Nystagmus Causes and Clinical Implications

Introduction to Nystagmus

• Nystagmus is primarily caused by disorders affecting the visual pathways, vestibular system, or central nervous system structures, with specific etiologies differing between infantile and acquired forms 1, 2

Infantile Nystagmus

• Most common causes include albinism, retinal diseases, low vision, and vision deprivation (e.g., congenital cataracts) in infants 1, 2
• Fusion maldevelopment syndrome can occur in children with normal ocular development and retinal function 1

Acquired Nystagmus

• Anterior optic pathway lesions, such as tumors, can cause acquired nystagmus 1
• Lesions of the brainstem/cerebellum, including structural or space-occupying lesions, can also cause acquired nystagmus 1
• Metabolic diseases, including leukodystrophies and mitochondrial diseases, are associated with acquired nystagmus 1
• Multiple sclerosis is particularly associated with convergence retraction nystagmus 3
• Arteriovenous malformations can cause acquired nystagmus 3
• Chiari malformation is found in 3.4% of children with isolated nystagmus 1, 4
• Optic pathway glioma is found in 2% of children with isolated nystagmus 1
• Vestibular disorders affecting either peripheral or central vestibular pathways can cause acquired nystagmus 1, 5

Specific Types of Nystagmus

• Downbeat nystagmus strongly suggests disorders affecting the cerebellum or cervicomedullary junction 5
• Convergence retraction nystagmus is associated with dorsal midbrain syndrome and can be caused by multiple sclerosis 3
• Vestibular nystagmus results from dysfunction of peripheral or central vestibular pathways 1
• Vestibular nystagmus is associated with Ménière's disease, vestibular neuritis, labyrinthitis, and superior canal dehiscence syndrome 5

Clinical Implications

• Spasmus nutans is a rare form of nystagmus characterized by nystagmus, head bobbing, and torticollis, typically appearing at 1-3 years of age 1
• Abnormal T2 hyperintense signal in white matter is the most common MRI finding (4%) in children with isolated nystagmus 1
• Neuroimaging (preferably MRI) is indicated for acquired nystagmus, late onset nystagmus, concurrent neurological symptoms, decreased visual acuity, or asymmetric/unilateral/progressive nystagmus 1, 2
• MRI of the brain is the preferred imaging modality for evaluating nystagmus, particularly for convergence retraction nystagmus and downbeat nystagmus 3, 5

Referral Timing for Infants with Mild Nystagmus

Classification and Timing of Referral

• Infants with congenital nystagmus and children with early-onset nystagmus should be referred to a pediatric ophthalmologist as early as possible, ideally at the time of detection, according to the American Academy of Pediatrics 6, 7
• Pediatric nystagmus can be classified as infantile (onset in first 6 months of life) or acquired (later onset), as stated by the American College of Radiology 8

Reasons for Immediate Referral

• Nystagmus may indicate underlying conditions including albinism, retinal disease, low vision, or vision deprivation, according to the American College of Radiology 8
• Early referral is critical as nystagmus may be the first sign of serious underlying conditions that can affect vision development and overall health, as noted by the American College of Radiology 8
• Even "mild" nystagmus warrants immediate evaluation, as 15.5% of children with isolated nystagmus have abnormal intracranial findings on MRI, according to the American College of Radiology 8

Diagnostic Approach

• Clinical ophthalmological examination and genetic workup are typically first-line evaluations, as recommended by the American College of Radiology 8
• Neuroimaging (preferably MRI) is indicated for acquired or late-onset nystagmus, nystagmus with concurrent neurological symptoms, or asymmetric/unilateral or progressive nystagmus, according to the American College of Radiology 8

Nystagmus Associated with Medial Longitudinal Fasciculus Lesions

Diagnostic Imaging

• The American College of Radiology recommends MRI as the preferred imaging modality for evaluating nystagmus associated with MLF lesions, particularly in patients with suspected multiple sclerosis or stroke 9
• MRI is useful in identifying demyelinating plaques in multiple sclerosis, which is a common cause of MLF lesions in younger patients, while stroke is more likely in older patients 9

Evaluation and Treatment of Nystagmus in Children

Initial Clinical Assessment

• All children with nystagmus require thorough neuro-ophthalmological evaluation to distinguish between infantile and acquired forms, as this distinction fundamentally determines the diagnostic workup and urgency of intervention, according to the American College of Radiology 10
• Associated symptoms such as oscillopsia, head bobbing, torticollis, or concurrent neurological symptoms mandate urgent evaluation, as recommended by the American College of Radiology 11

Neuroimaging Indications

• MRI of the brain without and with IV contrast is the imaging modality of choice when neuroimaging is indicated, as suggested by the American College of Radiology 10, 12, 11
• In children with isolated nystagmus who undergo MRI, 15.5% have abnormal intracranial findings, including abnormal T2 hyperintense signal in white matter, Chiari 1 malformation, and optic pathway glioma, according to the American College of Radiology 10, 12, 11

Imaging Protocols

• MRI head and orbits may be obtained concurrently for comprehensive evaluation, as recommended by the American College of Radiology 10, 12
• IV contrast is not required in all cases but should be considered if a suspicious lesion is identified, according to the American College of Radiology 10
• CT imaging has no role in the initial evaluation of isolated nystagmus, as stated by the American College of Radiology 10, 12, 11

Common Pitfalls to Avoid

• Do not confuse spasmus nutans with benign infantile nystagmus, as it requires MRI to exclude anterior visual pathway tumors, as recommended by the American College of Radiology 10, 11
• Do not use CT imaging, as it has no role in nystagmus evaluation and provides inferior soft tissue detail, according to the American College of Radiology 10, 12, 11

Concerning Types of Nystagmus

Red Flag Nystagmus Patterns Requiring Immediate Evaluation

• The American Academy of Otolaryngology-Head and Neck Surgery suggests that downbeat nystagmus, direction-changing nystagmus without head position changes, baseline nystagmus without provocative maneuvers, gaze-evoked nystagmus, and any acquired or asymmetric/unilateral nystagmus are concerning findings that strongly suggest central nervous system pathology requiring urgent neuroimaging 13
• Downbeat nystagmus is the most concerning pattern, strongly suggesting disorders affecting the cerebellum or cervicomedullary junction, and does not fatigue or suppress by visual fixation 13
• Direction-changing nystagmus occurring without changes in head position indicates central pathology rather than benign peripheral causes 13
• Baseline nystagmus manifesting without any provocative maneuvers suggests a neurological cause requiring investigation 13
• Gaze-evoked nystagmus is definitively a central form indicating brainstem or cerebellar pathology, does not fatigue, and is not easily suppressed by visual fixation 13

Critical Pitfalls to Avoid

• The American Academy of Otolaryngology-Head and Neck Surgery warns not to mistake central nystagmus for benign paroxysmal positional vertigo (BPPV), as downbeat nystagmus on Dix-Hallpike maneuver without a torsional component indicates central pathology, not BPPV 13
• The American Academy of Otolaryngology-Head and Neck Surgery advises not to rely on symptom resolution to rule out serious pathology, as central nystagmus from vertebrobasilar insufficiency may present with isolated transient vertigo lasting less than 30 minutes, potentially preceding stroke by weeks or months 13

Distinguishing Central from Peripheral Causes

• Central nystagmus characteristics include not fatiguing with repeated testing, not being suppressed by visual fixation, often being accompanied by severe postural instability, and may have additional neurological signs 13
• Peripheral vestibular nystagmus characteristics include typically having a torsional component, being suppressed by visual fixation, and fatiguing with repeated maneuvers 13

Nystagmus Causes and Characteristics

Infantile Nystagmus

• Latent nystagmus, characterized by horizontal jerk oscillations under monocular viewing conditions, is part of the infantile esotropia syndrome, as reported by the American Academy of Ophthalmology 14
• Manifest-latent nystagmus has an identical waveform to latent nystagmus but is evident under binocular viewing conditions, with amplitude increasing during monocular occlusion, according to the American Academy of Ophthalmology 14

Acquired Nystagmus

• Peripheral vestibular pathology, including Ménière's disease, vestibular neuritis, labyrinthitis, and superior canal dehiscence syndrome, causes vestibular nystagmus, as stated by the American Academy of Otolaryngology-Head and Neck Surgery 15
• Posterior circulation transient ischemic attack and stroke can cause acquired nystagmus, as reported by the American Academy of Otolaryngology-Head and Neck Surgery 15
• Benign paroxysmal positional vertigo (BPPV) causes direction-changing nystagmus with specific positional triggers, but this must be distinguished from central causes, according to the American Academy of Otolaryngology-Head and Neck Surgery 15
• Posterior canal BPPV produces torsional upbeating nystagmus, while lateral canal BPPV produces strongly horizontal nystagmus, as stated by the American Academy of Otolaryngology-Head and Neck Surgery 15

Diagnostic Considerations

• Do not confuse nystagmus blockage syndrome with simple infantile esotropia: children with nystagmus blockage syndrome use excessive convergence to damp nystagmus amplitude, and the esotropia magnitude increases with prism neutralization, as reported by the American Academy of Ophthalmology 14

Red Flags and Diagnostic Criteria for Nystagmus (Evidence from the American Academy of Otolaryngology‑Head and Neck Surgery)

1. Central vs. Peripheral Nystagmus Patterns

• The American Academy of Otolaryngology‑Head and Neck Surgery states that pure downbeat nystagmus without a torsional component is not characteristic of posterior‑canal BPPV, which instead produces a torsional up‑beating nystagmus; isolated downbeat nystagmus therefore signals possible central pathology and warrants urgent neuroimaging. 16

• According to the same society, peripheral vestibular nystagmus—which shows a torsional component, is suppressed by visual fixation, and fatigues with repeated testing—is typical of Ménière’s disease, vestibular neuritis, labyrinthitis, and superior canal dehiscence syndrome. 16

2. Vascular Etiologies

• The American Academy of Otolaryngology‑Head and Neck Surgery notes that acute posterior‑circulation stroke or transient ischemic attack can manifest as newly acquired nystagmus, making prompt neuroimaging essential to exclude cerebrovascular events. 16

3. Clinical Decision‑Making Algorithm

• The society recommends that when positional nystagmus displays a torsional component and fatigability, clinicians should first consider benign paroxysmal positional vertigo (BPPV) but must also systematically exclude central causes through appropriate examination and imaging. 16