Duane's & Brown's Syndrome Flashcards
What is an incomitant deviation?
The angle of the deviation changes in different directions of gaze
What are the mechanical characteristics of incomitant deviations
FUG-LEG
- Forced Duction Test reveals limitation
- Up or down shoots
- Globe retraction
- Limitation is opposite the positions
- Equal limitation on duction and version
- Doesn’t have full muscle sequelae
What is the Forced Duction Test?
The eye is moved forcefully with forceps in different gazes, if there is a full movement then it is NOT a mechanical deviation
What are up-shoots or down-shoots?
Occurs due to tight lateral rectus muscle attached to the globe which causes the muscle to slip off the globe when the eye is adducting
How are up-shoots and down-shoots different from up-drift and down-drift?
An up drift is when theres a slow progression upwards but upshoots go horizontal, horiz, vertical )
What is globe retraction?
Eye physically pulled back into the orbit
What does Limitation is opposite the positions mean?
Eg. adduction and abduction
What does equal limitation on duction and version
A duction is an eye movement involving only one eye. A version involves both eyes.
On ocular motility ,one eye and both eyes. have same amount of movement
What does it mean that it Doesn’t have full muscle sequelae ?
Only has over action of cotralateral synergist?
What is Duane’s Retraction Syndrome?
A congenital condition, people are born with it (but may be identified later in life)
It is an abnormal horizontal eye movement in either direction,
Which gender is duane’s more common in
females
Does duane’s affect one eye or both eyes?
Unilateral is most common but can be bilateral and symmetric in 20%
What is a risk factor for duane’s
Family history
What is duane’s caused by?
Neurogenic-relating to nerves
Myogenic-relating to muscle tissues
Which cranial nerve supplies the lateral rectus?
6th
What cranial nerve supplies the medial rectus?
3rd
Describe the neurogenic cause of duane’s
Abnormal innervation of the LR- due to an absent or hypoplastic 6th nerve
What does hypoplastic mean?
Underdeveloped
What happens if the 6th nerve is absent or is underdeveloped ?
If ABSENT= then LR will be supplied by branches of 3rd nerve
If UNDERDEVELOPED= If underdeveloped- then the LR will be supplied by both 3rd and 6th nerve
What problem arises when the 3rd nerve starts to supply the LR?
3rd usually supplies MR but if it is also supplying LR, u get co-contraction (simultaneous contraction of agonist and antag) = limitation of horizontal eye in either direction
Describe. the myogenic cause of duanes
Fibrosis or inelasticity of the LR & MR muscle inserts abnormally
LESS COMMON, people usually go with the neurogenic theory
What are the 4 clinical signs of duane’s syndrome?
- Complete or partial absence of abduction (partial is less common)
- Due to co-contraction there will also be partial loss off adduction (sometimes)
- Deviation in primary position-=Eso/Ex/orthophoria (if problem is mainly abduction eye becomes esotropic and if it’s mainly adduction then exotropic)
-Compensatory head posture (CHP)
Face turn to the affected side in the distance- ESO
Face turn to the unaffected side for near -EXO