Part 13

Question 1

what are saccades

Answer 1

rapid eye movements that bring target into focus on fovea

Question 2

what is the latency of saccades

Answer 2

200ms

Question 3

abnormal saccades

Answer 3

over or undershoot or slow

Question 4

procedure for testing saccade

Answer 4

hold indexes 15 degrees to side of nose, alternate fast left and right (non-rhymtically), horizontal vertical and diagonally

Question 5

abnormalities in saccades are due to

Answer 5

brainstem or cerebellar pathology (central)

Question 6

excitatory burst neurons (EBN)

Answer 6

8-12 ms before saccade
silent during fixation and slow movements

Question 7

inhibitory burst neurons

Answer 7

inhibit antagonist OMN

Question 8

omnipause neurons (OPN)

Answer 8

maintain stable fixation
- stops firing before saccade and starts immediately after saccade ends

Question 9

Long lead burst neurons

Answer 9

40-100ms before saccade
synchronize onset and end of saccades
inhibit and hold opn

Question 10

smooth pursuit eye movement (tracking)

Answer 10

ability to track a target image and stabilize on fovea

Question 11

what does smooth pursuit depend on

Answer 11

visual information
predictive
brainstem output

Question 12

when does smooth pursuit decline and what happens

Answer 12

with age it becomes saccadic and choppy

Question 13

smooth pursuit impairment disease

Answer 13

Parkinsons
Progressive supranuclear palsy
cerebellar disorders
large cerebral lesions

Question 14

smooth pursuit procedure

Answer 14

follow moving target which moves 10-20 degrees L R and up down at slow speed (0.2-0.8Hz)

Question 15

with smooth pursuit what are we looking for

Answer 15

smooth conjugate eye movement

Question 16

what does abnormalities in smooth pursuit show

Answer 16

brainstem or cerebellar abnormality

Question 17

what are the abnormalities of smooth pursuit

Answer 17

catch up saccades (eyes fall behind target)
back up saccades (eyes faster than target, congenital nystagmus, latent nystagmus, maldevelopment of cortical tracking system)

Question 18

optikinetic reflex

Answer 18

allows eyes to follow objects in motion when the head remains stationary (e.g., looking out car window)

Question 19

hypermetria

Answer 19

overshoot

Question 20

when are OKN present

Answer 20

normally present

Question 21

what does OKN comprise of

Answer 21

smooth eye movements interspersed by saccades

Question 22

OPN procedure

Answer 22

ask patient to follow fast changing repetitive image
think iPad example during class

Question 23

abnormal OKN

Answer 23

absent OKN

Question 24

unilateral vestibular deficit will show slow OKN on what side

Answer 24

same side as vestibular deficit

Question 25

fixation

Answer 25

gaze holding, neural integrator makes fixation possible but fixation itself is high eye level control

Question 26

abnormal fixation

Answer 26

when nystagmus present

Question 28

fixation procedure

Answer 28

hold patient head with. one hand and have them follow finger 30 degrees to L R up down and pause in each position

Question 29

VOR supression

Answer 29

ability of vestibulocerebellar system to surpress a vestibular signal

Question 30

VOR supression procedure

Answer 30

patient in chair, hold out arms with thumbs in front of eyes, fixate on thumbs, patient rotated side to side in chair

Question 31

VOR supression procedure abnormal

Answer 31

if VOR suppression abnormal almost always sign of cerebellar brainstem

Question 32

VOR suppression look for

Answer 32

patients ability to maintain visual fixation or if the patient makes saccadic eye movements