Nystagmus

1. Nystagmus
Presenter:Dr.Vikram S Nakhate
Moderator: Dr.Atul Seth

2. Defination
 Nystagmus is a regular,repetitive to and fro
movement of the eyes (horizontal,vertical or
torsional) with 2 phases
 1. slow drift from the target of interest f/b
 2. corrective saccade back to the target

3. Terminologies
• Amplitude
• Frequency
• Intensity
• Null zone
• Pursuit / Saccade
• Conjugate / Dissociated
• Jerk / Pendular

4. Amplitude
 Amplitude is the excursion of the nystagmus and
described as
 Fine : less than 50
 Moderate: 50-150
 Large greater than 150

5. Frequency
 Frequency is the number of to and fro movements in
one second
 Described an cycles/sec or Hertz (Hz)
 Slow : (1-2 Hz)
 Medium : (3-4 Hz)
 Fast: (5 Hz or more)

6. Intensity
 Intensity = amplitude * frequency
 Null zone: position where nystagmus is minimised
 Patient assumes a head posture, such that the eyes are
in null zone

7. Pursuit /Saccade
 Pursuit eye movements allow the eyes to closely
follow a moving object.
 Pursuit differs from the vestibulo-ocular reflex, which
only occurs during movements of the head and serves
to stabilize gaze on a stationary object
 Saccades are quick, simultaneous movements of both
eyes in the same direction

8. Conjugate/Dissociated
 Conjugate : nystagmus which is symmetric in
direction,amplitude and rate
 Dissociated: when it differs in any one of the
parameters between two eyes

9. Jerk / Pendular
Jerk nystagmus Pendular nystagmus
Alternation of slow phase drift f/b rapid
corrective saccade in opp direction
Sinusoidal oscillation with slow phase
in both directions and no corrective
saccade
Direction of jerk nystagmus= direction
of the fast phase
Pendular nystagmus may be horizontal
or vertical
Right or left beating nystagmus
Upbeat or downbeat nystagmus
Not characterised by right,left,up,down
beating as there is no fast phase

11. Alexanders law
 It states that the amplitude of jerk nystagmus is
largest in the gaze of direction of fast component
 1 degree: nystagmus only in the direction of the fast
component
 2 degree: nystagmus in primary gaze position
 3 degree: nystagmus in addition to above gazes,also
present in the direction of the slow component

12. Mechanism of nystagmus
 Foveal centration of an object of regard is necessary to
obtain the highest level of visual acuity
 Three mechanisms are involved in maintaining foveal
centration of an object of interest:
 Fixation
 The vestibulo-ocular reflex
 The neural integrator.

13. Fixation
 Fixation in the primary position involves the visual
system's ability to detect drift of a foveating image
and signal an appropriate corrective eye movement to
refoveate the image of regard.
 The vestibular system is intimately and complexly
involved with the oculomotor system

14. Vestibulo-ocular reflex
 The vestibulo-ocular reflex is a complex system of
neural interconnections that maintains foveation of
an object during changes in head position.
 The proprioceptors of the vestibular system are the
semicircular canals of the inner ear.
 The semicircular canals respond to changes in
angular acceleration due to head rotation

15. Neural integrator
 When the eye is turned in an extreme position in the
orbit, the fascia and ligaments that suspend the eye
exert an elastic force to return toward the primary
position
 To overcome this force, a tonic contraction of the
extraocular muscles is required.
 A gaze-holding network called the neural integrator
generates the signal. The cerebellum, ascending
vestibular pathways, and oculomotor nuclei are
important components of the neural integrator.

16. Classification
 Congenital
 Acquired

17. Infantile nystagmus
 Usually not noted at birth but becomes apparent
during first few months of life

18. Characteristics
 Horizontal nystagmus ( mixed pendular and jerk)
 b/l conjugate movements of the eyes
 Nystagmus not present during sleep
 Associated latent nystagmus
 Head turn to achieve null point
 Decreases with convergence
 Increases with fixation

19.  Reverse response to OKN stimulus ( fast phase in
direction of moving OKN drum)
 May be seen in isolation or associated with
strabismus,afferent visual defects

20. Treatment
 Base out prisms to induce convergence ( dampens the
nystagmus and may improve visual acuity)
 Use of prisms to shift the viewing position to null
position
 Contact lenses may dampen nystagmus
 Gabapentine may dampen nystagmus

21. Surgical
 Includes moving the extraocular muscles to place the
null zone in primary position(kestenbaum procedure)
 Recessing all 4 rectus muscles to decrease tension
(large recession procedure)

22. Spasmus nutans
 Triad of symptoms:
 Nystagmus
 Head nodding
 Torticollis (head tilt or head turn)

23.  Onset usually in the first year of life (3-15 months)
 Disappears by 3-4 yrs of age
 The nystagmus typically consists of small-amplitude,
high frequency oscillations and usually is bilateral,
but it can be monocular, asymmetric, and variable in
different positions of gaze
 Usually benign
 Neuroimaging recommended ( gliomas may mimic
spasmus nutans)

24. Infantile monocular pendular
nystagmus
 Usually due to visual loss( often optic neuropathy or
chiasmal glioma)
 In cases of b/l visual loss,there is b/l nystagmus ,with
nystagmus greater in eye with poorest vision

25. Acquired
 Physiological:
 End point nystagmus
 Vestibular (caloric or rotational) nystagmus
 Optokinetic nystagmus

26. End point nystagmus
 Jerk nystagmus
 On looking extreme lateral or upwards
 Angle of gaze > 450

27. Vestibular nystagmus
 Jerk nystagmus
 Altered inputs from vestibular nuclei to PPRF
 Demonstrated by caloric test: normal response
 Cold water : opposite side
 Warm water : same side
 Cold water in both ears: upwards
 Warm water in both ears : downwards

28. Optokinetic nystagmus
 Jerk nystagmus
 Induced by moving a full visual field stimulus
 Slow phase (pursuit) : eye follows the target
 Fast phase ( saccade): eye fixates on next target
 Uses: Detecting malingering
Testing visual potential in children

29. Pathological causes
 Nystagmus associated with poor vision (sensory)
 Anterior segment: cataract,aniridia
 Retinal diseases: RB,ROP,Intrauterine infections

30.  Nystagmus associated with neurological diseases
(motor)
 1.End gaze paretic nystagmus ( horizontal gaze
center)
 2.Convergence retraction nystagmus( vertical
gaze,parinaud’s)

31.  3.Vestibular nystagmus:
 Central ( brainstem nuclei)
 Peripheral ( labyrinths, VIII CN)
 4.Downbeat nystagmus( cervicomedullary junction)
 5.Upbeat nystagmus( cerebellum,medulla)

32.  6. Seesaw nystagmus (parasellar lesions)
 7. periodic alternating nystagmus

33. Gaze paretic nystagmus
 Most common type
 Absent in primary position and is not visually
disabling
 Beats in the direction of gaze
 Causes: anticonvulsants
brainstem lesions
cerebellar lesions

35. Convergence-retraction
nystagmus
 Not truly a nystagmus
 b/l adducting saccades causing convergence of both
eyes
 Elicited by having the patient to look up,at which
time the eyes converge & retract
 Causes: midbrain lesions

37. Vestibular nystagmus
Feature Peripheral Central
Disease of vestibular
origin
Disease of the brainstem
Direction Intensity increases when
the eyes are turned in
direction of fast phase
Direction of nystagmus
may change with gaze
Visual fixation Inhibits nystagmus No inhibition
Severity of vertigo Severe Mild
Induced by head
movements
Often Rare
Associated eye movement
deficits
None Pursuit or saccadic
defects
Other findings Hearing loss CNS involvement

38. Upbeat nystagmus
 Type of jerk nystagmus with fast phase upward in
primary position
 Often worsens in upgaze
 Causes: lesions of medulla,
cerebellar vermis,midbrain
 Rx: base up prisms in reading glasses can be used to
force the eyes downward

40. Downbeat nystagmus
 Type of jerk nystagmus with fast phase downward in
primary position
 Often worsens in downgaze
 Oscillopsia is usually prominent
 Causes: lesions at cervicomedullary junction
 Rx: base down prisms in reading glasses can be used
to force the eyes upward

42. Seesaw nystagmus
 Defined as pendular nystagmus with elevation and
intorsion of one eye simultaneous with depression
and extorsion of other eye
 Followed by reversal of cycle,so that the eyes move
like a seesaw

43.  Causes: parasellar lesions,pituitary tumors
 Produces very disabling oscillopsia that responds
poorly to any Rx

44. Periodic alternating
nystagmus(PAN)
 PAN is a conjugate, horizontal jerk nystagmus with
the fast phase beating in one direction for a period of
approximately 1-2 minutes.
 The nystagmus has an intervening neutral phase
lasting 10-20 seconds
 The nystagmus begins to beat in the opposite
direction for 1-2 minutes then, the process repeats
itself

45.  Periodic alternating head turn to minimise nystagmus
& oscillopsia
 Causes: lesions of the cerebellum

47. Acquired Congenital
Form Pure sinusoidal Variable waveform
Direction Omnidirectional
(vertical,torsional)
Horizontal,uniplanar
Rarely vertical or
torsional
OKN reversal Never Frequent
Oscillopsia Frequent Mild (if present)

48. Nystagmus associated with
strabismus
 Latent /manifest-latent nystagmus
 Manifest nystagmus
 Nystagmus blockage syndrome

49. Manifest nystagmus Manifest-latent nystagmus
Pendular nystagmus Jerk nystagmus
No change on abduction Increased on abduction
No change on covering one eye Increase on covering one eye
Null zone is present Fast phase always towards fixing eye
Less commonly associated with
infantile esotropia
Always associated with esotropia
Binocular visual acuity same as
uniocular
Binocular visual acuity better than
uniocular

50. Nystagmus blockage syndrome
 Inverse relationship with esotropia
 Esotropia is a mechanism of blocking the nystagmus
 The fixing eye is preferred to be in adduction ,face
turn is in the direction of fixing eye

51. Nystagmoid conditions
 Movements which are not regular and rhythmic:
 Oculopalatal myoclonus
 Opsoclonus
 Ocular bobbing

52. Oculopalatal myoclonus
 Type of vertical pendular nystagmus
 Coexisting with tremor of the facial
muscles,larynx,palate
 Present during sleep
 Cause : usually develops months after an infarction or
h’hage involving mollaret triangle
 Rx: Gabapentine

54. Ocular bobbing
 Characterised by conjugate eye movements,
 beginning with a fast downward movement
 f/b slow drift back to midline
 Causes: 1. comatose patients with massive
pontine lesion
2.metabolic encephalopathy

55. Superior oblique myokymia
 Defined as oscillation of one eye due to intermittent
firing of the superior oblique muscle
 Produces oscillopsia or intermittent diplopia elicited
by having the patient look in the direction of the
superior oblique muscle
 Characterised by monocular,rapid,intorsional
movements

56.  Usually benign
 No underlying etiology is found
 Neuroimaging : r/o post fossa tumors
 Refractory cases: surgical weakning of the superior
oblique muscle can be performed

58. Treatment
 Nonsurgical : non neurological causes
 1.Optical devices
Glasses: overminus lenses stimulate accomodative
convergence and thus dampens nystagmus
Contact lenses: helpful in high refractive errors by
giving good visual stimulus for fusional control

59.  Prisms : can be used for 2 purposes
 1. to induce fusional convergence by using 7 PD base
out prism in front of each eye
 2. pre op evaluation in a patient with face turn
prisms are inserted with the apex in direction of gaze
Useful as a diagnostic trial ,but as a therapeutic
alternative are not helpful

60.  Occlusion therapy:
 Trials with conventional occlusion have been found to
be effective
 As amblyopia gets corrected and vision
improves,nystagmus finally decreases

61. Pharmacologic Mx
 These drugs hypothetically inhibit excitatory
neurotransmitters within CNS
 Baclofen : congenital nystagmus, seesaw
nystagmus,periodic alternating nystagmus
 Carbamazepine: widely used for superior oblique
myokymia

62. Pharmacologic denervation
 Botulinum toxin A act by blocking the neuromuscular
transmission
 used in 2 distinct ways to dampen nystagmus
 3 units of toxin is injected in each of the 4 horizontal
rectus muscles
 Single large dose of drug into the retrobulbar space
 Effect last for only few months

63. Surgical
 Based on 3 principles:
 To shift the null position if any to the primary
position
 To induce extra convergence innervation by
weakening medial recti,to dampen nystagmus
 To reduce the amplitude of the nystagmus by
weakening the muscle force of all recti

64. Kestenbaum surgery
 Devised first surgical approach using recession-
resection of all four horizontal recti
 Advocated an equal amount of 5 mm for all recti
 Left face turn (null in dextroversion):
 Right eye: LR recession & MR resection
 Left eye : MR recession & LR resection

65. Anderson surgery
 Advocated only recessions
 Left face turn (null in dextroversion):
 Right eye : LR recession
 Left eye : MR recession

66. Parks surgery
 Recommended lesser amount of recessions and for
medial rectus surgery compared to lateral rectus
surgery.
 Advocated a 5,6,7,8 plan
 MR recession : 5 mm
 MR resection : 6 mm
 LR recession : 7 mm
 LR resection : 8 mm

67.  Carlow TJ : medical treatment of nystagmus and
ocular motor disorders.Int Ophthalmol Clin
1986;28:355
 Rosenberg ML,Glaser JS:Superior oblique
myokymia.Ann Neurol 1983;13:667
 Helveston EM, Pogrebniak AE : Treatment of acquired
nystagmus with botulinum toxin A. Am J Ophthalmol
1988;106:584