Duane’s And Browns Syndrome - Miriam Flashcards
What are characteristics of mechanical anomalies?
- Limited movement on forced duction test
- Globe retraction
- Up-shoots and down-shoots
- Equal limitation on duction and version
- Limitation opposite positions (abd and add)
- Does not have 3rd or 4th muscle sequeale
What is the forced duction test?
A surgically done test to see if the eye muscles are working well and there are not restrictions/ mechanical anomalies
Describe what a muscles sequelae is ?
u/a of a muscle (e.g right SR)
o/a of contralateral synergist (e.g left IO)
o/a of ipsilateral antagonist (e.g right IR)
u/a of contralateral antagonist (e.g left SO)
*if all this occurs then it is concomitant
What is Duane’s retraction syndrome?
A classed congenital cranial dysinnervation disorder (CCDD)
- non-progressive
-abnormalities are caused from defects cranial nerve
- involves abnormal horizontal eye movements
- abnormal branch of the 3rd nerve innervating the lateral rectus muscle as a result of hypoplasia or aplasia of the 6th nerve
What are epidemiology of Duane’s?
- Congential
- 1/1000 have it
- F(60%)>M (40%)
- Genetic link (2-5%)
- Abormal H eye movement. Unilateral more common.
What is the aetiology of Duane’s? (There are two causes)
Neurogenic Theory - LR is innervated by 6th AND 3rd nerve or by the 3rd nerve ONLY (due to absent or underdeveloped 6th nerve)
OR
Myogenic fibrosis (thickening of muscle) or inelasticity of the LR & MR muscle inserts abnormally
What are clinical signs of Duane’s?(there is a lot )
- Complete or less often partial absence of abduction
- Partial loss of adduction. (this is becasue of co-contraction of the 3rd nerve and the 6th nerve)
- Deviations in PP. Abduction problem = eso. Adduction problem = exo
- CHP
- Poor convergence
- A or V pattern
- Reduce BV (they may have suppression)
- Up/down shoots
- Globe retraction on adduction + narrowing of palpebral aperture (induced ptosis)
- Widening of palpebral aperture on abduction attempted
If someone had their face turned towards affected side, at distance will they have and eso or exo deviation?
ESO ; to get away from abduction
If someone had their face turned to unaffected side, at near would they have an eso or exo deviation?
Exo ; to get away from aduction
What are the three classifications of Duane’s (Browns method using OM)?
Type A
Type B
Type C
What does Type A mean + what deviation would they have?
Loss of aBduction> aDduction
eso
What is Type B + what deviation would they have?
Loss of aBduction only
Eso
What is Type C + what deviation would they have ?
Loss of aDduction> aBduction
Exo
What are the three classifications of Duane’s (using Huber’s method of electrophysiology EMG)?
Type I
Type II
Type III
What is Type I + what deviation would they have + what browns classification does it correspond to?
Max innervation LR in aDduction, eso, Type B ABd only
What is Type II + what deviation would they have + what browns classification does it correspond to ?
Co-contraction of the MR and LR on aDduction, Exo, Type C ADd>ABd
What is type III + what deviation would they have + what browns classification does it correspond to?
Co-contraction of the MR and LR on aDduction and loss of innervation to LR on ABduction, ESO, type A ABd> ADd
What type of Duane’s is the most common and what CHP would they have?
Duane’s type A/ type III
Face towards affected side
What CHP would a type B/ type I have?
Face turned towards affected side
What CHP would a Type C / type II have and what other issue may they have?
Face turned to unaffected side + could have poor convergence
What are other associated developmental ocular abnormalities with Duane’s?
Coloboma
Heterochromia
Lens opacities
Microphthalmos
Persistent pupillary membrane
Crocodile tears
What are some systematic associations with Duane’s?
Goldenhar’s syndrome
Klippel-Feil syndrome
Other syndromes
Abnormal ear formation
Deafness
Syndactyly
Thalidomide syndrome (those no arm kids by the pool)
How would you investigate Duane’s?
- FH
- VA
- CT
- OM
- BSV (PFR/Stereo)
- Measurement (Hess, field of BSV, PCT)
- Refraction
- Fundus/ media
- (you may want to do a forced duction test too)
After diagnosis, what should happen?
General physical examination, evaluation of other family member
How is Duane’s managed in under 8 year olds?
1.Non-urgent referral,
check ocular/ systemic association,
ensure BSV is maintened,
treat amb,
give specs,
treat if severe
How are over 8 year olds with Duane’s managed?
- Can refer, check ocular/systemic associations
treat if severe which will improve symptoms + cosmesis
What treatment is included in management of Duane’s?
- Refraction if significant,
2.use of CHP,
3.occlusion for amb,
4.prisms,
5.surgery
6.botulinum Toxin
Which CN innervates the lateral rectus?
VI
If the VIth nerve is underdeveloped, which nerve innervates the LR as a secondary dysinnervation?
IIIrd
Similarly, if VIth is absent then LR will be innervated by III nerve only
What is the aetiology of Browns syndrome?
Congenital abnormality of SO muscle/ tendon
(Short tendon sheath, short tendon, inelastic muscle, orbital adhesions)
Or
Acquired due to Trochlear damage or SO tendon abnormalities
What are some examples how Trochlear damage can occur?
Traumatic event such as a vehicle accident, iatrogenic, inflammatory, orbital masses
What are some causes of SO tendon abnormalities?
Inflammatory, SO tendon cyst, iatrogenic
What does iatrogenic mean?
Caused by medical examination or treatment
Which palsy is browns similar to?
IO palsy as it is only mechanical
Why cant some with Brown’s elevate their eyes?
When the eye is aDducted at 51 degrees it becomes a pure elevator, agonist IO contracts producing elevation but the antagonist SO is unable to relax so there is no elevation
What symptoms are associated with Brown’s?
- Sporadic
- Pain/ discomfort
- Diplopia
- CHP with their chin/ head up
- Unable to elevate
- Uni lateral (in 90% of cases)
What are clinical signs of browns syndrome?
- Limitation of elevation in aDduction with elevation
- Down drift of affected eye
- O/a of contralateral synergist
- A or v pattern
- Forced duction- restricted in elevation in adduction
- Chin elevation
- Head tilt towards affected side
- Face turn towards normal side
- Straight in PP
What are treatment options for early onset Brown’s?
No treatment, less problematic as grow older because dont need to look up as much
What is the management for under 8s with Brown’s?
Non-urgent referral to confirm binocularly stable + monitor
What are treatment options for over 8s with Brown’s?
No need to refer if binocularly stable, non-urgent referral if symptomatic
What are treatment options for acquired Brown’s?
Refer and treat pathology, steroid injection, occasionally surgery
What is the acutal problem with browns?
The superior oblique muscle cannot relax. (it is able to contract just not relax)
Because the superior oblique muscle can contract can the eye look down?
Yes
what is happening then with the muscles with elevation?
The inferior rectus is contracting but the superior oblique cannot relax, which is causing problems
What would the hess chart look like?
