What is the initial approach to managing a patient with nystagmus?

Initial Approach to Managing a Patient with Nystagmus

The initial approach to managing a patient with nystagmus should include a thorough neuro-ophthalmological evaluation followed by MRI of the brain, particularly in cases of acquired, asymmetric, or progressive nystagmus to rule out potentially serious underlying causes. 1, 2

Diagnostic Evaluation

History and Physical Examination

• Determine onset (congenital vs. acquired)

  • Congenital/infantile: Usually appears in first 3-6 months of life 3
  • Acquired: Appears later and often accompanied by oscillopsia (sensation of visual world movement) 4, 3

• Characterize the nystagmus:

  • Direction (horizontal, vertical, torsional)
  • Symmetry (unilateral or asymmetric nystagmus suggests neurological disease) 3
  • Waveform characteristics
  • Triggering factors (positional, gaze-evoked)

• Associated symptoms:

  • Oscillopsia (visual world appears to move) - typical of acquired nystagmus 4
  • Vertigo or dizziness
  • Decreased visual acuity
  • Neurological symptoms

Key Diagnostic Tests

1. HINTS Examination for patients with acute vestibular syndrome:

   • Head Impulse test
   • Nystagmus evaluation
   • Test of Skew
   • Sensitivity 96.7% and specificity 94.8% for detecting central causes 2

2. Positional Testing:

   • Dix-Hallpike maneuver for posterior canal BPPV
   • Supine roll test for lateral canal BPPV 1, 2
     • Geotropic type: More intense nystagmus when rolled to affected side
     • Apogeotropic type: Nystagmus beats toward uppermost ear 1

3. Laboratory Testing (selective based on clinical presentation):

   • Essential: Serum glucose (hypoglycemia can present with dizziness) 2
   • Consider: Electrolytes, CBC, BUN, creatinine, TSH 2
   • For women of childbearing age: Pregnancy test 2

4. Imaging:

   • MRI of the brain is the preferred initial imaging for patients with:

     • Acquired nystagmus
     • Late-onset nystagmus
     • Concurrent neurological symptoms
     • Asymmetric/unilateral or progressive nystagmus 1
     • Abnormal HINTS examination 2

   • MRI findings in nystagmus may include:

     • Abnormal T2 hyperintense signal in white matter (4%)
     • Chiari 1 malformation (3.4%)
     • Optic pathway glioma (2%) 1

   • CT has limited value and is not recommended as initial imaging for isolated nystagmus 1, 2

Treatment Approach

Treatment depends on the underlying cause and type of nystagmus:

1. For BPPV-related nystagmus:

   • Canalith repositioning procedures based on the affected canal 1

2. For acquired nystagmus (pharmacological options):

   • Downbeat nystagmus: 3,4-diaminopyridine, 4-aminopyridine, gabapentin, baclofen, or clonazepam 4, 5
   • Periodic alternating nystagmus: Baclofen (first-line) 4, 5
   • Acquired pendular nystagmus: Gabapentin, clonazepam, valproate, or memantine 4, 5

3. For infantile nystagmus syndrome:

   • Optical devices to improve visual acuity 4, 6
   • Consider surgical intervention for obvious head posture to shift null zone to primary position 3
   • Emerging pharmacological options: gabapentin and memantine 3

Special Considerations

• Spasmus nutans: Characterized by nystagmus, head bobbing, and torticollis in children 1-3 years old. Requires thorough MRI evaluation as it can mimic nystagmus associated with anterior visual pathway tumors 1

• Vestibular nystagmus: May result from peripheral or central vestibular pathway dysfunction. Imaging is primarily to exclude VIII cranial nerve or brainstem lesions 1

• Warning signs requiring urgent evaluation:

  • Acute onset with neurological symptoms
  • Asymmetric or unilateral nystagmus
  • Progressive worsening
  • Association with headache, ataxia, or other neurological deficits

Common Pitfalls

• Failing to distinguish between congenital and acquired nystagmus
• Missing central causes by over-relying on laboratory testing rather than proper neurological examination 2
• Not performing appropriate positional testing for BPPV
• Neglecting to order MRI in cases of acquired or asymmetric nystagmus

Remember that treatment should target the underlying cause when possible, and symptomatic treatment should be considered when visual disability is present, even if the underlying cause cannot be fully addressed 4, 6.