What causes nystagmus?

Causes of 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

Infantile Nystagmus (onset in first 6 months of life)

• Most common causes include albinism, retinal diseases, low vision, and vision deprivation (e.g., congenital cataracts) 1
• Idiopathic infantile nystagmus can be caused by mutations in the FRMD7 gene 2
• Fusion maldevelopment syndrome in children with normal ocular development and retinal function 1
• Sensory nystagmus due to defects in the visual system including retinal dystrophies, congenital stationary night blindness, and structural ocular defects 2

Acquired Nystagmus (later onset)

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

Specific Types of Nystagmus and Their Causes

Downbeat Nystagmus

• Strongly suggests disorders affecting the cerebellum or cervicomedullary junction 5
• Can be caused by bilateral floccular lesion or dysfunction 6

Upbeat Nystagmus

• Results from lesions in the midbrain or medulla 6

Convergence Retraction Nystagmus

• Associated with dorsal midbrain syndrome 3
• Can be caused by multiple sclerosis 3

Vestibular Nystagmus

• Results from dysfunction of peripheral or central vestibular pathways 1
• Associated with Ménière's disease, vestibular neuritis, labyrinthitis, and superior canal dehiscence syndrome 5

Seesaw Nystagmus

• Associated with suprasellar and mesodiencephalic lesions 2
• Rarely associated with retinal dystrophies 2

Special Considerations

• Unilateral nystagmus often indicates an anterior visual pathway lesion 2
• Asymmetric or unilateral nystagmus should raise suspicion for neurological disease 7
• Spasmus nutans is a rare form 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

Clinical Implications

• Neuroimaging (preferably MRI) is indicated for acquired nystagmus, late onset nystagmus, concurrent neurological symptoms, decreased visual acuity, or asymmetric/unilateral/progressive nystagmus 1
• MRI of the brain is the preferred imaging modality for evaluating nystagmus, particularly for convergence retraction nystagmus and downbeat nystagmus 3, 5
• Nystagmus can cause decreased visual acuity due to inability to maintain stable foveal vision and oscillopsia (disabling subjective sensation of movement of the visual world) 8