Duanes Retraction syndrome Flashcards
Features of Duanes
- Congenital (Case reports of acquired but rare)
- Limited abduction
- Limited adduction common though may not be present
- Retraction of the globe and narrowing of the palpebral fissure on adduction
- Protrusion of the globe and widening of the palpebral fissure on abduction
- Can be unilateral or bilateral
Further features
Limited abduction
Narrowing palpebral fissures
BSV in pp
LR and MR affected restrictions in horizontal gaze and globe retraction
What can you see in the side view in Duane’s
Often easiest to see Retraction & Protrusion from the side view
Globe retraction
Possible features
- AHP – usually face turn to achieve BSV and can fuse, updrift or down drift on adduction, they learn to suppress double vision and often see them when decompensating, defective convergence, positive FDT (dependant on aetiology and duration)- more likely in longer fibrosis, unilateral – more common in females, bilateral - more common in males, often asymmetrical so look for subtle limitations in other eye
Fibroses muscle
causes restriction
Fibrosis happens because muscle is inactive
Epidemiology of duanes
Occurs in around 1-5% of strabismus
1 in 1,000 – 1 in 10,000 of population
May be unilateral or bilateral (10-24%)
80% cases are sporadic (Kirkham 1970)
Left eye (74%) and females (60%) more commonly affected (Mohan et al 2008)
Common in Saudi arabia and other Asian cultures
Duanes IS…
MECHANICAL
Theories of duanes
-Initially caused by a tight LR, described as an inelastic band
-Congenital anomalous of the LR, tight due to nuclear aplasia or birth truama
-Dual insertion – MR was rotated and inserted posteriorly, used to explain globe retraction
Surgery
After surgical procedures in Duane’s patients found these theories to be unlikely
Innervation theories
- Breinin (1956) measured electrical potentials generated by the muscles at various potentials
- No LR activity in attempted abduction but maximum LR generated in adduction, possible reason for co-contraction and globe retraction
- Strachan and Brown – paradoxical innervations observed using electromyography which revealed variable LR activity but MR consistent
- Occasionally synergistic innervation between MR and vertical recti/obliques
Reduced saccadic velocities showed reduced
Classifying Duanes
Type A-C
Type 1-3
Duanes A-C Brown 1950
Classified based on Ocular Motility
Type A- Marked limitation of abduction and much less limitation of adduction
Type B- Limited abduction but normal adduction
Type C- Limited adduction which exceeds the limitation of abduction
Duanes 1-3 Huber 1974
Type 1, with limitation of abduction only - most common
Type 2, with limitation of adduction only
Type 3, with limitation of both ab- and adduction.
Type 4- Schliesser et al 2016:
- 19/179 (5%) Synergistic Divergence
- Exotropia in Primary position, AHP, Palpebral fissure changes
- Full to nearly full abduction with absent adduction, and simultaneous abduction when viewing unaffected side
- Cause? Requires further investigatioN
MRI findings
Each type of DRS has different MRI findings (11 Patients)
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)
Splitting of LR
*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
Okanobu et al (2009)
Supra nuclear/ infranuclear defect
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
Hereditary?
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 (Chung et al, 2000). Monozygotic twins – concordant (Dirani et al, 2006) and discordant (Smith and Cibis, 1996) for Duane’s reported
Genetic basis
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- seen in all family members
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
Reasons for reduction of globe on adduction
- Co-contraction MR and LR
- Inelasticity of LR
- Anomalous insertion MR
- SR and IR try to help to adduct
Reasons for narrowing palpebral fissure
- Mechanical ptosis due to retraction of globe
- Decrease in electrical activity of levator
Reasons for protrusion and widening palpebral fissures
- Inhibition MR
- Co-relaxation
- SO and IO trying to aid abduction
- Mechanical effect of lid
Reasons for updrift or downdrift on adduction
- Retracted eye more in line with the obliques
- Co-contraction of SR and/or IR with the LR
- Slippage of the LR up or down (‘Bridle’ effect)
Reasons for A V, X pattern
*Changes in innervation to LR on elevation or depression
Acquired duanes causes
Tumour in wall of 4th ventricle
(case report)
Report of skull base meningioma
Differential diagnosis of acquired Duanes
Trauma
Mechanical cause: e.g Thyroid eye disease; myositis; neoplasms
Neurogenic palsies
Congenital ET
Investigation
presentation, history and AHP
Presentation- Often within the first year of life but can be later and occasionally will present in adulthood
History- Particularly of Family History and Inheritance Pattern
AHP- Face turn to affected side if abduction greatest deficit. To unaffected side if limitation of adduction greatest
Further investigation
VA,CT, OMs
Visual Acuity- Good where BSV maintained, risk of amblyopia if manifest in pp
Cover Test- Often BSV in pp or with AHP, Esotropia if abduction most affected, Exotropia if adduction most affected
Ocular Movements- As described in features and classification note: Limitations and grade, Changes to palpebral fissure, Retraction / Protrusion, Upshoots / downshoots, Alphabet patterns
Type A,B,C
Type B- mechanical features restriction of adduction
Type C- restriction of abduction
Type A- adduction greater than abduction
Management of Duanes
Correct refractive error, treat amblyopia, observation, prisms, BT and surgery if Marked AHP
decompensating, unacceptable appearance of deviation or retraction, diplopia which is troublesome
Innervation to LR is…
unknown surgery on muscles known to innverate normally
Botox
Used to ascertain if likely to reduce AHP and or increase field of BSV to reduce symptoms.
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)
Surgery based on
- Deviation – ET vs XT
- Size of AHP
- Severity of Globe retraction and overshoots
- Degree of limitations
- FDT
- Extent of Field of BSV as central as possible less use of AHP
Surgery ET in pp
- 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)
Surgery XT in pp
- 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
Surgery globe retraction
Mild globe reaction, can be MR recess and resection of LR, if severe recess both MR and LR
Surgery for over shoots
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
