Week 2.03 Evaluation & Management Flashcards
What are the pathways of neurogenic incomitancy
Supranuclear pathway - saccades, pursuits, vestibular
Internuclear pathways - gaze centres, ocular motor nuclei
Infranuclear pathways - ocular motor nerves
Which isolated palsies (on their own) are rare and usually congenital
Inferior rectus palsy
Superior rectus palsy
Fairly rare to have isolated palsies of any muscle which isn’t LR6 and SO4 as they are all associated with the same 3rd cranial nerve. Due to therefore be congenital
What are the main causes for acquired neurogenic palsies?
• Trauma
• Space-occupying lesions
o Tumour
o Vascular (aneurysm, carotid cavernous fluid)
• Vascular (microvascular: diabetes; hypertension vasculitis
• Inflammatory – e.g. tolosa-hunt syndrome, post viral (herpes zoster meningitis)
• Metabolic disorders
What is the most common neurogenic incomitancy
Most common neurogenic incomitancy is 6th nerve palsy (abducens) then 3rd nerve palsy (oculomotor) and then 4th nerve palsy (trochlear)
What is the aetiology of 6th nerve palsy
Birth trauma: instrumentation (forceps pressed against temporal bone)
Childhood: meningitis, pneumonia
Adult: diabetes, hypertension, trauma, demyelinating tissues
Old age: strokes
What’s the management for 6th nerve palsy
- Prism base out to distance portion of bifocals - alleviate sxs of diplopia
- An injection into opposing MR reduces esotropia to alleviate dip and prevents contracture of ipsilateral MR
- Surgery
What is mobius syndrome
- Congenital
- 6th and 7th nerve palsy
- loss of abduction and facial weakness
- expressionless face, incomplete lid closure, bilateral loss of abduction
3rd nerve palsy aetiology
- unilateral
- aetiology: aneurysm, vascular disease - diabetes, hypertension, closed head injury
Complete oculomotor palsy
- divergent strabismus
- ptosis
- mydriasis
- loss of pupil action
- accomodation
- ‘down and out eye’
Incomplete or partial paresis
- paresis of ciliary muscle and iris sphincter
- can affect only superior or only inferior or single muscle palsy
- double elevator palsy - px unable to raise eye cuz of palsy of SR and IO
Single muscle paresis
- rare
- congenital
- SR with V pattern esotropia - check for ptosis to eliminate superior division palsy
- MR very rare - check for Duane’s
- IR not common - exclude mechanical restriction
- IO very rare - diff diagnosis browns syndrome
If sudden onset of complete third nerve palsy with pupil involvement what do u do
Due to an intracranial aneurysm = neurosurgical emergency
If recent onset
Pain
Blown pupil
Go straight to CASUALTY
Management of third nerve palsy
Prisms - limited use diplopia only present if incomplete ptosis
Pilocarpine to reduce photophobia
Surgery?
What does Hess plot for 3rd nerve palsy look like
One eye the smaller inner square is massive
The other eye both squares are small and in and is down and out
4th nerve palsy (trochlear) - superior oblique
- Least common neurogenic incomitancy
- Common as both congenital and acquired
- can be bilateral or unilateral
What can be the cause of 4th nerve palsy
- familial defect
- brain abnormality
- many unknown
- closed head injury - damage to the trochlea in upper cut blow in boxing
- diabetes
- intracranial tumour
What are some mechanical incomitant deviations
Congenital:
Duanes retraction syndrome - problem with lateral rectus muscle
Browns syndrome - problem with SO
Mobius syndrome
Acquired:
Orbital injuries - fracture stopping the muscles
Dysthyroid eye disease
Duanes retraction syndrome
Loss of movement of lateral rectus so can’t abduct
Psedotosis when looking away from underacting muscle
What’s the cause of Duane’s retraction syndrome
- Congenital structural abnormalities – fibrotic non elastic lateral rectus muscle
- Paradoxical innervation – anomalous co-contraction of the medial and lateral rectus muscles
- Innervational disturbance of brain stem origin
What are some characteristics of Duane’s retraction syndrome
Bilateral or unilateral - more often affecting LE
Incidence higher in females
Incidence higher in females
What does Duane’s retraction syndrome look like on Hess plot
Looks compressed
Don’t developed sequelae (mechanical) so hard to tell if recent or long standing
Management of Duane’s syndrome
- Treatment of amblyopia and correction of refractive error
- Surgery for cosmetic correction of AHP, if necessary
What’s browns syndrome
The problem when it goes through the trochlea. Failure to relax as it gets trapped in the trochlea. Muscle can do the job but when it relaxes gets trapped in the trochlea
What can be the cause of browns syndrome
- Superior oblique tendon sheath syndrome
- Develops in infancy
- mainly unilateral can be bilateral
Short tension sheath, swelling on SO tendon
