Transcript Clinical Correlate: Examination of Nystagmus

Clinical Correlate:
Examination of Nystagmus
Najwa Al-Bustani
Neurology AHD
July 20-2011
Objectives:

Define Nystagmus.

How to describe Nystagmus.

Types.

Physiological & Physilogical Nystagmus.
What is Nystagmus ?

A repetitive rhythmic involuntary
oscillation of the eyes that is usually
conjugate.

Biphasic ocular oscillation containing slow
eye movement that are responsible for its
genesis and continuation.
How to describe Nystagmus ?
Waveforms:
Jerk (most common): slow drift ‘slow phase’
followed by quick reset ‘quick phase’.
 Slow phase waveforms can be:
a) Increasing velocity exponential = congenital.
b) Decreasing velocity exponential = gazeevoked.
c) Constant (linear) velocity = vestibular.
1.
2. Pendular: sinusoidal oscillation ‘like pendulum’,
phases have equal speed.
Waveforms:
Trajectory:

Horizontal.

Vertical.

Torsional.

Combination of all three.
Direction:

Usually defined by its fast phase.
Conjugacy:
 Conjugate: both eyes move in same
direction.
 Disconjugate: eyes move in different
direction >> disjunctive.
Alexander’s law:

Jerk nystagmus usually increases in
intensity when looking in the direction of
the fast phase.
Null zone:

The field of gaze where nystagmus
intensity is minimal.
Grading of jerk Nystagmus:

Grade 1: present only when looking in the
direction of the quick component.

Grade 2 : also present when looking straight
ahead.

Grade 3 : present when looking in the
direction of the quick component, when looking
straight ahead and when looking in the
direction of the slow component.
Not all Nystagmus is
Pathological
Physiologic Nystagmus:

End-position: few beats of horizontal
nystagmus when the eyes are first moved
to extreme horizontal positions in the
orbit.
Vestibular Nystagmus:
1.


Caloric Nystagmus:
Irrigation with worm water (in the head up
supine position) causes endolymph in the
horizontal canal to move toward the ampulla,
exciting the hair cells & driving a slow phase
eye movement away from the irrigated side.
Cold water: inhibits the horizontal canal,
produce slow phase toward the irrigated side.
Vestibular Nystagmus:
2.


Rotational Nystagmus (VOR):
Prolonged head rotation produces a
slow phase in the direction opposite to
the head movement interrupted by
quick phases in the same direction as
head movement.
This serves to stabilize retinal images as
head moves.
Optokinetic Nystagmus:

Driven by prolonged full-field visual
motion.

Supplements the VOR to stabilize vision.
Pathological Nystagmus
38 year old female, c/o vomiting X few
hours.
 ? left earache and tinnitis.

http://www.youtube.com/watch?v=y
o-zA1CuKUI&feature=related
Peripheral Vestibular Nystagmus:

Jerk nystagmus due to imbalance of
vestibular inputs.
Unilateral Vestibular hypofunction:

Acute lesion to one labyrinth or
vestibular nerve >> spontaneous
horizontal/torsional nystagmus.

Because of the tonic input from the intact
side is suddenly unopposed.
Unilateral Vestibular hypofunction:

The eyes drift (slow phase) toward the
lesioned side and quick phase beat
toward the intact side.

The intensity usually greatest when
looking toward the intact side
(Alexander’s law).

Direction does not change with gaze,
unlike gaze-evoked nystagmus.
Unilateral Vestibular hypofunction:

May be partially or fully suppressed by
vision and is best seen when fixation is
removed:
I.
Frenzel goggles.
I.
When looking at one optic nerve with
direct ophthalmoscope, cover the fellow
eye.
Vestibular hypofunction:

Bilateral vestibular lesions do not cause
nystagmus because the lesion is
symmetric and there is no imbalance.
Bruns Nystagmus
Rt.
Primary
position
Lt.
Bruns Nystagmus:
May be seen in large tumors in the CP
angle.
 2 components:
 Horizontal nystagmus beating away from
the lesion when looking away from the
lesion (vestibular nystagmus-accentuated
by Alexander’s law) due to vestibular
nerve involvement.

Bruns’ Nystagmus:

Horizontal nystagmus beating toward the
lesion when looking toward the lesion
(unilateral gaze-evoked nystagmus) due to
compression of the adjacent brainstem
and cerebellar flocculus.
Benign Paroxysmal Positional
Nystagmus (BPPN):

Brief (<1min) nystagmus provoked by changes in
head position relative to gravity.

Caused by free-moving otoconia that have
become lodged in a semicircular canal.

Usually affects the posterior canal: slow phase
directed downward with a torsional component
in which the upper pole of the eyes rotate away
from the affected ear (upbeating-torsional
nystagmus).
Benign Paroxysmal Positional
Nystagmus (BPPN):

Diagnosed by Dix-Hallpike maneuver.

Treated by repositioning maneuvers
(Epley) that move the otoconia out of the
affected canal.
Dix-Hallpike maneuver: Rt. Ear.
Epley Maneuver
Congenital Nystagmus:

May be present at birth, more commonly appears
later in infancy.

Sporadic or Genetic: AD (6p12), AR, X-linked
recessive.

Associated with oculocutaneous albinism.

Commonly accentuated by attempted fixation or
anxiety.

Typically damped by eye closure, sleep &
convergence.
Congenital Nystagmus:

Does not cause oscillopsia.

Distinct waveforms:
a) Conjugate
horizontal-torsional pendular
and/or jerk nystagmus.
b) Similar amplitude in both eye.
c) Jerk nystagmus has increasing velocity slow
phases.
Congenital Nystagmus:

Foveation periods: brief cessation of eye
motion, often following quick phases,
during which clear vision is possible (if
there are no afferent visual
abnormalities).

There is often orbital position (null point)
where nystagmus is minimal and vision is
best.
Congenital Nystagmus:

May be associated with other
abnormalitis:
 Strabismus, latent
oscillations.
nystagmus, head
Spasmus Nutans
Spasmus Nutans:

Triad of: head turn, head nodding and
nystagmus.
Typically develops during the first year of
life.
 Resolves by age 10.
 Horizontal or vertical pendular nystagmus
with low amplitude and high frequency.

Spasmus Nutans:

May be monocular or of different
amplitude and/or phase in each eye.

Optic pathway glioma can cause acquired
monocular nystagmus and should be ruled
out by MRI.
Convergence-retraction
nystagmus
Convergence-retraction nystagmus:

Convergence and/or retraction of the
eyes elicited by attempted upward
saccades or quick phases.

Best seen during stimulation with a
downward-moving OKN stimulus.
Convergence-retraction nystagmus:
Part of the dorsal midbrain syndrome:
1. Impaired vertical gaze (particularly
upwoard).
2. Light-near dissociation of pupillary
responses.
3. Lid retraction (Collier’s sign).
4. Convergence-retraction nystagmus.
5. Spasm or paresis of convergence,
accommodation.
6. Skew deviation.

Convergence-retraction nystagmus:

Due to lesion affecting the area of the
posterior commissure:
a) Tumors
(pineal).
b) Hydrocephalus (e.g aqueductal stenosis).
c) Hemorrhage or infarction (midbrain,
thalamus).
d) Multiple sclerosis or inflammatory lesions.
Upbeat Nystagmus
Upbeat Nystagmus:

Spontaneous nystagmus with downward
slow phases in primary position.
Etiologies:
a) Focal lesions: (infarction, tumor,
demyelinating) of the medulla or
cerebellum.
b) Cerebellar degeneration.
c) Wenicke’s encephalopathy.

Downbeat Nystagmus:
Downbeat Nystagmus:

Spontaneous upward drift of the eyes.

Characteristic sign of a lesion of the
vestibulocerebellum or its pathway or its
pathway in the brainstem (cerebellar
degeneration, MS, stroke).

Other causes: drug toxicity ‘Li, AED’,
Wernicke’s encephalopathy.
Downbeat Nystagmus:

Often occurs in the context of a more
general cerebellar syndrome but may
present in isolation & be progressive.

Slow phase waveform may have constant,
decreasing, or increasing velocity.

Commonly enhanced by down and lateral
gaze.
Gaze-Evoked Nystagmus
Gaze-Evoked Nystagmus:

Loss of eccentric gaze holding, eyes tend
to drift back to the center of the orbit.

Weak neural intergrator does not
produce suffeciently strong tonic
innervation to hold the eyes against
elastic forces.
Gaze-Evoked Nystagmus:

Direction of nystagmus depends on gaze
direction.

Typically horizontal.

May also include upbeat nystagmus with upgaze.

With sustained gaze >> nystagmus will often
diminish.
Gaze-Evoked Nystagmus:

Upon return to center position, there
may be a brief oppositely directed
nystagmus (rebound nystagmus).

Gaze-evoked & downbeat nystagmus
often occur together in patients with
cerebellar degeneration.
Gaze-Evoked Nystagmus:

Etiologies:
Vestibulocerebellar lesions >> cerebellar
degeneration.
 Functional neural integrator impairment
due to drugs (sedatives, AED), metabolic
derangements.

Pendular Nystagmus
Pendular Nystagmus:
Sinusoidal oscillation (no quick phase).
 May have complex waveform that include
horizontal, vertical, and torsional
components.

Elliptical nystagmus: horizontal & vertical
components out of phase.
 Congenital or acquired.

Pendular Nystagmus:

Etiologies:
1. MS.
2. Oculopalatal
tremor syndrome.
3. Whipple’s disease.
4. Toulene toxicity.
5. Severe visual loss.
6. Pelizaeus-Merzbcher disease.
Seesaw Nystagmus
Seesaw Nystagmus:

The interstitial nucleus of Cajal (INC),
adjacent to the medial longitudinal
fasciculus in the midbrain tegmentum, has
been frequently implicated in the
pathogenesis of SSN.
Seesaw Nystagmus:

Disconjugate vertical-torsional nystagmus.

Torsional component has the same
direction in both eyes, vertical movement
is in opposite direction.

During each cycle, one eye moves upward
and intorts and the other eye moves
downward and extorts.
Seesaw Nystagmus:
May be pendular (seesaw) or jerk (hemiseesaw).
 Associated with:
1. Midbrain stroke.
2. Medial medullary stroke.
3. MS.
4. Chiari Malformation.
5. Visual loss
6. Parasellar masses.
7. Congenital.

Periodic Alternating Nystagmus
(PAN):

Horizontal jerk nystagmus that changes
direction every 2 minute.

Present in the primary position, unlike
gaze-evoked nystagmus.

May be accompanied by periodic head
deviations that reduce the nystagmus by
moving the eyes into relative null position.
Periodic Alternating Nystagmus
(PAN):

Results from lesions to the
vestibulocerebellum (nodulus/uvula)
combined with either
flocculus/paraflocculus lesions or visual
loss.

Baclofen abolishes nystagmus.
Periodic Alternating Nystagmus
(PAN):

In cases of visual loss >> improvement of
vision (viterectomy, cataract extraction) may
eliminate nystagmus.

Congenital PAN is less regularly periodic
than acquired, does not respond well to
baclofen.

In comatose patient with no quick phase,
PAN may be seen as periodic alternating
gaze deviation.
Latent Nystagmus
INO
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