dunes retraction syndrome

Question 1

what are the features of duanes

Answer 1

congenital (case reports) but rare

limited abduction

limited adduction common though may not be present

retraction of globe and narrowing of peripheral fissure on adduction

can be unilateral or bilateral

Question 2

what happens when you widen the palpebral fissure

Answer 2

limited adduction when the palpebral fissure is widened

bsv in primary position

Question 3

what globe changes happen in duanes

Answer 3

retraction of the globe

protrusion of the globe

Question 4

what are other features of duanes

Answer 4

possible features

ahp - usually face turn to achieve bsv

updrift or downdraft on adduction

defective convergence

positive force duction test (dependent on ateiology and duration)

unilateral more common in females

bilateral - more common in males -

Question 5

what are the 3 types of browns

Answer 5

type a - marked limitation of abduction but less adduction

type b - limited abduction but normal adduction

type c - limited adduction which exceeds the limitation of abduction

Question 6

what are the mri findings for each type of duanes

Answer 6

Type 1 absence of VIth nerve, hypoplasia of SO muscle and aberrant innervation of LR by extra branch of IIIrd nerve
Type 2 dual innervation of LR from both the VIth and an aberrant IIIrd nerve branch and hypoplasia of SO muscle
Type 3 hypoplasia of IIIrd nerve, the MR, IR & IO muscles (one patient)
(Xia et al 2014)

Question 7

what are the associations between duanes and splitting of the lateral rectus

Answer 7

Splitting caused by incomplete fusion of the superior and inferior mesodermal complexes

Speculation that upper part innervated normally by 6th nerve and lower part receives branch of inferior division 3rd nerve

2/5 pts with DRS showed split LR

Question 8

how are supra nuclear and infranuclear defects associated with drs

Answer 8

Findings at autopsy:1) Absence of cell bodies of 6th nerve
2) Absence of nerve itself

Supply to LR from inferior division 3rd nerve
Fibrosis present where LR has poor innervation
Association with other conditions:
Marcus Gunn, Crocodile tears and unilateral abducting nystagmus

Combination of absence of nerve and absence of innervation - Mechanical Fibotic syndromes to Congenital Cranial Dysinnervation discorders (CCDD) of which Duane’s is the most common, followed by CFEOM

Question 9

is their a heditary aspect to duanes retraction syndrome

Answer 9

reports of families and evidence of a genetic basis

large cohorts of ccdd in some parts of the world e.g. Saudi Arabia

25/110 affected in one extended family

monozygotic twins concordant and discordant for duanes reported

Question 10

is their a heditary aspect to duanes retraction syndrome

Answer 10

reports of families and evidence of a genetic basis

large cohorts of ccdd in some parts of the world e.g. Saudi Arabia

25/110 affected in one extended family

monozygotic twins concordant and discordant for duanes reported

Question 11

is their a genetic basis for duanes

Answer 11

DURS1 – location Chr 8q13 (Vicent et al, 1994)
Multiple patients mapped to this gene.
Complexity of cytogenetic causes.
DURS2 – CHN1 gene – Chr 2q31.1 (Miyake et al, 2008)
Autosomal Dominant
MRI studies show absent/hypoplasia of 6th, small ON and small 3rd Nerve and hypoplasia SO muscle
3rd Nerve dysinnervation of the LR is secondary due to failue of innervation by the 6th nerve
Duanes Type 1 and 3 observed

Question 12

what genes are involved in the development of duanes

Answer 12

DURS3 – MAFB gene – Chr 20q12 (Park et al, 2016)
Autosomal Dominant
Occurs with or without hearing loss
Mouse and embyro models reveal MAFB is expressed where the abducen nerve develops and in the absent of the nerve aberrant innervation of the LR by fibres from the Ocular Nerve
Duanes Type 1 and 3 observed

Duane-Radial Ray Syndrome (DRRS/Okihiro syndrome) – SALL4 Gene Chr:20q13.2 (Al-Baradie et al, 2002)
Autosomal Domiant
DURS with hand and upper extremities
Variable expression of cardiac, renal, hearing and vertebral abnormalities in addition to DURS

HOXA1 Chr: 7p15.2 (Tischfield et al, 2005)
Bosley-Salih-Alorainy Syndrome
Athabaskan brainstem dysgenesis syndrome

Question 13

what are some possible reasons for retraction of the globe on adduction and narrowing of palpebral fissures

Answer 13

Retraction of the globe on adduction

Inelasticity of LR
Co-contraction MR and LR
Anomalous insertion MR
SR and IR try to help to adduct

Narrowing of palpebral fissure
Mechanical ptosis due to retraction of globe
Decrease in electrical activity of levator

Question 14

what are reasons for profusion and widening of palpebral fissure and updrift or downdraft on adduction

Answer 14

profusion and widening of palpebral fissure

Inhibition MR
Co-relaxation
SO and IO trying to aid abduction
Mechanical effect of lid

updrift or downdraft on adduction

Question 15

what are the possible reasons for a or v or x patterns

Answer 15

changes in innervation to lateral rectus on elevation or depression

Question 16

how likely is acquired duanes retraction syndrome

Answer 16

very rare

tumour in 4th wall ventricle (case report)

report of skull base meningioma

differential diagnosis

traumna

mechanical cause e..g thyroid eye disease , myositis , neoplasms

neurogenic palsies

congenital esotropia

Question 17

how would you manage duanes retraction syndrome

Answer 17

correct refractive error

treat any amblyopia

observation

prisms

botulinum toxin

surgery if marked ahp

decompensating

unaaccpetbale appearance of deviation of retraction

diplopia which is troublesome

Question 18

how is botulinum toxin used diagnostically

Answer 18

To ascertain if likely to reduce AHP and or increase field of BSV to reduce symptoms

Question 19

how is botulinum toxin used therapeutically

Answer 19

As results of surgery can be unpredictable some patients choose to continue with maintenance BT (14%)
Some patients (53%) demonstrate a long term reduction in the deviation (Dawson et al 2010)

Question 20

when is surgery indicated for duanes

Answer 20

Based on:
Deviation – ET vs XT
Size of AHP
Severity of Globe retraction and overshoots
Degree of limitations
FDT
Extent of Field of BSV

Question 21

what surgery is indicated if they have esotropia In primary position

Answer 21

MR recession of affected eye
Large contralateral recession of unaffected eye (-2 or better) caution with large co-contraction
Large deviation or bilateral duanes, bilateral MR recession
With large globe retraction – LR recess
Transposition of vertical recti muscles to LR, with or without augmentation sutures and adjustable (Britt et al 2004, Snir et al 2005)

Question 22

what surgery is indicated if they have a exotropia in primary position

Answer 22

Exotropia in primary position
Unilateral LR recession (XT common in type 3/2)
Bilateral LR recession in large deviation
Vertical recti transposition can also be performed
Synergistic divergence – no definite surgical procedure

Question 23

how would you surgically correct globe retraction and overshoots with surgery

Answer 23

Globe retraction
Mild globe reaction, can be MR recess and resection of LR, if severe recess both MR and LR
Overshoots
Y splitting of the LR with or without recessions (Rao et al, 2003)
Each half balances the other
IO myectomy with or without horizontal recti recess

Question 24

if someone has duanes estortopia and there globe retraction is. more than 50 % then what surgery is perfumed

Answer 24

lateral rectus recession

Question 25

if someone has duanes and they have a ahp and a primary positon angle is more than 20 degrees

Answer 25

medial rectus recession

vertical recti transposition and foster suture

if it less than or equal to 20 degrees than medial rectus recession and vertical recti transposition

Question 26

if someone has a up or down shoot what surgical procedure will be done

Answer 26

mechanical

lateral rectus recession and y split

innervational - vertical rectus recession