What can cause vertical nystagmus?

Causes of Vertical Nystagmus

Vertical nystagmus is primarily caused by central nervous system pathology affecting the brainstem (particularly the midbrain or medulla) or cerebellum, and should prompt urgent neuroimaging to identify structural lesions, demyelinating disease, or vascular pathology. 1, 2

Central Nervous System Causes (Most Common)

Brainstem Lesions

• Midbrain lesions cause upbeat nystagmus and affect structures including the rostral interstitial nucleus of the medial longitudinal fascicle, interstitial nucleus of Cajal, or posterior commissure 3
• Medullary lesions produce upbeat nystagmus through disruption of vertical gaze-holding mechanisms 4, 3
• Pontine lesions can contribute to vertical nystagmus patterns, particularly when combined with other ocular motor deficits 4

Cerebellar and Cervicomedullary Junction Disorders

• Downbeat nystagmus strongly suggests bilateral floccular dysfunction or cervicomedullary junction pathology and is the most concerning vertical nystagmus pattern 1, 2, 4
• Cerebellar lesions from stroke, demyelination, or neurodegenerative disease commonly produce downbeat nystagmus 2, 3
• Chiari malformation affects 3.4% of children with isolated nystagmus and typically causes downbeat nystagmus 1

Specific Neurological Conditions

• Multiple sclerosis causes convergence retraction nystagmus (associated with dorsal midbrain syndrome) and can produce various vertical nystagmus patterns through demyelinating plaques 1
• Stroke in the posterior circulation (vertebrobasilar territory) affecting brainstem or cerebellum 2, 3
• Space-occupying lesions including tumors, arteriovenous malformations, and arachnoid cysts 1, 2
• Progressive supranuclear palsy (PSP) and Niemann-Pick type C cause impaired vertical saccades and vertical nystagmus 3

Metabolic and Systemic Causes

• Metabolic diseases including leukodystrophies and mitochondrial diseases 1
• Drug toxicity, particularly antiepileptic medications and chronic alcohol abuse, though these more commonly cause gaze-evoked nystagmus in all directions 3

Vestibular System Causes

Peripheral Vestibular Disorders (Rare for Pure Vertical Nystagmus)

• Posterior canal BPPV produces torsional upbeating nystagmus (not purely vertical) 1
• Purely vertical upbeat nystagmus in BPPV is exceptionally rare and typically indicates bilateral posterior canal involvement 5
• Vestibular neuritis, labyrinthitis, Ménière's disease, and superior canal dehiscence syndrome primarily cause horizontal or horizontal-torsional nystagmus, not pure vertical 1, 2

Critical Distinction

• Pure vertical nystagmus without a torsional component strongly indicates central pathology, not peripheral vestibular disease 1, 2
• Downbeat nystagmus on Dix-Hallpike maneuver without torsional component indicates central pathology, not BPPV 1, 2

Anterior Visual Pathway Causes

• Optic pathway lesions including optic pathway gliomas (found in 2% of children with isolated nystagmus) can cause acquired nystagmus 1
• Hypoxic-ischemic encephalopathy damages anterior and posterior visual pathways, producing nystagmus patterns that vary with injury distribution 6

Red Flag Features Requiring Urgent Evaluation

The following characteristics mandate immediate neuroimaging (MRI preferred): 1, 2

• Downbeat nystagmus (most concerning pattern)
• Direction-changing vertical nystagmus without head position changes
• Baseline vertical nystagmus without provocative maneuvers
• Gaze-evoked vertical nystagmus (definitively indicates brainstem/cerebellar pathology)
• Asymmetric or unilateral nystagmus
• Associated neurological symptoms including ataxia, hemiparesis, sensory loss, dysarthria, or Horner's syndrome 7

Common Pitfalls to Avoid

• Do not mistake central vertical nystagmus for BPPV: Pure vertical nystagmus without torsion indicates central pathology 1, 2
• Do not rely on CT imaging: MRI is mandatory for evaluating vertical nystagmus as CT provides inadequate visualization of posterior fossa structures 1, 2
• Do not assume symptom resolution excludes serious pathology: Central nystagmus from vertebrobasilar insufficiency may present with transient symptoms but can precede stroke by weeks to months 1
• Do not delay neuroimaging in acquired vertical nystagmus: 15.5% of children with isolated nystagmus have abnormal intracranial findings on MRI 1, 6