neuroopthalmology Flashcards
what are the muscles of thee upper lid ?
superior tarsal
levator palpebral superiors
what is the main retractor of the lower lid ?
the inferior rectus
what is the nerve supply of the inferior rectus and the levator muscles ?
occulomotor
what is lagopthalmus ?
failure to close the eyes due to facial paralysis
what is the most common complication of the cornea that happens as a consequence of lagopthalmos ?
exposure keratitis
what are the different causes of ptosis ?
congenital
paralytic
neuromuscular
involutional
mechanical
what is the etiology of myasthenia gravis ?
formation of auto antibodies against acetylcholine receptors in the neuromuscular junction
what are the clinical tests that can bee used to help in the diagnosis of myasthenia gravis ?
increased ptosis with upwards gaze
improved ptosis with icee packs to the lids
IV injection of edrophonium causes rapid improvement of ptosis
what is the mediical therpay for myasthenia gravis ?
pyridostigmine
oral steriods
what is the surgical therapy associated with myasthenia gravis ?
removal of the thymus gland
what are the causes of paralytic strabismus ?
lesions of the motor nerve nucleus
lesions of the nerve trunk
lesions of the muscles
what is paralytic strabismus ?
strabismus caused by the affection of the extra occular muscles
what is the nerve supply of the extra occular muscles ?
CN3 supplies sphincter pupillae and ciliary muscles
supplies the medial , superior and inferior rectus, inferior and superior oblique
CN4 supplies the superior oblique
CN6 supplies the lateral rectus
all extra occular muscles ar supplied by the occulomottor nerve except for the lateral rectus and supeerrior oblique
what are thee compensatory mechanisms for diplopia ?
- suppression - more common in children and easier with them due to high brain plasticity
- abnormal head posture
suppression as a compensatory mechanism for diplopia increases the risk for ?
Amblyopia ( lazy eye)
what is the clinical picture of 3rd CN palsy ?
the eye will bee looking downwards and outwards
pupils will be dilated and fixed
lid ptosis
accommodation is completely lost
complete ptosis ? no diplopia
what is the most common cause of isolated CN3 palsy ?
posterior communicating artery aneurysm
what is the clinical picture of CN4 palsy ?
the head would be tilted away from the lesion to reduce the diplopia
affected eye is deviated upwards
ipsilateral hypertropia
what is the function of the superior oblique muscle ?
depression
intorsion
what is the clinical picture of CN6 palsy ?
- Limitation of abduction with esotropia
what are the causes of CN6 palsy ?
any increase in intracranial pressure
microvascular disease due to HTN or DM
what are the causes of CN6 palsy in children ?
secondary to severe otitis media
trauma
post viral disease
where is the lesion if RAPD is positive ?
asymmetrical lesion that exists before the lateral geniculate body
what is the presentation in RAPD ?
shine light in normal eye causes constriction in both pupils
shine light in diseased eye then both pupils dilate
lesion of the visual field at the optic nerve ?
left or right anopia
lesiion of the visual field at the optic chiasm ?
bitemporal hemianopia
lesion of the visual field after the optic chiasm ?
homonymous hemianopia ( right or left )
lesion of the visual field in the optic tract ?
quandrantopias
when should diseease of the optic nerve be suspected ?
vision loss over hours or days
visual field loss
color vision loss
headache or pain
pain upon eye movement
what is papilledema ?
passive non inflammatory swelling of the optic nerve head (optic disc)
case of bilateral papiloedema differential diagnosis ?
intracranial space occupying lesion until proven otherwise
what systemic diseases may be associated with papilledema ?
malignant hypertension
polycythemia
anemia
what are thee symptoms of early papilledema ?
may bee asymptomatic
amaurosis
headache , vomiting due to increased ICP
may experience diplopia due to CN6 affection
what are the symptoms of early papiloedema ?
may bee asymptomatic
amaurosis
headache , vomiting due to increased ICP
may experience diplopia due to CN6 affection
what is the presentation of IIH ?
idiopathic intracranial hypertension is a diagnosis of exclusion , common in young females who are obese and other causes of inc ICP have been excluded
always present with papilloedmea
what is the differential diagnosis of IHH ?
sleep apnea
what is the presentation of a late case of papiloedema ?
gradual painless loss of vision
due to secondary optic atrophy
what are the investigations required for cases of papilledema ?
CT scan
MRI
MRV
lumabr puncture
what are the complications of papilledema ?
post papilledema optic atrophy
the optic disc becomes flat and greyish in colour with ill defined borders
obscured lamina cribrosa
what is the treatment for papilledema ?
treatment of the cause
decrease ICP pressure
carbonic anhydrase drops
weight loss
surgery is indicated
what surgery is performed in cases of papiloedema ?
optic nerve sheath fenestration
CSF shunting procedures
what is the difference between papillitis and retrobulbar optic neuritis ?
papillitis - inflammation of the optic nerve head
retrobulbar optic neuritis - inflammation of thee optic nerve along with the orbital part of the nerve
what is the etiology of optic neuritis ?
infective disease
demyelinating disease
inflammatory conditions
Uveitis and retinitis may cause secondary papillitis
what are the signs associated with optic neuritis ?
pain on ocular movement
RAPD can be detected
fundus examination is normal
