8.1.7 Manages patients presenting with an incomitant deviation. Flashcards
What is an incomitant deviation?
Angle of deviation changes depending on direction of gaze or which eye fixes. Congenital or acquired
Diplopia Questioning:
- Location - Is it side to side? One above the other or elsewhere? Can you describe it? At distance or near? Does it occur when both eyes are open?
- Onset - When did it start?
- Frequency - When do you normally notice it? During any particular task/time of day?
- Associated symptoms - HAs? Eyestrain? Photophobia? Pain?
- Treatment - Done anything to alleviate it?
3 Limitations of Eye Movement
- Neurogenic - infranuclear - lesion between nucleus & muscle
- 6th, 4th & 3rd nerve
- Mechanical - factors preventing muscle contraction or relaxation
- Brown’s (congenital)
- Duanes (congenital)
- TED (fibrotic, dry phase)
- Blow out fracture
- Myogenic - muscle problem
- Myasthenia gravis
- Myositis
- TED (wet phase)
Acquired causes of palsies
- Microvascular
- Trauma
- Aneurysm (3rd nerve)
- Space occupying lesion
- Congenital
- Increased ICP
Congenital Vs Acquired
On presentation
- Congenital complains of cosmesis, Vague diplopia onset if decompensating or none if suppressed so possible amblyopia, Unaware of longstanding AHP (old photos)
- Acquired very aware of diplopia & even knows when it started, Hates their new AHP
Motility
- Congenital has full muscle sequelae
- Acquired does not!! Unless longstanding
Binocular functions
- Congenital may have larger than expected vertical phoria due to larger than expected vertical fusional reserves (4th nerve) so smaller AHP than expected, Suppression normally present
- Acquired has normal fusion range & no suppression!
Hess
- Congenital has equal fields
- Acquired has field of affected being larger
Neurological Vs Mechanical
Deviation
- Normally marked in neuro (depending on palsy extent)
- Small in primary position of mechanical even if large limitations of motility
Diplopia
- Remains sames in other gazes besides 3rd & bilateral 4th nerve
- Sometimes reversed in mechanical e.g. reversed in up & then down gaze
AHP
- Common in longstanding neuro
- Rarer in mechanical
Motility
- Movement gradually fades away in direction of limitation in neuro. Better on ductions than versions
- Movement stops suddenly in mechanical. Ductions = Versions
Pain
- None in neuro
- Pain in acquired & sometimes in Brown’s
IOP
- Neuro has it same in all directions of gaze
- Mechanical has it higher when looking away from position of limitation
Forced duction test
- Full passive limitation in neuro
- Limited passive movements in mechanical
Abnormal Head Postures
- Face turn is for HORIZONTAL DEVIATIONS
- Turned toward position of BSV e.g. in 6th nerve palsy, head turn toward palsied side (generally speaking)
- If MR palsy or SO palsy then face turn towards unaffected side instead
- Head tilt is for VERTICAL DEVIATIONS
- Towards the lower eye! Left HyperT means tilt towards right side
- Chin up or down is for A OR V PATTERNS
- Chin down if deviation is in inferior gaze i.e. eyes elevated away from deviation
- Vice versa for chin up
- Used if px has ptosis (chin up)
- Differences between A eso & A exo alongside V eso & V exo
- A & V patterns are physiological normally. Pathological means meeting certain criteria:
- V pattern is 15 dioptres difference between angle on elevation & depression
- A pattern is 10 dioptres
- Pathological only managed with AHP or if marked AHP/sxs/cosmesis then surgery considered - surgery to reduce H deviation to restore control of elevated & depressed deviation
- Y, Upside down Y, X & diamond patterns as well
Learn how to do muscle sequalae
What is muscle sequalae
If a muscle of the eye is underacting, it will cause a domino effect & lead to other muscles not working as they’re supposed to
Must Consider Herring & Sherrington’s Laws’
- Herring - how muscles work together as a team e.g. the right LR works with the left MR
- Sherrington - how one muscle does the work & the other relaxes e.g. the right LR works & the right MR relaxes
How does the sequelae develop?:
- Primary under-acting muscle
- OA of the contra-lateral synergist
- OA of ipsilateral antagonist
- UA of contra-lateral antagonist
- EXAMPLE:
- Primary underacting muscle = Right LR
- Contralateral synergist = Left MR (overacts) (Herrings)
- Ipsilateral antagonist = Right MR (overacts) (Sherrings)
- Contra-lateral antagonist = Left LR (underacts) (Herrings)
- It ends full circle i.e. it starts with the right LR underacting & ends with the left LR underacting, so the same muscle but on the opposite side
Mechanical Palsies presentation
- 2 Main Mechanical Types: Brown’s & Duane’s
- Causes:
- Duanes - Mechanical; fibrosis or inelasticity of LR & that the MR inserts abnormally. Neurogenic; abnormal innervation of LR due to embryonic developmental issue at 4-8 weeks
- Brown’s - short or tight SO tendon sheath hence stiffer & less flexible. Acquired or congenital. Injury to trochlea, RA
- Motility:
- In Duane’s - the eye affected will Widen its fissure on moving towards the area of limitation & will Narrow its fissue when moving the opposite way
- Causes:
- H&S
- Ask same questions as in 8.1.4
- Cover Test:
- Brown’s —> HypoT in up gaze but normally no movement or little in primary
- Duane’s —> Normally EsoT in primary or next to nothing due to it being mechanical
- AHP:
- Brown’s - Chin up, tilt to lower eye (eye with Brown’s)
- Duane’s - Face turn
- Management for both:
- Correct refractive error
- Treat any amblyopia (unlikely)
- Possible surgery (unlikely) as condition controlled in PP but considered if marked AHP or poor cosmesis
Orbital Injuries
Blow out fracture - bony injury - most commonly to inferior or medial wall (thinnest). A break of one or more of the bones that surround the eye due to the force of the strike.
- Enophthalmos normally occurs - globe displaced backwards & down due to fracture in orbital floor
- Limitation of movement caused by entrapment of tissue - if medial wall fractured then medial rectus trapped for example making it difficult to move in the opposite direction
- Retraction of the globe - if eyes move towards opposite side of site of entrapment
- IR wall fracture causes hypoT & no normal elevation
- Symptoms - diplopia (possibly easier to deal with if eyes are straight in p.p), pain on eye movement, blurred vision (ON damage, RD etc)
-
Management - don’t always need surgery unless wanting to improve field of BSV if px has tropia or to get rid of fracture wall debris & put implant in place.
- Diplopia should improve with time & prism can be used if needed
Myogenic Palsies
Myasthenia Gravis:
- Cause - autoimmune condition where immune system attacks the communication system between the nerves & muscles making the muscles weaker & more tired
- Adult Version:
- 2 Types are Ocular or Generalised
- Ocular means only ocular signs from condition
- Generalised can mean ocular AND other muscle groups affected (must ask if respiratory involvement)
- Ocular Signs: REMEMBER: The more fatigued px is, the worse the symptoms! Everything is variable!
1. Ptosis - Unilateral or Bilateral & asymmetrical. If one side affected more than other, hold that side up with thumb & see if other eyelid goes down. Otherwise if bilateral ptosis, then hold either up & watch the other eyelid (enhanced ptosis)
2. Cogan’s Lid Twitch - Make px look down then straight & lid should overshoot upwards before settling due to excess acetylcholine release
3. Obicularis Weakness - Get px to close eyelids as tightly as possible. They can’t “bury” eyelashes very easily. Then try & open the lids & you should do it with ease.
4. Frontalis Overaction - One or both eyebrows look almost angry & curved in
5. Levator weakness - Prolonged upgaze will make the ptosis worse
6. Extra Ocular Movement - Can mimic any other neurogenic palsy (3rd, 4th, 6th), Supra nuclear or Inner nuclear problem - Tensolin test - anticholinesterase drug improves muscle weakeness for short period
- Ice pack test
- CT scan may show enlarged thymus (important lymphoid for immune system)
- Management:
- Urgent referral for CT scan, systemic steroids & monitoring under neurology
Myogenic Palsies
Thyroid: Description
-
Description - the thyroid, a gland on the lower part of your neck, produces T3 & T4 which are hormones that regulate your nerves, metabolism, energy & heat production & so on. If these hormones are over or underproduced, it can sometimes cause a condition called thyroid eye disease. This causes swelling of the muscles and some of the fat that’s situated within & around the eye. This then causes the eye to bulge a little & come forwards. It also causes symptoms of red, swollen eyelids, dryness & double vision.
- This does need to be taken seriously as the swelling can get to the point of compressing the optic nerve towards the back of the eye, which connects itself to the brain and is greatly responsible for helping you view the world and see.
- Bilateral but assymetrical condition
- TED can occur in hyper or hypo active thyroid conditions
-
Tests to do:
- Visions, Pupils (RAPD), Cover test (tropia?), Motility (pain? restriction?), Slit lamp exam (NaFl, lid eversion, AC check for cells & flare, fundus check), Colour vision or desaturation check
Myogenic Palsies
Thyroid: Signs
-
Signs: (wet phase - myogenic)
- It starts with Mild Lid signs like…
- Lid lag - person looks down but their upper lid is retracted i.e. their upper sclera shows
- Lid retraction - person has a startled looking appearance due to proptosis
- Scleral show - in primary position, upper limbus should not show but if it does then bad news
- Soft tissue involvement…
- Periorbital oedema, Swollen & red lids, Gritiness, Dryness, Bulbar hyperaemia
- Later…
- Corneal exposure - reduction in vision possibly
- More severe oedema & inflammation of the orbit & the muscles - pain on eye movement
- Enlarged recti muscles & increased orbital contents cause more proptosis - px struggles to close their eyes!
- This can start to stretch the ON/compress it causing more bad news i.e. possible optic neuropathy!!
-
Dry phase - mechanical
- Inflammation subsides, muscles become fibrotic
- Normally IR affected most commonly. Next most common is MR, then…
- E.g. if IR affected then it is essentially more stiff & hardened, causing it to stay down but not letting it more up to elevate the eye as the fibrosis is on top of the muscle
- This might cause diplopia and possibily a unilateral limitation in eye movement
- It starts with Mild Lid signs like…
DD of thyroid eye disease
- Allergic conjunctivitis - more itching & acute, no proptosis but papillae!
- Myasthenia gravis - diplopia worse towards end of day & improves with rest, ptosis!
- Orbital myositis - no eyelid retraction, unilateral
- Orbital tumour - unilateral, no eyelid retraction or lid lag but can still cause proptosis
3rd Nerve
- Can either be affecting superior or inferior division
- Superior = SR + Levator
- Affected eye become HYPOtropic & partial PTOSIS
- AHP = Chin elevation
- Inferior = IO, IR, MR, Sphincter pupillae & Ciliary muscle
- Exotropic with little or no vertical deviation
- AHP = Face turn to eye without the palsy, Tilt to lower eye if vertical deviation
- Superior = SR + Levator
- What does it look like?
- Primary position - ExoT & HypoT, Ptosis
- Abduction is AOK, Adduction is not
- Limited elevation & depression
- Pupil dilation (if pupillary involvement - this is really bad for the px!)
- Causes - M (microvascular) A (aneurysm) T (trauma) E (episodic)
- Management - urgent referrral within 1 week, emergency if pupil involvment as could be aneurysm.
- HES need to determine cause so CT/Blood tests/MRI ordered
- Px made comfortable with prism (fresnel), occlusion, Botox
- Palsy may take up to 12 months to recover so fresnel can be changed later on
- Surgery if recovery inadequate or symptomatic/poor cosmesis
4th Nerve
- SO affected
- What does it look like?
- Primary position - HyperT, Head tilt & chin depression
- Adduction causes IO overaction, Abduction AOK
- Limited depression on adduction
- 3 Step Test
1. Look at primary position: affected eye has HyperT
2. WOOG - worse on opposite gaze. Deviation will increase
3. BOOT - better on opposite tilt. Deviation will increase on same side tilt - Management - same as 3rd nerve, ignoring pupil involvement
6th Nerve
- Abducens nerve
- What does it look like?
- Marked EsoT in the (distance?)
- Adduction AOK, Abduction limited
- Management - same as 3rd nerve, ignoring pupil involvement. If associated papilloedema then emergency
Herrings law of equal innervation:
Sherrington’s law of reciprocal innervation:
Herrings law of equal innervation: when increased innervation is sent to a muscle to cause it to contract, a simultaneous and equal impulse is sent to the contralateral synergist
Sherrington’s law of reciprocal innervation: increased innervation is sent to a muscle to contract, decrease innervation goes to the direct antagonist which is therefore caused to relax
Muscles actions
MR – adduction
LR – abduction
RADSIN FOR THE REST…
Recti adduct
Obliques abduct
Superiors intort
Inferior extort
Muscle sequelae
Sequence of oculomotor changes in response to over/under action of a muscle, it consists of 4 stages:
1. Under action of the primary affected muscle
2. Overaction of the contralateral synergist – Hering’s Law
3. Overaction of the ipsilateral antagonist – Sherrington’s Law
4. Inhibition palsy of the contralateral antagonist
Recent onset = only 1st & 2nd
Longstanding = full sequelae established
BHHT
Allows differentiation of SO palsy from one affecting the contralateral SR
Positive BHHT = SO palsy
Method:
o Performed at 3m – SO works best at 1/3 meters, SR works best at 6m
o Head is tilted 30 degrees to affected side = if hypertropia increased = SO palsy is present, i.e. increase in R over L
o When tilting to affected side, the eye elevated as the SO isn’t there to keep it straight
o Head tilt to unaffected side should show little different in deviation
o Cover test should be performed to compare amount of hyper deviation, PCT result obtained in each position
o Positive result = 5^ difference from tilted R to L
Mechanical
Duane’s retraction syndrome
Caused by innervation of the LR by extra branches of CN3 due to an absent/atrophic cn6
3 types can be classified with 1,2,3 or ABD
1. Limitation of abduction
2. Limitation of adduction
3. Limitation of abduction and adduction
Adduction: narrowing of PAH, upshoots and globe retraction
Abduction: limitation and widening of PAH
Depression of abducted eye
A or V pattern
Surgery if strabismus in PP, symptomatic px, cosmetically poor AHP, severe upshoots/downshoots
Mechanical
Browns syndrome
Mechanical restriction of the SO
Usually unilateral
Mimics IO palsy; limitation of elevation on adduction
Little deviation in PP
Overaction of contralateral SR
Clicking browns – module gets through tendon and becomes stuck
Most recover spontaneously due to recurrent movement
