Term
Importance:
-vHIT allows each ___ ___ to be measured individually
-Caloric testing and rotational chair testing both measure ___ semicircular canal (SCC)
-___ organs of balance in each ear
-Need to measure more than a ___ organ in each ear
-Disorder or disease may be present in a ___ semicircular canal, ___ semicircular canals, or any ___ of semicircular canals
-First test that measures and quantifies function for each semicircular canal |
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Definition
| semicircular canal; horizontal; Five; single; single; all; combination |
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Term
VOR:
-Triggered by ___ ___ motion
-___, ___, and ___ movements
-Keeps visual field ___ as body and/or head move |
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Definition
| quick head; Yaw, pitch and roll; stable |
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Term
| What contributes to stabilizing the visual field? |
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Definition
| VOR, smooth pursuit, saccade, optokinetic, cervical input, and cerebellum |
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Term
vHIT:
-Measures ___ (head turn delivered by clinician) as well as ___
-Analysis related to each ___ to the stimulus which caused it
-Patient is given an ___ (start and stop) small head turn by the clinician (passive)
-Passive, ___ head movement stimulus, and eye movement response are measured |
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Definition
| stimulus; response; response; abrupt; unpredictable |
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Term
| How would you instruct a patient for the vHIT? |
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Definition
| Try not to blink “keep your eyes wide open”. Relax the neck muscles “like a rag doll”. Do not help with the head turns. I am going to move your head. Sometimes that movement will include a fast start and stop. Keep your eyes on the target throughout the test and try not to blink |
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Term
Saccade-Overt:
-Eyes do not receive adequate ___ drive from SCC on affected side to compensate for head turn. Eyes do not ___ for head turn; eyes do not stay ___ on the earth-fixed object but move with head. At the end of the turn, eyes must make a ___ saccade to return to target
-Tell-tale sign of deficient SCC function on side to which head has ___
-Overt saccade after passive left horizontal movement indicates ___ horizontal SCC loss |
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Definition
| neural; correct; focused; corrective; turned; left |
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Term
| A corrective saccade which occurs during the head turn |
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Definition
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Term
| Can't see a corrective saccade without the ___ ___. |
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Definition
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Term
| What are some uses for the vHIT? |
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Definition
-Emergency room – to distinguish quickly between patients with severe peripheral vestibular loss and patients with stroke
-Quantify extent of bilateral vestibular loss due to ototoxicity (when caloric responses may not be tolerated on a daily schedule for monitoring) |
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Term
| What instrumentation do you need for vHIT? |
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Definition
| Pair of glasses or goggles, operator's hands, and software |
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Term
What Is Being Measured:
-Camera acquires images of ___ position within head
-Measured by ___ camera attached to the glasses
-High speed ___ tracks pupil position |
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Definition
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Term
Software calculates:
-___ of eye movement
-For VOR gain calculations removes ___
-Removing saccades allows measurement of ___ phase velocity
-Software measures center of ___ and how center moves with respect to the head-fixed camera |
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Definition
| Velocity; saccades; slow; pupil |
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Term
-Test in a well ___ room
-Put the patient facing an evenly illuminated wall about __ meter away from patient
-Visual ___ does not occur because the impulse ends just as the VOR suppression begins |
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Definition
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Term
| Where does the audiologist stand in relation to the patient? |
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Definition
| Stand behind patient with hands on patient’s head. Computer on adjacent table. Operator delivers the stimulus |
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Term
| The camera speed is about ___ frames per second |
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Definition
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Term
Head Velocity Sensor:
-Measures ___ velocity of the head in three dimensions
-Head velocity ship (gyroscope) has ___ term stability
-No need for repeated ___ of head velocity |
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Definition
| angular; long; calibration |
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Term
Calibration:
-Usually two laser dots projected onto ___ with patient in position for test
-Patient asked to ___ at each, and computer logs data
-Computer uses that data to calculate eye ___
-If patient is unable to perform this, the ___ calibration may be used |
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Definition
| wall; look; velocity; default |
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Term
| How do you instruct the patient for calibration? |
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Definition
-Should make clear that patient needs to keep looking at exact center of fixation spot the whole time
-Keep eyes wide open (no blinks during trial)
-If gaze slips off fixation point, re-fixate as soon as possible
-Relax neck muscles |
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Term
Head Movement:
-Small angle __ to __ degrees
-Not size of head movement, but ___ of head movement
-Acceleration at ___ activates SCC creating eye movement
-Give patient a few head turns prior to starting to help ___ neck muscles |
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Definition
| 10 to 20; acceleration; onset; loosen |
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Term
Starting Position:
-Recommended start with head in ___ position with nose pointing straight at fixation target
-Target position is then ___
-___ head turns not accepted as valid stimuli
-Slowly return head to ___ position
-Direction and timing should be unpredictable |
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Definition
| central; unpredictable; Slow; central |
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Term
Number of impulses:
-Each head turn is a separate test of vestibular SCC function on the side to which head is ___
-___ improves confidence about functional state of VOR
-Recommended __ to __ repetitions
-Quality of impulse requires less ___
-Velocity of more than ___ degrees per second to avoid false negatives |
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Definition
| turned; Repetition; 20 to 30; repetition; 150 |
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Term
Time:
-About __ second or so between end of one head turn and start of next
-No fixed interval – must be ___ |
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Definition
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Term
Blinks:
-Some software can ___ blinks
-Let patient blink then give impulse for patients who are ___ to blinking |
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Definition
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Term
LARP and RALP:
-Patient head turned ___ degrees to median plane of head
-Creates LARP or RALP with ___ canals aligned toward the fixation target
-Allows measurement of just ___ eye movement component |
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Definition
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