Eye movement in health and disease Flashcards
what muscle controls adduction of the eye and which cranial nerve
medial rectus
CN3
what muscle controls abduction of the eye and what CN
lateral rectus
CN6
what muscles control elevation of the eye and CN
inferior oblique
superior rectus
what muscles control depression of the eye and cranial nerves
superior oblique - CN4
inferior rectus CN3
what muscles control intorsion( nasal rotation) of eye
superior oblique CN4
what muscle control extorsion (temporal rotation) of the eye?
inferior oblique CN3
rectus muscle pull towards themselves and the obliqeu muscles
pull away from themselves e.g. superior obliqeu pulls inf
LR6, SO4, 3
convergence means both eyes must point medial to see near objects
if this dosent work what happens
inability to alternate between distant and near objects
conjugation is eyes must move together
if this dosent happen what happens
double vision - diplopia
accommodation is when the lens must be shaped to focus light coming from the viewed objects if this dosent work what happens
short or near sightedness
the centres fro conjugate gaze is found int h mid Brain and cranial nerve eye nuclei found in pons or midbrain so people with lesions here what will happens
won’t be Able to move their eyes with coordination or focus on near of far objects
6th uncle pons
3/4 in midbrain
vergence
eyes move in opposite directions to focus on near and far.objects
if the oculomotor nerve is injured what will the present with
Down and out appearance
Down to SO
and out due to LR
those are still working
elevation won’t work - SR an IO
depression and adduction IR and MR respectively
if the trochlear nerve is injured what will happen
Head tilt
depression and intorsion will not work - SO
if abducens nerve is injured what happens
move medially due to MR and no LR
abduction lost
Levator palpebrae superioris
Ciliary muscle
Pupillary sphincter
controlled by what nerve
oculomotor
Levator palpebrae superioris fucntion and if damaged
eye lid elevation
ptosis
ciliary muscle normally and If injured
Changes lens shape
focusing, accommodation
Pupillary sphincter
constricts the pupil
mydriasis
pupil dilator muscle is controlled by what never
trigeminal
CN palsies
Ischaemia (strokes) Compression (tumour, abscess, aneurysm) Trauma (concussion, whiplash) Microvascular damage (diabetes) Migraines (e.g. ophthalmoplegic migraines) Raised intracranial pressure Congenital
A 55-year-old man with a history of hypertension and diabetes presents on a Friday night to the emergency department. He was found by an ambulance crew wandering in the road. He looks dishevelled, and is slurring his words and staggering around the department. You also note his eyes are jerking horizontally when he is looking at you. You put him in a bed with some IV fluids running to let him “sleep it off”, but 10 hours later he is still looking and acting the same way.
Where is the lesion likely to be?
Middle cerebral artery
Anterior cerebral artery
Superior cerebellar artery
Posterior communicating artery
sup cerebellar artery
Cerebellar signs: DANISH
Dysdiadochokinesia Ataxia Nystagmus Intention tremor Slurred speech (or scanning dysarthria) Hypotonia
A 38-year-old man presents to his GP with double vision. He has a history of poorly controlled HIV, and reports headaches and fevers over the past few weeks. When you examine him, you note he is holding his head so it is pointing up and to his left, he reports this makes the double vision better.
You send him to hospital where a CT-scan confirms a brain abscess, later confirmed to be caused by cryptococcus.
What nerve was affected which led to the diplopia?
Right oculomotor
Left oculomotor
Right trochlear
Left trochlear
Patient is moving their head up and left so that both eyes are pointing down and to the right when looking at an object, as this is the only way the right eye can point.
A 45-year-old woman with a history of MS presents to A+E complaining of vision changes that have occurred over the previous 2 days. She reports that she has double vision when she tries to look to the right, but not when she looks to the left. She has no other eye movement signs or symptoms.
What nerve was affected which led to the diplopia?
Right oculomotor
Left oculomotor
Right trochlear
Right Abducens
double vision sign of right abducens
Patient cannot look right due to failure of the right lateral rectus muscle. When she looks left, her eyes point together so no diplopia. LR is innervated by CN VI.
A 23-year-old man presents to his GP with a sensation like the room is spinning. He reports this has happened over the last 2 days and he has been feeling fluey with it, with myalgia and general fatigue and malaise. He looks ataxic when mobilising, and you note nystagmus on examination.
What is the most likely diagnosis?
viral labyrintitis
viral labyrintitis
Inflammation of the inner ear
Normally due to a viral infection (30% will have a cold before symptoms arise)
Causes nystagmus, vertigo, hearing loss/tinnitus, and viral symptoms
Can take 2 months to fully recover
No specific treatment unless bacterial or other cause
Strokes don’t affect the young and don’t cause viral symptoms.
Infection of the labyrinths causes failure of postural sensation, which leads to vertigo and nystagmus (failure vestibulo-ocular reflex), and viral symptoms
68-year-old man with a history of hypertension, diabetes, and MI, presents to hospital with drooping of the right side of his face, as well as weakness in his left arm and leg. He also reports visual changes that he struggles to quantify. Full visual field testing reveals the following defect:
Where is the lesion?
defect of upper right quadrant of both eyes gone
left temporal lobe damage
A 32-year-old woman with a history of lupus presents to A+E with loss of vision. She says her vision has been getting worse for the last few days, and she is now almost completely blind in both eyes. She also reports worsening weakness in her arms and legs on both sides.
On examination she can see the difference between light and dark only, with normal eye movement and fundoscopic findings shown below. She also has reduced sensation and power bilaterally below the level of C8. An MRI of her spine is shown below.
What is the pathogenesis of this condition?
anti-aquaporin 4 antibodies
neuromyelitis optica NMO
RARE condition (10 per 100,000)
Caused by anti-aquaporin 4 antibodies
Presents with optic neuritis (like MS) and transverse myelitis (inflammation of a section of the spinal cord, usually >3 vertebral bodies in height)
ON is more severe and can be bilateral (Unlike MS)
Can be relapsing and remitting or monophasic
You don’t get brain lesions, unlike in MS
myopia
short sighted
signals from the bottom of the eye correlate to parietal lobe and signals from the top of the eye correlate with the temporal lobe visual fields. Therefore a lesion in the parietal lobe cause what
inf quantanopia
temporal casue superior quadrantopia
superior radiation fibres go into temporal lobe which are the ones that look wider
inferior radiation fibres go to parietal lobe and are closer to mid line of diagram
PITS
optic nerve - optic chiasm - optic tract - lateral geniculate nucleus - optic radiations
all optic fibres must go through the LGN
if the upper bank of the calcimine fissure is injured it presents with what
contralateral inferior quadranopia - parietal
if the lower bank of the calcimine fissure is injured it causes
contralateral superior quadraopia - same as temporal
is the posterior cerebral artery is occluded the whole of the calcimine fissure is injured so complete loss of one side but with what
a central sparing
PPRF - parapontine reticular formation
6th cranial nearby same side however 3rd cranial nerve on the other side as through the medial longitudinal fasciutlus
1 and half syndrome is most commonly caused by MS and is characterised by what
where is the lesion
a lateral gaze palsy on looking toward the side of the lesion ( only LR left) and INO looking in the other direction
location of the lesion is the paramedic pontine reticular formation or VI nerve nucleus
