Vestib 1 Midterm Flashcards
What are the causes of vestibular disorders?
Head trauma, otitis media, bacterial or viral labyrinthitis, ototoxic medications, ischemia, vestibular schwanomma, & meniere’s
Up to _____ of “true” vertigo and balance dysfunction may be inner ear related.
85%
_____ of individuals over 70 years old will experience BBPV
50%
Falls are the leading cause of?
brain injury (TBI) and fractures
Vertigo refers to?
an illusory sense of motion of self or the external world(spinning) and is more likely to be peripheral (inner ear)
How to patients often describe their vertigo?
vertigo, syncope, lightheadedness, disequilibrium, unsteady, floating, rocking, tilting, foggy feeling, motion sickness, etc.
What is true vertigo?
when the room is spinning or you are
Dizziness / Lightheadness is?
a more general term and less likely to be peripheral
Our ability to maintain balance depends on information from?
our visual, somatosensory, and vestubular receptors
Sensory information picked up from our visual, somatosensory, and vestibular receptors is sent to?
the brainstem for integration and ultimately to the cortex for perception and processing
How do the cerebellum and cerebral cortex streamline the balance process?
they coordinate incoming impulses and add information from thinking and memory
What does peripheral mean? Central?
Peripheral - Inner ear (labyrinth and 8th nerve up to the point they enter the brainstem)
Central - CNS (brainstem to cortex)
What does the peripheral vestibular system do?
allows us to interact and maintain contact with our surroundings in a safe and effienct manner
What is vision denied? vision allowed?
denied - patient without a visual target aka eyes closed or covered
allowed - patient with a visual target, able to fixate aka eyes open or uncovered
What are the 2 types of sensory structures within the peripheral vestibular system
semicircular canals (sensory epithelia = cristae ampullaris) & otolithic organs (sensory epithelia = maculae)
What are semicircular canals?
-Fluid filled (endolyph), bony tubes that are interconnected
-They detect angular (rotational) acceleration of the head/body
-3 SCC per labyrinth (anterior, posterior, horizontal)
What is pitch? yaw? roll?
pitch - shaking head yes
yaw - shaking head no
roll - tilting head to the side
What are otolithic / macular organs?
Utricle & Saccule
-gelatinous structures with otoconia embedded on top
-detect linear or translational movement including gravitational acceleration and percention of up and down
-1 utricle & 1 saccule in each labyrinth
The utricle is …
superior, larger, oriented horizontally and is sensitive to linear horizontal acceleration.
plays a large role in postural control and primarily senses changes in respect to gravity such as moving forward in a car.
What are the sensory structures of the otolithic organs?
otoconia
The saccule is …
inferior, smaller, oriented verically and sensitve to linear acceleration
The bony labyrinth is filled with perilymph. What is perilymph?
similar compostion to cerebrospinal fluid and has a high sodium to potassium content. the membranous labyrinth is suspended in perilymph.
What fluid is in the membranous labyrinth?
endolymph, which has a high potassium to sodium content
There are 5 sensory organs housed in each labyrinth, what are they?
Utricle macula
Saccule macula
3 crista ampullaris
The otoconial membrane also known as the macula consists of?
a layer of calcium carbonate crystals known as otoconia (“ear dust”).
How are the SCC paired?
The lateral canals are paired to eachother but the anterior canal is paired with the posterior canal of the opposite ear
What is the cupula? What happens if there is a change in density?
The cupula sits on top of the cristae and has the same density as endolymph. If the density changes it will cause the illsuion of vertigo
What are vestibular hair cells
There are 2 types. They are stimulated by the movement of the SCC and the position relative to gravity. They have kinocilium and stereocilia (arranged in a “stair step” pattern).
How are vestibular hair cells oriented in the SCC?
In the horizontal canal, they face the utricle. In the anterior and posterior canal they face the canal side of the ampulla.
How does the horizontal canal become inhibited and excited?
movement of endolymph away from the ampulla causes inhibition and movement towards the ampulla causes excitation
How do the posterior and anterior canals become inhibited and excited
movement of endolymph toward the ampulla causes inhibition and movement away from the ampulla causes excitation
When the stereocilia flow toward the kinocilium, what happens?
depolarization with an increase in electrical potential
When the stereocilia flow away from the kinocilium, what happens?
hyperpolarization and a decrease in electrical potential
What are the 3 important functions of the vestibular system?
- to provide a subjective sensation of movement and/or displacement in 3 dimensional space
- to maintain upright body posture (balance)
- to stabalize the eyes during head/body movement
What is the VOR Reflex?
Vestibulo-ocular reflex - generates reflexive eye movements that are equal and opposite to the movement of the head so we can maintain a clear image
an intact VOR should be able to keep eyes on the target, if there is a problem they will slip
What is oscillopsia
a deficit causing retinal slip
What is the VCR Reflex?
Vestibulocollic reflex - acts on the neck musculature to stabilize the head helping to keep the head in a horizontal gaze position relative to gravity (head upright position)
How to assess the VCR reflex?
Vemp
What is VSR reflex?
Vestibulospinal Reflex - generates compensatory body movements to maintain head and postural stability in upper and lower limbs
If the VSR if damaged, what happens?
patients could walk or bend the opposite way
How to assess the VSR?
postural stability exams
What cranial nerves control which eye muscles?
CN 3 : medial rectus, superior rectus, inferior rectus and inferior oblique
CN 4 : superior oblique
CN 6 : lateral rectus
What happens when eyes reach the limit of how far they can go?
When they move to the side and hit their limit the CNS causes the eyes to move back to the center in order to create a new focal point through a saccade
what are some of the bedside screening evaluations we can perform?
Romberg/tandem Romberg, Fukuda/stepping Fukuda, halmalgi head thrust, active or passive head shake, and dynamic visual acuity
what is the romberg/tandem romberg assessing?
screens the body’s proprioception (somatosensory) system and the amount of disequalibrium caused by central vertigo, peripheral vertigo, and head trauma
how do you perform the romberg/tandem romberg?
the patient stands with their feet together and arms out to the side, we ask them to stand still for 10-15 seconds first with eyes open them again with their eyes closed. If you want to make it tandem they put one foot infront of the other.
what does a positive romberg mean? (what will you see the patient do)
it means the patient swayed or fell with non-fluid motions. they will typically lean toward the side of the problem.
what does the fukuda/stepping fukuda assess?
screens laryrinthine function via vestibulospinal reflexes
how to you perform the fukuda/stepping fukuda?
tell the patient to hold their arms out straight in from of them and close their eyes, then ask them to march in place for 50 steps
how do you interpret the fukuda/stepping fukuda results?
if the patient is normal they wont rotate more than 45 degrees. if the patient is abnoral they will rotate more than 45 degrees and this is considered a positive fukuda
what does the halmalgi head thrust assess?
screens SCC dysfunction in all canals & the detection of peripheral vesibulopathy
how do you perform the halmalgi head thrust?
hold the patients head and instruct them to keep their eyes open during the test. then slowly move their head back and forth, then rapidly move the head to each side. after the rapid movement hold it there briefly to check for refixation saccades
how do you interpret the results of the halmalgi head thrust?
if they are normal there will be no corrective saccades, if they are abnormal corrective saccades will be present.
you will have refixation saccades in the direction of the damage
what does the active/passive head shake assess?
screens the patients velocity storage integrator, telling us if function is balances
good way to determine is vestib organs are compensated or not. shaking their head trigers both sides and as they go up you can see the discrepancies
how to you perform the active/passive headshake test?
the patient has their eyes closed or is vision denied under goggles. shake their head back and forth and after 20 sec have them open their eyes and watch for nystagmus
how do you interpret the results of the active/passive headshake?
if they are normal you will not see nystagmus, if they are abnormal nystagmus will be present after the headhshake or enhanced
active/passive headshake patterns
no pre & post HS : balanced function
no pre but present post HS : unbalanced vestibular function
present pre & increased post HS : asymmetry but we made it greater, means it is recent
present pre & post : central
what does dynamic visual acuity assess?
screens for oscillopsia (often caused by vestibular loss). looks at the VOR
how do you perform the dynamic visual acuity test?
the patient stands the proper distance from the eye chart (letters) and you ask them to read the lowest line they can. then stand behind them and move their head back and forth and ask them to read the lowest line possible while you move their head.
how to interpret the results of the dynamic visual acuity test?
if there was no line change or a slight line change they are normal indicating their VOR is functioning properly. if they have a line change of 2 or greater they are abnormal, indicating oscillopsia
what is nystagmus?
an involuntary rhythmic oscillation of the eyes. it can be pathological or physiological
what does the fast phase of nystagmus tell us?
direction
driven by the CNS
does not tell us about vestib system
coordinated response SLOWER 70 ms
what does the slow phase of nystagmus tell us?
magnitude (degrees/sec)
driven by the ears (peripheral vestib)
tells us how the vestib system is operating
relfex repsonse FAST 5-10 ms
nystagmus will beat?
away from the affected side
how do we assess nystagmus?
oculography with VNG, rotational tests, & head thrusts or vHIT
what is pendular nystagmus?
the speed of motion of the eyes is the same in both directions
what is jerk nystagmus?
there is a slow and fast phase. the eyes move slowly in one direction and then seem to jerk back in the other direction.
if the patient has a central lesion and we ask them to fixate how will the nystagmus change?
it will stay the same or become enhanced
if the patient has a peripheral lesion and we ask them to fixate how will the nystagmus change?
it will decrease
tell me the difference between downbeating vs upbeating nystagmus?
downbeating = the fast phase is going down and slow phase is going up
upbeating = fast phase is up and slow phase is down
what is alexanders law?
when the patients nystagmus increases when they look the same way of the beating & decreases or is eliminated when they look the opposite way. in order for it to be alexanders law they MUST have central gaze nystagmus
when do we typically see alexanders law?
in the early stages of a vestibular disorder
what is torsional/rotary nystagmus?
when the eyes rotate about the central axis of the globe (twist in circular motion). pure torsional is a sign of central problems but if we see it with positional testing it indicates a peripheral finding.
what is gaze evoked nystagmus?
shows up when you move the eyes away from center gaze. you will see corrective saccades
what is acquired horizontal jerk nystagmus?
when the intensity of the nystagmus increases when the person looks toward the fast phase and the intensity decreases (with central lesions may reverse directons) when the person looks toward the slow phase
the ONLY finding in oculomotor studies that is peripheral
what is physiologic (end point nystagmus)?
when the patients is asked to stare at a target on the side for 30 sec+ causing the eyes to get tired, resutling in nystagmus. occurs when you are looking too wide and for too long.
what are the 3 types of nystagmus that are considered normal?
fatigue nystagmus, unsustained end point nystagmus, & sustained end point nystagmus
what is geotropic nystagmus?
when the eyes beat toward the ground (geo means earth aka the ground/land)
what is ageotropic nystagmus?
when the eyes beat away from the ground
what are 3 eye recording techniques?
Electro-oculography (ENG/EOG), Infrared Video-oculography (VOG/VNG), & Scleral Search Coils
What is Electro-oculography (ENG/EOG)?
when we record the corneo-retinal potential (CRP). the potential changes (polarity) when the eyes change the direction they are looking
what needs to be done before an EOG/ENG can be completed?
Remove oils and makeup from this skin because they give you high impedance values and less accurate tracings
When conducting an ENG/EOG how does the recording change when the eyes move to the right? to the left?
movement to the right = causes the recording to deflect upward
movement to the left = causes the recording to deflect downward
What is infrared video oculography (VOG/VNG) ?
uses pupil localization technology and the reflective nature of the corneal surface to calculate the pupil location and angle. the goggles have infrared (this light is invisible to humans) diodes to illuminate the eyes and reflect the image into cameras for recording
what instructions do we give patients before they come in for a VNG?
we ask them to refrain from taking certain medications including sleeping meds for at least 12 hours prior, to not drink alcohol, not to eat a big meal. we ask ask them to wear comfortable clothing and remove their makeup.
What are sclereal search coils?
coils embeded into a contact lens or rubber ring that adheres to the eye. alternating magnetic fields are generated by magnets positioned around the eye and through electromagnetic induction
What do we need to ask for a vestibular case history?
description- why are they there
timing
frequency
provoking factors
associated symptoms
other medical history
medications
seperate vertigo from non-vertigo patients
What is BPPV?
the most common cause of vertigo. caused by otoconia becoming detached from their otoconial layer by either degeneration, head trauma, or viral infection. they become settled into the SCC resulting in gravity sensitive organs to be in a place of acceleration. can be canalithiasis or cupulothiasis.
What is the most common canal for BPPV to occur?
the posterior SCC
What is the least common canal for BPPV to occur?
the anterior SCC
How do we classify BPPV?
BPPV is bilateral so we classify it by the side that is worse
What criteria needs to be present in order to diagnose BPPV?
- latency beginning 1 or more seconds after head tilt
- duration of at least 1 min
- linear rotational nystagmus
- reversal observed when sitting & fatiguability over time
What is canalithiasis?
when the otoconia moves freely in the endolymph within the SCC. usually has delayed onset after we place a patient in a provoking position and has fatigue over time.
What is cupulothiasis?
when the otoconia adhere to the cupula within the SCC. BPPV of this type has immediate onset after placing the patient in a provoking position and little to no fatigue over time.
What is the standard oculomotor battery?
- Spontaneous (gaze center)
- Gaze (horizontal, vertical), postion maintenance
- saccades
- pursuit/tracking (horizontal,vertical)
- Optokinetic (OPK,OKN)
- VOR
vergence - not performed due to inability of systems to track torsional (3D) movement
What are the parameters for interpretation for saccades?
velocity = speed of eye movement
latency = how long after target moves do the eyes
accuracy = does the eye reach the target
What is hypometria?
undershooting the target
What is hypermetria?
overshooting the target
What are the parameters for interpretation for pursuit?
gain = eye movement relative to target movement
phase = rightward vs. leftward
some systems also include the # of saccades
What are the parameters for interpreting OPK/OKN?
symmetry = rightward versus leftward
gain normative values exist but are less sensitive
What is the weakest test in the oculomotor test battery?
OPK/OKN
What is position maintenance (gaze holding)?
center (spontaneous), left, right, up, & down
performed with & w/o fixation
What are saccades?
rapid shift in gaze, saccadic testing is the ability to track a fast moving target
What is pursuit?
stabilize image of moving object, test by having them track moving object
What is fixation?
stabilize image of still object
What is a vergent movement
change in depth focus, brining things toward you or away
What is an ENG/VNG test battery made up of?
oculomotor exams, positional exams (dynamic & static), and caloric irrigation
What does positional testing consist of?
- supine head center (open & closed)
- supine head turned right
- supine head turned left
if they pass the first 3 then that’s it, if not then you do …
4. whole body
test all in the dark
What are the positional nystagmus criteria that make it pathological (abnormal) ?
- it changes direction in any head position, or
- it is persistent in at least 3 head positions, or
- it is intermittent in all head positions, or
- it’s slow phase velocity exceeds 6 degree/sec in any head position
What are the dynamic & static postional tests?
dynamic = dix hallpike
static = supine head roll
What does the dix hallpike assess?
anterior and posterior canal BPPV
abnormal = torsional nystagmus
What does the supine head roll assess?
horizontal canal BPPV
abnormal = linear geotropic or ageotropic nystagmus
What are the treatments for BPPV?
habituation techniques & excersises
particle repositioning maneuvers
surgical intervention (rare)
What is the treatment for Anterior/Posterior canal BPPV ?
epley - most common
semont
What is the treatment for Horizontal canal BPPV?
BBQ roll
What will the patient complain of if they have unilateral vestibular damage vs bilateral vestibular damage?
unilateral = perceived spinning
bilateral = feeling of off balance, the patient would not have nystagmus based on asymmetry
Vestibular testing is a test of?
function not structure
What is the purpose of a vestibular assessment?
to determine if the symptoms are caused by the inner ear, brain, or both
What is the difference between OPK & smooth pursuit?
smooth pursuit is tracking a single target back and forth, the OPK test is tracking a moving field (test with the moving image)
What are the sensory structures in the peripheral vestibular system? and what are their sensory structures?
The two types of sensory structures within the peripheral vestibular system are semi circular canals and otolithic organs. The otolithic organs are the utricle and saccule and the sensory structures of the otolithic organs are the otoconia.
What is direction changing nystagmus?
key points is that it beats in one direction. Slows down and stops. Goes in the other direction. BUT it has to happen just in center gaze they cannot be moving positions and that happen or its something else
What is a disconjugate eye movement?
anytime the eyes do not look symmetrical in their movement
What are the vestibular reflexes?
- VOR - generates movements that are equal and oppsoite to the head movement so we can maintain a clear image - assess with dynamic visual aquity
- VSR - maintain postureal stability, if damaged pt will bend or walk opposite way - assess using postural stabilty exams
- VCR - vestibulocollic - acts on neck muscles to stabalize head - assess using Vemp
What are the tests used for central findings?
- oculomotor testing ENG/VNG
- having them fixate if they come in with center nystagmus
What is BPPV? What tests do you use to diagnose it? What are the treatments?
- the most common cause of vertigo. can be caused by degeneration, head trauma, & viral infection. the otoconia become detached - from here is can either be canalithiasis or cupulothiasis. canalthiasis is when the otoconia move freely in the SCC, usually delayed onset after we place the patient in a provoking position, has fatigue over time. cupulothiasis is when the otoconia adhere to the cupula, usually immediate onset after placing the patient in a compromising positionm, little to no fatigue over time. BPPV most commonly occurs in the posterior canal and least common is anterior. We classify BPPV by which side is worse.
- Diagnosing - dix hallpike (anterior posterior bppv) abnormal for this is torsional nystagmis & supine head roll (horizontal bppv) abnormal for this is geotropic & ageotropic
- What do we need to diagnose :
- latency beginning 1 sec or more after head tilt
- last a least 1 min
- rotational nystagmus
- reverseal observed when sitting and fatiguability over time
- General treatments - habituation techniques, particle repositioning maneuvers, and raely surgery
- Specific treatment - for anterior BPPV is the epley or semont & for horizontal it is bbq roll
