- Fluctuating low-frequency sensorineural hearing loss in the affected ear.
- Tinnitus and aural fullness on the same side.
- A normal MRI, which excludes retrocochlear pathology such as vestibular schwannoma.
The low-frequency sensorineural loss with normal high frequencies is characteristic of early Ménière's, reflecting involvement of the apical cochlear turns. The fluctuating nature and the combination of cochlear and vestibular symptoms in the same ear are the key features.
Diagnostic criteria (AAO-HNS) require two or more spontaneous episodes of vertigo lasting 20 minutes to 12 hours, audiometrically documented low-to-medium frequency sensorineural hearing loss in the affected ear on at least one occasion, fluctuating aural symptoms in the affected ear, and no better explanation by another diagnosis. This patient meets these criteria.
2. How do you explain the normal MRI to her, and what is your initial management?
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Explaining the scan: I would say that the MRI was done specifically to look for a tumour of the hearing and balance nerve, and that a normal scan is good news - it excludes a vestibular schwannoma or other structural cause. Ménière's disease is a disorder of the inner ear fluid (endolymph), not a growth, so it does not show on MRI. The scan being normal is consistent with, not against, the diagnosis.
Initial management:
- Reassurance and education - explain the natural history: episodes are episodic, many patients have long remissions, and it is not life-threatening.
- Dietary and lifestyle measures - reduce salt, caffeine and alcohol; avoid triggers; some patients benefit from a low-salt diet.
- Acute attack treatment - vestibular sedatives (prochlorperazine, betahistine) for short-term symptom control, avoiding prolonged use.
- Prophylaxis - betahistine is widely used first-line; a diuretic (e.g. bendroflumethiazide) is an alternative.
- Vestibular rehabilitation for persistent imbalance between attacks.
- Audiological follow-up to monitor hearing and consider hearing aids if the loss progresses.
I would also document the diagnosis and arrange review, and address her anxiety explicitly, as psychological distress worsens symptom perception.
3. She returns 8 months later with persistent disabling vertigo despite medical therapy and now a moderate hearing loss. What are the next steps, and how do you counsel her about ablative options?
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This is medically refractory Ménière's disease with progressive hearing loss. Options in escalating order:
- Intratympanic gentamicin - chemical ablation of the vestibular end organ; effective for vertigo control but carries a risk of worsening hearing loss (roughly 10-30%). Given her progressive hearing loss, this is a reasonable option but the hearing risk must be explicit.
- Intratympanic steroids - less effective than gentamicin but hearing-sparing; a reasonable trial before gentamicin.
- Endolymphatic sac decompression - controversial, low morbidity, hearing-preserving, but evidence is weak.
- Surgical ablation - labyrinthectomy (only if hearing is non-serviceable) or vestibular nerve section (hearing-preserving but intracranial).
Counselling:
- The goal of gentamicin is vertigo control, not hearing improvement; hearing may deteriorate further.
- Ablation causes acute vertigo and imbalance for days to weeks, followed by central compensation; vestibular rehabilitation is essential.
- Bilateral disease occurs in a minority and would make ablation hazardous; the other ear must be monitored.
- If hearing becomes non-serviceable, labyrinthectomy offers excellent vertigo control.
I would involve the MDT, document the discussion, and ensure she understands that the priority is quality of life and fall prevention.