What are the possible causes of nystagmus and dizziness?

Causes of Nystagmus and Dizziness

Nystagmus and dizziness arise from three broad categories: peripheral vestibular disorders (most common), central nervous system lesions, and non-vestibular systemic causes, with the specific pattern of nystagmus and timing of symptoms being the key to distinguishing life-threatening central pathology from benign peripheral conditions. 1

Classification by Timing and Triggers

The American Academy of Otolaryngology–Head and Neck Surgery recommends first categorizing dizziness by timing (acute, episodic, chronic) and triggers (positional vs. spontaneous) to narrow the differential diagnosis. 2

Four Clinical Syndromes:

• Triggered episodic vestibular syndrome – Episodes lasting seconds to <1 minute, provoked by head-position changes (e.g., BPPV). 2
• Spontaneous episodic vestibular syndrome – Episodes lasting minutes to hours without positional triggers (e.g., vestibular migraine, Ménière's disease). 2
• Acute vestibular syndrome – Continuous dizziness for days to weeks with nausea, vomiting, and intolerance to head motion (e.g., vestibular neuritis, stroke). 2
• Chronic vestibular syndrome – Persistent dizziness for weeks to months (e.g., anxiety, medication effects). 2

Peripheral Vestibular Causes

Benign Paroxysmal Positional Vertigo (BPPV)

• Most common cause of peripheral vertigo, accounting for 42% of vertigo cases in primary care settings. 1
• Characterized by brief episodes (<60 seconds) triggered by specific head movements (rolling over, looking up, bending forward). 2
• Posterior canal BPPV (85–95% of cases) produces torsional, up-beating nystagmus on Dix-Hallpike testing with 5–20 second latency and crescendo-decrescendo pattern. 2
• Lateral canal BPPV produces direction-changing horizontal nystagmus on supine roll testing. 1
• No hearing loss, tinnitus, or aural fullness—presence of auditory symptoms excludes BPPV. 1, 2

Vestibular Neuritis

• Presents as acute vestibular syndrome with sudden severe vertigo lasting 12–36 hours, profound nausea/vomiting, and persistent baseline horizontal nystagmus without provocation. 2
• No hearing loss—distinguishes it from labyrinthitis. 2
• Unidirectional horizontal nystagmus beating away from the affected side. 3

Ménière's Disease

• Episodic attacks of sustained vertigo (minutes to hours) with fluctuating sensorineural hearing loss, aural fullness, and tinnitus in the affected ear. 2
• The presence of fluctuating hearing loss is the key distinguishing feature from BPPV. 2

Other Peripheral Causes

• Labyrinthitis – Similar to vestibular neuritis but with hearing loss. 1
• Superior canal dehiscence – Vertigo induced by pressure changes (Valsalva, loud sounds) rather than head position, with conductive hearing loss on audiometry. 2
• Perilymph fistula – Episodes triggered by pressure changes rather than positional changes. 2
• Vestibular migraine – Requires ≥5 episodes lasting 5 minutes to 72 hours, history of migraine, and migraine features (headache, photophobia, phonophobia, visual aura) in ≥50% of dizzy episodes; episodes are spontaneous, not positional. 2

Central Nervous System Causes

Red-Flag Nystagmus Patterns Indicating Central Pathology

The American Academy of Otolaryngology identifies these nystagmus findings as strong indicators of neurologic causes requiring urgent neuroimaging: 2

• Down-beating nystagmus on Dix-Hallpike without a torsional component. 2
• Direction-changing nystagmus occurring without head-position changes (periodic alternating nystagmus). 2
• Gaze-evoked nystagmus (beats in the direction of gaze). 2
• Persistent baseline nystagmus present without provocative maneuvers (may also occur in vestibular neuritis). 2

Specific Central Causes

• Posterior circulation stroke/TIA – Can present with vertigo, especially vertebral artery dissection; associated with dysarthria, dysmetria, dysphagia, focal sensory/motor deficits, or Horner's syndrome. 1
• Cerebellar lesions (lower cerebellum) – May cause direction-changing apogeotropic positional nystagmus or unidirectional horizontal nystagmus enhanced when lying on the non-affected side; truncal ataxia becomes apparent when standing. 3
• Demyelinating diseases (multiple sclerosis) – Can affect brainstem/cerebellar pathways. 1, 4
• Central nervous system lesions – Tumors of the posterior fossa, cerebellopontine angle tumors. 1, 5
• Vertebrobasilar insufficiency – Vascular flow abnormalities detectable by transcranial Doppler ultrasound. 6
• Vestibular nucleus infarction – Can produce direction-changing spontaneous nystagmus. 5

Localization by Nystagmus Pattern

• Gaze-evoked nystagmus in all directions indicates cerebellar dysfunction (drugs, alcohol, neurodegenerative disorders). 7
• Purely vertical gaze-evoked nystagmus indicates midbrain lesion. 7
• Purely horizontal gaze-evoked nystagmus indicates pontomedullary lesion. 7
• Downbeat nystagmus generally indicates bilateral floccular dysfunction (cerebellar). 7
• Upbeat nystagmus indicates midbrain or cerebellar lesion. 7

Non-Vestibular Systemic Causes

• Anxiety or panic disorder – Common cause of chronic vestibular syndrome. 1
• Medication side effects – Particularly antiepileptics causing cerebellar dysfunction. 1, 7
• Postural hypotension – Presents as triggered episodic syndrome. 1
• Cervicogenic vertigo – Variable presentation. 1
• Toxic, infectious, and metabolic conditions. 1

Critical Diagnostic Approach

When to Image

• Do NOT image patients who meet BPPV diagnostic criteria with typical Dix-Hallpike findings and no additional concerning features. 6, 2
• MRI of the brain is indicated when: 6, 2
  • Neurologic red-flag signs are present (dysarthria, dysmetria, dysphagia, focal deficits, Horner's syndrome)
  • Positional testing is negative or atypical despite compatible history
  • Symptoms persist despite repositioning maneuvers
  • Post-traumatic onset in younger patients
  • Elderly patients with new-onset vertigo
  • Short-term recurrence of symptoms

Common Pitfalls

• A negative Dix-Hallpike does NOT exclude BPPV (sensitivity only 82%, negative predictive value 52% in primary care); repeat testing or supine roll test is required. 2
• Central paroxysmal positional vertigo (CPPV) can clinically mimic BPPV but has negative or atypical Dix-Hallpike testing; MRI detected acute brain lesions in 11% of CPPV cases. 6
• Positional downbeat nystagmus can indicate anterior canal BPPV, atypical posterior canal BPPV, or central causes (vestibulocerebellum lesions); brain MRI focusing on posterior fossa is required when diagnosis is uncertain. 8
• Direction-changing spontaneous nystagmus (without positional provocation) occurs in various central and peripheral vestibulopathies including vestibular neuritis, lateral canal cupulopathy, cerebellopontine angle tumors, and vestibular nucleus infarction; observation for ≥2 minutes is needed to detect it. 5