investigation of neurogenic palsies Flashcards
what is the difference between concomitant and incomitant deviations
a concomintant deviaition is where the angle of deviation is the same fixing either eye and in all positions of gaze – squint occurs in all directions of gaze - the eye that does not fixate usually has amyblyopia
incomitant deviaiton is where the angle of deviaiton varies depepnding on the eye used for fixation and direction of gaze- incomitant squint occurs when there is an acquired defect of movement of the eye - the squint and double vision is maximally demonstrated in the direction of action of the weakend muscle
what are the causes of incomitant deviations
incommitant devaitons are caused by
neurogneic palsies
mechanical limitations
anisemtropia
what is a neurogenic palsie
where the nerve supply to a muscle is affected - it may affect one individual muscle or a group of muscles
how is visual acuity affected in neurogenic palsies
normal acuity usually-
reduced acuity
previously present e.g. old amblyope
traumatic myadriasis - mydriasis= dilation of the pupil of the eye - dilation = less accomodation - reduced va
related to neurogenic condition e..g. retrobulbar neuritis in ms
if recent can contribute to decompensation of longstanding palsy
co - incedintal pathological cause
how do you test the superior rectus and what is its actual action
superior rectus - testing - up and out
actual action - elevate - intort - adduction
how do you test the action of the inferior rectus and what is its actual action
inferior rectus - actual action - depression - extorison - addcution
testing - ask patient to look down and out
how to test the action of the superior oblique vs its actual action
superior oblique - actual action -depression - intorsion - abduction
get patient to down and in
how to test for the inferior oblique vs its actual action
actual function - elevation , abduction , extorison
testing - get the patient to look up and out
what does rad sin mean
superiors intort and recti adduct
what things are important to consider with neurogenic palsies
the deviaiton in the primary postion
fixing with the unaffected eye = primary deviation
fixing with the affected eye - secondary deviation
abnormal head posture - compensatory head posture to avoid deviaiton
what do you have to observe for a abnormal head posture
oberve for - head turn, head tilt, head elevation/ depression
observe during visual task
put head straight and observe return to ahp
look for facial assymetrry - suggests longstanding
why do people acquire ahp with neurogenic palsies
head turn to place eyes away from the action of the affected muscle
what do you have to record on the cover test -
record ahp - single cover removes reason for ahp
record first with ahp near and distance then without ahp
record size and type of deviation
also note degree of incomitance fixing either eye
difference in vertical deviaition between near and distance
obliques larger at near
recti larger at distance
what are some general obsrvations that need to be made during ocular movements
smoothness of movement during pursuit
head movements in child may indicate avoidance of affected movement
pupils
lid position changes
globe position changes
nystagmus
define underaction
reduced ocular rotation which improves on testing duction
define restriction
abnormal ocular rotation where the movement does not improve fully when testing ductions
define limitation
abnormal ocular rotation
what do you have to check for during ocular movement
check versions and ductions
interpret development of muscle sequelae
include the different eye movement systems
what are the four different eye movement systems
smooth pursuit
saccades
okn
vor
what would you expect to find in the assesment of bsv
most commonly normal bsv or potential for
may have previous deviaiton with suppression or ac , diplopia may occur with change in angle
traumatic loss of fusion
what would you use the lees screen for in the investigation
used to measure the deviation in the nine positions of gaze
compares one eye to fellow eye
aids identification of affected eye and muscle
aids differential diagnosis of neurogenic and mechanical limitations
illustrates degree of concomitance
used for monitoring the patient
not good for biltateral conditions
what is the field of uniocular fixation used for
excellent to record the eye movements when ductions are affected
a good representation of eye movements in bilateral condtions and mechnaical limitations such as graves orbitopathy
what does the field of bsv record
records area in which bsv is maitained
excellent record of patients symptons
what does the investigation determine
determines
nerves affected - unilateral or bilateral
possible causes
longstanding or recently acquired
presence of a or v patterns
recovery, regression , stability
need for refferal
management plan
