Vestibular Rehabilitation Utilizing Virtual Environments to Train Sensory Integration for Postural Control in a Functional Context
Phase: NA
Conditions: Dizziness Chronic, Vertigo, Peripheral, Fall
Sponsor: New York University

Vestibular Rehabilitation utilizing Virtual Environments to Train Sensory Integration for Postural 
Control in a Functional Context 
NCT04268745 
 
STUDY PROTOCOL 
 
May 6th, 2021 
 
 
 

Methods 
 
This study including all covid modifications was approved by the BRANY institutional review board (IRB, # 19-
02-223), the IRB at Icahn School of Medicine at Mount Sinai and New York University Committee on activities 
involving research subjects.  
 
Participants 
All patients signed consent prior to enrolling in the study. We recruited patients referred to an outpatient vestibular 
rehabilitation clinic with chief complaints of dizziness and/or imbalance. The participants first underwent an initial 
vestibular physical therapy evaluation of approximately 60 minutes. The evaluation included: detailed history, 
oculomotor screening which included saccades, smooth pursuit and convergence, assessment of spontaneous 
and gaze evoked nystagmus with and without infrared goggles, Dix-Hallpike and roll test to rule out benign 
paroxysmal positional vertigo (BPPV), and bedside head impulse test to screen for vestibulo-ocular (VOR) 
impairment. The assessment also included gait speed and gait stability with head turns in both horizontal planes 
and vertical planes, as well as the modified clinical test of sensory integration to assess static balance. Peripheral 
vestibular hypofunction was diagnosed by either positive findings on bithermal caloric testing during 
videonystagmography and/or positive bedside head impulse test, head shaking nystagmus and gaze evoked 
nystagmus and/or clinical history characterized by sudden onset of vertigo lasting hours, aural symptoms 
unilaterally and ruling out other central causes. Central vestibular conditions were diagnosed based upon history 
of head injury leading to symptoms, history of resected acoustic neuroma or migraine history with episodic 
vertigo. We excluded patients if they had bilateral or unstable vestibular loss or another neurological condition, 
active BPPV, acute orthopedic injuries, peripheral neuropathy and visual impairment not corrected with glasses.   
 
Procedure 
When a clinician identified a patient as eligible, they reviewed the informed consent and explained the study 
procedures. Following consent, patients underwent a baseline assessment including functional measures 
(Functional Gait Assessment [FGA], Timed-Up and Go [TUG], The Four-Square Step Test [FSST]), and self-
reported questionnaires (Visual Vertigo Analog Scale [VVAS][27–29], Activities Specific Balance Confidence 
Scale [ABC], The Dizziness Handicap Inventory [DHI].  The assessment also included a postural control test 
using HMD. Standing hips-width apart on the floor, participants experienced two levels of visual surround and 
white noise while their head sway was recorded via the HTC Vive Pro headset. The total duration of the session 
was approximately 45 minutes. After the baseline assessment, the patients were randomized to 8 sessions of 
either traditional vestibular rehabilitation or C.S.I training followed by an immediate post assessment.  
 
System 
Our platform runs at 120 frames per second with either HTC Vive or Oculus Rift, on a Windows 10 laptop with 
8GB RAM, Intel i7-7820HK CPU, Nvidia GTX 1080 Max-Q GPU, and Bose SoundTrue around-ear headphones 
II. The software was developed in C# with Unity3D 2018.2.0f1(64-bit) (Unity Technologies, San Francisco, 
California). The system utilizes SteamVR.  Oculus Rift and HTC Vive both operate at 90 Hz refresh rate, 110 
degrees field of view, and a high-definition video of 1080x1200 resolution for each eye. The graphics of the 
subway station, airport terminal building, and subway trains are modeled in Maya and imported to Unity3D. The 
rest of the 3D objects are modeled in Unity3D. The subway station model and airport model replicate a real 
subway station in New York City and a real airport terminal in the US. The contents in the system are fully 
controllable by the user interface (see Figure 3). Three-dimensional sounds were implemented using Wwise 
middleware and Google Resonance audio plugin. Using the head-tracking data, audio is modulated according 
to the position of the listener's head. The technology allows for creation of a rich soundscape in all directions 
around the listener. Audio assets used in the system are divided into two main groups: sound objects and 
ambiances. Sound objects are attached to the visual objects in the scene and their position is changing 
accordingly. Sounds include: footsteps, trains, announcements, cars, balls, airplanes, etc. Ambiances are 
created from original recordings from different locations in New York. These include different background sounds, 
i.e. sounds of the crowd chatter, distant trains, wind, birds, traffic, and general room tone of each of the spaces. 
All of the sounds used in the system are assigned to three different intensity levels which relate to the increasing 
complexity of the soundscape.  
 
  

Randomization and Group Allocation: We used a blocked randomization method. Instead of randomizing each 
patient individually, this scheme randomizes several patients at a time in such a way as to ensure that equal 
numbers are allocated to each group across each segment of time during the length of the study. For example, 
if the block size is four, we randomize four patients at a time ensuring that two patients are allocated to the C.S.I 
group and two patients to the traditional group. As it happens, there are six different possible ways we could 
randomize four patients equally to two treatments. The randomization was done following the baseline 
assessment and only the study statistician had access to the randomization sequence.  
 
Interventions 
Following the baseline assessments, we randomized patients to a C.S.I. group or a traditional vestibular 
rehabilitation control group. We planned each program to be 8 weeks (1 30-minute weekly session + home 
program). We conducted a post-assessment, identical to the baseline assessment, within one week from the 
completion of the 8th intervention session.  
 
The main difference between participants was the timing of progression which was individualized based on 
patient symptoms (dizziness and / or instability). Each exercise (in clinic or home) was prescribed at the highest 
level of challenge that was considered safe (i.e., no loss of balance or no significant increase in dizziness). We 
assigned all patients a home exercise program (the C.S.I group had similar exercises without eyes closed tasks, 
effectively 2 minutes less exercise per day) which they were asked to complete twice daily, for 5 to 10 minutes. 
Their home program consisted of gait, gaze stability, and static balance activities.  
 
For patients in the C.S.I. group the progression of environments started with the most salient to the patient and 
this varied from patient to patient and eventually most patients completed several different environments (e.g., 
street, subway, airport). The duration varied with starting point at 1 minute with increase in time up to 5 minutes 
based upon patients’ symptoms. Beyond duration, the exact progression the patient underwent varied by 
therapist. Some therapists chose to change the complexity of the scene (i.e., increased amount people, 
increased speed of people adding sounds, or changing directions of walking), while others chose to add tasks 
in the scene (i.e., walking for a maximum. of 4-5 steps, changing base of support or adding head turns).  
 
The following are the exercise variation for the traditional group: Gait: walking with head turns, progress with 
range, speed and planes of head movement; change of walking base of support: wide, normal, tandem; Gaze: 
focus on a target while moving head side to side / up down. Progress with speed, duration, busier background, 
standing to walking; Balance: standing balance tasks, progress with BOS (wide to narrow to tandem), support 
surface, eyes closed, duration, head turns. See Table 1 for further details. 
 
 
 

 
Table 1. A detailed description of the study’s intervention programs 
 
Experimental Group 
Control Group 
Study 
Initiation 
Eligible participants will be provided with patient education and a basic home exercise 
program (gait, balance, no exercises with eyes closed) while they are considering 
participation in the study. 
Program 
Dose 
8 weeks, 1 visit per week, 30 minutes long 
In-Clinic 
Activities  
Progressive immersive training with 
the C.S.I. app 
Progressive gait, gaze stability and balance 
exercises 
Program 
Guidelines  
Scenes: start from most salient to 
the patient, eventually do all 
Duration: start at 60 seconds, 
increase over time up to 3 minutes 
per scene 
Complexity: start minimal, gradually 
increase up to most complex  
Tasks: standing with diverse base of 
support (BOS), head turns (progress 
with speed, planes); stepping, turning 
Gait: walking with head turns, progress with range, 
speed and planes of head movement; change of 
walking BOS: wide, normal, tandem 
Gaze: focus on a target while moving head side to 
side / up down. Progress with speed, duration, 
busier background, standing to walking. 
Balance: standing balance tasks, progress with 
BOS (wide to narrow to tandem), support surface, 
eyes closed, duration, head turns. 
Progression / 
Regression 
Rule  
The highest level of challenge that can be done for 60 seconds with no loss of balance 
(LOB); No more than moderate symptoms in clinic based on the Simulator Sickness 
Questionnaire53; If symptoms persisted over 2 hours post-session, we will scale back the 
next time. If symptoms improved immediately, we will repeat the task with the same 
intensity and duration. 
Home Dose 
8 weeks, 6 times per week, twice per day, 10 minutes long 
In-Home 
Activities 
Gait and balance exercises, No 
exercises with eyes closed 
Gait, gaze stability and balance exercises, 
including exercises with eyes closed 
Home 
Prescription  
Highest level of challenge that is safe (no LOB, no increased symptoms) for 60 seconds 
per task