What is the most likely cause of sudden onset severe vertigo in a patient?

Most Likely Cause of Sudden Onset Severe Vertigo

Benign paroxysmal positional vertigo (BPPV) is the most common cause of sudden onset severe vertigo, accounting for 42% of all vertigo cases in general practice settings, though you must actively exclude life-threatening central causes—particularly stroke—which can present identically. 1

Primary Differential Based on Clinical Presentation

The most likely causes depend critically on the duration and pattern of symptoms:

Brief Episodes (<1 minute) Triggered by Head Position

• BPPV is overwhelmingly the most common cause, characterized by brief rotational vertigo triggered by specific head movements with no hearing loss 1
• Confirm with Dix-Hallpike maneuver showing torsional and upbeating nystagmus with 5-20 second latency, crescendo-decrescendo pattern, and resolution within 60 seconds 2

Continuous Severe Vertigo Lasting Days

• Vestibular neuritis accounts for approximately 41% of peripheral vertigo cases, presenting with sudden prolonged rotary vertigo lasting 12-36 hours with severe nausea and vomiting, but no hearing loss 1, 3
• Distinguished from labyrinthitis by the absence of auditory symptoms (no hearing loss, tinnitus, or aural fullness) 3

Episodes Lasting Hours with Hearing Symptoms

• Ménière's disease presents with vertigo episodes lasting 20 minutes to 12 hours accompanied by fluctuating hearing loss, tinnitus, and aural fullness 1
• Accounts for approximately 10% of vertigo cases in general practice 1

Critical Red Flags Demanding Immediate Neuroimaging

You must actively exclude stroke in every patient with acute vertigo, as 75-80% of stroke-related acute vestibular syndrome patients have no focal neurologic deficits, making stroke easy to miss 1. The American College of Radiology states that approximately 25% of patients with acute vestibular syndrome have cerebrovascular disease 2.

Immediate MRI with Diffusion-Weighted Imaging Required If:

• Severe postural instability with falling (most important distinguishing feature of central causes) 1, 2
• New-onset severe headache with vertigo 2
• Any additional neurologic symptoms (dysarthria, dysmetria, dysphagia, sensory/motor deficits, diplopia, Horner's syndrome) 1, 2
• Downbeating nystagmus on Dix-Hallpike without torsional component 1, 2
• Direction-changing nystagmus without head position changes 1
• Nystagmus that does not fatigue with repeated testing and is not suppressed by visual fixation 1, 2
• Purely vertical nystagmus without torsional component 2
• Failure to respond to appropriate peripheral vertigo treatments 1, 2

Diagnostic Algorithm

Step 1: Perform Dix-Hallpike Maneuver Immediately

The American Academy of Otolaryngology-Head and Neck Surgery recommends performing this test on all patients with vertigo 2:

Peripheral (BPPV) findings:

• Torsional and upbeating nystagmus with 5-20 second latency 2
• Crescendo-decrescendo pattern 2
• Fatigues with repeat testing 2
• Resolves within 60 seconds 2

Central pathology findings (requires urgent imaging):

• Immediate onset without latency 2
• Persistent nystagmus that does not fatigue 2
• Purely vertical without torsional component 2

Step 2: Assess for Hearing Loss and Associated Symptoms

• No hearing loss → BPPV or vestibular neuritis most likely 1, 3
• Fluctuating hearing loss with tinnitus and aural fullness → Ménière's disease 1
• Stable or absent hearing loss with migraine features → vestibular migraine 2

Step 3: Evaluate Vascular Risk Factors

Even if presentation suggests vestibular neuritis, patients with significant vascular risk factors (age >50, hypertension, diabetes, smoking, atrial fibrillation) should be evaluated for possible stroke 3. Remember that 10% of cerebellar strokes present identically to peripheral vestibular disorders 1.

Common Pitfalls to Avoid

• Assuming absence of focal neurologic deficits rules out stroke: 75-80% of stroke patients with acute vestibular syndrome have no focal deficits 1
• Relying on symptom severity: Both peripheral and central causes produce severe vertigo with nausea and vomiting—this does NOT distinguish between them 1
• Ordering routine CT head: Diagnostic yield is less than 1% in isolated dizziness; MRI with diffusion-weighted imaging is required if central cause suspected 4, 2
• Missing vertebrobasilar insufficiency: Isolated transient vertigo may precede stroke by weeks or months, with episodes typically lasting <30 minutes 1, 2