Week 4 - Duanes

Question 1

What is Duanes syndrome and its aetiology?

Answer 1

• Congenital Disorder but very often not detected until the child is slightly older

Aetiology:-
Innervation of lateral rectus by extra branches of the IIIN in place of absent or deficient VIN fibres.
• Genetic components

Question 2

What are the different types of Duanes?

Answer 2

• Type 1:
- Limitation of Abduction
• Type 2:
- Limitation of Adduction
• Type 3:
- Limitation of Abduction and Adduction

Question 3

What are the classic features of Duane’s?

Answer 3

• Mechanical Limitation of Abduction or
Adduction
• Widening of Palpebral Aperture on attempted Abduction
•Narrowing of the Papebral Aperture on
Adduction
• Globe Retraction on Adduction

Question 4

What is 6th nerve palsy?

Answer 4

• Most Common Acquired Cranial Nerve Palsy
• Over 50 aetiology most likely Vascular
• Neurgenic therefore Ductions are greater than Versions

Question 5

What are the 6th nerve clinical features?

Answer 5

•Eso deviation that is greater on Distance fixation and to the side of the lesion
• Neurogenic weakness of abduction
• Ductions will be larger than versions
• Patient will have diplopia which is wider apart in the distance and far distance
› Look for Papilloedema esp in younger patients

Question 6

What are some clinical signs of Duanes syndrome?

Answer 6

• Restricted motility, different for all 3 types
• Retraction : in primary position or attempted adduction
• Palpebral fissure changes : due to globe retraction (widens abd narrow add)
• Sudden up/downshoots: caused by slippage of globe under LR muscle due to tension
• Sudden Y patterns

Question 7

What is synergistic divergence in Duans?

Answer 7

• Abduction occurs when attempting to adduct the eye
• Cosmetically poor but rare (also difficult to treat)
• Caused by innervation of LR by IlIrd nerve and concurrent poor innervation of MR by same nerve
• Causes LR to act more than the MR when attempting to adduct

Question 8

What are the aims when investigating Duanes syndrome?

Answer 8

• Diagnose type of Duane’s Syndrome
• Document all motility defects and any other signs
• Establish level of binocular vision
• Gather clinical information to determine management plan

Question 9

What would be found on clinical tests - LEES?

Answer 9

• Squashed field and overaction of contralateral synergist muscles (i.e. Mechanical restriction)
• Up and downdrifts on adduction
• May need to tape lid up when doing adducted positions due to retraction

Question 10

How is Duanes syndrome managed?

Answer 10

• Aims:
+ Refer or not?
+ Restore or strengthen BV
+ Treat amblyopia if present
+ Reduce AHP if uncomfortable or musculoskeletal changes occurring

Question 11

When is Duanes syndrome referred?

Answer 11

• If first time being diagnosed, refer to hospital for screening for developmental anomalies

• If poor cosmesis, binocular function compromised or uncomfortable AH and conservative management options fail, refer to discuss surgical options

• Otherwise can manage within practice

Question 12

How is Amblyopia with Duanes syndrome managed?

Answer 12

• Amblyopia infrequent due to adoption of AHP to preserve BV
• If amblyopia present, treat with short doses of occlusion spaced throughout the day to reduce chance that deviation will decompensate

Question 13

How can Alignment be managed?

Answer 13

• Usually best to leave alone, often well controlled with head movements, AHP doesnt cause discomfort

•. Practical advice can be given - positing objects away from affected side
• If decompensating despite use of AHP/discomfort…
- Fresnel prism to reduce deviation primary gaze
- yolk prisms can be used
- can refer to surgical options