Final Exam Study Guide (New Content) Flashcards
who first described caloric reflexes? what did he earn? who is he
First described by Robert Bárány in 1906; earned the Nobel Prize in 1914.
Father of neurotology → first described caloric testing after noticing nystagmus during earwax irrigation
Most informative VNG subtest, isolating one vestibular organ at a time
calorics
Uses warm or cool water/air to stimulate
horizontal semicircular canal (HSCC) and induce nystagmus
describe what calorics primarily assesses
Primarily assesses vestibular function and detects asymmetries between ears
Assesses asymmetric vestibular function and peripheral vestibular pathways (up to CN VIII)
Normally, both sides work together. Stimulating one while the other is at rest induces vertigo
what can calorics also assess
Can also help assess brainstem function (e.g., in cases of brainstem death)
what is the bs critical for
cardiac, respiratory, and CNS regulation
Involved in all life-sustaining measures → heart rate, body temperature, sleep cycle, etc. (automatic things)
what is the major function of the flocculus
inhibit vor
More severe damage affects ____ responses first before impacting ______.
LF
HF
LF Tests
Calorics, Slow Rotary Chair.
HF tests
Head Impulse Test
Normal body temp
37 deg C or 98.6 deg F
types of caloric testing
bi-thermal tests (standard method)
mono-thermal
bilateral irrigation
balloon test
ice water
what is monothermal test
ice water irrigation in one ear → larger response further away from body temp you are
bilateral irrigation
both ears stimulated simultaneously
balloon test
water-filled balloon instead of direct irrigation
confirms complete vestibular loss
Ice water caloric test
Open systems/stimulations
Direct air/water irrigation
Closed loop systems
Inflated water-filled balloon transfers temperature
caloric testing position
The patient lies supine with head elevated 30° to align HSCCs perpendicular to gravity
what is included in irrigations
Cold & Warm Water or Air
describe water procedures
44/30 for 30 sec
Warm → 44oC
Cool → 30oC
describe air procedures
50/24 for 1 min
Warm → 50oC
Cool → 24o
6 up and 6 down
air and water calorics
Nystagmus response recorded for
90s
reversal
perform RW, LW, LC, RC or RC, LC, LW, RW
Allow around ____ min between each irrigation to let vertigo subside
5
should you task during calorics
YES
transfer effects endolymph density/neural firing rate around 6-10s post onset & we are stimulating HSCC
t
Physiological Responses
COWS
cold opposite
warm same
describe how physiological responses occur
Temp transfer changes density of endolymph; density changes causes movement w/in HSCC through convection; convection current generates excite/inhibit response in HSCC of TE
describe cold physiological responses
opposite/contralateral → nystagmus beats to the opposite side
I
ncreased endolymph density → ampullofugal flow → inhibitory response in TE
describe warm physiological responses
same/ipsilateral → nystagmus beats to the same side
decreased endolymph density → ampullopetal flow → excitatory response in TE
Cold in RE
LB nystagmus
Cold in LE
RB nystagmus
Warm in RE
RB nystagmus
Warm in LE
LB nystagmus
what are the metrics to measure/interpretation criteria
unilateral weakenss (UW)
directional preponderance (DP)
fixation suppression/fixation index
caloric inversion
caloric perversion
hyperactive/hypoactive
bilateral caloric weakness
total response
what is unilateral weakness
caloric paresis/relative vestibular reductin (RVR
comparison of bi-thermal RE responses to LE responses
significance of UW
abnormality is on the weaker side
abnormal UW & what does it suggest
≥ 25% interaural difference = clinically significant asymmetry (abn) → suggests pathology in the HSCC or superior vestibular nerve
what is the jongkees formula for UW
(RW+RC) - (LW+LC)/(RW+RC+LW+LC) x 100
caution of UW
ensure good irrigations, no ‘stragglers’ (asymmetric)
causes of UW
Damage to the vestibular organ, vestibular nerve (VIII), or root entry zone of the VIII nerve
most common cause of UW
End organ disease
clinical significance of UW
Identifies the affected side but not the exact location of damage
what is directional preponderance
GA/BS
Comparison of right-beating to left-beating eye responses
exists when the nystagmus response is greater in one direction than the other
significance of DP
non-localizing finding, low diagnostic utility
produces right eye movement
RW & LC
produces left eye movement
LW & RC
clinically significant DP
> 30% difference in intensity of max SPV bw 2 RB responses and 2 LB responses
35% difference
DP references what side
Referencing the stronger side → eye has the desire to go in this direction
what is jongkee’s formula for DP
(RW+LC) - (LW+RC)/total x 100
or right going +right going eyes - left going + left going eyes / total x100
caution with DP
most commonly seen with pre-existing spontaneous nystagmus or w/ asymmetric responses due to poor irrigation
what is fixation suppression
degree to which caloric nystagmus is attenuated by visual fixation → varies depending on lab data set used
After irrigation and eye movement is recorded, fixation light occurs and we are looking at what can the normal system do when a light is present (stops or goes low ) what was the max nystagmus we can induce
what is a normal fixation suppression/fixation index
> /=60% suppression of caloric-induced nystagmus w/ visual fixation
what does fixation suppressino check for
cerebellar fixation compression
what is a normal fixation
nystagmus lessens with fixation
assesses if connections bw vestibular nuclei and midline cerebellar structures are intact - cerebellar flocculus
functional index
what is caloric inversion
entire response is reversed
Entire caloric response that beats in the opposite direction to that expected
Rare & associated w/ BS disease
More commonly w/ technical error
example of caloric inversion
Irrgating R ear w/ warm should generate RB but here it will generate LB nystagmus
what is caloric perversion
generation of an oblique or vertical nystagmus
Linked to disease affecting BS structures @ 4th ventricle
Linked to disease affecting BS structures @ 4th ventricle
caloric perversion
Rare & associated w/ BS disease
caloric inversion
Measure that looks at the system as a whole
describes the general state of how sensitive or responsive the system is
Hyperactive/Hypoactive Responses
what is hyporesponsiveness
comparison of total responses from both ears (sum of all) → may indicate bilateral vestibular loss
non-localizing
Caution: alertness of PT (fatigue, meds), appropriate tasking
< 30 deg/s (Stockwell, 1980), < 26 deg/s (Jacobsen, 1993), < 20 deg/s Hain
< 12 deg/s per ear (Barin, 2008) accounts for UW bias
hyporesponsive
what is hyperresponsiveness
comparison of total response individually (sum of each ear) → may indicate central pathology (e.g., cerebellar dysfunction)
Rare finding
Caution: most common w/ bad calibration, abnormal ME (mastoid cavity, perf, PE tube) or bad irrigation temp
> 140 deg/s total RE responses, >140 deg/s total LE responses
hyperresponsiveness
most common w/ bad calibration, abnormal ME (mastoid cavity, perf, PE tube) or bad irrigation temp
hyperresponsiveness
alertness of PT (fatigue, meds), appropriate tasking
hyporesponsiveness
what is total response
Useful to determine possible BVL (hypo) & hyper responsive even though used less clinically
Do not use calorics alone for bilateral diagnosis; rotary chair used to confirm
Total response / total eye speed
TR (RC + LC + RW + LW)
Rotary chair testing is the only true way to diagnose a bilateral vestibular loss - reduced calorics DOES NOT indicate BVL (hypo)
true
causes of bilateral vestibular loss
Systemic infections
CNS disease (benign intracranial hypertension, inherited and acquired BS & cerebellar neurodegenerative diseases (Friedreich’s ataxia, Wernick-Korsakoff syndrome)
bell’s phenomenon
(doll eyes)
Reflex averting (rolling up) and adducting (moving laterally toward one another) of the eyes that occur upon eye closure - ENG only w/ eyes closed
common errors of calorics
Was the irrigation good? - operator error is the most common
Visualize the ™ to direct water/air to it to ensure adequate temperature
What can affect the temp transfer
wax, hair like a jungle, ME effusion,
If you have three responses that look good and one that doesn’t, the assumption must be made that the one irrigation was bad and you should re-do it. If you have 2 of 4 bad, on the same side, it is more likely a unilateral weakness
true
advantages of calorics
Ear specificity/laterality of the test → physiologic integrity of L & R horizontal canal; periphery can be directly assessed
Caloric stimulus is nonphysiologic →The caloric test isn’t a natural way to stimulate the balance system because, in everyday life, both sides of the inner ear work together when we move our head and body. However, when we put warm or cool water in one ear, it changes the movement of fluid in the nearby balance canal on that side. This, in turn, affects the signals sent from that ear’s balance system to the brain
Can rule out mild deficits
Affects LF first
limitations of calorics
Level of stimulation reaching the system varies
Only assesses LF VOR function (0.002–0.004 Hz)
Not suitable for some patients (e.g., young children, surgical ears, severe middle ear pathology, microtia/anotia, otorhhea, etc.)
Variable & slightly uncomfy
Can infer but not definitely diagnose for BVL - no statement about VOR & BVL should be based on calorics alone
Central compensation can restore function over time, but caloric testing will always show past damage & cannot determine level of functional compensation (rotary chair can help)
true
what is ice water calorics used for
Primarily used when bi-thermal irrigations are very low or to confirm diagnosis of BVL
Rotary chair is still gold standard
Useful in confirming ablative procedures - gentamicin injections & vestibular nerve section
Sees if there is any function of the vestibular system left
gold standard for BVL
rotary chair
No universally standardized procedure or temperature but typically a single bolus approximately 2cc of ice water (~18℃) is delivered to the ear
ice water
why would you do ice water calorics
confirm BVL
PT undergoing ablative surgery for intractable vertigo - If PTis getting surgery to disable one side of their balance system because of severe vertigo, having some remaining function in that ear means they will likely feel very sick after the procedure. Knowing this ahead of time helps the doctor prepare for their recovery and manage their symptoms right after surgery
Good to know if there is any residual vestibular function when PTs are treated with vestibulotoxic medications to the peripheral vestibular system
Vestibular pathways undergo ________ following a unilateral damage
compensatory changes
Stages of Compensation:
Clamping Down - minimizes tonic imbalance & PT symptoms
Static compensation: Reduces spontaneous nystagmus at rest
Dynamic compensation: Reprograms the VOR to adjust for movement
Full compensation: Requires an intact cerebellum; vestibular rehabilitation can speed up adaptation
describe the process initally after acute unilateral vestibular loss
After insult, resting neural activity on damaged side decreases & is why we can measure caloric weakness on that same side & why person perceives vertigo
Tonal imbalance produces spontaneous nystagmus accompanying weakness
uncompensated (partially-compnesated) peripheral loss
how do we see nystagmus in acute vestib loss (uni)
Tonal imbalance of strong side drives the eyes slowly toward the weaker side & the brain’s compensatory mechanism rapidly jerks it back in the other direction
Causes a spontaneous nystagmus with fast-phase movement beating away from the damaged ear
Ex: L caloric weakness causes a RB spontaneous nystagmus
describe central compensation & its stages
First step - clamping down on resting neural activity on the healthy side to minimize tonic imbalance
Reduces asymmetry of VOR pathway and decreases vertigo symptoms
Over time clamping of the good side lets up as resting activity on the damaged side is restored
Static compensation - spontaneous nystagmus disappears & PT symptoms improve as long as their head is still
Patients with acute VOR deficits typically complain of vertigo whereas those with chronic VOR deficits complain of motion-provoked disequilibrium or disorientation as head movement results in blurring of the visual environment.
Last stage - dynamic compensation - involves reprogramming of VOR pathways to deal with long-term effects of labyrinthine loss on damaged side
Individual returns functionally to normal
Can be sped up by VRT/VR exercises
Good compensation relies on intact cerebellum (flocculus & paraflocculus specifically)
calorics will not always show weakness after compensation
F
Calorics will always still show weakness through the process and permanently after compensation
Abnormal findings on oculomotor exams
what should you do
Re-instruct
Repeat the test
True abn is always abn
Oculomotor data points
Use conservative criteria - 50% or more points for abn/normal criteria
what are patient confounding factors
Poor vision, eye abnormalities, fatigue, medications, inability to perform tasks
Textbook Feature - DOCUMENT
Use to take notes about subjective complaints or patient inability to perform tests or anatomical or other factors that might skew results
positional testing best practices
Turn PT head BEFORE recording to avoid appearance of nystagmus tracings
Be quick
Instruct PT to keep eyes open during positional testing
calorics best practices
Clean up & verify caloric data bw irrigations
Give PT 4-5 in between irrigations and work in reverse order
Avoids two irrigations in a row for same direction
Basic vestibular evaluation
includes: spontaneous nystagmus test with eccentric gaze fixation test, with recording, positional nystagmus test (minimum of 4 positions) with recording, optokinetic nystagmus test, bidirectional foveal and peripheral stimulation, with recording and osciallting tracking test, with recording
CPT 92540
In order for 92540 to be billed correctly, each procedural component listed under that code must be completed in their entirety (for example; 4 positional tests = Dix Hallpike, positional each position)
what can you do if you do not perform them all under that code
Add -52 modifier if only perform part of a code (e.g. only 3 irrigations for 92537) and -22 modifier if perform more than four irrigations (for example ice water also
Caloric vestibular test with recording, bilateral; bi-thermal
CPT 92537
Caloric vestibular test with recording, bilateral; monothermal (ie, one irrigation in each ear for a total of two irrigations)
CPT 92538:
reimbursement for VNG
Reimbursement 2020: ~$150 for CMS
If entire ENG/VNG is not performed, may be able to bill individual components rather than bundled (92540) code
true
Spontaneous nystagmus test, including gaze and fixation nystagmus, with recording
92541
Positional nystagmus test, minimum of 4 positions, with recording
92542
Optokinetic nystagmus test, bidirectional, foveal or peripheral stimulation, with recording
92544
Oscillating tracking test, with recording
92545
Add the -59 modifier if bill two or three of 92541, 92542, 92543, or 92544 on the same patient on the same date of service
Billing multiple vestibular tests on the same day
true
Canalith Repositioning Procedure(s) (e.g., Epley maneuver, Semont), per day
95992
reimbursement for canalith repositioning
Reimbursement 2020: ~$50 for CMS Not covered under Audiology benefit
what is the code for saccades
there is no code
how does VOR work if you turn head to R
Acceleration to the right, endolymph flow to the left, eyes stay to the left
SCC work in pairs
Senses strength & direction of acceleration and deceleration
describe 3 instances during an impulse
vor slow phase (latency & gain)
- head impulse start - time when the head velcoty exceeds 20 deg/s
- peak acceleration/velocity - where velocity/acceleration reaches max values
- head impulse end - head velocity crosses 0 deg/s & usually repounds
computerized way to look at how the eyes are moving relative to the head movement
vHIT
what is the head impulse test / head thrust test
Bedside screening to detect SCC dysfunction in ALL canals
Useful to detect peripheral vestibulopathy
who discovered HIT? what did they do and find
Described by Halmagyi & Curthoys 1988 in study of 12 PTs w/ unilateral vestibular neurectomy
Found altered VOR gain and re-fixation (catch-up) saccades in abn individuals during head thrus
how to perform vHIT
Patient keeps eyes focused on fixed point
Head moved rapidly (200+degrees/second), 10-20 deg range only
Keep unpredictable
Can be performed from 10 months old to elderly
what are covert saccades
saccades happening DURING head movement; unable to see w/ naked eye
Hidden when head moves; cannot see
Compensated lesions
what are overt saccades
saccades happening AFTER head movement; can see w/ naked eye
See after head stops; through instrumentation or bedside
Uncompensated lesion
Instrumented version of the bedside technique (Halmagyi) used to diagnose reduction in vestibular function
Quantifies gain measures & detects both overt and covert
vHIT
best way to perform vHIT
Head rotations should be rapid & unpredictable in direction and time, small amplitude (10-15 deg), and peak head velocity (150+ deg/s
lateral/horizontal vHIT
right and left (typical)
RALP vHIT
right anterior and left posterior
head turned to the left
LARP
left anterior and right posterior
head turned to the right
how to analyze vHIT
Gain → eye movement relative to the head movement
Normative >0.7 some systems, >0.8 other systems
Presence of re-fixation saccades (covert & overt)
vHIT gives site specificity about where the damage is located
t
adv of vHIT
fast, easy to do, anyone can tolerate it, gives us more anatomical information (multiple canals & nerve branches), in line with how our system normally functions, ear pathology, compensation status, VRT, portable
disadv of vHIT
HF information only (can have mild and miss it), no cpt codes so reimbursement is either free or OOP for the PT (advanced beneficiary notice - says ins might not cover something) technique is challenging, some research suggests dysfunction secondary to meniere’s disease
dysfunction secondary to meniere’s disease
vor/vhIT
how does calorics differ from vHIT
Highly variable, affected by alertness & meds, unpleasant, time consuming, only tells about HSCC fxn, not portable & need dark environment, & are reimbursable by insurance, and catches milder UW
what are the disadv of calorics compared to vhit
Evaluates VOR in frequency below physiological range (.003 Hz)
Induces non-physiologic endolymphatic flow in HSCC & creates technique problems (failed irrigation, asymmetrical transmission of thermal energy or persistent stimulation bw irrigations & alertness)
Time consuming, discomfort to PTs
Results cannot determine compensation
how does vHIT differ from calorics
Not reimbursable by insurance, misses milder UW (~<40%), insensitive & not performing as well as calorics, greater specificity than calorics
Evaluates physiological HF range of VOR in HSCC, ASCC, PSCC (up to 5 Hz)
Fast & well tolerated, allows for re-testing
Results can determine compensation process
Instantaneous gain analysis gives direct measure of how balance system controls eye movement because it isn’t affected by slower brain or eye movement adjustments but position gain analysis can be influenced by these factors and makes it less of a pure test of function
what does HINTS stand for
Head Impulse, Nystagmus, Test of Skew
what is hints
Strokes can be distinguished from benign acute vestibulopathies using bedside oculomotor tests
Pro → more sensitive (<24hrs) and less costly than early stage MRI for stroke
Con → requires expertise not routinely available in ER
Conceptually similar to ECG to diagnose acute cardiac ischemia
interpretation of HINTS
Head impulse = - central
Head impulse = + peripheral
Test of skew = - peripheral
Test of skew = + central
onset from per and cen
sudden
sudden or gradual
severity of peri and cent
intense
ill-defined, less intense
pattern of peri and cent
paroxysmal, intermittent
constant
worse w/ movement for per and cen
yes in peri
variable in cent
nausea/diaphoresis peri and cent
frequenty in per
variable in cent
nystagmus in peri and cent
horizontal
vertical or multi-directional
fatigue signs in peri and cent
yes
no
HL or tinnitus in peri or cent
maybe in peri
no in cent
CNS signs
peri no
central usualy present
what is the variant to vhit and who reported it
SHIMP
macdougall 2016
what is SHIMP variant to vHIT
PTs view a laser dot that moves with their head and PTs turn off their VOR than to use it
Anticompensatory saccades are elicited in normal controls but less commonly found in those who have less VOR to suppress
If vHIT is normal
perform other vestibular function tests
vHIT alone doesn’t conclude normal vestibular function
If vHIT is abnormal
use hx, symptoms, medical hsitory and other testing to triage PT
vHIT is a great quick easy test to tell about function of the VOR for all 6 SCCs, state of superior & inferior VN, and can indicate if the issue may be central
true
what is a concussion
type of traumatic brain injury (TBI) caused by bump, blow or jolt to the head or a hit to the body that causes the head and brain to move rapidly back and forth
doesn’t appear on mri or ct
no diagnostic test for it
how does a concussion happen
Sudden movement causes the brain to bounce around and twist in the skull creating chemical changes in the brain and sometimes stretching and damaging brain cells
how do you daignose concussion
based on groups of symptoms or signs that may be immediately present or arise over weeks after
Some develop no symptoms after a concussive event and some can takes weeks
what symptoms of vestibular disorders aligns with concussion/TBI
Dizziness / Vertigo
#2 Imbalance or unsteadiness
Blurred or bouncing vision
Problems with coordination, thinking, memory
#8 Headache
#9 Sensitivity to noise / bright lights
#10 Fatigue
only test we have to split the vestibular system and test each ear individually
ear specificity
calorics
the only true way to diagnose a bilateral vestibular loss
rotary chair
hypo responsiveness indicates a bilateral VL
FALSE
does not
who had the earliest written acount of vertigo
Aristotle (384-322 BC)
Normal daily activities - produce head velocities up to ______, accelerations up to _______and frequency from _____
550 deg/s
6000 deg/s
0-20Hz
Best way to evaluate VOR
Very LFs - calorics
Low & mid frequencies - rotary chair
HFs - active head rotation
f
what is the VOR
reflexive eye movement occurring in response to head movement
allows for stable gaze
who is barany? what did he win? who was he? what did he create
Barany chair- 1876-1936; nobel prize in 1914
Hungarian physiologist
Device stimulating SCC through controlled rotation
types of rotational tests
passive
active
passive rotational tests
PT is moved by the examiner directly
Head or whole body
HIT/Head thrust, rotary chair tests, off-axis rotations (SVV & SVH)
active rotational test
PT moves their own head
Can be active or passive headshake
Vestibulo-authorotation test (VAT/Vorteq)
eval parameters of VOR
gain, symmetry & phase
axis of rotation of rotational tests
centered bw both labyrinths (bilateral stimulation)
CCW rotations
LB nystagmus - L HSCC excites & R HSCC inhibits
CW rotations
RB nystagmus - R HSCC excites & L HSCC inhibits
what does rotational chairs evaluate
Examines HSCC, central systems & vestibular nuclei
Only concerned w/ slow phases & all are combined in sinusoidal form for analysis
what are the clinical applications of rotational testing
Evaluates for BVL or PT w/ low calorics
Monitors ototoxicity
Evaluates for CNS disorders
determine compensation status and rehab recommendations
Evaluates vestibular function on those who can’t undergo caloric testing (Surgical ears (mastoid cavity, PE tubes, perf, otorhea)
microtia/anotia
Young kids or handicapped)
