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79 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What passive rotary test doesn't use a rotary chair?
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Halmagyi head thrust
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What is another name for the Head thrust and what is an abnormal result?
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Head Impulse test
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Abnormal: catch-up saccade when the head thrust is in the direction of the impaired system (in both directions with bilateral)
Normal: a compensatory eye movement close to 180 degrees out of phase from the movement of the head |
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Name 2 active rotary tests
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Headshake
Vestibular Autorotation Test (VAT) |
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When is the rotary chare most clinically valuable?
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-Bilateral caloric weakness
-when ENG/VNG cannot be conducted(ME fluid/TM perf/mastoidectomy) -Pediatric patients -serial monitoring |
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What does post-rotary nystagmus represent in the Velocity Step test?
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Central integration or summation of the rotary stimulation that continues to drive the eyes
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What are the measurement parameters for Sinusoidal Acceleration Testing and how are they calculated?
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-p= phase in time or degree
-Gain = b/a asymmetry=(b2-b1/b2+b1)x100 gives you a % |
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What happens to the VOR during the Sinusoidal Harmonic Acceleration Test when you as the patient to fixate?
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The light is mounted on the rotary chair so that the light moves with the patient, causing the visual signal to not match the vestibular signal.
This causes the brain to think the vest info is incorrect. Visual suppression will drop the gain of the VOR, so the ratio of ey speed to head speed will drop |
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What information can you gather regarding phase leads in the Sinusoidal Harmonic Acceleration Test?
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Abnormally long phase leads can be seen is cases of peripheral lesions of the vestibular system
Abnormally short leads, not as clear cut, have been observed in cerebellar lesions |
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Why is it difficult to use asymmetry in isolation to determine side of lesion with the Sinusoidal Harmonic Acceleration Test
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Asymmentry isn't necessarily uniquely indicative of uncompensated periph weakness or asymmetry in the responsiveness from the vestublar system. It actually can be influenced by an excitation or an irritative lesion contralaterally
Meineres disease and tumors are examples or irritative lesions |
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What is the time constant in the velocity step test and what is considered normal?
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The time taken for eye velocity to decline to 30% of its max value
It is an indicator of the velocity storage mechanism within the brainstem. 10 seconds indicates a normal response, with 10-13 second responses considered normal by some researchers |
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What passive rotary test doesn't use a rotary chair?
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Halmagyi head thrust
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What is another name for the Head thrust and what is an abnormal result?
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Head Impulse test
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Abnormal: catch-up saccade when the head thrust is in the direction of the impaired system (in both directions with bilateral)
Normal: a compensatory eye movement close to 180 degrees out of phase from the movement of the head |
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Name 2 active rotary tests
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Headshake
Vestibular Autorotation Test (VAT) |
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When is the rotary chare most clinically valuable?
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-Bilateral caloric weakness
-when ENG/VNG cannot be conducted(ME fluid/TM perf/mastoidectomy) -Pediatric patients -serial monitoring |
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What does post-rotary nystagmus represent in the Velocity Step test?
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Central integration or summation of the rotary stimulation that continues to drive the eyes
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What are the measurement parameters for Sinusoidal Acceleration Testing and how are they calculated?
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-p= phase in time or degree
-Gain = b/a asymmetry=(b2-b1/b2+b1)x100 gives you a % |
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What happens to the VOR during the Sinusoidal Harmonic Acceleration Test when you as the patient to fixate?
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The light is mounted on the rotary chair so that the light moves with the patient, causing the visual signal to not match the vestibular signal.
This causes the brain to think the vest info is incorrect. Visual suppression will drop the gain of the VOR, so the ratio of ey speed to head speed will drop |
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What information can you gather regarding phase leads in the Sinusoidal Harmonic Acceleration Test?
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Abnormally long phase leads can be seen is cases of peripheral lesions of the vestibular system
Abnormally short leads, not as clear cut, have been observed in cerebellar lesions |
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Why is it difficult to use asymmetry in isolation to determine side of lesion with the Sinusoidal Harmonic Acceleration Test
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Asymmentry isn't necessarily uniquely indicative of uncompensated periph weakness or asymmetry in the responsiveness from the vestublar system. It actually can be influenced by an excitation or an irritative lesion contralaterally
Meineres disease and tumors are examples or irritative lesions |
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What is the time constant in the velocity step test and what is considered normal?
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The time taken for eye velocity to decline to 30% of its max value
It is an indicator of the velocity storage mechanism within the brainstem. 10 seconds indicates a normal response, with 10-13 second responses considered normal by some researchers |
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2 Off-Axis Rotational tests
What info do they provide? |
Vertical Axis Rotation
Unilateral Centrification Test |
-equipment not widely available
-vertical axis rotation might induce significant nausea -some people respond with a neurovegtative response to simultaneous SSC and utricle stimulation |
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How and why do we perform the dynamic visual acuity test and would we expect change over time on this test
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provides a more practical measurement of the impact of vestibular disorder and impaired VOR and accompanying retinal slip and its influence on visual acuity and the ability to use vision
can document improvement due to therapy and successful compensation |
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What is the main goal of the Pulse-Step-Sine test?
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-to create bias
-to take away all the afferents on the side away from where you are rotating and drop the firing rate to 0 -to look at the response of the R and L vestibular neurons separately |
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What is the expected response on the Pulse-Step-Sine test with a unilateral left-sided vestibulopathy?
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-normal response with acceleration to the right
-abnormal response when rotating to the left -assymetry between ears |
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What does NEGATIVE ASYMMETRY indicate in Sinusoidal Harmonic Acceleration testing?
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Patient has greater gain to the left or a directional preponderance showing greater right-beating nystagmus compared to left beating (pg 260)
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What is the purpose of the Saccade Factor in sinusoidal harmonic acceleration testing?
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-# represents the limit of eye velocity accepted by the software for the slow phase
-purpose is to eliminate nystagmus fast phases and to retain nystagmus slow phases that are vestibular in origin |
a multiplier that you multiply times 50*/sec
-ex saccade factor of 1.2 would discard any fast phases greater than 60*/sec (pg 261) |
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What causes low gain in the sinusoidal harmonic acceleration testing?
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-If everything is working, this is a sign of a bilateral deficit
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Gain values may be artificially reduced if:
-patient is not adequately alerted -light leaks -disorders affecting the ability to generate eye movements -calibration errors |
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What in caloric testing is analogous to the asymmetry calculation in sinusoidal harmonic acceleration testing?
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directional perponderance
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What 2 frequencies are typcially used for chair rotation in the velocity step test?
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60 degree/sec
240 degree/sec |
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How do you calculate the dime constant during Velocity Step test and what would be an abnormal time constant?
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Values less than 10 seconds suggest the loss of central velocity storage and may be related to unilateral or bilateral peripheral deficit of a central vestibualr disorder
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TC=1/(3.14*Freq*TAN*Phase angle of output to input)
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What is the main difference between young children and adults on rotary chair testing?
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Infants and young children will produce LARGE AMP Slow Phase eye movements but FEWER SACCADES for a give stimulus
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What patient population experiences visually induced sensation of self-rotation during optokinetic tests using the entire field of vision and what is the name of the phenomenon?
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Normal population
Circular Vection Missing in 40% of TBI patients |
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What are the FIRST 2 tests that should always be done during rotary chair testing and why?
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Patient Calibration
-if not set correctly, you can't interpret the test results |
Spontaneous Nystagmus Test
-this can influence the test result by interacting with the rotary chair generated nystagmus |
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Why are the otolith organs not typically tested during standard rotary chair testing?
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The otoliths have equal centrifugal forces applied to the 2 sides, the effect is a cancellation of the response if the otolith organs are normal and functioning symmetrically
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When might a disordered patient feel like they are tilted during sinusoidal harmonic acceleration testing?
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If they have HYPOFUNCTIONING otolith organ
patient might feel tilted or some other sense of linear motion |
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What rotary test is best to use to monitor changes in the vestibular system over time?
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Sinusoidal Harmonic Acceleration test
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What is a typical cupular time constant in the Velocity STep test? Why does nystagmus preserve for 15-16 seconds when the head is accelerated?
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Cupular time constant = 4-7 seconds
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Preservation of nystagmus must be due to a central veloxity storage mechanism
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Why do we use the higher (240 deg/sec) step velocity during testing?
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-Drive the system into saturation
-generates highre gain values for patients with unilateral peripheral lesions -high velocity step rotation toward the intact ear generates higher gain values than when rotating toward the ear with the lesion because the lagging ear is unable to drive the afferent firing rate below 0 (Edward's 2nd law) |
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Which rotary test do we not want to alert the patient or have him/her talk?
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Visual fixation supression testing
-must concentrate on task |
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The presence of circulare vection during full field optokinetic testing tells about the health of what system?
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Central vestibular velocity storage mechanism
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What is the visual-vestibular enhancement and in which patient is it an especially important test?
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-during rotational chair testing, turning on a fixed OKN light generator
-a patient with poor peripheral vestibular function will produce a significant increase in the gain and bring the phase lead down to a near 0 or below because of the addition of the vestibular cues (opposite result of fixation) |
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What are the things evaluated during the VAT?
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-Phase and gain of the VOR
-Spectral Coherence -Dynamic Corneoretinal Potential |
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What is a typical VAT pattern for a patient following gentamicin ototoxicity?
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Low Gain
High Phase |
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What are findings that are more typical of CENTRAL LESIONS during the VAT?
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High Horizontal gain
-seen in head trauma -also look for saccades during smooth pursuit in 1st 6 sec High horizontal phase -if accompanied by high horizontal gaine, CNS involvement or head trauma |
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What is Computerized Dynamic Posturography?
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A non-invasive specialized clinical assessment technique used to quantify the central nervous system adaptive mechanism (sensor, motor and central) involved in the control of posture and balance, both in normal and abnormal conditions
-particularly in the diagnosis of balance disorders |
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The 3 primary test situations of the computerized posturography are?
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1-Sensory Organization test
2-Motor Control Test 3-Posture Evoked Responses |
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What is the importance of Translations?
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-translations produce characteristic sway responses
-look at symmetry of sway -if sway occurs in a reasonable time and if it slides suddenly backward or forward -record myographic potentials by using electrodes to record from leg musculature and measuring the responses |
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What is the Sensory Organization test?
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-a measurement of sway energy under various visual and support conditions
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What is the Motor Control Test?
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-measures sway in response to a tilt or translation in the support surface on which the patient stands
-a tilt would be either toes down or toes up -in that rotation or tilt the patient will learn fairly quickly how to adapt to the response |
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What is Posture Evoked Responses?
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EMG recordings during the Motor Control Test
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How can you determine if a person is using an ankle or hip strategy?
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By comparing vertical (ankle) and horizontal (hip) shearing forces.
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How fare in any given direction can you lean away from midline without altering your base of support?
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12.5* total
8* forward 4.5* back |
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What is Balance?
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trying to maintain you center of gravity over your base of support
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What 2 things are necessary to maintain your equilibrium?
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Sensory intergraion
motor coordination |
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To produce body movements that are going to bring your center of gravity into a vertically centered position over your base of support you're going to...
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select and adjust different muscles contractile patterns, either around the ankle or around the thigh, in the trunk
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What does Dynamic Equilibrium depend on?
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1Sensory Organization
-determination of teh body position, compare, select and combine senses (visual, vestib, somatasensory) -environmental interaction |
2-Motor Coordination
-choice of body movement 3-Select & Adjust muscle contractile patterns -ankle, thigh, trunk -generation of body movement |
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What are the limits of stability?
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8* forward
4.5* backward 12.5 theoretical limits of stability |
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How do you calculate Equilibrium Score?
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Theoretic limits of stability (12.5) and subtract from that the max sway front-back and divide by 12.5, then multiply by 100 for a %
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100(12.5-Max sway/12.5)
100% = no sway 0%= sway reaches LOS scores are normed for age and height |
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Describe the Sensory Organization test
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-6 positions
-1-3, surface is fixed -4-6 support surface is referenced to the person's sway - this provides distorted visual information |
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Describe conditions 1, 2 & 3 in the SOT
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1: eyes are open, support fixed
2: eyes closed, support fixed 3: Eyes open and visual field sways with patients sway |
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Describe conditions 4,5, 6 in SOT
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4: Eyes open, visual field fixed, floor moves with sway
5: Eyes closed, floor moves with sway 6: Eyes open, visual field is sway referenced, floor moves with sway |
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How do you score the SOT
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-3 trials per condition
-equilibrium score exceeds norms for the age, green on histogram -below score for age, red on histogram -composite score is separate |
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How do you determine which sensory systems may be compromised or somewhat more dependent?
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Somatasensory: 2/1 - ability to use input form the somatasensory system to maintain balance
Visual: 4/1 - ability to use input from visual for balance Vestibular: 5/1 - ability to use input from vest system for balance Preference:3+6/2+5 - degree to which the patient relys on visual info to maintain balance even when the info is incorrect |
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Somatasensory Ratio
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-Compares conditions 1 and 2
-condition 1= eyes open flore fixed, visual fixed, 2= eyes closed, floor fixed |
-good info from or dependent on somatasensory system: no difference
-sway with eyes closed, difficulty getting info from somatasensory system -information about the ability to use somatasensory system for balance |
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Visual Ratio
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-compare condition 1 and 4
-condition1= eyes open, visual field fixed, floor stable -condition 4= floor variable moving with patient, eys open and visual field stable -condition 4 removes or distorts the somatosensory cues |
-good visual info, remain stable in 1 and 4
-not good visual info, say more on 4 and score on 4 will drop comared to 1 -tells us about person's ability to use visual information |
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Vestibular Ratio
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-compare 5 and 1
-condition 1=eyes open, floor fixed, visual field fixed -condition 5= eyes closed and floor moves with sway, removes visual and somatosensory info |
-vestibular problem: not stable in 5
-good use of vestibualar info, stable in 5 -tells about ability to use vestibular information |
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Visual Preference Scale
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-tells about the degree to which the patient relies on visual information fro their balance even when the information is incorrect
-compareison between conditions 3 & 6 and 2 & 5 -3 & 6: visual field is sway referenced -2 & 5: eyes are closed comparing distorted vision to no vision |
-less stable in distorted than no vision: visually dependent (3=6 less than 2+5)
-may have adapted to somatosensory, neuromuscular or vestibular problem by depending on vision -score gives direction about kinds of things to do in therapy: teach to become less dependent on vision |
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Describe the ankle strategy
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-lower frequency
-slower responses -predominantly vertical forces -pushes down into the floor -center of gravity is not near the limits of sway and you have to adjust quickly, use ankle |
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Describe the hip strategy
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-faster reaction
-higher frequency reaction -center of gravity approaching your limits of sway, bend at hips to do something quickly -generates horizontal sheer forces |
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When are hip and ankle strategies used?
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-ankle strategy in more stable conditions, results in higher equilibrium scores
-hip strategy when less stable, results in lower equilibrium scores, closer to their limits of sway and a quick reaction is quite approprate |
a person who is fairly stable but constantly using a hip strategy usually has a problem, a potential problem
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What is the Center of Gravity Alignment?
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Looks at the center of gravity alignment and the average weight distribution in two dimensions, front-back, left-right
-looks at how close to their normal range, which is typically shown by the small circle in the center they are |
if shifted away, may indicate and may include, a peripheral sensory problem, a neurological problem, a musculosketetal problem, be an adaptation to a long-tem problem
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What muscles are included in the muscles of sway?
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abdominal
paraspinal quadriceps hamstring gastrocnemius tibialis interior |
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Describe the Motor Control Test
MCT |
-patient is on a surface that suddenly sloughs forward or backward
-the amplitude of their sway and latency between stimulus, the sliding of the surface, and the peak sway amplitude are measured -how the person maintains their symmetry of wieght on the left and right sides as they react is determined -asymmetry inidcates some kind of orthopedic, neuromuscular or other neurologic problem |
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Describe the stimuli for the MCT
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-come in 3 different sizes, small shift, medium shift, and large shift
-shifts go forward and backward |
How measured?
1-how long in time it takes before the person produces the large reaction to bring themselves back 2-strength of their response 3-how symmetrical it is, left and right |
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MCT test results
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NOrmal
-latencies are shorter for the large and medium displacements -stronger stimulus should result in a faster response -latencies should be the same between the left and the right |
Abnormal
-prolonged latency: if on one side may be caused by an orthopedic injury, either in the extremities or spinal cord, or spinal areas, or problem with the neurologic pathways -if isolated kind of problem the prognosis and the person's functionality is likely to be minor -if in a combination with other sensory deficits it may be a more serious problems. the person is at much greate risk for falling -possible treatments: rehab, referral to or use of PT to provide therapy, modification sin lifestyle |
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If latencies are prolonged on both sides this may indicate
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-peripheral neuropathy
-MS -spinal or orthopedic problem -brainstem lesions |
If it is combination with other things pt may need:
-changes in lifestyle -assistive device such as quad cane or walker -other things to help in fall prevention and amelioration |
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Describe the Adaptation Test of Motor Control
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-at least 5 trials
-sway energy & latency response should decrease as you get experience with the 1st trial and can make conscious preparations for that event |
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Interpreting the Adaptation Test of Motor Control
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No adaptation with increased trials may be due to:
-poor central adaptation: when ther is ankle weakness, sufficient central performance but ankle not stable enough to make the movements -range of motion impairment: unable to accomplish quickly, can't produce th emotion and force needed to bring the COG back due to the range of motion problems -greater problem on irregular surfaces and is going to be a good candidate for PT |
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Which modified test can be used as a clinical test for Sensory Interaction of Balance?
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Force Plate in the modified CTSID
-can be done using the neuro-com balance master -clinical test for sensory interaction of balance |
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