2. INTRODUCTION
Nystagmus- is defined as repetitive to and fro movement of the eyes that is
initiated by a slow phase(drift) followed by rapid corrective eye movement.
Saccadic intrusions- spontaneous rapid eye movement without slow phase.
Thus the difference between the two lies in the initial eye movement.
3. PATHOPHYSIOLOGY
Foveal centration of an object of regard is necessary to obtain the highest level of visual
acuity.
3 control mechanisms maintain steady gaze
1) FIXATION
2) THE VESTIBULO-
OCULAR REFLEX
3) THE NEURAL
INTEGRATOR
4. TERMINOLOGIES
Amplitude – is the excursion of the nystagmus.
1. Fine- less than 5º
2. Medium - 5º-15º
3. Coarse- greater than 15º.
Frequency – number of to and fro movements in one second.
slow- (1-2 Hz)
Medium- (3-4 Hz)
Fast – (5Hz or more)
Intensity – amplitude × frequency
Null zone – position where intensity of nystagmus is minimized .Patient assumes a
head posture, such that the eyes are in null zone.
5. JERK AND PENDULAR NYSTAGMUS
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 PHASE
PENDULAR NYSTAGMUS MAYBE
HORIZONTAL OR VERTICAL
. RIGHT OR LEFT BEATING NYSTAGMUS
. UPBEAT OR DOWNBEAT NYSTAGMUS
NOT CHARACTERIZED BY RIGHT, LEFT,UP
,DOWN BEATING AS THERE IS NO FAST
PHASE
6. CONJUGATE/DISSOCIATE
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 oscillations differ between two eyes.
7. ALEXANDER’S LAW
It states that the amplitude of jerk nystagmus is largest in the gaze
of direction of fast component.
Grade 1- nystagmus only in the direction of fast component
Grade 2 – nystagmus in primary gaze position.
Grade 3 – nystagmus evident in all positions of the eyes.
9. PHYSIOLOGICAL NYSTAGMUS
TYPES OF PHYSIOLOGICAL NYSTAGMUS
END POINT NYSTAGMUS
VESTIBULAR(CALORIC OR ROTATIONAL)
OPTOKINETIC
10. END POINT NYSTAGMUS
Fine jerk nystagmus of moderate frequency
Seen in extremes of gazes
Fast phase in the direction of gaze
Common in older patients.
Pathological if :
1. Asymmetric
2. Persistent
11. OPTOKINETIC NYSTAGMUS
Jerk nystagmus
Induced by – moving repetitive targets across visual field
Slow phase(pursuit) – eye follows the target
Fast phase(saccades)- eye fixates on next target
Uses :
1. Detecting malingering
2. Functional blindness
3. Testing visual potential in children
4. Assessment of isolated homonymous hemianopia.
12. VESTIBULAR NYSTAGMUS
Jerk nystagmus due to altered inputs from vestibular nuclei to PPRF
SLOW PHASE – vestibular nuclei
FAST PHASE – brainstem and frontomesencephalic pathway
Vestibular nystagmus maybe elicited by caloric stimulation
• Cold water – opposite side
• Warm water – same side
• Cold water in both ears – upwards
• Warm water in both ears - downwards
14. CONGENITAL NYSTAGMUS
80% of all nystagmus
Infantile nystagmus syndrome
Usually diagnosed during infancy
Almost always conjugate and horizontal
Pathophysiology:
Sensory deficit (afferent nystagmus)-impairment of central vision in early life.
Congenital motor(efferent) nystagmus-
I. family history common
II. X-linked(dominant or recessive)
III. Visual acuity better than sensory deficit
15. CHARACTERISTICS
Elicited when tries to fixate on an object/attention/anxiety
Eyelid closure/convergence might suppress
Decreases when eyes moved to null position
Distinctive feature – waveforms (increasing velocity and pendular)
Hallmark- FOVEATION PERIODS
Other associated finding – “inverted pursuit” or “reversed optokinetic
nystagmus”
Head turns – adaptive strategy
No oscillopsia
16. LATENT NYSTAGMUS
Horizontal conjugate jerk nystagmus
Appears when one eye is covered
After mono-ocular occlusion- fast phase beats towards viewing eye and slow
phase towards the other.
Usually associated with strabismus- esotropia
Amblyopia is frequent
Pathophysiology – defect in cortical motor processing
Results from lack of development of binocular vision.
17. SPASMUS NUTANS
TRIAD OF SPASMUS NUTANS
Pendular
nystagmus
Head
nodding
Spasmus
nutans
Anomalous
head
position
18. CHARACTERISTICS
Onset usually in the first year of life
Disappears by 3-4 yrs.
Intermittent , binocular , small- amplitude, high frequency ,
Pendular oscillations
Can be monocular , asymmetric and variable in different positions of gaze
Usually benign
Head nodding- first abnormality noticed
Neuroimaging recommended
19. ACQUIRED NYSTAGMUS
Clinical features of nystagmus with lesions affecting visual pathway
Diseases of retina- congenital or acquired retinal disorders causing blindness lead to continuous jerk
nystagmus
With components in all three planes.
Diseases of optic nerves-
1. Pendular nystagmus
2. Monocular pendular nystagmus in monocular ON affection
3. Binocular ON disease- HEIMANN BIELSCHOWSKY PHENOMENON
20. LESIONS AFFECTING OPTIC CHIASMA-
Parasellar lesions such as pituitary tumours a/w – SEE-SAW NYSTAGMUS
POST CHIASMAL LESIONS-
Horizontal nystagmus documented with unilateral disease of cerebral hemisphere
Especially when lesion is large and posterior
23. TYPES OF CENTRAL VESTIBULAR NYSTAGMUS
3 TYPES
1. UPBEAT
2. DOWNBEAT
3. TORSIONAL
24. DOWNBEAT NYSTAGMUS
Nystagmus intensity is greatest in downgaze , least in upgaze.
Enhanced- patient looking down and to one side.
Most commonly associated with disease affecting cerebellum, craniocervical
junction.
Manifestation of drug toxicity- lithium
Convergence- may convert it to upbeat.
Consequences- oscillopsia and postural instability
27. UPBEAT NYSTAGMUS
Nystagmus intensity greatest in upgaze.
Doesn’t increase in left or right gaze
Convergence may enhance , suppress or convert upbeat to downbeat
Causes- lesions of lower pontine tegmentum , medulla
midbrain
28. CAUSES OF UPBEAT NYSTAGMUS
CEREBELLAR DEGENERATIONS
MS
INFARCTION/TUMOURS OF MEDULLA,MIDBRAIN OR CEREBELLUM
WERNICKE’S ENCEPHALOPATHY
BEHCET’S SYNDROME
TOBACCO
LEBER’S CONGENITAL AMAUROSIS
MIDDLE EAR DISEASE
30. TORSIONAL NYSTAGMUS
LESS COMMON
CAUSES-
1. SYRINGOBULBIA
2. CHIARI MALFORMATION
3. BRAINSTEM TUMOUR
4. HEAD TRAUMA
5. MS
6. OCULAR TILT REACTION
7. CONGENITAL
31. PERIODIC ALTERNATING NYSTAGMUS
Conjugate horizontal jerk nystagmus
Periodically reverses direction
During active phase- frequency first increase and then decrease
Active phase followed by interlude lasting 4-20s(eyes are steady)
Followed by similar sequence in opposite direction
Cause – cerebellar disease, ataxia telangiectasia ,phenytoin.
32. CONVERGENCE-RETRACTION NYSTAGMUS
Jerk nystagmus
Cause- co-contraction of extraocular muscles(esp medial recti)
Induced by rotating OKN drum downwards.
Refixation brings two eyes towards each other.
Associated retraction of globe into orbit
Causes- lesions of pretectal area such as pinealoma and vascular accidents.
33.
34. TREATMENT OF NYSTAGMUS
AMBLYOPIA AND REFRACTIVE ERROR CORRECTION-
CONTACT LENSES
COMBINATION OF HIGH MINUS CONTACT LENS WITH HIGH PLUS SPECTACLE LENSES
MEDICATIONS – BACLOFEN AND GABAPENTIN
BOTULINUM TOXIN INJECTION INTO THE EOM
SURGERY – RECESSION OF HORIZONTAL RECTI
35. TAKE HOME MESSAGE
NYSTAGMUS CAN BE PHYSIOLOGICAL, CHILDHOOD ONSET AND PATHOLOGICAL
ASSOCIATED WITH STRABISMUS AND AMBLYOPIA
NEURO-CONSULTATION SHOULD BE DONE
VISUAL REHABILITATION SHOULD BE CONSIDERED IN SEVERE RETINAL AND OPTIC NERVE DISEASE.
PROPER GENETIC COUNSELLING
