nystagmus namrata

Nystagmus and

Spontaneous eye

movement disorders

DR. NAMRATA GUPTA

Definition

Fixation instabilities that are involuntary and rhythmic

Nystagmus- inability to maintain fixation due to slow drift away from fixation followed by rapid corrective eye movement

Saccadic intrusion and saccadic oscillations result from spontaneous rapid eye movement without slow phase

Background

Foveal centration of an object of regard is necessary to

obtain the highest level of visual acuity

Three main control mechanisms maintain steady gaze—

• Fixation

• The vestibulo-ocular reflex

• The neural integrator

Fixation

Involves the visual system's ability to detect drift

of a foveating image

Signal an appropriate corrective eye movement

to refoveate the image of regard

Vestibulo-ocular reflex

Neural integrator

A gaze- holding network : Complex integration

between cortical centers, cerebellum, ascending

vestibular pathways and ocular motor nuclei

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

Failure of control system- disruption of steady fixation

A. Nystagmus

B. Saccadic intrusion or saccadic oscillations

Nystagmus

Nystagmus is a repetitive, involuntary to and fro

movement of the eyes (horizontal, vertical or

torsional) with 2 phases:

1. Involuntary defoveating drift of the eye from

the target of interest followed by

2. Corrective refixation saccade back to the

target

Terminologies

• Saccade/ Pursuit

• Jerk / Pendular

• Null zone

• Amplitude

• Frequency

• Intensity

• Conjugate / Dissociated

Saccade/ Pursuit

Saccades are sudden, simultaneous movements of

both eyes in the same direction to place the object

of interest on to the fovea

Pursuit eye movements allow the eyes to closely

follow a moving object located by the saccadic

system

Pursuit differs from the vestibulo-ocular reflex, which

only occurs during movements of the head and

serves to stabilize gaze on a stationary object

Jerk / Pendular

Jerk nystagmus Pendular nystagmus

Alternation of slow defoveating

drift and rapid corrective

saccade in opposite direction

Sinusoidal oscillation with slow

phase in both directions and no

corrective saccade

Direction of jerk nystagmus =

direction of the fast phasePendular 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

Pendular nystagmus

Jerk nystagmus

Amplitude

Amplitude is the excursion of the nystagmus

Fine : less than 50

Medium : 50-150

Coarse : greater than 150

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)

Intensity

Intensity = amplitude x frequency

Null zone: position where intensity of nystagmus is

minimized, foveation period long

Patient assumes a head posture, such that the eyes

are in null zone

Conjugate/Dissociated

Conjugate : Nystagmus which is symmetric in

direction, amplitude and rate between two eyes

Dissociated: When it differs in any one of the

parameters between two eyes

Disconjugate: Direction of the oscillations differ

between two eyes

Schematic for Nystagmus

Nystagmus

waveforms

Alexanders law

It states that the amplitude of jerk nystagmus is

largest in the gaze of direction of fast component

Grade I : nystagmus only in the direction of the fast

component

Grade II : nystagmus in primary gaze position

Grade III : nystagmus evident in all positions of the

eyes

Classification

• Optokinetic

• Vestibular

• End-point

Physiological

• Congenital nystagmus

• latent nystagmus

• Spasmus nutans

Early onset (childhood)

• Gaze-evoked

• Vestibular

• Upbeat/downbeat

• Dissociated nystagmus

• Periodic alternating nystagmus

Pathological

Physiological

End point nystagmus

Vestibular (caloric or rotational) nystagmus

Optokinetic nystagmus

End point nystagmus

Jerk nystagmus

On looking extreme lateral or upwards

Small amplitude <20 and Angle of gaze > 450 , dampens in 6 secs

Common in older patients

Pathological if-

Asymmetric

Persistent nystagmus

Other features

physiological

Vestibular nystagmus

Jerk nystagmus due to

altered inputs from

vestibular nuclei to PPRF

physiological


Types:

Rotatory vestibular nystagmus- stimulation of

vestibular labyrinth or nerve secondary to rotation

Caloric vestibular nystagmus:

• Cold water : opposite side

• Warm water : same side

• Cold water in both ears: upwards

• Warm water in both ears : downwards

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

physiological

Early onset (childhood)

Congenital nystagmus

Latent nystagmus

Spasmus nutans

Congenital nystagmus(Infantile nystagmus syndrome)

80% of all nystagmus

Usually not noted at birth , apparent during first few

months of life

Positive family history may be present

Characteristics

Horizontal nystagmus ( mixed pendular and jerk)

Bilateral conjugate movements of the eyes

With or without normal visual acuity

Head turn to achieve null point

Accentuation with distant fixation and decreased

by convergence

Abolished in sleep

No oscillopsia

Strabismus present in 15% patients


Reverse response to OKN stimulus ( fast phase in

direction of moving OKN drum)

Exponential increase in velocity of slow phase with

distance from fixation


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


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)


Latent nystagmus

(Fusional maldevelopment nystagmus

syndrome)

Conjugate jerk nystagmus

Beginning or accentuation when binocular fusion is

disrupted

After mono-ocular occlusion- fast phase beats

towards viewing eye; slow phase towards the other

Congenital esotopia

May co-exist wit INS

Manifest latent nystagmus- latent nystagmus present

with both eyes open during physiological suppression

Spasmus nutans

Triad of symptoms:

Pendular Nystagmus

Head nodding

Torticollis (head tilt or head turn)

Spasmus nutans

Onset usually in the first year of life (3-15 months)

Disappears by 3-4 yrs of age

Intermittent , binocular, small-amplitude, high

frequency, horizontal pendular nystagmus

oscillations

It can be monocular, asymmetric, and variable in

different positions of gaze

Usually benign

Neuroimaging recommended ( gliomas may mimic

spasmus nutans)

Infantile monocular pendular

nystagmus

Monocular vertical or elliptical high frequency

nystagmus

Heimann-Bielchowsky phenomenon- with long

standing poor vision

Usually due to visual loss(optic neuropathy,

amblyopia or chiasmal glioma)

Acquired nystagmus

Nystagmus associated

with poor vision (sensory)

Anterior segment:

cataract, aniridia

Retinal diseases: RB,

ROP, Intrauterine

infections

Nystagmus associated with

neurological diseases (motor)

End gaze paretic nystagmus


Downbeat nystagmus

Upbeat nystagmus

Periodic alternating

nystagmus

Dissociated nystagmus

Gaze paretic nystagmus

Most common type

Jerk nystagmus at 30° of fixation

Fast phase in direction of eccentric target

Absent in primary position and is not visually

disabling


Dysfunction of neural integrator- nucleus prepositus

hypoglossi and medial vestibular nucleus

Symmetric- mental fatigue: barbiturates,

anticonvulsants, tranquilizers

Asymmetric- lesions of brain stem, cerebellum and

cerebrum

Vestibular nystagmusFeature Peripheral Central

Disease of vestibular origin

Rotary nystagmus

Disease of the brainstem

Pure horizontal, vertical

Direction • Decreased innervation-

slow component

towards affected ear

• Increased innervation-

fast component toward

affected ear

• Direction of

nystagmus may

change with gaze

• Lesion contralateral to

fast component

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, tinnitus CNS involvement

Upbeat nystagmus

Type of jerk nystagmus with fast phase upward in

primary position

Often worsens in upgaze

Causes: lesions of lower pontine tegmentum,

medulla, cerebellar vermis, midbrain

• Multiple sclerosis, infarction, intra-axial tumor, brainstem

encephalitis, cerebellar degeneration

Rx: base up prisms in reading glasses can be

used to force the eyes downward

Upbeat nystagmus

Downbeat nystagmus

Type of jerk nystagmus with fast phase downward in

primary position

Often worsens in downgaze(convergence)

Oscillopsia is usually prominent

Causes:

lesions at cerebellum and pons- infarction, cerebellar

degenerations, tumors, multiple sclerosis, congenital

malformations

Vitamin B12 deficiency, magnesium deficiency, lithium

toxicity, Wernicke’s encephalopathy

Rx: Base down prisms in reading glasses can be used

to force the eyes upward

Downbeat nystagmus

Periodic alternating

nystagmus (PAN)

A repetitive cycling of right beating and left

beating nystagmus in primary gaze

PAN is a conjugate, horizontal jerk nystagmus with

the fast phase beating in one direction for a period

of 1-2 minutes

An intervening null phase lasting 10-20 seconds

Nystagmus begins to beat in the opposite direction

for 1-2 minutes then, the process repeats itself

Periodic alternating head turn towards fast

component to minimise nystagmus & oscillopsia

Causes:

lesions of the cerebellum

Severe binocular vision loss- vitreous hemorrhage,

cataract, chronic papilloedema

Periodic alternating nystagmus

Periodic alternating nystagmus

Dissociated Nystagmus

Difference between two eyes in amplitude of ocular

oscillations

A. Acqiured pendular nystagmus in adults:

• Lesions of pons, medulla, midbrain, cerebellum

• Oculopalatal myoclonus- associated tremors of soft

palate tongue, facial muscle, pharynx

B. Monocular or bilateral vision loss

1. Monocular -

• Children: High frequency pendular nystagmus

• Adults: low frequency, irregular, vertical dift and jerk nystagmus

• Abolished with recovery of vision

2. Binocular:

• large amplitude oscillations superimposed with small amplitude ones

• Impaired vestibulo-ocular response

• Head nodding present



C. Seesaw nystagmus:

Disconjugate vertical pendular nystagmus

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

Causes:

Parasellar lesions, pituitary tumors

Less common- head trauma, brain stem infarction

Produces very disabling oscillopsia that responds

poorly to any Rx

Seesaw nystagmus


D. Inter nuclear

ophthalmoplegia

Lesion of medial longitudinal

fibers

Isolated slowing of

adduction of ipsilateral eye

Abducting nystagmus of

other eye in horizontal gaze

opposite to lesion

Convergence-retraction

nystagmus

Not truly a nystagmus

b/l adducting saccades causing convergence of both eyes

Elicited by having the patient to look up, the eyes converge & retract

Co-contraction of all extra-ocular muscle

Causes: Dorsal midbrain lesions

Collier’s sign- paresis of upgaze, pupillary light near dissociation, skew deviation, bilateral eyelid retraction

Convergence-retraction nystagmus

Nystagmus associated

with strabismus

Manifest-latent nystagmus

Manifest nystagmus

Nystagmus blockage syndrome

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

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

Nystagmoid conditions

• Reflex saccades to objects in visual field is inhibited by

pathways from frontal lobe to basal ganglia and

superior colliculus

• Frontal lobe disease- inappropriate saccades

• Alzhimer’s disease, Huntington disease, progressive supranuclear palsy, schizophrenia

Saccadic intrusions:

1. Normal intersaccadic intervals

2. Without normal intersaccadic intervals

Saccadic intrusion with normal inter-

saccadic interval

Square wave kerks

Macro- square wave kerks

Macrosaccadic oscillation

Saccadic intrusion without normal

inter-saccadic interval

Ocular flutter- Burst of small amplitude, high

frequency, horizontal movements

Opsoclonus (saccadomania) – multidirectional

eye movements, high frequency, high amplitude

Ocular flutter/Opsoconus

Etiology –

• Unknown in healthy individuals

• Omnipause neurons of pons

• Neuroblastoma

• Small cell carcinoma of lung

• Cancer of breast and ovaries

• Multiple sclerosis, brainstem encephalitis

Saccadic intrusion without normal inter-saccadic interval

Ocular bobbing

Characterized by rapid downward movement of

both eyes

Followed by slow drift back to midline

Causes:

• Comatose patients with massive pontine lesion

• Metabolic encephalopathy

Superior oblique myokymia

Defined as high frequency oblique oscillation of one

eye due to intermittent firing of the superior oblique

muscle

Produces oscillopsia or intermittent vertical diplopia

Very small amplitude observed in slit lamp

Superior oblique myokymia

Usually benign

No underlying etiology is found

Neuroimaging : r/o post fossa tumors

Refractory cases:

• Carbamazepine

• Surgical weakning of the superior oblique muscle can be

performed

Treatment

Nonsurgical : non neurological causes

Optical devices

• Glasses: High minus lenses stimulate accommodative

convergence and thus dampens nystagmus

• Contact lenses: helpful in high refractive errors by

giving good visual stimulus for fusional control

Prisms :

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


Occlusion therapy:

Trials with conventional occlusion have been found

to be effective

As amblyopia gets corrected and vision improves,

nystagmus finally decreases


Pharmacologic management

The drugs hypothetically inhibit excitatory

neurotransmitters within CNS

1. Baclofen (GABAB receptor agonist) : congenital

nystagmus, seesaw nystagmus, periodic

alternating nystagmus

2. Carbamazepine: widely used for superior oblique

myokymia

Pharmacologic

denervation

Botulinum toxin A act by blocking the

neuromuscular transmission

• 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

Surgical

Based on 2 principles:

To shift the null position if any to the primary position

To reduce the amplitude of the nystagmus by

weakening the muscle force of all recti

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

Anderson surgery

Advocated only recessions

Left face turn (null in dextroversion):

Right eye : LR recession

Left eye : MR recession

Parks surgery

Recommended lesser amount of recessions and

resections 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

Summary

Nystagmus- Slow defoveating drift followed by rapid

corrective saccade eye movement

Physiological, childhood onset, pathological

Abnormalities of cortical, subcortical and ocular

motor nuclei with vesibular nuclei and cerebellum

Inability to maintain fixation, decreased fixation and

oscillopsia

Saccadic intrusions- not ture nystagmus with lack of

slow component, rapid defoveating drift with fixation

intervals

Medical, optical, surgical management may be

satisfactory in achieving null point

Bibliography

American Academy of Ophthalmology. Neuro-

Ophthalmology. Section 5. 2013-2014

Kanski Jack J. Clinical Ophthalmology: A

Systematic Approach. 7th ed. Elsevier;2013: 841-

846.

Myron Yanoff & Jay Duker. Ophthalmology,3rd

edition,2008: 9:1040-1048.

Khurana AK. Anatomy and physiology. 2nd ed.

New Delhi; rerinted 2010

Thank you

nystagmus namrata

Health & Medicine

slow phasecorrective

spontaneous rapid eye

nystagmus nystagmus

slow drift

saccadic system pursuit

rapid corrective saccade

abt fixation

saccadic oscillationssaccadic