21 - noncomitant deviations

What are the most common causes of an incomitant deviation in an adult?

trauma

vascular

neoplasm

What are the most common causes of a incomitant deviation in a kid?

congenital

trauma

viral

what does paralysis or palsy mean? paralytic?

paralysis or palsy: complete loss of impairment of motor function

paralytic affected with or pertaining to paralysis

what does paresis mean? paretic?

paresis: slight or incomplete paralysis

paretic: pertaining to or affected with paresis

paretic vs non-paretic strabismus onset?

paretic: sudden

nonparetic: gradual

paretic vs non-paretic strabismus age of onset?

paretic: any

nonparetic: during childhood

paretic vs non-paretic strabismus hx of head trauma?

paretic: common

nonparetic: uncommon

paretic vs non-paretic strabismus comitancy?

paretic: noncomitant

nonparetic: comitant

paretic vs non-paretic strabismus head posture?

paretic: abnormal

nonparetic: usually normal

paretic vs non-paretic strabismus diplopia?

paretic: common

nonparetic: uncommon

paretic vs non-paretic strabismus neurologic/systemic disease?

paretic: may be present

nonparetic: usually absent

what is dissociated vertical deviation (DVD)?

each eye moves up under the cover and moves down as uncovered → appears to be a bilateral hyper deviation bc no hypo deviation when fixation is switched

what test reveals latent DVD?

on CT (dissociated) → most common

what is manifest DVD?

eye drifts up spontaneously (when tired or daydreaming)

is DVD symmetrical?

commonly asymmetrical → one eye comes down more

what age does DVD occur?

before 3

what other disorder is DVD associated with?

infantile esotropia

what is a differential diagnosis for DVD?

bilateral OA IO

what do OA inferior obliques look like on version testing?

over elevation in adduction →

-L hyper on R gaze

-R hyper on L gaze

is OA inferior obliques typically unilateral or bilateral?

bilateral

what is the difference between primary and secondary OA inferior obliques?

primary: not associated with SO palsy

secondary: associated with SO palsy or contralateral SR palsy

what are the characteristics of secondary OA of IO d/t paretic SO?

1. hyper in primary gaze

2. head tilt

3. (+) 3 step test

4. cyclotorsion

what are the differential diagnosis for primary OA inferior oblique?

1. DVD

2. secondary OA of IO d/t paretic SO or contralateral SR paresis

3. duane retraction syndrome

4. contralateral IR muscle restriction (orbital floor fracture)

5. skew deviation

6. craniofacial syndromes

what is most to least common pattern deviation?

V-eso (most)

A-eso

V-exo

A-exo

1. v patterns

2. eso > exo

what is the etiology of V-pattern strabismus?

UA of SO

secondary OA of IO

how does OA of IO cause a V pattern?

in up gaze → horizontal action of IO is abduction

what is the etiology of A pattern strabismus?

UA of IO

secondary OA of SO

how does OA of SO cause an A pattern?

in down gaze → horizontal action of SO is abduction

in pattern deviations, if obliques are normal what do you do?

look at horizontal and vertical muscles as the cause

which pattern deviation are most symptomatic?

A pattern exo

V pattern eso

most and least common

what is a common associated finding of V pattern ET?

chin depression

maybe ET cancels out XT in upgaze?

what must you rule out when you see a V pattern ET?

bilateral SO palsy

what are common associated findings with V pattern XT?

chin elevation

may be due to OA of IO

what are common associated findings with A pattern ET?

chin elevation

may be due to OA of SO

maybe ET cancels out XT during downgaze

what are common associated findings with A pattern XT?

chin depression

OA of SO

what is the pathway of spread of comitance?

1. weakness of paretic muscle

2. OA of direct antagonist

3. contracture of direct antagonist

4. deviation spreads into all DAFs

5. becomes increasingly comitant

What is browns syndrome (SO tendon sheath syndrome)?

restricted elevation of adducted eye due to SO tendon restriction

What are the signs that indicate browns syndrome?

1. chin elevation

2. no OA of antagonist SO

3. (+) forced duction test

What normal findings are seen in browns syndrome?

1. normal elevation in primary gaze and abduction

2. ductions=versions

What is the main ways to differentiate between browns syndrome and a IO paresis?

Browns: positive forced duction test

IO paresis: negative forced duction

what are the differential diagnosis for brown's syndrome?

1. inferior oblique paresis

2. orbital floor fracture

3. thyroid orbitopathy

what eye does Duanes syndrome typically affect?

left eye

What causes Duanes syndrome?

agenesis of CN VI → LR and MR to be innervated by inferior division of CN III

What is Duanes syndrome?

co-contraction of MR and LR on attempted adduction of involved eye → that causes retraction of the globe

What are the signs of Duanes syndrome?

1. retraction of globe/narrowing of palpebral fissure on adduction

2. widening of palpebral fissure of abduction

3. may have up or downshift on adduction

What is Type 1 Duanes syndrome according to the Huber classification ?

limitation of abduction

*most common*

What is Type 2 Duanes syndrome according to the Huber classification?

limitation of adduction

What is type 3 Duanes syndrome according to the Huber classification?

limitation of both abduction and adduction

what is the differential diagnosis for duane's?

CN VI palsy

who does paretic deviations mainly affect?

90% >19 years

What are the main causes of paretic deviations?

1. undetermined

2. trauma

3. vascular

4. other

5. neoplasm

6. aneurysm

what are signs of complete CN III paresis?

1. exotropia

2. hypotropia

3. intorsion

4. ptosis

5. fixed/dilated pupil

what is part of the superior and inferior division of CN III?

superior → SR and levator

inferior → MR, IR, IO, iris sphincter, CB

what are common causes of CN III paresis in adults?

1. vascular/ischemic

2. aneurysm

3. undetermined

what are common causes of CN III paresis in children?

1. congenital

2. trauma

3. tumor

what is the most common cause of vertical deviation?

CN IV paresis

what are the signs of CN IV paresis?

1. hyper deviation of affected eye

2. unable to depress eye with adduction

3. facial asymmetry (head tilt)

4. SOTO → superior oblique tilt opposite

which CN paresis is least indicative of serious disease?

CN IV paresis

What are the main signs of a CN VI paresis?

1. ET in primary gaze

2. limited abduction

3. face turn toward affected muscle

what are the common causes of CN VI paresis in adults?

1. undetermined

2. neoplasm

3. trauma

4. vascular

what are the common causes of CN VI paresis in children?

1. neoplasm

2. trauma

3. elevated ICP

what is the most common cause of multiple nerve palsy?

neoplasm

where would the cause of multiple nerve palsies be located?

cavernous sinus or superior orbital fissure where the 3 nerves are in close proximity