Final Exam Calorics Flashcards
(99 cards)
1
Q
Caloric Tests cold and warm air temps
A
Air
cool = 24oC;
warm = 50oC
2
Q
Caloric Tests cold and warm water temps
A
Water
cool = 30oC;
warm = 44oC
3
Q
COWS
A
CO: Cold Opposite
WS: Warm Same
4
Q
For Calorics Nystagmus results are calculated to obtain what?
A
Nystagmus results are calculated to obtain Unilateral Weakness and Directional Preponderance
Only horizontal canal
5
Q
Advatanges of caloric tests
A
- You can evelaute each ears horizontal canal separately
- Test low frequencies and majorty of vestibualr disorders affect low frequencies.
- By putting a stimulus in the ear canal you are able to stimulate the horizontal SSC of that side which changes the neural activity. (changing endolymph)
6
Q
Disadvatanges of caloric tests
A
- Results are affected by the status and barriers of the middle ear. (temp transfer)
- Only tests LF’s it simulates movements of the head that are slower than those that are natural movements.
- Calorics are not site specific. They only evaluate the horizontal canal and superior vestibular nerve.
7
Q
Caloric Testing
Calculation of Parameters
A
- Unilateral Weakness (UW): Compares right ear vs. left ear response differneces. (RC & RW same ear)
- Directional Preponderance (DP): Compares right beating vs. left beating eye movements. (RC & LW - both left beating)
- fixation suppression (FS): Normal cerebellar function is what is able to reduce the nystagmus with fixation suppression.
- hyperactive/hypoactive responses and bilateral caloric weakness: This is the total eye speed where we add together all responses.
DP - left VS right beating eye movement
UW- Left VS right ear
8
Q
What does the Total number (total reponses) tell you?
A
The total number tells you if its hyperactive/hypoactive responses and bilateral caloric weakness
This is the total eye speeds (all reponses added together)
Hyper = greater than 140
Hypo = less than 26
* not responsing as it should bilteral vestbualr loss
9
Q
what total response is indicitive of bilateral vestibular loss?
A
Hypoexcitability = less than 26
not responsing as it should = signs of bilteral vestbualr loss
10
Q
Caloric Testing
Calculation of Parameters
The capability of the CNS to exert control over the vestibular nuclei and thereby attenuate caloric nystagmus when the eyes are opened and gaze is fixed on a point this is referred to as
A
fixation suppression [FS]
* Normal cerebellar function is what is able to reduce the nystagmus with fixation suppression.
11
Q
Caloric Unilateral Weakness
Equation & passing criteria
A
Normal: Under 25%
Abnormal: Above 25%
12
Q
Caloric Directional Preponderance
Equation & passing criteria
A
Normal: below 35%
Abnormal: above 35%
13
Q
Name the test type
A
Directional Preponderance
Calorics
14
Q
Name the test type
A
Unilateral Weakness
Calorics
15
Q
What Assess the connections between the vestibular nuclei and the midline cerebellar structures.
A
The fixation index (FI)
16
Q
The ____ is used to assess the intactness of connections between the vestibular nuclei and the midline cerebellar structures.
A
The fixation index (FI)
17
Q
Normal or Abnormal & why
A
Normal fixation, when the lights turn on nystagmus gets smaller.
* Because Normal cerebellar function is able to reduce nystagmus w/ fixation suppression.
18
Q
Normal or Abnormal & why
A
Abnormal, light turns on and nystagmus does not change.
Failure of fixation suppression
19
Q
A clinically significant unilateral weakness is defined as an interaural difference in____
A
A clinically significant unilateral weakness is defined as an interaural difference in mean maximum SPV of 20-25% or greater.
20
Q
SPV
A
Slow
Phase
Velocity
21
Q
what is the significance of A clinically significant unilateral weakness (greater than 25%)
A
The significance of this is that there is an asymmetry in the magnitude of information entering the brain stem to drive the VOR.
22
Q
what is the interpretation of A clinically significant unilateral weakness (greater than 25%)
A
The interpretation of these findings is that the patient is demonstrating evidence of a significant peripheral vestibular system deficit.
23
Q
what is the findings of A clinically significant unilateral weakness (greater than 25%)
A
The finding of a significantly reduced caloric response on one side provides lateralizing information (the disorder is usually ipsilateral to the side demonstrating the reduction) but does not provide localizing information (end organ, or nerve, or root entry zone).
Thus, a unilateral weakness can be caused by damage occurring within the vestibular end organ, the vestibular portion of the VIII N, or the root entry zone of the VIII N.
24
Q
UW can be caused by damage of the what?
A
UW can be caused by damage of the vestibular end organ, superior CN8, or root entry zone of the CN8
25
COWS inverstion is indicative of what?
1. Technical error
2. Brainstem disease
3. Middle ear pathology
26
**true** COWS inverstion is indicative of what?
Brainstem disease very rare but you need to rule out technical error and ME pathology
27
what is perversion COWS
* nystgamus is oblique or verticle not side to side
28
perversion of COWS is indictive of
1. Brainstem
29
# True or False
Calorics are site specific
FASLE could be
* Horisonal
* SVN
30
What is the caloric test order
RW LW LC RC
or
RC LC LW RW
| basically keep the colds and warms together
31
A DP exists when what?
A DP exists when **the nystagmus response is greater in one direction than in the other.**
32
A clinically significant directional preponderance is defined as ___
A clinically significant directional preponderance is defined as **a 30% or greater difference** in intensity of the maximum SPV between the two right beating responses and the two left beating responses.
33
DP is useful when
Useful when you have one eye already beating a certain way or when caloric data is not in agreeance with COWS.
- DP by itself is not useful.
34
DP is most often seen in patients who ....
A DP is most often seen in patients who have a **strong spontaneous nystagmus.**
35
DP patients who have a strong spontaneous nystagmus demonsttrate what caloric response?
Patients with spontaneous nystagmus tend to show **stronger reactions** to caloric stimulation that aligns with & beats **towards** their existing spontaneous nystagmus direction.
* This response is expected because the stimulated side is likely already more active or dominant.
36
What is the Fixation Index?
Fixation Index: A measure of how much nystagmus (involuntary eye movement) is reduced when the person visually fixes their gaze on a target.
37
What is Failure of Fixation Suppression
Failure of Fixation Suppression: When a person cannot adequately reduce nystagmus through visual fixation.
38
# True or False
For Fixation Suprression studies have shown varying results in how effectively people can suppress this eye movement using visual fixation.
TRUE
Different research studies have shown varying results in how effectively people can suppress this eye movement using visual fixation.
* The degree to which caloric nystagmus is attenuated by visual fixation has been reported in the literature as varying depending upon which laboratory data set is used.
39
# Calorics
Fixation index in normal individuals should be able to suppress caloric-induced nystagmus_____
It is suggested that physiologically normal individuals should be able to suppress caloric-induced nystagmus **60% or more with visual fixation.**
40
What is Caloric Inversion?
Caloric inversion is defined as an entire caloric response that beats in the opposite direction to that expected.
**DOES NOT FOLLOW COWS**
41
Caloric inversions are __ and have been associated with ___
Caloric inversions are **rare** and have been associated with **brain stem disease**.
42
Caloric Inversion is most commonly a result of what?
Caloric Inversion is more commonly a result of a **technical error or in patients with PE tubes**
43
What is caloric Perversion
Caloric perversion refers to the generation of an **oblique or vertical nystagmus** following stimulation of the horizontal semicircular canal during caloric testing.
44
# name the nystgamus
Diagonal motion
Oblique nystagmus = Diagonal motion
* Diagonal movement (combines horizontal and vertical motion)
45
# name the nystgamus
Up-and-down motion
Vertical nystagmus = Up-and-down motion
* Pure up-and-down movement
46
# name the nystgamus
Twisting/spiral motion
Rotational nystagmus = Twisting/spiral motion
* Eyes rotate or "twist" around the visual axis (like a spiral motion)
47
Caloric Perversion is link to what disease?
Caloric Perversion has been linked to disease affecting **brain stem** structures at the *floor of the fourth ventricle.*
48
BVL
Bilateral Vestibular Loss
49
what is used rimarily when bi-thermal irrigations are very low or to help confirm diagnosis of BVL though rotary chair is gold standard?
Ice Water Calorics
50
What can also be useful for confirmation of ablative procedures such as gentamycin injections and vestibular nerve section?
Ice Water Calorics
51
Ice Water is used primarly when?
Used primarily when **bi-thermal irrigations are very low or to help confirm diagnosis of BVL** though rotary chair is gold standard
52
# True or False
Ice Water calorics are the best tool to diagnosis BVL?
FALSE
* IWC is to help confirm diagnosis of BVL BUT you have to use rotary chair to be able to diagnosis
* (Rotary chair is gold standard)
53
Ice Water is also useful for confirmation of what?
seful for confirmation of ablative procedures such as **gentamycin injections and vestibular nerve section**
54
How do you conduct Ice water Calorics?
No universally standardized procedure or temperature but typically a single bolus approximately **2cc of ice water (~18℃)** is delivered to the ear
* traditional caloric position **(Supine, head elevated 30deg, vision denied)** or supine head rotated and held before returning to caloric position or prone
55
Name the main uses for Ice Water Calorics?
* confrim BVL
* Detect is any damage occured during any procedures (surgery was sucess or not)
* determine any residual vest function remaining due to toxicity
* when alternate bithermal caloric testing (ABB) yields no recordable responses.
56
ABB
alternate bithermal caloric testing
57
What is alternate bithermal caloric testing
Same as regular calorics
58
Describe the traditional caloric position
**Supine, head elevated 30deg, vision denied**
* HSCCs are now perpendicular to ground
59
# True or false
When evaluating nystagmus obtained from the ABB test assume that the absence of a response = no vestibular function in the horizontal semicircular canal.
FALSE
When evaluating nystagmus obtained from the ABB test **do not** assume that the absence of a response reflects no vestibular function in the horizontal semicircular canal.
* The identification of residual vestibular function (even minimal) in an impaired system is important for several reasons.
60
what testing has been primarily used for instances when alternate bithermal caloric testing (ABB) yields no recordable responses.
ICE WATER CALORICS
61
# True or False
The identification of residual vestibular function ( even minimal) in an impaired system is important for several reasons.
TRUE
62
Name the Variants of the Caloric Test
* **Bi-thermal** water test (the standard); bi-thermal air
* **Mono-thermal** test - a single large bolus of ice water is given rather than two irrigations with hot and cold OR
* **Bilateral irrigation** - both sides are irrigated simultaneously
* **Balloon test** - a water filled balloon is used instead of water
* **Ice water caloric** - used to confirm complete loss
63
the standard Calorics
Bi-thermal water test (the standard); bi-thermal air
64
a single large bolus of ice water is given rather than two irrigations with hot and cold
Mono-thermal test
* a single large bolus of ice water is given rather than two irrigations with hot and cold
65
both sides are irrigated simultaneously
Bilateral irrigation
* both sides are irrigated simultaneously
66
a water filled bag is used instead of water
Balloon test
* a water filled balloon is used instead of water
67
used to confirm complete loss
Ice water caloric
* used to confirm complete loss
68
what is has greater variabiliity air or water?
**Air** has greater variability than water
69
what is has the least amount of variabiliity air or water?
Water
* Water is more consistent; it is less prone to technical errors like bad irrigation.
70
Caloric Irrigations
* Allow for ‘ear-specific’ evaluation of vestibular system via VOR
* Patient must be placed in the ‘caloric position’
* Performed with air or water (warm & cool stimulation)
71
Air:
Temps, time, record time & protocol
Air:
* Warm 50°C, Cool 24°C
* 1 minute (flow 8L)
* Record for at least 90 seconds. while Reverse protocol. TASKING!
* Measure the peak SPV of the nystagmus generated
* C.O.W.S. mnemonic (for supine irrigations)
* Provide Target of nystmus is still present so you can stop nytsgmus
| Tasking is so they dont supress nysgmus while recording
72
Water:
Temps, time, record time & protocol
Water:
* Warm 44°C, Cool 30°C
* 30 seconds (250mL)
* Record for at least 90 seconds. while Reverse protocol. TASKING!
* Measure the peak SPV of the nystagmus generated
* C.O.W.S. mnemonic (for supine irrigations)
* Provide Target of nystmus is still present so you can stop nytsgmus
| Tasking is so they dont supress nysgmus while recording
73
Pros to water
* **faster**
* **more reliable** (better test/re-test, less prone to inadequate stimulation from cerumen occlusion, hitting canal wall, etc)
74
Pros to air
* more tolerable
* less messy
* can be done on those w/ various middle ear pathology that would preclude water (otitis externa, PE tubes, etc)
75
Reverse protocol
* The test is conducted in a sequence that ensures each successive irrigation triggers nystagmus in the opposite direction of the previous one.
* Allow the previous nystagmus response to fully subside.
* Approx 5 mkinutes inbetween each caloric
Example
Standard Reverse Protocol:
Right Warm (RW) → Left Warm (LW) → Left Cool (LC) → Right Cool (RC)
Option 2 Reverse Protocol:
Right Cool (RC) → Left Cool (LC) → Left Warm (LW) → Right Warm (RW)
76
How do we do the reverse Protocol?
By alternating the direction of nystagmus with each step, this
* Prevents "additive responses" — a situation where consecutive responses build on each other, potentially skewing the results.
* Reduces the risk of misinterpreting the patient’s vestibular response as stronger or weaker than it actually is.
77
# True of False
oblique and rotational nystagmus are same.
FALSE
Oblique would mean there is some horizontal and vertical movement (would look almost like slanting if you watched the eyes) whereas rotational is third dimension (clockwise or CCW). If you were only looking at a 2-D recording (tracing) though, they would look pretty much the same.
78
What is the point of the different temptures for calorics?
* Temperature transfer from air/water stimulus changes endolymph density within small portion of HSCC
* Altered density causes endolymph movement (relative to gravity) within HSCC via convection
79
Convection current generates a whart?
Convection current generates an **excitatory or inhibitory response in the HSCC of the test ear**
80
Warm stimulation =
Warm stimulation = decreased endolymph density = ampullopetal flow = excitatory response for test ear
81
Cool stimulation
Cool stimulation = increased endolymph density = ampullofugal flow = inhibitory response for test ear
82
____ = increased endolymph density = ampullofugal flow = inhibitory response for test ear
**Cool stimulation** = increased endolymph density = ampullofugal flow = inhibitory response for test ear
83
____ decreased endolymph density = ampullopetal flow = excitatory response for test ear
**Warm stimulation** = decreased endolymph density = ampullopetal flow = excitatory response for test ear
84
excitatory response for test ear
Warm stimulation = decreased endolymph density = ampullopetal flow = excitatory response for test ear
85
inhibitory response for test ear
Cool stimulation = increased endolymph density = ampullofugal flow = inhibitory response for test ear
86
* Comparison of bi-thermal RE responses to LE responses
* Abnormal Significance: indicates pathology on weaker side
Unilateral Weakness
87
Unilateral Weakness Criteria for interpretation
* Comparison of bi-thermal RE responses to LE responses
* Abnormal = > 25% inter-aural difference (asymmetry)
* Significance: indicates pathology on weaker side
* HSCC or Superior portion of vestibular nerve
* Caution: ensure good irrigations, no ‘stragglers’ (asymmetric)
88
* Comparison of right-beating to left-beating responses
* Abnormal Significance: non-localizing finding; low diagnostic utility
Directional Preponderance
89
Directional Preponderance Criteria for interpretation
* Comparison of right-beating to left-beating responses
* Abnormal = greater 35% difference
* Significance: non-localizing finding; low diagnostic utility
* Caution: most commonly seen with pre-existing spontaneous nystagmus or w/ asymmetric responses due to poor irrigation
90
Jongkee’s formulas for calorics Unilateral Weakness
91
Jongkee’s formulas for calorics Directional Preponderance
92
What is Total Response benefical for?
* Useful for determining possibility of **bilateral vestibular hypofunction (BVL)**
* Useful for determining **hyper-responsive** though much *less useful clinically*
| Total Response is just the total of all the R&L W&C responses.
93
* Comparison of total responses (sum of all) from both ears
* Equal or less tham 26 deg/s
Hypo-Responsive
94
* Comparison of total responses (sum of each ear) individually
* Equal or greater then 140 deg/s
Hyper-Responsive
95
# Total Response
* MAY indicate bilateral vestibular loss
* Non-localizing finding (can be central or peripheral)
Hypo-responsive
96
# Total Response
central (typically cerebellar); rare finding
Hyper-Responsive
97
Hypo-Responsive Criteria for interpretation
* Comparison of total responses (sum of all) from both ears
* < 26 deg/s
* Significance: MAY indicate bilateral vestibular loss
* Non-localizing finding (can be central or peripheral)
* Caution: Alertness of patient (fatigue, meds), appropriate tasking
98
Hyper-Responsive
Criteria for interpretation
* Comparison of total responses (sum of each ear) individually
* >140 deg/s total RE responses, >140 deg/s total LE responses
* Significance: central (typically cerebellar); rare finding
* Caution: most common w/ bad calibration, abnormal middle ear (mastoid cavity, perforation, PE tube) or bad irrigation temperature
99
Caloric Limitations:
* Only tests VOR at very low frequency
* Only tells us about function of HSCC & SVN
* Variable & slightly uncomfortable
* Can’t be performed / evaluated on some patients (Perf, PEtube)
* Can infer but not definite for bilateral vestibular loss (BVL)
* can not determine the level of functional compensation
