Session 7 - vHIT presession

Question 1

What is vHIT?

Answer 1

and objective efficient means of testing the vestibular asysete that provdes immediate results regarding side specific vestibular dysfunction

Question 2

what are the problems with traditional vHIT/

Answer 2

1 -subjective results as it’s the examiners opinion whether or not an abnormal eye movement has occurred in response to head movement

2 -the human eye can only detect the more obvious eye movements that occur after head movements (known as Overt Saccades)

3- the human eye isn’t capable to detecting eye movements that occur within the head movement (known as Covert Saccades

Question 3

why is vHIt better than traditional HIT?

Answer 3

1 - vHIT using EyeSeeCam allows the professional to accurately and objectively assess the dizzy patients for vestibular dysfunction on the 1st office visit without the time and expense of ENG saving the patient and healthcare professional time and money

2- the EyeSeCam is objective, portable and reliable and easy to use making vHIt ad obvious choice as a starting point for Vestibular Assessment

Question 4

what does vHIt measure?

Answer 4

vHIt is a measure of the VOR in response to head movement

-a patient with a healthy vestibular system should be able to keep their eyes focused on a vestibular system even when head is in motion

Question 5

What is Catch- saccade?

Answer 5

in patients, with vestibular dysfunction, when the head moves, the eyes will move with the head, requiring a corrective movement back to the target = inability to remain focus

Question 6

how does vVIt tell us a pateint has catch-up Saccade?

Answer 6

-vHIT captures this abnormal eye movemnt, analyses and puts it into a digital graph which is easily read and understood

Question 7

what equipment is used in vHIT?

Answer 7

dedicated goggles made of 2 major components:

1- Inertial Measurement Unit (IMU)= is a combined Gyroscope and Accelerometer that measures head movement WHILE

2- Infared Camera capturend records eye movement

Question 8

How is vHIT perfromed?

Answer 8

1- secure goggles
2-perform brief calibraton of eye movement
3- exmainer asks patient to maintain eye focus on a stationary object
4-the examiner manipulates the pateint head with quick precisie head movements

Question 9

when putting the goggles on for vHIt, what do you ensure?

Answer 9

the goggles must be fitted securely to avoid slippage

Question 10

how long does vHIT take to perform?

Answer 10

the entire process should take less than 10 mins to perform and provides immediate side specific results

Question 11

what does the EyeSeeCam software do?

Answer 11

-its designed to perform intricate and repeatable calculations of the relationship between head and eye movements to determine whether there is a weakness in 1 or both vestibular systems

• shows an analysis of instantaneous gain. specifically at 40, 60 and 80milli seconds
• the software provides and analysis of velocity regression meaning a calculation is derived form a comparison of eye and head velocity in the time range of 0-100 milli seconds after impulse onset, to give a quick estimate of symmetry of symmetry between vestibular systems

Question 12

how does vHIT represent its calculations?

Answer 12

-as tracings which clearly show the presence of overt and covert saccades

Question 13

what is the clinical application of vHIT?

Answer 13

• to differentiate between no vestibular dysfunction and peripheral vestibular dysfunction and central vestibular dysfunction

Question 14

what does a vHIT showing no vestibular dysfunction mean?

Answer 14

normal horizontal semi-circular vestibular dysfunction at high velocity head movements between -4 Hz

Question 15

what is the next step after seeing either peripheral or central vestibular dysfunction from vHIT?

Answer 15

referral for more advance testing such as:
- Video Nystagmography
- Electrocohleography

Question 16

what are the clinical benefits of EyeSeeCam?

Answer 16

• Quick, side specific information regarding vestibular function

-Portable equipment allows for bedside testing for non ambulatory patients. Further recommendation for care can be made based on vHIT results

• easily tolerated by most patients as its quick test that utilises natural head movements

-utilises natural head movements that emulate normal, daily activities particularly in 1-4 H range (such high frequency info can only be attained by vHIT

-accurate data interpretation and storage allows for objective reporting ad comparsions of vestibular nerve function to measure vestbular compenstation over time to see effectiveness of vestibular therapies

• can be used as a pre-operative and post operative evaluation of vestibuar function

Question 17

which patients may not be able to tolerate the vHIT?

Answer 17

• (those who are those with cervical issues with the neck or spine
• those who cannot relax enough for quick head movements required
• patients who are visually impaired as they won’t be able to see the target

Question 18

what are some unique features of EyeSeeCam?

Answer 18

1- lightweigh goggle with bilt in laser calibration

2- switchable left/ right camera- The easy ball-and- socket camera design allows testing of either eye.

3- Instantaneous gain plots at 40, 60 and 80ms - gives you a more complete data analysis and helps the examiner to understand patterns that might be associated with different vestibular pathologies

4- velocity regression analysis- allows for graphical data analysis over the entire frequency range of the head impulses

5- USB-driven camera- simply plug in the USB adapter from the device into the computer

6- the software generates PDF reports easily that can read at a glance

Question 19

which is normal overt or covert?

Answer 19

neither