Nystagmus - Details and classification

1. Dr. Md. As-Aad Habib
MS Phase B
Department of Ophthalmology, DMCH

2. An involuntary oscillation of the eyes that can
be a
 Physiological phenomenon (following the
rotation of an optokinetic drum)
 Pathological phenomenon

3.  Plane: May be –
◦ Horizontal
◦ Vertical
◦ Torsional
 Amplitude: Extent of Excursion –
◦ Fine
◦ Coarse
 Frequency: Describes how rapidly the eyes
oscillate –
◦ High
◦ Moderate
◦ Low

4.  Jerk nystagmus:
 Saccadic
 Slow defoviating ‘drift’ movement
 Fast corrective saccadic movement.
 Direction of jerk nystagmus is reported as the
directioon of it’s fast component.
 Slow phase component indicates the pathology.

6.  Pendular nystagmus:
 Non-saccadic
 Both the foveating and defoveating movements
are slow; the velocity of nystagmus is
equal in both directions.
 No fast phase.

9.  Mixed nystagmus:
 Pendular nystagmus in primary position
 Jerk nystagmus on lateral gaze.

10.  Conjugate nystagmus:
 Symmetric in direction, amplitude and rate.
 Dissociated/ Disconjugate nystagmus:
 Amplitude of oscillation differs in each eye.
 Disjunctive nystagmus:
 Direction of oscillation differs between two eyes.

11.  Pursuit/ Saccade:
 Pursuit eye movements allow the eyes to
closely follow a moving object.
 Pursuit differs from 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.

12.  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 fast
component.
 2 degree: nystagmus in primary gaze position.
 3 degree: nystagmus in addition to above gazes,
also present in the direction of slow component.

14.  May be asymptomatic.
 Oscillopsia - a sensation of environmental
movement. It commonly occurs with acquired
nystagmus. And with jerk nystagmus, the
environment is perceived to move in the
direction of fast phase.

15.  Monocular or binocular
 Conjugate (ie, the eyes behave similarly)
 Horizontal, vertical, torsional, or mixwd in
paatern
 Continuous or induced by a particular eye
position.
 Characterized by slow phases only, fast and
slow phases, or fast phases only
 Reduced at a null point.

16.  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:
1. Fixation
2. The vestibulo-ocular reflex
3. The neural integrator

17.  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 complexly and
intimately involved with the oculomotor
system.

18.  A complex system of neural inteconnections
that maintains foveation of an object during
changes of head position.
 The propioceptors of vestibular system are
the semicircular canals of the inner ear.
 The semicircular canals respond to changes
in angular acceleration due to head rotation.

19.  When the eye is turned in an extreme position
in the orbit, the fascia and ligaments that
suspend the eye exert and elastic force to
return toward the primary position.
 To overcome this force, a tonic concentration
of the extraocular muscles is required.

20.  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.

21. A simple classification modified from
“Classification of Eye movements
Abnormalities and Strabismus (CEMAS)” –
1. Physiological nystagmus
2. Pathological nystagmus

22.  Physiological nystagmus:
1. Endpoint nystagmus
2. Optokinetic nystagmus
3. Physiological vestibular nystagmus

23.  Pathological nystagmus:
• Early onset (childhood) nystagmus:
Infantile nystagmus syndrome/ Congenital nystagmus
Fusional maldevelopment nystagmus syndrome (Latent
nystagmus)
Spasmus nutans
• Acquired nystagmus:
Nystagmus due to disorders of visual fixation
Nystagmus caused by vestibular imbalance
Nystagmus due to disorders of gaze holding

24.  Jerk nystagmus
 Induced by moving repetitive targets (e.g. OKN
drum) across the visual field.
 Slow phase- pursuit movement- eyes follow the
target.
 Fast phase- saccadic movement- Opposite
direction as the eyes fixate on the next target.

25.  If the OKN tape or drum is moved
from right to left, left parieto-occipito-
temporal region controls the slow
(pursuit) phase to the left and the
left frontal lobe controls the
rapid (saccadic) phase to the right.

26.  Uses-
Detection of functional (non-physiological)
blindness.
Testing VA in the very young.
Aeessment of isolated homonymous hemianopia.

27.  Moderate frequency jerk nystagmus in
extremes of gaze.
 Fast phase- in the direction of gaze.

28.  Jerk nystagmus
 Caused by altered input from the vestibular
nuclei to the horizontal gaze centres.
 Slow phase- Vestibular nuclei
 Fast phase - brainstem and
frontomesencephalic pathway.

29.  Can be elicited by caloric stimulation:
◦ Cold water- nystagmus of opposite side
◦ Warm water- same sided/directional nystagmus
◦ Cold water in both ears simultaneously- nystagmus
with fast phase upwards
◦ Warm water in both ears simultaneously –
nystagmus with fast phase downwards.
◦ Abnormal test result- peripheral vestibular disease.

30.  Often recognized in the first few months
of life but may not become evident
until several years of age.
 Can occur secondary to poor vision
or to a motor deficit with nystagmus
itself causing poor vision.
 Can be associated with systemic conditions.

31.  Almost always horizontal and conjugate, even
in upgaze and downgaze.
 May be continuous or intermittent.
 Can appears as jerk or pendular movements
in different gazes.

32.  There is usually a null point – a position of gaze
in which nystagmus is minimal.
 Patients often adopt a head turn or posture that
places the eyes in the null position in order to
improve vision.
 Usually amplified by visual attention and fixation
 Dampened by convergence & absent during
sleep.

33.  Reverse response to optokinetic stimulus –
slow phase eye movement in the
opposite direction of the rotating
OKN drum.
 Children with INS usually do not have
oscillopsia.

34. Sensory deficit (afferent) nystagmus:
◦ More common form of infantile nystagmus
◦ In general, children with bilateral poor central vision
under 2 years of age develop nystagmus, the severity of
which is associated with the degree of visual loss.
◦ Causes –
 Congenital Cataract
 Macular hypoplasia
 Laber congenital amaurosis
 Optic nerve hypoplasia
 Albinism
 Achromatopsia

35. Congenital motor (efferent) nystagmus:
◦ Family history is common
◦ X-linked (dominant or recessive) inheritance –
common mode.
◦ Presentation is about 2-3 months after birth and
persists throughout life.
◦ VA – better than sensory deficit nystagmus, 6/12-
6/36.
◦ Primary position – low amplitude pendular
nystagmus, side gaze- jerk nystagmus.

37. Treatment:
◦ Correction of any refractive error.
◦ Use of contact lenses – enhance sensory feedback >
reduce abnormal eye movement > damp congenital
nystagmus.
◦ Prism therapy – Use of base out prism > to shift the
null point to primary position > or to induce
convergence which damp congenital nystagmus.

38. ◦ Eye muscle surgery : Anderson-Kestenbaum
procedure > reposition the eyes and move the null
point into the straight ahead position.
(Face turn to the right-eyes shift to a null point in the
left gaze> yolked left lateral rectus and right medial
rectus muscles are weakened/ recessed> left
medial rectus and right lateral rectus muscles are
strengthened/ resected)

39. ◦ Tonotomy- all four horizontal recti muscles are
detached and then reattached at their original site>
reported to improve foveation time and vision > but
it is controversial.
◦ Memantine and gabapentine > may improve visual
acuity and foveation times > not commonly used
due to side effects.

40.  Early onset, conjugate, horizontal, jerk
nystagmus.
 Both eyes open> No nystagmus> Eyes with
FMN are stable during fusion.
 Occlusion of one eye (elimination of fusion)>
horizontal nystagmus becomes apparent>
fast phase towards uncovered fixating eye.

41.  It becomes manifest under monocular
viewing conditions, i.e. in the presence of
decresed visio in one eye as in anisometropic
amblyopia, strabismic amblyopia, etc.
 Associated with infantile esotropia and
dissociated vertical deviation.

42.  While testing visual acuity in such patients,
one eye should be fogged (by adding plus
lenses in front) rather than occluding to
minimize induction of latent nystagmus.

43.  Presentation – 3 months to 18 months
 Unilateral or bilateral
 Small amplitude, high frequency, horizontal
nystagmus (‘Shimmering’ eye movements)
 Associated with head nodding and an abnormal
head posture (torticollis).

44.  Frequently asymmetrical, increased amplitude
in abduction. Vertical and torsional
components may be present.
 Head nodding, torticollis, or both occurs in
approximately 60% of patients and appear to
damp the nystagmus and improve vision.

46.  Cause:
 Idiopathic ( spontaneously resolve by the age of 3
years)
 Glioma of the anterior visual pathway
 Empty sella syndrome
 Porencephalic cyst

47.  Late onset or acquired nystagmus.
 Characterized by oscillopsia.
 Often associated with neurological abnormalities.
 Includes:
 Nystagmus due to disorders of visual function
 Vestibular nystagmus
 Nystagmus due to disorders of gaze holding.

48.  Also called ‘Vision loss nystagmus’
 May occur due to diseases affecting any part of the
visual system from retina to visual cortex or
conditions interrupting visual projection to the pons
and cerebellum as below:
◦ Nystagmus in diseases of the retina
◦ Nystagmus in diseases of the optic nerve
◦ Nystagmus in diseases affecting the optic chiasma
◦ Nystagmus in diseases affecting the post chiasmal visual
system

49.  Peripheral vestibular nystagmus
 Central vestibular nystagmus
 Upbeat nystagmus
 Downbeat nystagmus
 Torisional nystagmus
 Periodic alternating nystagmus
 See-saw nystagmus

50.  Tends to be solely horizontal, vertical or
torsional.
 Typically of fine amplitude.
 Fast phase away from the side of lesion.
 Improves with fixation.
 Worsens with gaze towards the fast phase.
 Causes:
 Labyrinthitis
 Meniere disease
 Middle or inner ear infections.

52.  Downbeat nystagmus
 Upbeat nystagmus
 Torsional nystagmus

53.  Most common form of central vestibular
nystagmus.
 Lesions compromising the vestibulocerebellum
(i.e. the nodulus, uvula, flocculus and
paraflocculus)> diminish the tonic output of
posterior semicircular canals to ocular motor
neurons> defective vertical gaze holding>
charecterized by an upward drift of the eyes ,
which is corrected with a downward saccade.

54.  May be present in primary position but more easily
elicited in downgaze and lateral gaze.
 Causes-
 Lesions at the foramen magnum:
 Arnold-Chiari malformation
 Syringobulbia
 Drugs:
• Lithium
• Phenytoin
 Wernicke encephalopathy
 Demyelination
 Hydrocephalus

55.  Treatment-
• Medicines-
 Clonazepam
 Gabapentin
 Baclofen
 Memantine
 4-aminopyridine
• Base out prism to induce convergence- it can
sometimes improve the oscillopia associated
with downbeat nystagmus.

57.  Vertical nystagmus
 Fast phase- beating upwards in all positions
 Causes-
 Posterior fossa lesions
 Drugs
 Wernicke encephalopathy

59.  Although peripheral vestibular nystagmus
may have a torsional component, purely
torsional nystagmus indicates a central
lesion.
 Causes-
• Medullary lesions:
 Syringobulbia
 Lateral medullary infarction
• May be a part of ocular tilt reaction.

60.  Conjugate horizontal nystagmus that
periodically reverses direction.
 Active phase- the amplitude and frequency of
nystagmus first peogressively increase than
decrease.
 An interlude- lasting 4-20 seconds, eyes are
steady, may show low-intensity, often
pendular movements.

61.  A similar sequence in the opposite direction
occurs thereafter.
 Whole cycle- between 1 to 3 minutes.
 Cause-
 Congenital
 Cerebellar disease
 Ataxia telangiectasia
 Drugs- Phenytoin.

62.  Pendular nystagmus
 One eye elevates and intorts while the other
depresses and extorts.
 Cause-
 Parasellar tumours (often with bitemporal hemianopia)
 Syringobulbia
 Brainstem stroke

63.  Gaze-evoked nystagmus
 Ataxic nystagmus
 Convergence retraction syndrome
 Brun’s nystagmus
 Rebound nystagmus

64.  Develops due to inability to maintain fixation
in eccentric gaze.
 Most commonly caused by dysfunction of
neural integrators.
 Fast phase- always in the direction of gaze.

65.  The amplitude of the nystagmus increases as
the eyes are moved in the direction of fast
phase.
 Cause-
 Toxic effects from drugs and medications (eg- alcohol,
sedatives, anticonvulsants antidepressents)
 Cerebellar disease.

66.  Jerk nystagmus due to the co-contraction of
extraocular muscles, often the medial recti.
 Can be induced by rotating an OKN drum
downards; the upward refixation saccade
brings the two eyes towards each other in a
convergence movement.

67.  Classically associated with retraction of the globe
into the orbit.
 Fast component- towards the medial side
 Cause-
 Pinealoma
 Stroke
 Trauma
 Multiple sclerosis

68.  Horizontal jerk nystagmus that occurs in the
abducting eye of a patient with INO.

69.  In one eye – A coarse cerebellar horizontal
jerk nystagmus. (Towards the side of lesion)
 In other eye – Fine, high frequency vestibular
nystagmus. (Opposite side of lesion)
 Cause- Cerebellopontine angle tumours such
as – acoustic neuroma

70.  In some patients with gaze evoked nystagmus,
prolonged eccentric gaze (>30 seconds) reduces
the amplitude of the nystagmus.
 However, when the patient resumes central gaze
position, a jerk nystagmus develops in the
opposite direction of the initial gaze-evoked
nystagmus.
 A condition referred to as rebound nystagmus.

71.  Resemble nystagmus, but the initial
pathological defoveating movement is a
saccadic intrusion;
 Only fast phase, no slow phase.
 Includes-
• Ocular flutter and opsoclonus
• Ocular bobbing

72.  Consist of saccadic oscillations with no
intersaccadic interval.
 In ocular flutter, oscillations are purely
horizontal and in opsoclonus they are
multiplaner.
 Cause:
 Viral encephalitis
 Myoclonic encephalopathy in infants (dancing eyes and
dancing feet)
 Drug induced, etc.

73.  Rapid downward conjugate eye movements
with a subsequent slow drift up to the
primary position.
 Cause-
 Pontine lesion (usually hemorrhage)
 Cerebellar lesions: compressing the pons
 Metabolic encephalopathy

74.  Rare condition
 Characterized by intermittent episodes of
oscillopsia and diplopia in one eye (usually
right eye).
 Cause not known.
 Condition may follow ocular or head injury
and rarely brainstem tumors.