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212- S + OM > Muscle sequelae > Flashcards

Muscle sequelae Flashcards

1
Q

what are the positions of gaze you can test

A

laeoversion = left

dextro= right

laevo- elevation - looking up and to the left (using the left superior rectus and the right inferior oblique

dextrose depression - looking down and to the right using the right inferior rectus and left superior oblique

version - movement of both the eyes into a gaze of position (binocular)

Duction - one eye is occluded (UNIOCULAR)

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2
Q

what are abnormal eye movements

A

occurs when ocular rotation is not within normal limits and includes limitation restriction
overaction
underaction

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3
Q

what is a underaction

A

reduced ocular rotation which improves on testing ductions , often associated with neurogenic palsies

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4
Q

what are the 6 extra ocular muscles

A

superior rectus

inferior rectus

medial rectus

lateral rectus

2 obliques - superior oblique

inferior oblique

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5
Q

what are the actions of the medial rectus and the lateral rectus

A

medial rectus- adduction

lateral rectus
abduction

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6
Q

what are the actions of the medial rectus and the lateral rectus

A

medial rectus- adduction

lateral rectus
abduction

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7
Q

what are the actions of the superior rectus

A

elevation

adduction

intorsion

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8
Q

what are the actions of the inferior rectus

A

depression

adduction

extorsion

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9
Q

what are the actions of the inferior oblique

A

inferior oblique - elevation , extorsion , abduction

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10
Q

what are the actions of the superior oblique

A

depression

abduction

intorsion

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11
Q

what does rad sin stand for

A

recti adduct

superior intort

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12
Q

what is a restriction

A

a term to describe abnormal ocular rotation where the movement does not improve when testing auctions and is often associated with mechanical aetiology

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13
Q

what is a incommitant strabismus

A

strabismus in which the angle of deviation differs depending upon the direction of gaze or according to which eye is fixing and it is associated with

defective movement of the eye
asymmetrical accomodative effort

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14
Q

what is concommitant strabismus

A

strabismus in which the angle of deviation remains the same in all directions of gaze , which ever eye is fixing

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15
Q

what are agonists

A

the primary muscle

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16
Q

what is an antagonist

A

eom whose action opposes that of the contracting muscle

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17
Q

what is a synergist

A

contralateral muscles which usually work together

18
Q

what is muscle sequelae

A
  • sequence of eom adaptation following muscle weakness or limitation - relates to hearings and sherringtons laws of innervation
19
Q

what is Donders law

A

a definite and invariable amount of torsion occurs for a given position of gaze irrespective of how that position was reached

20
Q

what is sherringtons law of reciprocal innervation

A

a law of reciprocal innervation - whenever a agonist receives an impulse to contract an equivalent inhibitory impulse is sent to its antagonist which relaxes

21
Q

what is herrings law of equal innervation

A

when an impulse goes to a muscle causing it to contract a simultaneous and equal impulse is sent to its contralateral synergist - this is a binocular law which aids the maintenance of bsv .

22
Q

describe the pattern of muscle sequelae

A
    • you have a primary underaction - this is the primary affected muscle - it can be underaction / restriction
  • you have an overaction of the
    contralateral synergist (herrings law of equal innervation)
  • overreaction of the ipsilateral antagonist (sherringtons law of reciprocal innervation )
  • secondary
    inhibition of the contralateral antagonist (herrings law of equal innervation)

sometimes called the secondary inhibiitonal palsy

occurs because the overacting ipsilateral antagonist requires less innervation less innervation is therefore sent to the contralateral antagonist

23
Q

what 3 factors affect the development of muscle sequelae

A

– duration of the palsy - all the steps of muscle sequelae develop over time

  • degree of primary underaction - more affected - more overaction / restriction
  • fixing eye - usually patient will fix with their unaffected eye but not always va and pre- existing strabismus will also have an effect
24
Q

what happens when muscle sequelae develops

A

over time the deviation will look less Incomitant and more concomitant

when a deviation is very inconstant the deviation in primary position will measure a different amount fixing with either eye (FEE) in primary position

25
Q

what is the fixing eye

A

the eye not behind the prism

26
Q

what is the primary deviation refer to

A

the angle measured when fixing with the unaffected eye

27
Q

what does the secondary deviation refer to

A

the angle measured when fixing with the affected eye

28
Q

in a incomittant deviation what is the significance of a primary and secondary deviation

A

in a inconstant deviation the secondary deviation will be greater than the primary deviation

29
Q

as muscle sequelae develops what happens to the primary and secondary deviation

A

as muscle sequelae develops the difference between the primary and secondary deviation reduces and may become concomitant over time

as a result of these changes overtime the muscle sequelae can be useful in determining whether a palsy is of recent onset or longstanding

30
Q

what is a diplopia chart

A

a diplopia chart provides a drawn record of the separation of the dipolopic images in 9 positions of gaze as described by the patient subjectively - the patient wears red and green goggles and views a linear light source which is presented vertically at 50cm the patient is then asked to describe the position of the images they see and you draw it on a chart

31
Q

when can diplopia charts be useful

A

a patient is bedridden/ has impaired mobility - preventing them to perform other tests e.g. lees screen

there is a subtle bilateral 4th nerve palsy i.e. in a head injury where the bilateral nerve palsy can be very asymmetrical

32
Q

how to interpret diplopia

A

important to consider where their is the widest separation of images indicating the position of gaze where the muscle is acting

is the horizontal diplopia crossed (heteronymous) or uncrossed (homonymous)

remember a higher eye will see a lower image and a extorted eye will see an intorted image

33
Q

how do you interpret a hess chart

A

the field showing the movements of the right eye has been plotted with the left eye fixing

the field showing the movements of the left eye has been plotted with the right eye fixing

34
Q

what things do you have to consider with a hess chart

A
  • comparison of the two charts

size of the overall field

smaller field= affected eye

primary position deviation

  • primary deviation vs secondary deviaiton

underactions (inward displacement)

look for largest underaction - primary affected muscle

deviation in other secondary and tertiary positions of gaze

muscle sequlaee- develops over time

overaction (outward displacement)
look for largest overaction

muscle sequelae

differential diagnosis

mechanical vs neurogenic

longestanding palsy with developed muscle sequelae may look like a concomitant deviation - difficult to identify primary effected muscle

equal field size

a or v pattern
sequential hess chart

35
Q

how is the size of deviation on a hess chart measured

A

1 square = 5 degrees of deviation

36
Q

what is the expected pattern of muscle sequelae for a left lateral rectus palsy

A
  • underaction of the left lateral rectus

overaction of the right medial rectus

overaction of left medial rectus

underaction of the right medial rectus

37
Q

acronym to remember pattern of muscle sequelae

A

People Underestimate Older ChildrenS Skills Obviously It Always Inevitably Creates Arguments

38
Q

what is the expected pattern of muscle sequelae of a left medial rectus palsy

A
  • underaction of the left medial rectus

overaction of the right lateral rectus

overaction of the left lateral rectus

underaction of the right medial rectus

39
Q

what is the expected pattern of muscle sequelae for a right superior oblique palsy

A

underaction of the right superior oblique

overaction of the left inferior rectus

overaction of the right inferior oblique

underaction of the left superior rectus

40
Q

what is the expected pattern of muscle sequelae for a right superior rectus palsy

A

underaction of the right superior rectus

overaction of the left inferior oblique

overaction of the right inferior rectus

underaction of the left superior oblique

212- S + OM (10 decks)

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