From WikiLectures

1. amplitude

  a. fine is < 5 degrees
  b. course is > 15 degrees
  c. medium between 

2. Jerk or pendular 3. onset

  a. congenital
  b. aquired-The chief symptom of individuals who manifest acquired forms of nystagmus is oscillopsia, the sensation that the visual world constantly shifts.
  c. 80% of cases being congenital and 20% acquired

4. Frequency

  a. slow
  b. med
  c. fast
     1) hysterical
     2) spasmas nutans

5. coordination

  a. Conjugate         
  b. disjunctive
     1) in convergency nystagmus right eye goes left, left right, with convergence
     2) divergence nystagmus right goes right, left left
     3) in see saw right eye rises then left falls

6. dissociated nystagmus

  a. ie the eyes go in different patterns, ie right up, left out
  b. is the hallmark of central lesions in adults
  c. May be seen in visual deprivation nystagmus

7. major diagnoses

  a. physiologic
     1) medications
     2) cold stimulous (caloric)
     3) end point
     4) optokenetic
     5) rotational
     6) galvanic stimulation of labrynth 
  b. ocular
  c. vestibular
  d. central
  e. congenital
  f. hysterical
  g. other

8. Barbituates, tranquilizers, sedation

  a. No nystagmus straight ahead
  b. increased horizontal end point nystagmus right and left
  c. on upgaze verticle nystagmus beating up
  d. no nystagmus down

9. Ocular nystagmus

  a. Visual deprivation
  b. pendular
  c. present from early childhood
  d. may see some horizontal jerk (not pendular) nystagmus at extremes of gaze
  e. from early vision deprivation
     1) if < 2 yo always get nystagmus
     2) 4 years old some do 
     2) seldom develop after 4 yo
  f. may see some dissociation
  g. also called nystagmoid motion of the blind

10. Unilateral nystagmus

  a. usually verticle
  b. causes
     1) spasmus nutans
     2) old amblyopia
     3) central nervous system disease

11. Direction

  a. Horizontal
  b. Vertical
     1) usually drugs
     2) if not drugs, posterior fossa lesion 
     3) downbeating
        a) usually foramen magnum level lesion  
        b) usually more noticable in down and lateral
  c. Rotory
     1) Rotational nystagmus is usually vestibular systeme disease 
     2) classify by the direction of the 12 oclock position