Duanes Retraction Syndrome

Question 1

DRS

Answer 1

A congenital disorder involving abnormal eye movement and head posture but very often not detected until child slightly older, when defective eye movement or an obvious abnormal head posture brings it to attention. Females > males

Question 2

DRS Aetiology :

Answer 2

Innervation of lateral rectus by extra branches of the IIIN in place of absent or deficient VIN fibres.
Occasional abscent CN 6 nucleus.
Genetic component.
Embryological Development:

Question 3

DRS ASSOCIATED SYNDROME

Answer 3

Goldenhars syndromes: t can cause incomplete development of bones in the face, affecting the ears, nose, soft palate, lips, and jaw. Usually, this happens on one side of the face only.

Question 4

DIFFERENTIATION DUANE’S + 6TH

Answer 4

Duanes: BSV in PP, No Diplopia, Ductions = Versions, Congenital, Features on Globe Restrictions with narrowing and widening of palberbral apertures

6th Nerve:
Esotropia > in distance , Diplopia , Ductions > Versions , Acquired , Most likely vascualr in older pateitns an urgent referral in younger patient , No palberbal changes

Question 4

DRS Features

Answer 4

Eye retracts within the globe in certain positions of gaze. Mechanical not neurogenic.
Type I: Marked limitation of abduction and widening of the palpebral fissure due to lack of innervation to the LR and normal or slight limitation of adduction with narrowing of the palpebral fissure and retraction of the globe due to maximum innervation of the LR when the eye is adducted (due to co-contraction of MR and LR)
Type II: Limitation of adduction by co-contraction of the horizontal recti on attempted adduction with normal or slightly reduced abduction
Type III: Limitation of both adduction and abduction.

Limitation of Horizontal Eye Movement:
Moderate to marked limitation of abduction.
Varying levels of restriction of adduction.
Abnormal Head Posture:
Esotropia: Common in patients.
Head Turn: Often to the affected side for esotropia and to the unaffected side for exotropia.
Manifest Strabismus:
Usually Esotropia: Often with marked incomitance in unilateral and bilateral cases.
Retraction of the Globe on Adduction:
Narrowing of Palpebral Fissure: Due to co-contraction of horizontal rectus muscles.
Up-shoot and Down-shoot on Adduction:
Mechanical or Innervational: Different causes and symptoms.
Binocular Single Vision:
Reduced or Absent Stereoacuity: Common.
Absence of Diplopia: Although it may be elicited during testing.
Poor Convergence: Sometimes present, especially with significant limitation of adduction.

Question 5

DRS Investigation Aims:

Answer 5

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 6

DRS Clinical Tests:

Answer 6

+ Birth history (prematurity, birth weight, development)
+ Family history (developmental anomalies, Duane’s)
+ General health (developmental anomalies)
+ Signs/symptoms (diplopia, strabismus, AHP, abnormal OM)

Refraction, fundus and media check:
+ Worth correcting small amounts of hypermetropia if esodeviation present
+ Fundus check to ensure no papilledema
+ Media check for congenital cataracts, hyaloid artery remnants, pupillary abnormalities etc.

Observe your patient carefully for facial anomalies (low set of ears + neck webbing)

VA – although amblyopia rare due to nature of condition

CT – strabismus surprisingly uncommon
+ Type I: Esotropia/phoria or orthotropic
+ Type II: Exotropia/phoria or orthotropic
+ Type III: Pretty much anything but most likely orthotropic
(Do CT with and without AHP)
May or may not be able to take up fixation to midline.
Eso > distance than near + to side of abnormality

OM – Look for all the signs, not all may be present.
+ Motility findings determine the type of Duane’s present.
Ductions = Versions (6th NP ductions > versions)

Convergence – may be reduced due to restriction

BSV:
+ Horizontal fusional amplitudes: Base in and base out
+ Stereoacuity

Measure angle of deviation (with and without AHP):
+ PCT if they can take up fixation to the midline
+ If they can’t, use Krimsky’s test (pen torch fixation target and equalise corneal reflections through prism), synoptophore, HESS chart + Big secondary deviation when fixating with unaffected eye

Question 7

DRS mx non-surgical

Answer 7

Aims: Restore or strengthen BV, Treat amblyopia if present, Reduce AHP if uncomfortable or musculoskeletal changes occurring
Surgical options

Management - Amblyopia
* 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

Management - Alignment
* Usually best to leave well alone – often well controlled with head movements and slight AHP that doesn’t cause any discomfort
* Practical advice, e.g. Positioning of objects away from affected side, can help with everyday life
* If decompensating despite use of AHP or AHP is uncomfortable…
* Try Fresnel prism to reduce deviation in primary position (blurs VA dependent on strength – if helpful then surgery will make a difference and better long-term option) + use yoke prism to reduce head posture
* + If all that fails, refer to discuss surgical options

Question 8

DRS sx

Answer 8

Muslce function cannot be restored – have to compensate instead.
* + Up/downshoots: Y-split LR muscle + recess it
* + Retraction: Recess MR as well as LR, or disinsert LR and fix to orbital wall
* + Primary position deviation: Recess LR if exotropic, MR if esotropic
* + If recessions don’t improve motility, transposition of vertical recti can replace LR function (more common in bilateral Duane’s