1. THE ENG BATTERY

2. Clinical Eye Movement Videos
ENG & VNG
Clinical Eye Movement Videos

3. Voltage/Infrared video feed
Calibration
Confirming relation between:
Voltage/Infrared video feed
and
Eye position
Fixed Targets/Sinusoidal Tracking

4. Gaze testing Gaze at visual targets. Eye movements are recorded
Spontaneous nystagmus
gaze evoked nystagmus
other extraneous movments
Pt. asked to close there eyes without shifting gaze.
There are 47 named types of nystagmus. This can be a very challenging and difficult area of eye movement
disorder to deal with clinically. However there are essentially only two divisions of nystagmus to worry about :
pathological and non-pathological.
The control and coordination of ocular movements depends on good connections between the eyes, the visual
conducting system, the occipital cortex, the visual memory areas, the frontal lobe, the cerebellum, brainstem and
finally the cranial nerves. It represents the biggest single functional unit in the Central Nervous System. Virtually
anything which disorganises the inputs in the cerebellar, vestibular of or brain stem regions will result in nystagmus.
Fortunately the most common form of nystagmus, congenital nystagmus, is non-pathological It is often familial and
there will always be a past history of it. Also the amplitude of the beat will often be augmented by covering one
eye (latent nystagmus). Most importantly, this nystagmus will always beat horizontally in up or down gaze. It is
benign and often associated with congenital difficulties with sight.
There is also no oscillopsia or sensation movement of the environment with it.
Pathological nystagmus is usually associated with oscillopsia and is of usually associated with recent onset. It will
tend to beat parallel to the direction of gaze. The distinction between beat and pendular nystagmus is useful for the
ophthalmologist but can be difficult for someone not used to watching eye movements.
The beat is applied to the direction of the fast phase and represents the correcting direction under the control of
the frontal cortex. Thus if the level of consciousness is reduced this phase will be less prominent and may
disappear. The most common form of acquired pathological nystagmus is vestibular, usually associated with a
labyrinthitis. It may however be associated with demyelinatve disease or space-occupying lesions.
Other forms of acquired nystagmus are:
1.Internuclear opthalmoplegia: the nystagmus appears in the ADDUCTING eye. This is due to a lesion in the
Median Longtitudnal Fasciculus.
2.Retraction nystagmus: this appears when a patient with a sylvian aqueduct syndrome is asked to look up,
the eyes converge and retract. Rara avis
3.Downbeat and Upbeat Nystagmus: Downbeat nystagmus is usually associated with disease in the region of
the foramen magnum. Upbeat is usually associated with drug overdose (barbiturates, phenothiazines or
Dilantin). In absence of drugs it is due to cerebellar disease.
4.Opsoclonus: characterised by congugate wild ocular pendular movements in all directions. This is dramatic
and usually associated with inflammation thus the prognosis is relatively good.

5. Peripheral Gaze Nystagmus:
strongest on gaze in direction of beating
never vertical
declines quickly (within days to a couple of weeks)
Alexander's Law: 1st degree Nystagmus: present only on lat. gaze 2nd deg: both on center and lat. side of beat 3rd deg: on center, and both lateral gazes.
Video Periph Gaze

6. Alexander's Law
Alexander’s system of grading vestibular nystagmus.

7. Central Nervous System Lesions:
Often bilateral beating
Can have vertical beating
declines slowly if at all

8. Some Central Gaze Nystagmi:
Bilateral Horiz. Gaze (Brun's) Nystagmus:
Rebound Nystagmus:
Periodic Alternating Nystagmus:
Vertical Nystagmus:
Congenital Nystagmus:
What is Going on here?:Voluntary Nystagmus

9. Bilateral Horiz. Gaze (Brun's) Nystagmus:
in large CPA tumors.
Gaze ipsi to lesion generates large slow nyst, with exp. decay in slow phase.
Gaze contra to lesion generates small fast nyst, in opposite direction of ipsi resp.
Video Bruns

10. Rebound Nystagmus: Cerebellar disease
movement-generated, decays rapidly (10-20s)
Beats in direction of movement
Video Rebound

11. Midline cerebellum is atrophied.

12. Periodic Alternating Nystagmus:
Medullary disease. Periodic Alternating Video
cyclic, 90 s one direction,
10 s nothing or vertical,
then 90s in other direction, 10 s down time,
and back again.
present w/ eyes open or closed.
strongest in middle of phases>>visual impairment.

13. Vertical Nystagmus: Brainstem/Cerebellar or Inf. olivary disease
Can be generated by alcohol, drugs, too.
Upbeat Video
Downbeat Video

14. Congenital Nystagmus:
From fixed brain defect either genetic or developmental in origin.
Pendular and/or jerk-type
Disorder of slow eye movement sub-system.
Null points or periods.
Convergence inhibition
Congenital Video

15. Saccade Testing Horizontal Vertical Regular pattern or random
Through 20 to 30 degrees. 

16. Saccadic Disorders: Occular dysmetria: CBL lesion
akin to dysdiadochokinesia
overshoots/undershoots
Saccadic Slowing: basal ganglia lesion
normal saccade for 20 deg = 188/sec
Internuclear Ophthalmoplegia: MLF lesion
rounded tracings
one eye lags, smoothing curve.
separate eye recordings to confirm INO VIDEO

17. Watch out for:
Superimposed nystagmi i) gaze nystagmus ii) congenital nystagmus
Drug effects: usually dysmetria
Patient problems: i) inattention ii) eye blinks iii) head movement: scalloped tracings

18. Tracking Tests: Following pendular movements Problems to look for
saccadic pursuit-eyes snap repeatedly to keep up with movement = CNS lesion
disorganized pursuit, wandering, slow, inaccurate tracking - CNS lesion, usually above the level of the occulomotor nuclei
disconjugate pursuit, eyes don't stay together in tracking - CNS lesion

19. Things to look out for: Drug influences
Inattention: multiple, rapid gaze deviations
Head movement: depressed amplitude
superimposed nystagmus
gaze: R, L, or bil. >> jerks at extremes
congenital: often overlies entire tracing

20. Optokinetic test
Repeated tracking of moving target, producing nystagmatic motion.
Disorders:
Asymmetry: CNS lesion diff of > 30 degs, at more than one stim rate.
Flat / declining resp. to faster rates. brainstem lesion, possible MS
Inverted movement: Congenital nystagmus