Nystagmus and related oscillations Flashcards
define nystagmus
an osicillation of eye movements
rthmic movement
could be horizontal vertical or rotational
could be unilateral or bilateral
- can be defined as a pursuit that takes the eye away from fixation and then a correwctive movement
happens in 2 satges - there is a slow eye movement which breaks fixation and then a corrective movement
the slow eye movement taking the eye away from fixation is where the pathology is
what are the types of nystagmus
physiological nystagmus
infantile nystagmus syndrome
acquired nystagmus
what are the types of physiological nystagmus
end point nystagmus - you ask a pt to look in extreme gazes e.g. extreme right or extreme left and you ask them to hold that position n- they have a break of fixation
usually results in a fine jerk with moderate frequency
okn- re fixation when looking at a moving object
caloric - when pouring hot or cold water into the ears you get nystagmus movement - - COWS- cold water intiates oppoiste nystagmus whilst cold water initates and opposite nystagmus
post rotation - if the body is moving quickly and then you stop the body suddenly - the eyes continue to roll for a few seconds
what things need to be noted on investigation of nystagmus
infantile vs acquired
position of nystagmus
- weather it is primary position nystagmus- is it present when looking in a straight ahead position or gaze dependent
waveform characteristics should also be noted
jerk nystagmus has slow phase which breaks the fixation and a and a quick phase to correct (that is a saccade) - we label it acccroding to the quick phasse not the smooth pursuit of it drifiting outwards
pendular - slow phase that takes you out of fixation and then a quick phase to regain fixation - so two pursuits back to back rather than a smooth pursuit followed by a saccade back which happens in jerk nystagmus
what are subgroups of infantile nystagmus syndrome
infatile idiopthaic :
- horzionatal jerk/pendular
null zone - nystagmus slows down in that area compared to other areas
reduced vision
inherited in 50% of cases
sensory deprivation - happens if child loses vision quite early in life
- pendualr #
roving eye movements- look in different directions- both eyes moving together
manifest/laten (fusion maldevelopment nystagmus) - usually happens in children who have congential esotropia
horizontal jerk
fast phase towards fixing eye
worse on occlusion
chnages direction depending on which eye is fixing
spasm nutans
- unilateral, bilateral, horizontal or multiplanar
- head nodding
- troticollis
what questions need to be considered in acquired cases of nystagmus
- pathological
- truly acquired?
- description:
effect on fixation (vestibular , central or peripheral)
other signs and symptons
what are adult nystagmus symptons
oscillopisa- i.e. feeling that their world is moving - everything is shifting - moving upwards , downwards or sideways
non - specific symptons
blurred vision
jumbled vision ‘
imbalance
no symptons
- present for as long as he can remeber
typical of infantile nystagmus
incidental finding by an optician
what should you first do when investigation nystagmus
- get a pateitn to look in the distance at a target with both eye open in primary position
what would the nystagmus look like if plotted on a graph
pendualr nystagmus - to and fro movements arre similar
slow phase and fast phase = jerk nystagmus
also need to document in what plane the eyes are moving e.g. horizontal/vertical/torisonal
what needs to be documented in terms of nysgatmus descri0ption
plane eyes are moving in
in what direction are the eyes noving e.g same direction in both eyes= conjugate
opposite direction = disjugate
jerk nysgatmus = described by the description of the fast phase
are both eyes doing the same thing
only in one eye = INO, SO, Myokymia
bilateral
different intesity between eyes = disscoiated
different waveform between eyes
what is disjugate nysgatmus
look at one eye at a time - e.g. right eye is moving horzionally and left eye is moving a vertically
what needs to be documeneted in terms of how easy it is to see the nystagmus
document - amplitude of the movement
measured in dgerees
graded as small, medium large
frequency of the movement
- beats within time
- graded as low, medium and high
intensity= amplitude x frequency
graded as low , medium and high
what should you observe before getting the patient to move their eyes
observe nystagmus before they move their eyes
varies with time
may change direction (PAN) -periodic alternating nystagmus - i.e. you look at the patient and then a few moments the direction of nystagmus changes - it is a specific type of horizontal nystagmus for a few moments it may be right beating but then it will become left beating -
what is alexanders law
intensity of nystagmus increased with gaze in the direction of the fast phase
pendular nystagmus can change to jerk nystagmus
jerk nystagmus can change its characteristics
upon near fixation - the intensity of nystagmus may reduce (especially in infantile nystagmus cases)
e.g. if they have right jerk nystagmus and you get them to look to the right the right jerk nystagmus will get worse
how are ocular movements recorded
recorded diagramatically with a 9 square grid with the
the direction of the arrow tells you weather it is horizontal or vertical
the intensity is the amount of arrows put
