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What is Pursuit system ?
area of brain controlled?
- maintains an object on the fovea while the object moves slowly
- Ipsilateral parietal lobe
What is Vestibular Ocular Reflex (VOR)? What is the delimna of the VOR system?
- Holds object steady on while the head moves during a pursuit
- It doesnt last long and OKN must take up for it.
How does Optokinetic Nystagmus (OKN) work with VOR?
OKN supplements VOR and holds image steady on fovea during sustained head movement
What does the saccade system function to do?
Controlled in the brain where?
- Quick movement to fast for pursuits. Rapidly brings object of interest to the fovea
- contralateral frontal lobe
What are saccadic intrusions?
What is the mcc type
What dz is it found?
- unwanted eye movements during fixation
- square wave jerks
- Progressive supranuclear palsy
Supernuclear control of saccades is initiated from the
- contralateral Frontal Eye Fields
- contralateral Superior Colliculus
Supernuclear control of Pursuits is initiated from the
ipsilateral parieto-occipital-temporal regions
What is the vertical gaze centers?
- riMLF (rostral interstial nucleus of MLF)
- Interstical nucleus of Cajal
What are the horizontal gaze centers?
- Parapontine reticular formation PPRF
- Location -PONS
- Medial vestibular nucleus
- nucleus prepositous hypoglossi accessory nucleus of 7
How do you test the VOR? Describe each.
- Dolls eye manuever; move head with visual fixation; if catch up saccade then abnl
- Calorics: irrigate H20 in ear and watch for type of nystagmus base of the temp of H20
What is the mnemonic
If warm water irrigated in right eye, what type of nystagmus
If cold water irrigated in right eye what type of nystagmus
- COWS: cold opposite/warm same
- warm H20- right ear -righting beat nystagmus
- cold H20- right ear -left beating nystagmus
If patient is comatose which ear does the eye move in caloric testing
toward the same side with slow phase movement
What is the etiology of Ocular tilt?
What is the disorder?
- otolithic organs
- head tilt
- ocular rotation
- skew deviation
In ocular tilt which way is the head tilted and cyclotorsion in respect to the lesion?
- head tilted towards lower eye away from the higher eye
- higher eye incyclotorted
How do you differentiate a skew from 4th nerve palsy?
hypertropia on opposite side of gaze (head tilt)
What is the lateral medullary syndrome of wallenberg?
- stroke without paralysis
- Ipsi loss of pain/temp on face
- ipsi cerebellar ataxia
- ipsi horner
- ocular tilt
How do you test VOR suppression?
- pt fixates on near card while being rotated in a swivel chair.
- nl eyes maintain fixation on near card during rotation without catch-up saccade.
- impaired VOR eyes move off the target during rotation
Progressive Supranuclear Palsy (PSP)
- slow disappearance of all ocular movements
- vertical gaze affected first aka (Dirty tie syndrome)
- horizontal pursuits late
Hypermetropic saccades indication dyfx where in the brain.
Congential Ocular motor apraxia
inability to initiate volitionally saccades; thus, use head thrust to see target
Gaze palsy-which direction is the gaze in respect to the lesion in the following?
- cerebral-inablitiy to produce contralateral gaze; thus tonic devatiation toward the lesion
- brainstem-inability to produce move ipsilateral to lesion
- Pontine-loss of horizontal movements
- Midbrain-loss of vertical movments
Dorsal Midbrain Syndrome Parinauds features include
- convergence retraction nystagmus ( co-contraction of EOM)
- convergence insufficency
- vertical gaze palsy
- light-near dissociation (middilated pupils with light)
- lid retraction
- skew deviation
increase square wave jerk
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