Neurological Conditions Flashcards
how is congenital nystagmus different to infantile nystagmus?
congenital nystagmus suggests the nystagmus has been since birth (but that is very rarely the case) whereas infantile nystagmus describes nystagmus from childhood
what are the two sub types of nystagmus?
-early onset: may have developed due to visual abnormality or can be idiopathic
-acquired: neuropathological like stroke or trauma or MS
name and describe what are the three types of early onset nystagmus
-Infantile
-Latent = where you cover the eye and the nystagmus is triggered or gets worse
-Spasmus nutans = comes on with head nystagmus and usually disappears within first year of life. Its high frequency low amplitude, and is accompanied by head oscillations (as is sometimes infantile nystagmus)
when does infant nystagmus seem to occur?
when theres another pathology in the visual system that causes a moderate moderate reduction in VA (severe vision loss can make you less likely to have visual nystagmus)
what is the null zone in nystagmus?
the position of the eyes where the nystagmus is at its best. Usually is achieved by the patient having an AHP.
how can you represent movements of nystagmus?
using a wave form graph (check ss)
on a waveform graph for nystagmus, what is the frequency?
frequency = 1/ cycle duration
on a waveform graph of nystagmus what is the intensity?
intensity = amplitude x frequency
ln a waveform graph for nystagmus, what does foveation mean?
the period of time when the eyes are moving most slowly, usually occurs when the eyes have just jerked back to fixation
in a waveform graph of nystagmus where is pathology most likely to occur?
in the slow phase
in a waveform graph for nystagmus, what is jerk form?
where the eyes drift to the left and then jerk back to the right and carry on in a cycle. This can be used to record and characterise the nsytagmus
what are the 3 types of waveform for nystagmus?
-Jerk = this tends to suggest a better functioning visual system as the patient is able to re-orient their gaze to the fixation target
-Pendular
-Dual jerk
what is oscillopsia?
where the world seems to oscillate back and forth but this is rare in infantile nystagmus. Could be due to efference copy.
in an eye trace graph what are the movements for infantile nystagmus?
horizontal are like zig zag lines and theres one straight line in the middle which is vertical movements because theres basically no vertical movements
what do people with infantile nystagmus see?
usually see images blurry as blurry or coming in and out of focus and people and oscillopsia may occur when the patient is very tired
for someone with oscillopsia, what nystagmus are they most likley to have?
acquired nystagmus
what is latent nystagmus also known as?
fusion maldevelopment nystagmus syndrome
what makes latent nystagmus manifest?
when nystagmus worsens when one eye is covered
what are the signs of latent nystagmus?
*only present when one one eye is covered
* Quick phases directed towards fixating eye
* Higher intensity in abduction (follows alexanders law)
* Slow phases do not accelerate
* (Almost) always accompanied by strabismus
for spasmus nutans, what are the signs?
High frequency, low amplitude
* Accompanied by head oscillations
* Spontaneous regression within first few years of life
if you see vertical nystagmus, what nystagmus is it most likely?
probably acquired as infantile nystagmus is usually horizontal but should still be checked
what are opsoclonus and ocular flutter?
eye movements that are not nystagmus because there’s no slow phase however these are suspicious of neurological damage
what are the main signs of acquired nystagmus and what are the most common causes?
-asymmetric nystagmus
-vertical nystagmus
most commonly MS or stroke
what is the difference between opsoclonus and ocular flutter
opsoclonus is involuntary rapid eye movements in all directions while ocular flutter is also rapid eye movements they are only in the horizontal so less severe and some people can do this voluntarily