Eyes Flashcards
(34 cards)
Where is the lesion in an INO?
In the medial longitudinal fasciculus in the brainstem
where can the CN III and VI nuclei be found
III - Midbrain
VI - Pons
Causes of a unilateral INO
MS
Stroke (brainstem - MIDBRAIN OR PONS)
Tumours
CNS Vasculitis
Infection i.e. syphilis
Causes of a bilateral INO
MS
Infection (syphilis, lyme, VZV)
toxicity - phenytoin
What is one and a half syndrome?
one eye will not move in any direction horizontally
The other eye, will fail to adduct, leaving only abduction of this eye when assessing horizontal eye movements
where is the lesion in oen and a half syndrome
paramedian pontine reticular formation (PPRF)
in what condition do you get a pseudo-INO?
Myasthenia gravis
What ix would you do in INO?
Depends on cause but generally:
MRI head to visualise brainstem
If MS picture -> MRI whole spike, MRI with gadolinium to assess new lesions
LP for unpaired oligoclonal bands
If older patient and stroke features:
- Stroke work up (bloods, ECG, holter, carotid dopplers etc etc)
what is a marcus-gunn pupil?
Abnormal dilatation of the pupil in affected eye on moving a light source from the normal eye to the abnormal eye
Clinical signs of optic atrophy
RAPD
Pale optic discs on fundoscopy
what can optic nerve pathology give rise to?
Reduced visual acuity
Reduced pupillary reflex
RAPD
What does an RAPD suggest?
pathology of the optic nerve
what would a bilateral RAPD look like
Would be unable to tell if the optic nerves are equally affected in each eye as it is relative
Causes of RAPD
Optic neuritis
Optic nerve compression
Optic atrohy
Retinal vein/artery occlusions
reduced VA with RAPD in a patient > 50 ?
GCA until proven otherwise
If you see optic atrophy on fundoscopy, what else would you like to look for?
RAPD and red desaturation with a red hat pin
INO
6TH NERVE PALSY OF RAISED ICP
Why may you find a temporal artery biopsy scar in a patient with optic atrophy?
Preivous GCA
Optic atrophy causes
Demyelination
Ischaemic optic neuropathy
- Arteritic (GCA)
- Non-arteritic (diabetes)
Compression
- optic n tumour/ pituitary tumour/craniopharyngioma
- thyroid eye disease
- chronic glaucoma
- Paget’s disease (hearing aid)
retinal disease
CRAO/CRVO
Iatrogenic
Meds: ethambutol
EtOH
B12 deficiency
Hereditary
LHON
Friedrich’s ataxia
RP
Inflammatory/infective
Infection: Lyme, HIV, syphilis, CMV
Inflammatory: sarcoid, SLE, Behcet
fundoscopy in optic atrophy
pale, waxy, well demarcated optic disc
optic atrophy + cerebellar signs in young pt
friedrich’s ataxia
what would a more rapid optic atrophy suggest?
demyelination
inflammation
ischaemia
trauma
what would a more gradual onset optic atrophy suggest?
compression
drug-induced causes
hereditary
CN involved in the cavernous sinus
3 4 V1 V2 6
3rd nerve palsy surgical causes (3C’s)
Communicating artery aneurysm (posterior)
Cavernous sinus pathology: tumour or infarct
Cerebral uncus herniation: raised ICP
