What is the approach to determining the causes of dizziness?

Determining Causes of Dizziness

Primary Diagnostic Framework

Focus exclusively on timing and triggers of dizziness episodes rather than patient descriptions of symptom quality, as patients cannot reliably characterize their dizziness type. 1, 2, 3 This timing-based approach categorizes dizziness into four distinct vestibular syndromes that organize your differential diagnosis systematically. 1

Step 1: Categorize by Timing Pattern

Brief Episodic (Seconds to Minutes)

• BPPV is the most common cause, accounting for 42% of all vertigo cases in primary care. 1
• Triggered specifically by head position changes (rolling over in bed, looking up, bending forward). 1
• Perform Dix-Hallpike maneuver immediately—this provides more diagnostic value than any imaging study. 2
• Positive test shows transient upbeating-torsional nystagmus lasting <1 minute. 1
• Critical distinction: No hearing loss, tinnitus, or aural fullness. 4, 1

Episodic (20 Minutes to 12 Hours)

• Ménière's disease requires fluctuating low-to-mid frequency hearing loss documented on audiometry, plus tinnitus or aural fullness in the affected ear. 4
• Vestibular migraine accounts for 14% of vertigo cases and requires ≥5 episodes lasting 5 minutes to 72 hours with migraine features (photophobia, phonophobia, headache, visual aura) during ≥50% of episodes. 4, 1
• Vestibular migraine can also present with episodes <15 minutes or >24 hours, making timing less reliable than for Ménière's. 4
• Hearing loss is typically absent or mild and stable in vestibular migraine, versus fluctuating in Ménière's. 4

Acute Continuous (Days to Weeks)

• Vestibular neuritis is the most common peripheral cause of acute vestibular syndrome. 1
• Presents with severe continuous vertigo, nausea, vomiting, and spontaneous nystagmus without hearing loss. 1
• Labyrinthitis has identical presentation but includes hearing loss. 4, 1
• This timing pattern carries the highest stroke risk—75-80% of posterior circulation strokes present without focal neurologic deficits on standard examination. 5, 2
• Perform HINTS examination (head-impulse, nystagmus, test of skew) if trained—this has 100% sensitivity for stroke when properly executed. 2

Chronic/Persistent

• Consider Parkinson disease, diabetic neuropathy, medication effects, or psychiatric disorders. 6
• Medication review is essential: antihypertensives, cardiovascular drugs, anticonvulsants (carbamazepine, phenytoin), and benzodiazepines all cause dizziness. 5, 7

Step 2: Identify Red Flags Requiring Immediate Action

Neurologic Red Flags (Central Pathology)

• Focal neurologic deficits: diplopia, dysarthria, facial numbness, limb weakness, sensory changes, dysphagia, dysphonia, or Horner's syndrome. 4, 5, 2
• Inability to stand or walk independently indicates severe vestibular dysfunction or central lesion. 2
• New severe headache with dizziness mandates immediate imaging for hemorrhage, dissection, or posterior fossa pathology. 2
• Downbeating nystagmus or direction-changing nystagmus without head position changes strongly suggests brainstem or cerebellar pathology. 4, 5, 2
• Normal head impulse test in acute vestibular syndrome suggests central cause (stroke), not peripheral. 2

Otologic Red Flags

• Sudden unilateral hearing loss with vertigo raises concern for labyrinthitis or anterior inferior cerebellar artery stroke. 2
• Unilateral or pulsatile tinnitus warrants neuroimaging to exclude cerebellopontine angle tumors or vascular malformations. 2

Critical Pitfall

• Loss of consciousness is never a symptom of peripheral vestibular disorders and indicates cardiac, neurologic, or systemic causes. 2

Step 3: Targeted Physical Examination

Essential Bedside Tests

• Orthostatic blood pressure measurement for presyncope evaluation. 6, 3
• Dix-Hallpike maneuver for triggered episodic dizziness—diagnostic for BPPV. 1, 2
• Assessment for nystagmus patterns:
  • Peripheral: unidirectional, horizontal-torsional, suppressed by visual fixation, fatigues with repeated testing. 5
  • Central: direction-changing, vertical (especially downbeating), gaze-evoked, does not fatigue or suppress with fixation. 4, 5
• HINTS examination in acute vestibular syndrome (if trained): abnormal test indicates stroke. 2

Neurologic Examination

• Evaluate for dysmetria, dysarthria, sensory deficits, motor weakness, and cranial nerve abnormalities. 4, 5
• Severe postural instability with additional neurologic signs suggests vertebrobasilar insufficiency. 5

Step 4: Distinguish Peripheral from Central Causes

Peripheral Vestibular Features

• Vertigo triggered by specific head positions (BPPV). 1
• Fluctuating hearing loss with episodic vertigo (Ménière's). 4
• Acute continuous vertigo without hearing loss (vestibular neuritis). 1
• Unidirectional horizontal-torsional nystagmus that fatigues. 5

Central Vestibular Features

• Downbeating or direction-changing nystagmus. 4, 5
• Baseline nystagmus without provocative maneuvers. 4, 5
• Any focal neurologic signs. 2
• Failure to respond to appropriate peripheral vestibular treatment. 4, 2
• Vertebrobasilar insufficiency presents with isolated transient vertigo <30 minutes without hearing loss, and can precede stroke by weeks to months. 5

Step 5: Selective Use of Diagnostic Testing

When Imaging is NOT Indicated

• Do not order routine imaging for isolated dizziness with typical peripheral features—diagnostic yield is extremely low and most findings are incidental. 2
• Do not order CT head for stroke evaluation—CT misses most posterior circulation infarcts with only 20-40% sensitivity. 2

When Imaging IS Indicated

• Any red flag features listed above. 2
• Acute vestibular syndrome in patients with vascular risk factors, even with reassuring bedside examination. 2
• MRI with diffusion-weighted imaging is the appropriate study for suspected stroke, not CT. 2
• Unilateral or pulsatile tinnitus requires imaging for cerebellopontine angle tumors. 2

Audiometry

• Essential for suspected Ménière's disease to document low-to-mid frequency sensorineural hearing loss. 4
• Helpful to distinguish labyrinthitis (with hearing loss) from vestibular neuritis (without). 1

Laboratory Testing

• Glucose testing in all dizzy patients. 8
• Cardiac rhythm monitoring in patients ≥45 years old. 8
• Otherwise, laboratory testing plays minimal role unless specific systemic disease is suspected. 6

Common Diagnostic Pitfalls to Avoid

• Do not rely on patient descriptions of "spinning" versus "lightheadedness"—these are unreliable. 1, 2, 3
• Do not assume normal neurologic exam excludes stroke in acute vestibular syndrome—most posterior circulation strokes have no focal deficits. 5, 2
• Do not miss medication-induced dizziness—benzodiazepines like lorazepam cause dizziness in 6.9% of patients, with higher incidence in elderly. 7
• Do not overlook superior canal dehiscence—it mimics BPPV but is triggered by pressure changes (Valsalva, coughing) rather than position changes, and may show conductive hearing loss. 4, 1
• Elderly patients may not describe classic "spinning" vertigo even with serious pathology. 2

Differential Diagnosis Summary Table

Most Common Causes by Setting

• Primary care: BPPV (42%), vestibular migraine (14%), Ménière's disease, medication effects. 1, 6
• Specialty clinics: Vestibular migraine, Ménière's disease, vestibular neuritis. 4
• Serious causes requiring urgent evaluation: Posterior circulation stroke (3% of general practice vertigo), brainstem/cerebellar stroke (10% of cerebellar strokes mimic peripheral processes), vertebrobasilar insufficiency. 5

Key Distinguishing Features

• BPPV: Brief (<1 minute), positional, no hearing loss, positive Dix-Hallpike. 4, 1
• Ménière's: 20 minutes to 12 hours, fluctuating hearing loss, aural fullness/tinnitus. 4
• Vestibular migraine: 5 minutes to 72 hours (or atypical), migraine features, minimal/stable hearing loss. 4, 1
• Vestibular neuritis: Days of continuous vertigo, no hearing loss. 1
• Stroke: Acute continuous, central nystagmus patterns, focal deficits (though often absent), vascular risk factors. 5, 2