Lecture 10 Duane's and Brown's Flashcards
What are the characteristics of a mechanical anomaly?
-limitation of movement on forced duction test
-globe retraction
-up shoots and down shoots
-equal limitation on duction and version
-limitation in oppositive positions (adduction and abduction of same eye)
-only 2nd step of muscle sequelae
What is Duane’s retraction syndrome classes as?
What causes it?
Is it progressive?
What is the prevalence?
Is it unilateral or bilateral?
congenital cranial dysinnervation disorder (CCDD)
*Affects the cranial nerves
*Secondary dysinnervation (one of the EOM is innervated by a cranial nerve that does not normally innervate it)
genetic link 2-5%
no
1/1000
females (60%) males (40%)
unilateral more common
bilateral in 20%
What is the etiology of Duane’s?
Neurogenic- absent or undeveloped 6th nerve.
*6th nerve supplies the lateral rectus. Px will have problems with abduction.
*If 6th nerve is slightly underdeveloped, LR will be innervated from underdeveloped 6th nerve and 3rd nerve.
*If 6th nerve is completely absent, LR is innervated by branches of 3rd nerve only
Myogenic
*Fibrosis or inelasticity of the LR and the MR muscle inserts abnormally
What are the clinical signs of Duane’s?
*Complete or less often partial absence of abduction
*Partial loss of adduction due to contraction from 6th and 3rd nerve.
*Deviation in primary position. (ESO/EXO/ORTHO)
*Compensatory head posture (CHP):
-ESO: will turn face towards affected side
-EXO: will turn face towards unaffected side.
*Poor convergence
*A or V pattern
*Reduced BSV but maintained by CHP
*Up or down-shoot on adduction
*Globe retraction on adduction
*narrowing of palpebral fissure on adduction (induced ptosis)
*widening of palpebral fissure on abduction
What is the classification of Duane’s based on OM?
Type A (most common)
* main problem is loss of abduction
* loss of abduction>adduction
* ESO
Type B
* loss of abduction only
* ESO
Type C
* main problem is loss of adduction
* loss of adduction>abduction
* EXO
What is the classification of Dunae’s based on EMG?
Type I
* Max innervation LR in adduction
* Type B brown’s
Type II
* Co-contraction of MR and LR on adduction
* Type C brown’s
Type III
* Co-contraction of MR and LR on adduction
* Loss of innervation to LR on abduction
* Type A brown’s
What congenital ocular associations are there with Duane’s?
*Coloboma
*Heterochromia
*Lens opacities
*Microphthalmos
*Persistent pupillary membrane
*Crocodile tears- px recovering facial palsy shed tears whilst eating or drinking.
Nerve fibres destined for a salivary gland are damaged and by mistake regrow into a tear gland.
What are the systemic associations of Duane’s?
*Goldenhar’s syndrome (incomplete or underdeveloped ear, nose, soft palate, lip and mandible)
*Klippel-Feil syndrome (fusion of vertebrae of the neck bones)
*Abnormal ear formation
*Deafness
*Syndactyly
*Cleft palate
*Thalidomide syndrome
What investigations should you do for Duane’s?
- Family history
- Ophthalmologic/orthoptic examination
- VA
- CHP
- CT with and without head posture
- OM- type of Duane’s
- BSV work up (PFR/Stereopsis)
- Measurement (Hess, Field of BSV, PCT)
- Refraction
- Fundus/media
- Optional forced duction testing and/or force generation testing.
- General physical examination
- presence of other associated syndromes
- Evaluation of family members within the first year of life
What is the management of Duane’s if px is under 8 years old?
*Check ocular/ systemic associations.
*Immediate referral if they break down into a tropia
*Ensure BSV is maintained
*Treat any amblyopia
*Give spectacles if necessary
What is the management if child is over 8 years old?
*Check ocular/ systemic associations
*Treat if severe
*Improve symptoms
*Improve cosmesis
*Deviation
CHP
*Can refer if need treatment due to large CHP, deviation, cosmesis
What does treatment for Duane’s include?
-Refraction
-Use of CHP
-Occlusion
-Prisms
-Surgery
-Botulinum Toxin
What is the etiology of Brown’s syndrome?
Congenital abnormality of SO muscle/tendon:
o Short tendon sheath
o Short tendon
o Inelastic muscle/tendon
o Orbital adhesions
Acquired:
Trochlear Damage
o Traumatic: Vehicle accident, dog bite, sports injury
o Iatrogenic: frontal sinus surgery, scleral buckle
o Inflammatory: chronic sinusitis, trocheilits, rheumatoid arthritis
o Orbital masses
SO tendon abnormalities
o Inflammatory
o SO tendon cyst
o Iatrogenic: SO tucking (during surgery for SO palsy)
Why does Browns syndrome occur?
What is the main problem?
*Problem is caused by SO (tendon or trochlear)
*SO can’t relax.
*Px can look down as SO will contract and IO will relax. No problem with depression.
*When px attempts elevation, the IO will contract but SO wont relax.
*IO palsy but mechanical in nature.
*Main problem is elevation, particularly in adduction
What are the symptoms for Brown’s syndrome?
*Congenital/most in infancy
*Sporadic
*Pain/discomfort
*Diplopia
*CHP (head/chin up). 1st thing parent notices.
*Unable to elevate eye.
*90% unilateral
