What is the differential diagnosis for an adult patient presenting with nystagmus and vertigo?

Differential Diagnosis for Nystagmus and Vertigo

The differential diagnosis for an adult presenting with nystagmus and vertigo must first distinguish between peripheral vestibular causes (most commonly BPPV, vestibular neuritis, and Ménière's disease) and central nervous system causes (including posterior circulation stroke, vestibular migraine, and cerebellar lesions), with the pattern and characteristics of nystagmus being the most critical distinguishing feature. 1, 2

Classification by Timing Pattern

The first step is categorizing the presentation by temporal pattern, which narrows the differential significantly 3:

• Brief episodic vertigo (seconds to <1 minute): Triggered by head position changes, strongly suggests BPPV—the most common cause accounting for 42% of all vertigo cases 1, 4
• Acute persistent vertigo (days to weeks): Constant symptoms suggest vestibular neuritis (41% of peripheral vertigo), labyrinthitis, or posterior circulation stroke 1, 3
• Spontaneous episodic vertigo (minutes to hours): Recurrent episodes suggest vestibular migraine (14% of all vertigo cases), Ménière's disease, or transient ischemic attacks 1, 3
• Chronic vestibular syndrome (weeks to months): Consider medication side effects, anxiety/panic disorder, posttraumatic vertigo, or posterior fossa mass lesions 3

Peripheral Vestibular Causes

Benign Paroxysmal Positional Vertigo (BPPV)

• Posterior canal BPPV produces torsional upbeating nystagmus toward the affected ear during Dix-Hallpike maneuver, with 5-20 second latency and resolution within 60 seconds 2, 4
• Lateral canal BPPV produces horizontal direction-changing nystagmus on supine roll test—geotropic (beating toward ground) or apogeotropic (beating away from ground) 2, 4
• Episodes last seconds only, triggered by specific head movements like bending forward/backward, looking up, or rolling in bed 4

Vestibular Neuritis/Labyrinthitis

• Presents with unidirectional horizontal nystagmus that persists without positional changes 5
• Acute onset with constant vertigo lasting days, accompanied by nausea, vomiting, and gait instability 1
• Labyrinthitis additionally includes hearing loss, distinguishing it from pure vestibular neuritis 6

Ménière's Disease

• Characterized by fluctuating low-to-mid frequency sensorineural hearing loss, aural fullness, and tinnitus in the affected ear 1, 3
• Episodes last minutes to hours, occurring spontaneously without positional triggers 3
• Hearing loss fluctuates, unlike the stable/absent hearing loss in vestibular migraine 3

Other Peripheral Causes

• Superior canal dehiscence (SCD): Vertigo triggered by pressure changes (Valsalva) rather than position, diagnosed via temporal bone CT or vestibular evoked myogenic potentials 1
• Perilymph fistula: Pressure-triggered vertigo, may occur post-surgery or spontaneously with fluctuating hearing loss 1

Central Nervous System Causes

Critical Nystagmus Patterns Indicating Central Pathology

These nystagmus findings mandate urgent neuroimaging 1, 2:

• Downbeating nystagmus on Dix-Hallpike without torsional component suggests bilateral floccular lesion or cervicomedullary junction pathology 1, 2
• Direction-changing nystagmus without head position changes (periodic alternating nystagmus) 1
• Gaze-evoked nystagmus that beats right with right gaze and left with left gaze 1
• Baseline nystagmus present without provocative maneuvers (though this can also indicate vestibular neuritis) 1
• Direction-changing apogeotropic positional nystagmus from cerebellar lesions, enhanced when lying on the non-affected side 5

Posterior Circulation Stroke/TIA

• Accounts for 25% of acute vestibular syndrome cases, rising to 75% in high vascular risk cohorts 1, 3
• Critical point: 75-80% of patients with posterior circulation infarct have NO focal neurologic deficits initially 3
• Cerebellar strokes present with truncal ataxia apparent only when standing, often without limb ataxia 5
• Risk factors include age >50, hypertension, diabetes, atrial fibrillation, and prior stroke 3

Vestibular Migraine

• Extremely common but under-recognized, accounting for 14% of all vertigo cases 1, 3
• Diagnostic criteria require: ≥5 episodes lasting 5 minutes to 72 hours, current/history of migraine, and ≥1 migraine symptom (headache, photophobia, phonophobia, visual aura) during ≥50% of dizzy episodes 1
• Distinguished from BPPV by longer episode duration and associated migraine features 1

Other Central Causes

• Multiple sclerosis: Demyelinating lesions can cause positional nystagmus 1
• Intracranial tumors: Particularly those near the fourth ventricle or dorsal vermis 1, 7
• Vertebrobasilar insufficiency: Brief episodes (<30 minutes) without hearing loss 3

Diagnostic Algorithm

Step 1: Perform Targeted Physical Examination

For triggered episodic symptoms 2, 4:

• Execute Dix-Hallpike maneuver bilaterally for posterior canal BPPV
• Perform supine roll test for lateral canal BPPV—failure to do both misses up to 30% of cases 4
• Check for baseline nystagmus in primary position before provocative maneuvers 2

For acute persistent vertigo 1, 3:

• Perform HINTS examination (Head Impulse, Nystagmus, Test of Skew) if trained—100% sensitivity for stroke vs 46% for early MRI 3
• Normal head impulse test, direction-changing or vertical nystagmus, and present skew deviation suggest central cause 3
• Warning: HINTS is unreliable when performed by non-experts 3

Step 2: Identify Red Flags Requiring Urgent Neuroimaging

Obtain MRI brain without contrast immediately for 1, 3:

• Focal neurological deficits on examination
• Sudden unilateral hearing loss
• Inability to stand or walk despite normal limb strength
• Downbeating nystagmus or other central nystagmus patterns
• New severe headache accompanying dizziness
• Failure to respond to appropriate BPPV treatment maneuvers after 2-4 attempts
• High vascular risk patients (age >50, hypertension, diabetes, prior stroke) with acute vestibular syndrome, even with normal neurologic exam 1, 3

Step 3: Imaging Decisions

No imaging indicated for 1, 3:

• Brief episodic vertigo with typical BPPV features and positive Dix-Hallpike test
• Acute persistent vertigo with normal neurologic exam and HINTS consistent with peripheral vertigo by trained examiner

MRI brain without contrast (preferred modality) for 1, 3:

• Any red flag features listed above
• Unilateral or pulsatile tinnitus
• Asymmetric hearing loss
• Progressive neurologic symptoms

MRI head and internal auditory canal with and without contrast for 3:

• Chronic recurrent vertigo with unilateral hearing loss or tinnitus to exclude vestibular schwannoma
• Suspected Ménière's disease requiring definitive diagnosis

CT head has extremely low yield (<1%) and misses most posterior circulation infarcts—should not be used instead of MRI when stroke is suspected 1, 3

Common Pitfalls to Avoid

• Misdiagnosing central positional nystagmus as BPPV occurs when proper diagnostic maneuvers are not performed or central features are overlooked 2
• Assuming normal neurologic exam excludes stroke is dangerous—most posterior circulation strokes initially lack focal deficits 3
• Failing to perform both Dix-Hallpike and supine roll testing misses lateral canal BPPV in up to 30% of cases 4
• Relying on patient's description of "spinning" vs "lightheadedness" instead of focusing on timing and triggers 3
• Overlooking medication side effects as a leading reversible cause, particularly antihypertensives, sedatives, anticonvulsants, and psychotropic drugs 3
• Under-recognizing vestibular migraine, especially in young patients—it accounts for 14% of all vertigo but is frequently missed 3