Eye Movements and Vestibular Disorders Flashcards
Definition: rapid eye movements to direct the eyes to the target
saccades
definition: eye movements following a moving object
smooth pursuit
definition: eyes directed to near or far targets
vergence
What are the conjugate eye movements?
saccades and smooth pursuit
What are non-conjugate eye movements
vergence
Saccades can be ___ or ___ guided
voluntary or memory
(true/false) Saccades can have a slow component
true
How do you label a saccade?
By the direction it is moving into
The eyes can move up to ___ degrees/second when saccades is present
700
What initiates saccades?
- Frontal eye fields of the frontal lobe
- superior colliculus
definition: structure that gets the eye to a target
PPRF (paramedian pontine reticular formation)
What provides voluntary and memory guidance for saccades?
frontal eye fields
What structure has neurons that help with reflexive movements?
superior colliculus
Having a R Saccade results in the ______ muscle of the ipsilateral eye to move and the _____ muscle of the contralateral eye to move.
ipsilateral side: lateral rectus muscle (abducens n.)
contralateral side: medial rectus muscle (oculomotor n)
What initiates smooth pursuit?
parietal and frontal cortex
Smooth pursuit is made up of (slow/fast) eye movements.
slow (30-100 degrees/sec)
Vergence involves the BILATERAL activation of the ____ or ____ muscles.
medial rectus or lateral rectus
With vergence, the eyes are moving in the (same/opposite) directions.
opposite
What initiates Vestibular Ocular Reflexes (VOR)?
semicircular canals w/ head movement
With VOR, the head and eyes move the (same/different) amount.
same
VOR has a ___ reflex.
plastic reflex
definition: slow eye movement in the direction of a moving object and a rapid return of eye position in the opposite direction.
optokinetic nystagmus
The type of nystagmus is determined by the (slow/fast) component
fast
What are the causes of optokinetic nystagmus?
- brainstem infarcts
- INO
- vestibular issues
- TBI
- cerebellar damage
- MS
- DM
- disruption of the MLF pathway
What are the s/s of optokinetic nystagmus?
- diplopia
- dizziness
- nausea
- vomiting
Semicircular canals detect the ___ motion of the head.
angular motion
Otoliths (utricle/saccule) detect the ____ motion of the head.
linear motion
definition: sensory organ for the semicircular canals
ampulla
The ampulla contains a ____.
cupula
definition: crystals that move the gelatinous substance and the hair cells in the ampulla
otoconia
Otoconia move with ___.
gravity
When bending to the R, the ipsilateral semicircular canal (increases/decreases) its firing rate while the contralateral semicircular canal (increases/decreases) its firing rate.
increases, decreases
What are common s/s of vestibular disorders?
- vertigo
- nystagmus
- nausea
- vomiting
- hearing loss
definition: the illusion of movement (can be described as “spinning”)
vertigo
definition: rhythmic oscillation of the eyes
nystagmus
Definition: the sudden sensation that you’re spinning or that the inside of your head is spinning
BPPV
What is the most common cause of vertigo?
BPPV
The incidence of getting BPPV increase when a person is in what age range?
> 50 y/o
What are the s/s of BPPV?
- dizziness
- (+) dix-hallpike maneuver
- Disrupted VOR
What indicates a (+) test for the dix-hallpike maneuver?
- paroxysmal vertigo
- nystagmus
Vestibular neuritis/labyrinthitis has a ____ etiology.
viral
definition: acute onset of rotational vertigo
vestibular neuritis/labyrinthitis (can look like BPPV)
(true/false) Vestibular neuritis never goes away
False
definition: the vestibular system is not properly functioning
vestibular hypofunction
Vestibular hypofunction is (unilateral/bilateral)
unilateral
What are the s/s of vestibular hypofunction?
- dizziness/vertigo
- balance difficulties
- difficulty walk in the dark and/or crowded areas
Meniere’s disease is associated with ___.
BPPV
What are the s/s of meniere’s disease AND acoustic neuromas?
- tinnitus (unilateral ringing in the ear)
- hearing loss
- episodes of vertigo
An acoustic neuroma is a BENIGN tumor of _____.
CN VIII (RARE)
What types of medications are used to treat meniere’s disease?
- anticholinergics
- antibiotics
- diuretics
- surgery
Tumors in the ___ and ___ can cause vestibular disorders.
brain and cerebellum
What are diseases/conditions that cause problems with equilibrium?
- MS
- Seizure medications
- alcohol abuse
- cortical lesions
What are the three medication groups used to treat vertigo?
- anticholinergics
- antihistamines
- benzodiazepines
