eye mvmt disorders Flashcards
What are the 4 main categories of eye movement disorders?
- binocular diplopia
- diplopia sub type: INO
- gaze palsy
- nystagmus
fusion is usually present, but the two eyes together cannot move into certain positions of gaze.
gaze palsy
technically, a specific type of unsteady fixation, characterized by a slow movement (pursuit) in one direction followed by a rapid (saccadic) eye movement in the other direction. There are many varieties. Know that any inability to stay fixated is a problem.
nystagmus
with both eyes open, the patient sees double some or all of the time. The implication is that when the patient reports diplopia, the eyes are out of alignment.
binocular diplopia
“internuclear ophthalmoplegia,” a very specific type of EOM anomaly that may or may not be accompanied by diplopia in some positions of gaze.
diplopia sub type
what is the final common pathway?
cranial nerves that control the muscles
what do the pre motor nuclei organize?
eye movements by coordinating the nuclei that control the muscles
what do supranuclear structures do?
control the nuclei
what do systems do?
maintain fixation
what are the supranuclear levels split up into?
cortical and subcortical
what are the 3 supranuclear levels?
saccades
pursuits
OKN
whats in the premotor level
premotor nuclei: riMLF and PPRF
vestibular nuclei
what level is VOR in?
subcortical
list the levels from premotor level to final common pathway
premotor nuclei
internuclear
nuclear level
external level
whats in the nuclear level?
CN 3
CN 4
CN 6
what does the nuclear level lead to?
external level
how many EOMs are there?
12
where are the 3 locations of pathology of the EOMS?
- in a muscle/muscles
- in a synapse (b/w a nerve ending and a muscle)
3 in the orbit
where are the 3 locations of pathology of a nerve that controls EOMs?
- in the brainstem nucleus
- in the brainstem where axons traverse the brain (interstitial)
- in the space from the exit of the axons from the brain to the muscle
where are the 4 locations of pathology of premotor structures that control the nerve nuclei that controls EOMs?
- PPRF
- riMLF
- vestibular nuclei, CN 8
- MLF (Internuclear)
Where are the 4 locations of pathology of structures that control the nuclei and EOMs to maintain fixation (premotor)?
- semicircular canals
- CN 8
- vestibular nuclei
- cerebellum (flocculondular lobes)
Where are the 3 locations of pathology of higher order (supranuclear) structures that control –> the premotor structures that control –> the nerve nuclei that controls –> the nerve that controls EOMS?
- superior colliculus
- frontal eye fields (scans)
- occipital eye fields (pursuits)
If patient presents with diplopia, where are the 5 locations of pathology?
- orbit
- EOM
- Synapse
- nucleus
- nerve
If patient presents with INO, where is the location of pathology?
premotor structures
If patient presents with gaze palsy, where is the location of pathology?
supranuclear structures
If patient presents with nystagmus, where is the location of pathology?
vestibular system, CN 8
Why is it clinically relevant to know your neurological anatomy?
Neuropathology strikes specific locations and affects ALL systems with parts that are present in that location.
associated signs/ symptoms of orbit
Space-occupying, CN5
system structures present in orbit
EOMS nerves fat fascia connective tissue
associated signs/symptoms of orbital apex
space occupying lesion
CN 2
system structures present in orbital apex
superior orbital fissure
optic canal
associated signs/ symptoms of nerve
aneurysm
space occupying lesion
inflammation
system structures present in nerve
subarachnoid space circle of willis cavernous sinus superior orbital fissure posterior orbit
associated signs/symptoms of nerve nucleus and interstitial axons (midbrain)
CONTRALATERAL voluntary somatic movement
incoordination
system structures present in nerve nucleus & interstitial axons (midbrain)
descending pyramidal system rostral to decussation red nucleus (motor system)
associated signs/symptoms nerve nucleus and interstitial axons (pons)
contralateral voluntary somatic movement incoordination dysmetria imbalance dizziness
system structures present in nerve nucleus and interstitial axons (pons)
Descending pyramidal system rostral to the decussation, vestibular nuclei,
cerebellum is nearby
associated signs/symptoms related to premotor (brainstem)
incoordination
dysmetria
imbalance
dizziness
system structures present with premotor (brainstem)
MLF,
SC,
vestibular system,
cerebellum
associated signs/ symptoms of premotor (supranuclear)
Aphasia,
psychological,
VF defects
system structures present with premotor (supranuclear)
Frontal & occipital lobes
associated signs and symptoms of vestibular system (CN 8)
Contralateral voluntary somatic movement,
facial asymmetry,
reduced auditory sensitivity
system structures present in vestibular system (CN 8)
Facial nerve (CN7),
auditory system,
descending pyramidal system rostral to decussation
3 things to look for under INO in EOM checklist
- incomitant exo to L and/or R
- unilateral end point nystagmus
- convergence intact
signs of elevated ICP
- spontaneous venous pulsation
- disc edema
- CN 6 dysfunction
