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 determining whether the nystagmus is congenital or acquired, characterizing its direction and pattern, and obtaining brain MRI for patients with acquired, asymmetric, or progressive nystagmus to rule out potentially serious underlying causes. 1

Diagnostic Evaluation

Step 1: Characterize the Nystagmus

• Determine onset (congenital vs. acquired)
• Assess direction (horizontal, vertical, torsional)
• Evaluate symmetry (unilateral vs. bilateral)
• Identify waveform characteristics
• Note triggering factors

Step 2: Perform Targeted Examination

• HINTS examination (Head Impulse test, Nystagmus evaluation, Test of Skew)
  • High sensitivity (96.7%) and specificity (94.8%) for detecting central causes 1
• Positional testing
  • Dix-Hallpike maneuver for posterior canal BPPV
  • Supine roll test for lateral canal BPPV

Step 3: Imaging

• MRI brain is the preferred initial imaging for:
  • Acquired nystagmus
  • Late-onset nystagmus
  • Concurrent neurological symptoms
  • Asymmetric/unilateral nystagmus
  • Progressive nystagmus
  • Abnormal HINTS examination 1

CT has limited value and is not recommended as initial imaging for isolated nystagmus due to poor sensitivity, especially for posterior fossa lesions 1

Step 4: Laboratory Testing (Selective)

• Serum glucose for all patients with dizziness
• Electrolytes (sodium, calcium, magnesium)
• Complete blood count
• Blood urea nitrogen and creatinine
• Thyroid-stimulating hormone
• Pregnancy test (for women of childbearing age)
• Liver function tests and drug screen (if alcohol-related issues or medication side effects are suspected) 1

Treatment Approach

Treatment should be directed at the underlying cause when identified. For symptomatic management:

Specific Nystagmus Types and Their Treatment

1. Downbeat nystagmus:

   • 4-aminopyridine
   • 3,4-diaminopyridine
   • Clonazepam 2, 3

2. Upbeat nystagmus:

   • Memantine
   • 4-aminopyridine
   • Baclofen 2, 3

3. Acquired pendular nystagmus:

   • Gabapentin (especially effective in multiple sclerosis)
   • Memantine 2, 4

4. Periodic alternating nystagmus:

   • Baclofen (first-line)
   • Memantine (for refractory cases) 2, 4

5. BPPV-related nystagmus:

   • Canalith repositioning procedures 1

6. Infantile nystagmus:

   • Gabapentin
   • Memantine
   • Acetazolamide
   • Topical brinzolamide
   • Contact lenses
   • Base-out prisms to induce convergence 2, 5

Warning Signs Requiring Urgent Evaluation

• Acute onset with neurological symptoms
• Asymmetric or unilateral nystagmus
• Progressive worsening
• Association with headache, ataxia, or other neurological deficits 1

Important Clinical Pearls

• Posterior circulation stroke can present with isolated vertigo in up to 25% of cases, increasing to 75% in high vascular risk cohorts 1
• The HINTS examination is more valuable than laboratory testing for distinguishing between benign peripheral causes and potentially life-threatening central causes 1
• Over-reliance on laboratory testing can lead to missing central causes of dizziness 1
• Routine testing of calcium, magnesium, or phosphate levels is not supported by evidence in otherwise healthy patients 1
• Spasmus nutans can mimic nystagmus associated with anterior visual pathway tumors and should be evaluated with MRI 1

By following this systematic approach to evaluation and management, clinicians can effectively diagnose the underlying cause of nystagmus and implement appropriate treatment strategies to improve patient outcomes.