Amr Hassan's Guide to Eye Movements and Nystagmus

Amr Hassan, MD, FEBN
Professor of Neurology - Cairo University
Nystagmus

AGENDA
• 3rd,4th, 6th nerves
• Extraocular muscles
• How to examine for ocular motility
• Ophthalmoplegia
• Diplopia and related disorders
• Gaze pathway
• How to examine for gaze
• Gaze palsy
• Types of eye movements
• How to examine for EM
• Nystagmus and non nystagmus ocular oscillation

Eye movements
Centres controlling the nuclei – Supranuclear
Pathways connecting the nuclei – Internuclear
Nerves supplying the EOM - Infranuclear

FAST EYE MOVEMENTS
(300°-600°/SEC)
1) SACCADES
2) NYSTAGMUS
SLOW EYE MOVEMENTS
(5°-50°/SEC)
1)SMOOTH PURSUIT
2) OPTOKINETIC
3) VESTIBULAR
4) VERGENCE
Eye movements

• Allows bifoveation of an object.
• Stimuli –
✓Retinal blur – accomodative vergence.
✓Disparity of location of images- fusional
vergence.
• Pathway : Occipital cortex – midbrain reticular
formation – 3rd nerve nucleus
Vergence

Nystagmus: Pathological anatomy

• Nystagmus is a repetitive, involuntary, to-and-fro
oscillation of the eyes, which may be physiological or
pathological.
• Ocular movements that bring about fixation on an
object of interest are called foveating and those that
move the fovea away from the object are defoveating.
Nystagmus: Definition

• In pathological nystagmus, each cycle of movement is
usually initiated by :
✓ an involuntary, defoveating drift of the eye away
from the object of interest
✓ followed by a returning refixation saccadic
movement.
Nystagmus: Definition

❑The plane of nystagmus may be horizontal, vertical,
torsional or non-specific.
❑The amplitude of nystagmus refers to how far the eyes
move (fine or coarse)
❑The frequency refers to how rapidly the eyes oscillate
(high, moderate or low).
Nystagmus: Metrics

❑Jerk nystagmus
• Saccadic with a slow defoveating ‘drift’ movement
and a fast corrective refoveating saccadic movement.
• The direction of nystagmus is described in terms of
the direction of the fast component.
Nystagmus: Morphology

❑Pendular nystagmus
• Non-saccadic in that both the foveating and
defoveating movements are slow.
(i.e. the velocity of nystagmus is equal in both
directions).

❑Mixed nystagmus involves pendular nystagmus in the
primary position and jerk nystagmus on lateral gaze.

Movement:
Pendular
Jerk
Mixed
Plane: Horizontal, vertical, torsional, or combination
Amplitude: amount of excursion
Frequency: cycles per time unit
Manifestation: manifest, latent, manifest-latent
Degree: 1st, 2nd, 3rd
Nystagmus: Description

EPN
VOR
OKN
Physiological Nystagmus

End-point nystagmus
• Fine jerk nystagmus of moderate frequency found when
the eyes are in extreme positions of gaze.
• Fast phase is in the direction of gaze.
Physiological Nystagmus: EPN

• OKN is a jerk nystagmus induced by moving repetitive
targets across the visual field.
• The slow phase is a pursuit movement in which the eyes
follow the target; the fast phase is a saccadic movement
in the opposite direction as the eyes fixate on the next
target.
• OKN is useful for detecting malingerers who feign
blindness and for testing visual acuity in the very young.
Physiological Nystagmus: OKN

• Turning the drum to the right elicits an
ipsilateral pursuit movement to the right and a
contralateral saccade to the left.
Physiological Nystagmus: OKN

• Jerk nystagmus caused by altered input from
the vestibular nuclei to the horizontal gaze
centres
Physiological Nystagmus: VOR

• ‘COWS’ (cold-opposite, warm-same)

• When cold water is poured into both ears
simultaneously, a jerk nystagmus with the fast
phase upwards develops.
• Warm water in both ears elicits nystagmus
with the fast phase downwards
‫داون‬ ‫دافي‬

• Presentation of this rare condition is between 3
and 18 months.
• Idiopathic which spontaneously resolves by age 3
years.
• Glioma of anterior visual pathway, empty sella
syndrome and porencephalic cyst.
Spasmas nutans

• Unilateral or bilateral small-amplitude high-
frequency horizontal nystagmus associated with
head nodding.
• It is frequently asymmetrical with increased
amplitude in abduction.
• Vertical and torsional components may be
present.
Spasmas nutans

• Latent nystagmus is associated with infantile
esotropia
• With both eyes open there is no nystagmus.
Horizontal nystagmus becomes apparent on
covering one eye or reducing the amount of light
reaching the eye.
• Fast phase is in the direction of the uncovered
fixating eye.
Latent nystagmus

• Occasionally, an element of latency may be
superimposed on a manifest nystagmus so that
when one eye is covered the amplitude of
nystagmus increases.
Manifest-latent nystagmus

Acquired Nystagmus: classification

Peripheral vestibular nystagmus is caused by disease
affecting the ear such as:
✓ Labrynthitis
✓ Ménière's disease
✓ Middle or inner ear infections.
Vestibular Nystagmus

Central Vs Peripheral Nystagmus

• Vertical nystagmus with the fast phase beating downwards,
which is more easily elicited in lateral gaze and downgaze.
• Causes
• Lesions of the craniocervical junction at the foramen
magnum such as Arnold–Chiari malformation and
syringobulbia.
• Drugs such as lithium, phenytoin, carbamazepine and
barbiturates.
• Wernicke encephalopathy, demyelination and
hydrocephalus.
Downbeat nystagmus

• Vertical nystagmus with the fast phase beating
upwards
• Causes include posterior fossa lesions, drugs
and Wernicke encephalopathy.
Upbeat Nystagmus

Looking to RIGHT
Nystagmus on abducting eye Failure of adduction with NORMAL III
Cr.N
:
INO: Internuclear Ophthalmoplegia

• Demyelination
• Vascular disease
• Tumours of the brainstem and 4th ventricle
• Trauma
• Encephalitis
• Hydrocephalus
• Progressive supranuclear palsy
• Drug-induced
• Miller fisher syndrome
• Wernick s’ encephalopathy
INO : Causes

Periodic alternating nystagmus

• Conjugate horizontal jerk nystagmus that periodically reverses
its direction.
• Each cycle may be divided into active and quiescent phases as
follows:
✓ During the active phase, the amplitude, frequency and slow-
phase velocity of nystagmus first progressively increase then
decrease.
✓ This is followed by a short, quiet interlude, lasting 4–20 sec,
during which time the eyes are steady and show low-intensity,
often pendular movements.
✓ A similar sequence in the opposite direction occurs thereafter,
the whole cycle lasting between 1 and 3 minutes.

Causes include
• Isolated congenital
• Cerebellar disease
• Ataxia telangiectasia (louis–bar syndrome)
• Drugs such as phenytoin.

Convergence-retraction nystagmus

• It is the result of co-contraction of the
extraocular muscles, particularly the medial
recti followed by a slow divergent movement.
• Associated retraction of the globe into the
orbit.
• Causes include lesions of the pretectal area
such as pinealoma and vascular accidents
(Parinaud dorsal midbrain syndrome).
Convergence-retraction nystagmus

• Coarse cerebellar horizontal jerk nystagmus in
one eye and fine high frequency vestibular
nystagmus in the other.
• CPA tumours such as acoustic neuroma. The
lesion is ipsilateral to the side with coarse
cerebellar nystagmus.
Bruns nystagmus

• Voluntary nystagmus is not true nystagmus
but ocular flutter under voluntary control.
• It consists of a series of fast (saccadic) back-to-
back eye movements, without any interval or
slow phase.
• The oscillations usually are horizontal but may
be vertical, torsional, or (rarely) cycloid—a
phenomenon reported as “volitional
opsoclonus” or multiplanar flutter.
Voluntary nystagmus

• The ability to induce flutter voluntarily tends
to be familial.
• Usually, persons with this ability must
converge their eyes to initiate the oscillation
but are unable to sustain it for longer than 30
seconds.
Voluntary nystagmus

Non Nystagmus ocular oscillation

• Opsoclonus is a spontaneous, chaotic,
multivector saccadic eye movement disorder
in which the abnormal movements are
virtually always conjugate.
• Opsoclonus is aggravated by attempts at
fixation
• It may be associated with myoclonic jerks of
the limbs and cerebellar ataxia (dancing eyes–
dancing feet syndrome).
Opsoclonus

• Dysfunction of the pause cells in the pons due
to cerebellar or brainstem disease is the
cause.
• The most common causes are: toxic,
metabolic, and paraneoplastic disorders.
Opsoclonus

• Ocular flutter consists of horizontal conjugate
back-to back saccades that occur
spontaneously in intermittent bursts.
• It is aggravated by attempts at fixation.
• Occasionally it is triggered by a change in
posture.
Ocular Flutter

• It results from loss of pause cell inhibition of
the burst neurons in the paramedian pontine
reticular formation (PPRF), caused by injury
either to the PPRF or to the cerebellar
neurons that influence the pause cells, or
both.
• It occurs with brainstem or cerebellar disease
Ocular Flutter

• Ocular bobbing is a rapid downward
movement of both eyes followed by a slow
drift back to primary position.
• The oscillation recurs between 2 and 15 times
per minute
• It is found in patients (usually comatose) with
severe central pontine destruction and
horizontal gaze palsies
Ocular Bobbing

• Square-wave jerks (SWJs) are spontaneous,
small amplitude, paired saccades with an
intersaccadic latency of 150 to 200 msec that
briefly interrupt fixation.
• They may occur physiologically in normal
subjects (particularly in darkness) without
fixation. They are more common in the elderly.
• SWJs are prominent in PSP, multiple system
atrophy (MSA), and cerebellar disease.
Square-Wave Jerks

Block the action of frontalis to differentiate between
partial and complete ptosis.
Ptosis : frontalis overaction

How to examine for Convergence

THANK YOU
amrhasanneuro@kasralainy.edu.eg

(3) Primary congenital nystagmus:
❑ Inheritance is XLR or AD, and rarely AR.
❑ Presentation is about 2–3 months after birth and persists throughout life.
Adults with congenital forms of nystagmus do not notice oscillopsia
❑ Signs
• In the primary position there is low-amplitude pendular nystagmus that converts
to jerk nystagmus on side gaze.
• In upgaze and downgaze the nystagmus remains in the horizontal plane.
• The nystagmus may be dampened by convergence and is not present during
sleep.
• There is usually a null point (a position of gaze) in which nystagmus is minimal.
• In order to move the eyes into the null point, an abnormal head posture may be
adopted.
Types of nystagmus

(3) Ocular Microflutter
❑ Ocular microflutter, previously called microsaccadic ocular
flutter (a redundant term), is a rare symptomatic ocular
oscillation requiring magnification for detection
❑ It may be a form of opsoclonus but in some patients is a
variant of voluntary nystagmus.
❑ Patients complain of episodes of “shimmering” vision. It is
reported with cerebellar degeneration and MS.
❑ When it is persistent, patients should be evaluated for occult
neoplasms.
❑ Microflutter may respond to propranolol or verapamil.

(5) Ocular Dysmetria
❑Ocular dysmetria occurs with refixation saccades that
overshoot the target and often oscillate with an
intersaccadic latency of approximately 200 milliseconds
before coming to rest
❑It results from dysfunction of dorsal vermis and fastigial
nuclei in the cerebellum.

(7) Ocular Myoclonus (Oculopalatal Tremor)
❑ Ocular myoclonus is a vertical pendular oscillation with a frequency of
approximately 160 Hz, usually associated with similar oscillations of the
soft palate (palatal tremor) and sometimes other muscles of branchial
origin.
❑ The palatal tremor, referred to as the oculopalatal syndrome, occurs after
brainstem infarction, particularly of the pons, involving the central
tegmental tract
❑ The association of a facial nerve palsy and the one-and-a-half syndrome
may predict the development of oculopalatal myoclonus, probably
because of the proximity of the central tegmental tract to the facial nerve.
❑ Also, oculopalatal myoclonus can occur spontaneously in association with
progressive ataxia, a fourth ventricular tumor, or hydrocephalus following
subarachnoid hemorrhage

(8) Superior Oblique Myokymia
❑ Superior oblique myokymia is a paroxysmal, rapid, small
amplitude, monocular torsional-vertical oscillation caused by
contraction of the superior oblique muscle, predominantly on
the right side.
❑ Patients may complain of monocular blurring, torsional or
vertical oscillopsia, torsional or vertical diplopia, or twitching
of the eye.
❑ It is caused by injury or compression to 4th nerve

(3) Wrong-Way Eyes:
➢ Conjugate eye deviation to the “wrong” side—that is, away from the lesion
and toward the hemiplegia (contraversive gaze deviation)—may occur with
supratentorial lesions, particularly thalamic hemorrhage and (rarely) large
perisylvian or lobar hemorrhage.
➢ The mechanism is unclear, but possibilities include the following:
1. 1. An irritative or seizure focus causing “contraversive ocular deviation” is
unlikely, because neither clinical nor electrical seizure activity has been
reported in these patients.
2. 2. Because eye movements are represented bilaterally in each frontal lobe, it
is conceivable that the center for ipsilateral gaze alone may be damaged,
resulting in contraversive ocular deviation.
3. 3. An irritative lesion of the intralaminar thalamic neurons, which discharge
for contralateral saccades, could theoretically cause contraversive ocular
deviation.
4. 4. Damage to the contralateral inhibitory center could also be responsible.
Selected disorders of horizontal gaze

(4) Ping-Pong Gaze:
❑Ping-pong gaze is a slow conjugate horizontal
rhythmic oscillation that cycles every 4 to 8
seconds.
❑It occurs in comatose patients as a result of
bilateral cerebral or upper brainstem lesions or
metabolic dysfunction
Selected disorders of horizontal gaze

Amr Hassan's Guide to Eye Movements and Nystagmus

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