Nystagmus

Aka: Nystagmus, Spontaneous Nystagmus, Horizontal Nystagmus, Vertical Nystagmus, Lateral Nystagmus, Direction Changing Nystagmus

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II. Definitions

  1. Nystagmus
    1. Repetitive, oscillating movement of the eyes
  2. Direction of Nystagmus
    1. Named for quick component of Nystagmus
    2. Right Nystagmus suggests a left-sided lesion, and left Nystagmus a right-sided lesion
  3. Speed
    1. Slow Nystagmus: <40 jerks per minute
    2. Fast Nystagmus: >100 jerks per minute
  4. Amplitude
    1. Fine Nystagmus: <1 mm
    2. Coarse Nystagmus: >3 mm
  5. Involvement
    1. Associated Involvement: Bilateral eyes
    2. Dissociated Involvement: Unilateral eye

III. Background

  1. Nystagmus is a slow involuntary eye movement in one direction, and then rapidly in the opposite direction
  2. Nystagmus is typically in the horizontal plane (right or left)
    1. Occurs normally on looking laterally
    2. Atypical findings include vertical or rotary Nystagmus
  3. Nystagmus is seen in Vertigo
    1. Most cases are peripheral (e.g. BPPV, Vestibular Neuronitis)
    2. Central cause (e.g. stroke) may be indicated by vertical or Direction Changing Nystagmus
  4. Nystagmus can be provoked
    1. Head turning
    2. Cold Calorics
      1. Infusing cold water into an ear
      2. Allows for testing the Cerebral Hemispheres and Brainstem in coma

IV. Indication: Vertigo Evaluation

  1. Absent Nystagmus in severe Acute Vestibular Syndrome (AVS) or Vertigo is unusual
    1. Casts doubt on the symptom (consider other causes of Dizziness)

V. Exam

  1. Midline gaze
    1. Observe for Spontaneous Nystagmus with the patient looking straight ahead
  2. Smooth Pursuit
    1. Patient follows examiners finger in all directions as the examiner moves the finger slowly up, down, left and right
    2. Observe for Nystagmus
  3. Lateral gaze
    1. Patient looks at the examiner's finger placed >60 degrees from midline
    2. Observe for Nystagmus (common, even in the absence of pathology)

VI. Interpretation: Normal Findings - Lateral gaze Nystagmus

  1. Associated with stretch receptor
  2. All patients have a few beats of end point Nystagmus

VII. Interpretation: Abnormal Findings

  1. Spontaneous on Forward gaze, on moderate lateral gaze
  2. Direction
    1. Horizontal Nystagmus
      1. May indicate either peripheral disease or Central DIsease
      2. Unilateral vestibular pathology
    2. Vertical Nystagmus (or torsional Nystagmus)
      1. Indicates Central DIsease
      2. Brain Stem lesion
    3. Direction Changing Nystagmus
      1. Rightward Nystagmus with rightward gaze and leftward Nystagmus with leftward gaze
      2. Suggestive of central Vertigo (e.g. posterior CVA)
  3. Other abnormal findings
    1. Peduncular Nystagmus
      1. Eyes move at equal speeds in both directions
      2. Seen in congenital disorders or with prolonged blindness

VIII. Causes: Nystagmus in Infants and Children

  1. Albinism (iris and Retinal Hypopigmentation)
  2. Bilateral Optic Nerve hypoplasia
    1. Seen in de Morsier's Syndrome
  3. Bilateral media opacities
  4. Achromatopsia
  5. Usher's Syndrome (Retinitis Pigmentosa)

IX. References

  1. Kattah (2009) Stroke 40: 3504-10 [PubMed]

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