Decoding Dizziness: Vertigo Essentials for MRCP Success

Few presentations sort candidates out faster than the dizzy patient. One moment you are watching a vignette about brief spinning when rolling over in bed (a diagnosis you can treat at the bedside in ninety seconds), the next you are looking at a normal head impulse test hiding a lateral medullary infarct. Dizziness is one of the most common reasons patients seek medical attention, and it is one of the MRCP's favourite testing grounds because it forces you to combine neuroanatomy, bedside clinical skills, imaging choices and prescribing judgement in a single answer.

This guide walks through the framework, the conditions, the guidelines and the exam traps you need to command vertigo questions confidently in MRCP Part 1, Part 2 Written and PACES.

Why Vertigo Deserves Dedicated Revision Time

• It is extremely common. Dizziness accounts for a substantial proportion of GP presentations and ED attendances, and BPPV alone affects a meaningful proportion of older adults.

• It is discriminative. The exam loves the peripheral-versus-central decision because it mirrors real clinical risk: missing a posterior circulation stroke has catastrophic consequences.

• It spans the curriculum. Cranial nerve anatomy, cerebellar pathways, audiology, pharmacology (vestibular suppressants, ototoxic drugs) and ethics (driving, falls) can all be wrapped into one scenario.

• It recurs across formats. Expect basic-science MCQs in Part 1, best-next-step vignettes in Part 2, and dizziness histories or cranial nerve findings in PACES.

Step One: Define What 'Dizzy' Actually Means

Resist the urge to jump to the vestibular system. First classify the symptom:

Exam tip: In a history-taking station, ask the patient to describe the sensation without using the word dizzy. Timing (seconds vs minutes vs hours vs continuous), triggers (position, head movement, standing, visual stimuli) and associated symptoms (hearing change, headache, focal neurology) do most of the diagnostic work.

Peripheral Versus Central: The Table That Answers Half the Questions

Two memory hooks:

1. Nystagmus direction is named by its fast phase. In acute unilateral peripheral lesions, the fast phase beats away from the affected ear.

2. A patient with acute continuous vertigo who cannot walk has a central lesion until proven otherwise, regardless of how 'peripheral' the story sounds.

The HINTS Examination: Small Test, Enormous Yield

In the acute vestibular syndrome (continuous vertigo of sudden onset with nystagmus and nausea), HINTS outperforms early diffusion-weighted MRI for detecting posterior circulation stroke when performed by experienced clinicians:

• H — Head Impulse test: an abnormal test (corrective saccade) supports a peripheral lesion. A normal test in this setting is the red flag pointing central.

• N — Nystagmus: unidirectional horizontal nystagmus supports peripheral; bidirectional (gaze-evoked, direction-changing) or vertical nystagmus suggests central.

• T — Test of Skew: alternately cover each eye; a vertical corrective movement (skew deviation) indicates a central brainstem lesion.

The paradox candidates must internalise: in acute continuous vertigo, the normal head impulse is the worrying finding. HINTS 'rules in' a benign peripheral cause only when all three components point peripheral; a single central sign rules in central.

Remember too that early MRI-DWI can be falsely reassuring in posterior circulation stroke, so a concerning presentation with an early normal scan still warrants repeat imaging and specialist review.

The Peripheral Heavy-Hitters

1. Benign Paroxysmal Positional Vertigo (BPPV)

• The commonest cause of peripheral vertigo, caused by displaced otoconia, most often in the posterior semicircular canal (~85–90%).

• Classic history: brief (seconds, under a minute) rotatory vertigo triggered by turning in bed, looking up or bending down. No hearing loss, no focal neurology.

• Diagnosis: Dix-Hallpike manoeuvre. After a short latency (a few seconds), you see geotropic torsional nystagmus with an upbeating component that fatigues with repetition while symptoms recur.

• Treatment: Epley repositioning manoeuvre (the Semont liberatory manoeuvre is an alternative). Success rates are high after a single properly performed attempt; Brandt-Daroff exercises can be taught if symptoms persist.

• Horizontal canal BPPV (less common) is diagnosed with the supine roll test and treated with a barbecue (Lempert) roll or Gufoni manoeuvre.

• Red flag modifier: atypical nystagmus on positional testing (for example downbeating nystagmus) demands MRI for a central lesion. A typical BPPV pattern does not require imaging at all.

2. Vestibular Neuritis and Labyrinthitis

• Neuritis: acute, severe, continuous rotatory vertigo for 24–72 hours, often after a viral illness, with unidirectional horizontal nystagmus (fast phase away from the affected ear), a positive head impulse toward the affected ear and no hearing loss.

• Labyrinthitis: the same picture plus sensorineural hearing loss and tinnitus — this distinction is a favourite MCQ point.

• Management:

  • Symptom control with vestibular suppressants (for example prochlorperazine or an antihistamine such as promethazine/cyclizine) for a maximum of around three days. Prolonged use delays central compensation — a classic Part 2 answer.

  • Encourage early mobilisation and vestibular rehabilitation for persistent symptoms.

  • A randomised trial showed a tapering course of corticosteroids improves vestibular recovery, whereas antivirals add no benefit.

• Ramsay Hunt syndrome (herpes zoster oticus) deserves special mention: ear vesicles, lower motor neuron facial palsy, hearing loss and vertigo, treated urgently with antivirals plus corticosteroids.

3. Ménière's Disease

• Endolymphatic hydrops producing the classic triad: recurrent episodic vertigo lasting 20 minutes to 12 hours, fluctuating low-frequency sensorineural hearing loss, and aural fullness ± tinnitus.

• Diagnosis requires documented audiometric sensorineural loss — audiometry is the investigation of choice.

• Hearing often becomes progressively worse over years, and disease becomes bilateral in a substantial minority.

• Acute attack: lie down, prochlorperazine (buccal or IM if vomiting); severe attacks may need admission for IV fluids and antiemetics.

• Prevention: salt restriction, reduce caffeine and alcohol, stress management, and betahistine (widely used in UK practice despite modest evidence). Refractory disease: intratympanic corticosteroids, or intratympanic gentamicin — deliberately vestibulotoxic to ablate the malfunctioning labyrinth, at the cost of hearing risk. Destructive surgery is a last resort.

• Tumarkin otolithic crises (sudden falls without loss of consciousness) are a dangerous complication worth knowing.

4. Vestibular Migraine

• Now recognised as one of the commonest causes of recurrent spontaneous episodic vertigo.

• Diagnostic essence: at least five episodes of vestibular symptoms lasting 5 minutes to 72 hours, with a migraine history and/or migrainous features (photophobia, phonophobia, visual aura) during most episodes.

• Management mirrors migraine: trigger avoidance, acute treatment as for migraine attacks, and prophylaxis (for example propranolol, amitriptyline, topiramate) for frequent episodes.

• A key discriminator from Ménière's: auditory symptoms may occur but progressive hearing loss does not.

Central Causes You Cannot Afford to Miss

• Lateral medullary (Wallenberg) syndrome — vertebral or PICA occlusion: acute vertigo with ipsilateral Horner syndrome, facial pain/temperature loss, dysphagia/dysphonia and limb ataxia, with contralateral body pain/temperature loss. Hiccups are a classic association.

• Cerebellar infarction or haemorrhage — severe vertigo, vomiting, marked truncal ataxia, inability to walk; risk of brainstem compression and hydrocephalus.

• AICA stroke — vertigo with ipsilateral sensorineural hearing loss and facial weakness: the exception to 'hearing loss means peripheral'.

• Vertebral artery dissection — neck pain, recent trauma or manipulation, younger patient.

• Multiple sclerosis — episodic vertigo with internuclear ophthalmoplegia or other disseminated signs.

• Vestibular schwannoma — progressive unilateral sensorineural hearing loss and tinnitus with imbalance rather than acute vertigo; MRI of the internal auditory meatus with gadolinium is the definitive investigation; bilateral schwannomas mean NF2.

• Chiari I malformation and cerebellar degeneration — look for downbeat nystagmus.

• Wernicke encephalopathy — nystagmus, ataxia and confusion; urgent IV thiamine. Do not forget alcohol, phenytoin toxicity and lithium as causes of central nystagmus and ataxia.

• Persistent postural-perceptual dizziness (PPPD) — chronic (more than three months) non-vertiginous dizziness worse on standing, with motion and in visually busy environments, often after an acute vestibular event; treated with explanation, vestibular rehabilitation, CBT and SSRIs/SNRIs. Increasingly examined as a 'recent concepts' topic.

Red Flag Box: When to Escalate Same Day

• Sudden-onset continuous vertigo with a normal head impulse, direction-changing or vertical nystagmus, or skew deviation

• Inability to stand or walk unaided

• Any focal neurological deficit: diplopia, dysarthria, dysphagia, weakness, sensory loss, severe headache or new neck pain

• Sudden sensorineural hearing loss with vertigo

• Significant vascular risk factors or prior stroke

• Action: same-day senior/ED assessment. MRI with diffusion-weighted imaging is the imaging modality of choice; CT is insensitive for the posterior fossa.

Choosing Investigations Wisely

Management at a Glance

Driving and safety: uncontrolled episodic vertigo has DVLA implications (notably for Ménière's), and recurrent attacks or Tumarkin falls demand a falls-risk discussion — both favourite PACES safety-netting points.

How the MRCP Actually Asks About Vertigo

Part 1 style: nystagmus direction and fixation characteristics, HINTS interpretation, which manoeuvre treats which canal, ototoxic drug lists, vestibular pathway anatomy, Ménière's diagnostic criteria.

Part 2 style: a best-next-step or best-initial-test vignette built on the peripheral/central fork — the normal head impulse with gaze-evoked nystagmus that screams MRI.

PACES style: a Station 2 dizziness history where timing and triggers steer you; a Station 5 consultation with Ménière's or BPPV needing explanation, treatment options and driving advice; cranial nerve findings in a station exam.

Rapid-Fire Self-Test

1. A 68-year-old has 20-second spins on turning in bed; neurologically normal. → Dix-Hallpike, then Epley.

2. Acute continuous vertigo, normal head impulse, direction-changing nystagmus. → Urgent MRI-DWI — suspect posterior circulation stroke.

3. Two-hour vertigo episodes with fluctuating low-frequency SNHL and ear fullness. → Audiometry; Ménière's; salt restriction and betahistine.

4. Recurrent 40-minute vertigo with photophobia in a lifelong migraineur. → Vestibular migraine; consider propranolol prophylaxis.

5. Three days of continuous post-viral vertigo with hearing loss. → Labyrinthitis; short-course suppressants, consider corticosteroids, stop suppressants by day three.

High-Yield Takeaways

1. Classify dizziness first: vertigo, presyncope, disequilibrium, nonspecific.

2. Nystagmus fast phase names the direction; peripheral nystagmus is unidirectional and fixation-suppressed; vertical or direction-changing nystagmus is central.

3. In acute vestibular syndrome, a normal head impulse is the danger sign — HINTS beats early MRI when applied properly.

4. BPPV: Dix-Hallpike diagnoses, Epley treats, no imaging needed if typical.

5. Hearing loss separates labyrinthitis from neuritis, but not AICA stroke from Ménière's — the whole picture decides.

6. Ménière's diagnosis needs audiometric SNHL; betahistine for prevention, intratympanic therapy if refractory.

7. Limit vestibular suppressants to about three days to protect central compensation.

8. Vertigo plus any brainstem sign, severe headache, or inability to walk means urgent MRI, not CT.

Final Word

Vertigo questions reward candidates who work through a structured sieve rather than pattern-matching the first sentence. Anchor every case in timing, triggers and the peripheral-versus-central table, let HINTS sharpen the acute presentations, and know the guideline-level management of the big five: BPPV, neuritis/labyrinthitis, Ménière's, vestibular migraine and posterior circulation stroke. Master this framework and the dizzy patient stops being the station you fear and becomes the station that wins you marks.

Good luck with your revision — and may your nystagmus always be unidirectional when you want it to be.