Muscle sequelae

Question 1

what are the positions of gaze you can test

Answer 1

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)

Question 2

what are abnormal eye movements

Answer 2

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

Question 3

what is a underaction

Answer 3

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

Question 4

what are the 6 extra ocular muscles

Answer 4

superior rectus

inferior rectus

medial rectus

lateral rectus

2 obliques - superior oblique

inferior oblique

Question 5

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

Answer 5

medial rectus- adduction

lateral rectus
abduction

Question 6

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

Answer 6

medial rectus- adduction

lateral rectus
abduction

Question 7

what are the actions of the superior rectus

Answer 7

elevation

adduction

intorsion

Question 8

what are the actions of the inferior rectus

Answer 8

depression

adduction

extorsion

Question 9

what are the actions of the inferior oblique

Answer 9

inferior oblique - elevation , extorsion , abduction

Question 10

what are the actions of the superior oblique

Answer 10

depression

abduction

intorsion

Question 11

what does rad sin stand for

Answer 11

recti adduct

superior intort

Question 12

what is a restriction

Answer 12

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

Question 13

what is a incommitant strabismus

Answer 13

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

Question 14

what is concommitant strabismus

Answer 14

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

Question 15

what are agonists

Answer 15

the primary muscle

Question 16

what is an antagonist

Answer 16

eom whose action opposes that of the contracting muscle

Question 17

what is a synergist

Answer 17

contralateral muscles which usually work together

Question 18

what is muscle sequelae

Answer 18

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

Question 19

what is Donders law

Answer 19

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

Question 20

what is sherringtons law of reciprocal innervation

Answer 20

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

Question 21

what is herrings law of equal innervation

Answer 21

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 .

Question 22

describe the pattern of muscle sequelae

Answer 22

• • 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

Question 23

what 3 factors affect the development of muscle sequelae

Answer 23

– 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

Question 24

what happens when muscle sequelae develops

Answer 24

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

Question 25

what is the fixing eye

Answer 25

the eye not behind the prism

Question 26

what is the primary deviation refer to

Answer 26

the angle measured when fixing with the unaffected eye

Question 27

what does the secondary deviation refer to

Answer 27

the angle measured when fixing with the affected eye

Question 28

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

Answer 28

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

Question 29

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

Answer 29

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

Question 30

what is a diplopia chart

Answer 30

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

Question 31

when can diplopia charts be useful

Answer 31

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

Question 32

how to interpret diplopia

Answer 32

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

Question 33

how do you interpret a hess chart

Answer 33

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

Question 34

what things do you have to consider with a hess chart

Answer 34

- 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

Question 35

how is the size of deviation on a hess chart measured

Answer 35

1 square = 5 degrees of deviation

Question 36

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

Answer 36

- underaction of the left lateral rectus overaction of the right medial rectus overaction of left medial rectus underaction of the right medial rectus

Question 37

acronym to remember pattern of muscle sequelae

Answer 37

People Underestimate Older ChildrenS Skills Obviously It Always Inevitably Creates Arguments

Question 38

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

Answer 38

- underaction of the left medial rectus overaction of the right lateral rectus overaction of the left lateral rectus underaction of the right medial rectus

Question 39

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

Answer 39

underaction of the right superior oblique overaction of the left inferior rectus overaction of the right inferior oblique underaction of the left superior rectus

Question 40

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

Answer 40

underaction of the right superior rectus overaction of the left inferior oblique overaction of the right inferior rectus underaction of the left superior oblique