What is the appropriate history and physical exam workup for an 8-month-old infant presenting with horizontal nystagmus?

History and Physical Exam Workup for an 8-Month-Old with Horizontal Nystagmus

A thorough neuro-ophthalmological evaluation and MRI of the head without and with IV contrast is essential for an 8-month-old presenting with horizontal nystagmus to rule out serious underlying pathologies. 1, 2

Initial History Assessment

• Age of onset: Determine if nystagmus appeared within first 3-6 months (infantile) or later (acquired) 3, 4
• Progression pattern: Sudden or gradual onset, worsening or stable
• Associated symptoms:
  • Oscillopsia (perception of visual environment oscillating)
  • Head posturing/tilting (indicates null point)
  • Visual behaviors suggesting poor vision
  • Neurological symptoms (irritability, developmental delay, seizures)
  • Vertigo, nausea, or balance issues 3
• Family history:
  • Nystagmus (especially X-linked FRMD7 gene mutations) 3, 4
  • Albinism or other genetic conditions
  • Neurological disorders
• Birth and developmental history:
  • Prematurity
  • Perinatal complications
  • Developmental milestones

Physical Examination Components

Ophthalmologic Examination

• Nystagmus characterization:
  • Direction (horizontal, vertical, torsional, or mixed)
  • Amplitude and frequency
  • Symmetry (asymmetrical/unilateral nystagmus is a neurological red flag) 2
  • Effect of gaze direction (null zone identification)
  • Effect of visual fixation (improves or worsens)
• Visual acuity assessment: Age-appropriate methods
• Pupillary responses: Check for afferent pupillary defect (red flag) 3
• Anterior segment exam: Look for congenital cataracts, iris transillumination (albinism)
• Fundoscopic examination:
  • Optic nerve appearance (hypoplasia, atrophy, papilledema)
  • Macular structure and foveal hypoplasia
  • Retinal abnormalities
  • Signs of albinism

Neurological Examination

• Head position/posture: Document any preferred head position 2
• Cranial nerve assessment: Focus on oculomotor function (III, IV, VI)
• Assessment of optokinetic nystagmus (OKN): Absence of physiologic OKN in infantile forms, preserved in acquired forms 3
• Developmental assessment: Gross and fine motor skills, cognitive milestones
• Signs of increased intracranial pressure

Diagnostic Testing

Imaging

• MRI of head without and with IV contrast: First-line imaging for nystagmus evaluation 1, 2
  • Evaluate for:
    • White matter abnormalities (found in 4% of cases)
    • Chiari malformation (3.4%)
    • Optic pathway gliomas (2%)
    • Brainstem/cerebellar lesions
    • Signs of leukodystrophies or metabolic diseases 1, 2

Additional Testing (Based on Clinical Findings)

• Electroretinogram (ERG): Essential to rule out retinal causes when eye exam appears normal 5
• Hand-held spectral domain optical coherence tomography (HH SD-OCT): To assess foveal structure 4
• Genetic testing: Consider if family history is positive or if albinism is suspected

Red Flags Requiring Urgent Evaluation

• Onset after 4 months of age
• Oscillopsia
• Asymmetric or unilateral nystagmus
• Preserved optokinetic nystagmus
• Afferent pupillary defect
• Papilledema
• Associated neurological symptoms 3

Common Etiologies to Consider

• Infantile nystagmus (onset in first 6 months):
  • Idiopathic infantile nystagmus
  • Albinism
  • Retinal diseases
  • Congenital cataracts
  • Optic nerve hypoplasia 2, 3
• Acquired nystagmus (later onset):
  • Anterior optic pathway lesions
  • Brainstem/cerebellar lesions
  • Metabolic diseases 2, 3

Management Approach

• Refer to pediatric ophthalmologist for primary evaluation 2
• Obtain MRI concurrently with ophthalmologic assessment 1, 2
• Consider refractive correction if indicated 2
• Evaluate need for low-vision rehabilitation 2

The comprehensive evaluation is crucial as approximately 15.5% of children with isolated nystagmus have abnormal intracranial findings on MRI 1, and early identification of underlying pathology can significantly impact morbidity, mortality, and quality of life outcomes.