THE ENG BATTERY

ENG & VNG

Clinical Eye Movement Videos

Calibration

• Confirming relation between:– Voltage/Infrared video feed

and– Eye position

• Fixed Targets/Sinusoidal Tracking

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.

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. gaze2nd deg: both on center and lat. side of beat3rd deg: on center, and both lateral gazes.

• Video Periph Gaze

Alexander's Law

Central Nervous System Lesions:

• Often bilateral beating

• Can have vertical beating

• declines slowly if at all

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

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

Rebound Nystagmus:

• Cerebellar disease

• movement-generated, decays rapidly (10-20s)

• Beats in direction of movement

• Video Rebound

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.

Vertical Nystagmus:

• Brainstem/Cerebellar or Inf. olivary disease

• Can be generated by alcohol, drugs, too.

• Upbeat Video

• Downbeat Video

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

Saccade Testing

• Horizontal

• Vertical

• Regular pattern or random

• Through 20 to 30 degrees. 

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

Watch out for:

• Superimposed nystagmii) gaze nystagmusii) congenital nystagmus

• Drug effects: usually dysmetria• Patient problems:

i) inattentionii) eye blinksiii) head movement: scalloped tracings

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 theocculomotor nuclei

– disconjugate pursuit, eyes don't stay together in tracking - CNS lesion

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

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