Subjective Visual Vertical (SVV)

16 February 2022
10 - 30 mins
Reading
The Orion Comprehensive Rotary Chair will provide you with license capabilities to perform static SVV tests. In addition to the static SVV, if you have an Orion Auto-Traverse Rotary Chair, you will also have the ability to perform dynamic off-axis SVV tests.

Patient safety

Before beginning any tests in the Orion rotary chairs, please ensure proper patient safety by checking the items in the pop-up message below. In addition to this list, ensure that the goggles are unplugged from the chair and removed from the booth for SVV tests.

Patient safety message. The introduction says the following: To ensure the safety of the patient before rotating the patient in the chair, please use this checklist as a guide to ensure the patient's safety during the test. The introduction is followed by four questions, each labeled with a checkmark: Is the patient's lap belt securely fastened? Is the patient's head restrained to the head support? Are the shoulder straps securely fastened? Has the ankle restraint been fastened? The four questions are followed by two options: OK and Cancel.

Figure 1 Rotary chair patient safety message

 

Performing the test

To begin testing, select SVV from your drop-down test menu.

Drop-down test menu, including vor suppression, visual vor, and subjective visual vertical. For subjective visual vertical, there are three options, including: static, left 4 cm 300 dps, and right 4 cm 300 dps.

Figure 2 Test menu for SVV

Provide the remote control for laser line adjusment to the patient inside of the booth and ensure that the lanyard is securely attached to the patient’s wrist, or alternatively, to the seat belt of the chair. This is esspeically important for the dynamic SVV tests when the chair will be rotating.

Person holding SVV remote control. Lanyard attached to patient's wrist, which is connected to the remote.

Figure 3 Patient with remote control securely fastened

The patient is instructed to press the arrows on the remote control to move the laser line until the line is perceived to be vertical.

Person holding SVV remote control.

Figure 4 SVV patient remote control 

 

Static SVV test

For the static SVV test the patient will be seated inside the enclosed rotary chair booth with the door securely closed and the booth light turned off to ensure a proper vision-free test environment. The goggles do not need to be worn by the patient for this test. The chair will be stationary for the static SVV test. Select the ‘static’ test from the test menu. When the patient is ready to begin the test, press start on the test screen to initiate the laser line inside the booth and begin the trials.

Figure 5 Static SVV test screen

As the patient adjusts the laser line with the remote control, the examiner will see the target angle on the test screen (depicted by the yellow line) change in the graph. When the patient indicates that they are satisfied with the adjusted laser line and feel it is in vertical alignment, press continue to move to the next trial. The patient’s response angle will appear in the table below the graph upon pressing continue. A minimum of 4 trials is recommended. More trials can be added as desired. This can be configured in protocol management.

 

Dynamic SVV test

If you have the Auto-Traverse chair, you will also be able to perform dynamic off-axis SVV tests. For the dynamic SVV test, the patient will be seated inside the enclosed rotary chair booth with the door securely closed and the booth light turned off. Be sure to remove the goggles from the booth before initiating a dynamic SVV test. Select the ‘left or right 4 cm 300 dps test from the test menu. When the patient is ready to begin the test and has been given appropriate instructions, press start on the test screen. This will initiate chair rotation. As the chair velocity ramps up to reach target velocity (approximately 70 sec), the following count-down message will be displayed in the test window.

Dynamic SVV count-down display. The message states the following: Wait for chair to reach target velocity. Time until test start 46s. Below the message, the following is apparent: chair velocity is left 234 dps. Chair offset is 0 cm.

Figure 6 Dynamic SVV count-down display

After the desired velocity has been reached, the chair will then move off axis 4cm to the specified direction.

A ruler-like indicator on the back of the Auto-Traverse chair, with the center of the chair at 4 cm.

Figure 7 Auto-Traverse chair positioned to 4cm right for dynamic test

The chair offset and chair velocity indicators in the software will turn green when ready.

Figure 8 Dynamic SVV test screen with chair at desired velocity and offset

When the chair has achieved desired velocity and offset, press continue to initiate the laser line inside the booth and begin the trials. As the patient adjusts the laser line with the remote control, the examiner will see the target angle on the test screen (depicted by the yellow line) change in the graph. When the patient indicates that they are satisfied with the adjusted laser line and feel it is in vertical alignment, press continue to move to the next trial. The patient’s response angle will appear in the table below the graph upon pressing continue.

When the final trial is complete, the chair will move back to a centered position and begin to slow down. The following message will appear in the test screen. This will take several seconds.

Wait for chair to stop rotation

Figure 9 Dynamic SVV chair stopping message

A minimum of 4 trials for each dynamic off-axis chair position (left and right 4cm) is recommended. It is also possible to perform a combined left, center and right dynamic SVV protocol. This can be configured in protocol management.

 

Results

After each subtest group of trials is complete, the patient’s responses will be displayed in a graph on the summary screen.

Results overview for static SVV and dynamic SVV, including the three subtests static, left 4 cm 300 dps, and right 4 cm 300 dps. For each of the subtests, a table shows target position, chair offset, and the patient's response.

Figure 10 Completed Test Summary Screen

There are no threshold levels available for static and dynamic SVV tests.

For further assistance, please refer to the Instructions for Use and Additional Information manuals, which can be accessed from the question mark icon on the main screen in the VisualEyes™ software.


Presenter

Cammy Bahner
Cammy Bahner is the Director of Audiology-Balance Division for Interacoustics U.S. In her role, she provides clinical training, education, and support for a variety of products, with a primary emphasis in vestibular and electrophysiologic assessment. She provides clinical input for the development of vestibular products. She received her Master’s Degree from the University of Nebraska-Lincoln in 1999 and her Au.D. from A.T. Still University, AZ School of Health Sciences in 2016. She has served as a guest speaker at state, national and international conventions and is a contributing author on published articles in hearing industry journals. Cammy is currently a member of AAA and ASHA.

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