Sensory Integration Balance Deficits in Complex mTBI: Can Early Initiation of Rehabilitation With Wearable Sensor Technology Improve Outcomes?
Phase: NA
Conditions: Mild Traumatic Brain Injury, Balance; Distorted, Gait, Unsteady, Quality of Life, Veterans
Sponsor: Oregon Health and Science University

 
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1. Protocol Title 
Rehabilitation of Complex TBI with Sensory Integration Balance Deficits; Can Early Initiation of Rehabilitation with 
Wearable Sensor Technology Improve Outcomes? 
 
2. Objectives 
In Aim I, we will 1) determine the role of timing in rehabilitation after mTBI and 2) determine meaningful change 
measures of novel head stability and gait metrics after rehabilitation. In Aim II, we will 1) validate 3D head and 
trunk motion inertial algorithms with Motion Analyses during the 3 specified exercises 2) develop reports with 
visual displays for the physical therapist to determine performance and compliance of home exercises done 
during each week and 3) compare the outcome of the subjects who used wearable sensors during the home 
exercise program versus those who did not. In Aim III, we will 1) develop and validate real-time algorithms for 
physical therapists to observe and measure head movement and trunk stability during exercises (head 
movement - range of motion of head movement and peak velocity; trunk – stability RMS); 2) determine 
feasibility of physical therapists using the feedback system in the clinic during rehabilitation, and 3) collect 
normative values on 50 healthy control subjects to enhance interpretation of feedback and report to the 
physical therapist. 
 
Our long-term goal is to clarify best practices for the rehabilitation of balance deficits in people with mTBI by 
comparing early vs late (standard of care) initiation of physical therapy with and without wearable sensors on 
balance deficits after mTBI. There are three objectives of this proposal: 1) To determine the role of timing in 
rehabilitation of balance deficits in people with mTBI 2) To determine if home monitoring of balance and 
vestibular exercises using wearable sensors improves outcomes and 3) To develop a novel feedback system 
using wearable sensors to provide physical therapists information, in real-time during training, about quality of 
head and trunk movement during exercise. To achieve these objectives, we have the following Specific Aims: 
Aim I. Early Intervention: To determine the effects of early versus late rehabilitation for balance deficits in mTBI. 
We hypothesize that early rehabilitation initiated at the initial physician visit will improve outcomes more than 
standard of care (later initiation of physical therapy) in people with mTBI who have complaints of imbalance. We 
will also determine clinically meaningful change measures due to rehabilitation for objective measures of head 
stability during gait, based on Patient Global Impression of Change Scale (Hurst and Bolton 2004). We will 
randomize 160 people with mTBI, between the ages of 18 and 60, into early rehabilitation (within first 2 weeks 
after physician visit) or late rehabilitation (standard of care; 60 days from first physician visit). People will be 
tested before and after a 6-week rehabilitation program and again 6 months later to determine long-term 
effects. Our primary outcome to measure efficacy of rehabilitation is the Dizziness Handicap Inventory (DHI). 
Secondary outcomes will be structured along the International Classification of Function and Disability (ICF) 
models framework. We will measure baseline peripheral vestibular and ocular motor function and other 
covariates in rehabilitation efficacy. In Aim I, we will 1) determine the role of timing in rehabilitation after mTBI 
and 2) determine meaningful change measures of novel head stability and gait metrics after rehabilitation. 
 
Aim II. Home Monitoring: To compare traditional balance rehabilitation versus balance rehabilitation with 
sensor-based home monitoring of compliance and quality of prescribed exercises. We hypothesize that 
providing physical therapists with objective measures on compliance and the quality of prescribed exercises 
performed at home, using wearable sensors, will improve outcomes in rehabilitation. Subjects entering 
rehabilitation in Aim 1 (both early and late rehabilitation) will be further randomized into either: 1) home 
exercise program or 2) the same home exercise program with wearable sensors worn on the forehead and trunk 
to monitor compliance and quality of performance during home exercises. The data from the sensors will be 
reviewed by the physical therapist at the subsequent weekly visit. All people will be seen 1x/week by a physical 
therapist and expected to do a home exercise program. People will be tested before and after a 6-week 
rehabilitation period and again 6 months later to determine long-term retention. In Aim II, we will 1) validate 3D 
head and trunk motion inertial algorithms with Motion Analyses during the 3 specified exercises 2) develop 
reports with visual displays for the physical therapist to determine performance and compliance of home 

 
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exercises done during each week and 3) compare outcome of the subjects who used wearable sensors during 
the home exercise program versus those who did not. 
 
Aim III. Real-time Monitoring for Training: To develop and evaluate a novel sensor system to provide real-time 
feedback to physical therapists on head and trunk movement during training. We hypothesize that real-time 
feedback on head and trunk movements during prescribed exercise will be feasible for a physical therapist to 
use during training sessions. Five physical therapists and 25 patients with mTBI will test and evaluate our new 
prototype head and trunk motion feedback system in preparation for future clinical efficacy trials. In Aim III, we 
will 1) develop and validate real-time algorithms for physical therapists to observe and measure head movement 
and trunk stability during exercises (head movement - range of motion of head movement and peak velocity; 
trunk – stability RMS); 2) determine feasibility of physical therapists using the feedback system in the clinic 
during rehabilitation, and 3) collect normative values on 50 healthy control subjects to enhance interpretation of 
feedback and report to the physical therapist. Input from researchers, physical therapists and mTBI patients on 
the perceived usability of the real-time feedback will be used for further tuning and optimizing the system. 
 
3. Background 
Every year 1.7 million people sustain a traumatic brain injury (TBI) in the United States and of these, 84% are 
considered mild TBI (mTBI) (Faul, Xu et al. 2010, Group 2016). According to data from the Defense and Veterans 
Brain Injury Center, 18,686 Service Members sustained a mTBI in 2015 (Defense 2015). The estimated annual cost 
to society from TBI, including lost productivity, was $60.4 billion (Corso, Finkelstein et al. 2006, Coronado, 
McGuire et al. 2012). Data suggest that during deployment as many as 20% of Service Members may have 
suffered a mTBI (Terrio, Brenner et al. 2009). Balance impairments are a common complaint after mTBI, with an 
estimated odds ratio of 3.14 in chronic mTBI compared to control subjects (Vanderploeg, Curtiss et al. 2007). 
Ongoing balance problems are significant contributors to anxiety, difficulty with return to work, and may even 
underlie the observation that people with a recent history of mTBI are at a threefold greater risk of sustaining a 
second mTBI (Guskiewicz, McCrea et al. 2003, McCrory 2011). 
 
Although balance is one of the most common and debilitating complaints after mTBI, we currently lack clear 
guidelines on when to initiate balance rehabilitation and it is unclear if early physical therapy is beneficial. A 
recent systematic review that focused on early rehabilitation for mTBI was inconclusive stating that there was a 
paucity of well-designed trials that could address the question adequately (Gravel, D’Angelo et al. 2013). 
However, some evidence suggests that prolonged or strict rest, while it continues to be common practice, may be 
counterproductive (Silverberg and Iverson 2013, Thomas, Apps et al. 2015). Rest within the first week is well 
established as a guiding principle for treating physicians. A paper in 2016 surveyed 572 physicians and reported 
that 97% recommended rest within the first week of injury (Rose, Fischer et al. 2016). However, when symptoms 
do not resolve after a few weeks, the guidelines and practices are less clear and less consistent. Preliminary 
evidence suggests that beginning subthreshold activity as part of a rehabilitation program may be beneficial 
(Grabowski, Wilson et al. 2016) but this approach is not standard practice. A retrospective chart review reported 
that, of 266 patients, only 25% of people were referred to PT and/or vestibular rehabilitation during the 
management of their protracted recovery after mTBI (Kostyun and Hafeez 2015). Another recent study reported 
that the median time from injury to PT visit was 60 days (Alsalaheen, Mucha et al. 2010). There is evidence for 
peripheral vestibular dysfunction after mTBI (Hoffer, Gottshall et al. 2004, Akin and Murnane 2011) as well as 
central sensory integration deficits from mTBI (Walker, Cifu et al. 2012), both of which could cause imbalance. A 
systematic review identified impaired balance after injury as one of the most prevalent and consistent indicators 
of mTBI, along with disorientation or confusion, slowed reaction time and impaired verbal learning and memory 
(Carney, Ghajar et al. 2014).  
 
There is a clear gap in our clinical care guidelines after mTBI and it is unclear if initiating rehabilitation early would 
improve outcomes related to imbalance. The timing of physical therapy has been studied most extensively for 
orthopedic, stroke and vestibular impairments and there is a general consensus that earlier intervention is better 

 
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for conditions such as acute low back pain (Wand, Bird et al. 2004), dizziness (Whitney, Alghadir et al. 2016), 
post-surgery (Schaller, Anstey et al. 2016), and stroke rehabilitation (Musicco, Emberti et al. 2003). However, the 
message is less clear after mTBI since early activity may exacerbate symptoms and there is concern over Second 
Impact Syndrome (Rose, Fischer et al. 2016). Although rest is a well accepted recommendation acutely after 
injury, the rest period is not specified. Further, strict rest acutely after concussion may be less beneficial than a 
stepwise return to activity within days of injury (Thomas, Apps et al. 2015). It is thought that the brain can 
undergo plastic change throughout one’s life and that there are critical periods during development and after 
injury in which neuroplasticity capabilities are highest (Nudo 2003). Experience–dependent plasticity during these 
phases may result in the largest behavioral changes (Wolf, Winstein et al. 2006, Kleim and Jones 2008, Holtmaat 
and Svoboda 2009). Conversely, maladaptive compensatory mechanisms may also develop after injury whereby 
avoidance of movements that provoke discomfort (i.e. dizziness or imbalance) may be inappropriate (Taub 1980, 
Shepard and Telian 1995). This notion of early intervention contradicts the ‘prolonged rest’ that many physicians 
adhere to in treating people with mTBI.  
 
Measures of imbalance are subjective and are easily overlooked as a treatable deficit. The most frequently 
administered clinical balance test after mTBI is the Balance Error Scoring Scale (BESS) in which people are asked 
to stand in varying conditions (i.e. eyes closed on firm surface or foam surface) to challenge their postural 
stability. Errors, such as loss of balance, are counted subjectively by the clinician (Riemann and Guskiewicz 2000). 
Recent studies have reported that the BESS has a high degree of subjectivity and provides only limited, low-
resolution information about the balance control system and does not provide a sensitive scale on which to judge 
progress or deficits (Finnoff, Peterson et al. 2009, Giza, Kutcher et al. 2013). Sub-optimal psychometric properties 
(sensitivity 34%–64% to detect mTBI) have also been reported for the BESS and are likely due to the subjectivity 
of the measurement (Finnoff, Peterson et al. 2009, Giza, Kutcher et al. 2013). We believe that such poor 
clinometric properties of this clinical test do not lend itself to timely referrals to physical therapy. Clinical balance 
tests with limited properties may lead to lower detection rates and make it difficult to detect those who might 
benefit from physical therapy. A more objective measure of balance may help identify people with impaired 
balance due to sensory deficits (i.e. vestibular) and/or central sensory motor integration deficits in which an early 
physical therapy may help recovery. Our work has provided evidence that instrumenting common balance tests 
with inertial sensors can better differentiate people after mTBI compared to standard subjective measures of 
balance (King, Horak et al. 2014) (See Preliminary Data).  
 
Even with rehabilitation, recovery of balance in people with mTBI is challenging, particularly in people with 
central vestibular and sensory integration deficits (Pfaltz and Kamath 1970). In addition to addressing the timing 
of physical therapy intervention, this proposal addresses 2 other potential obstacles for successful rehabilitation 
after mTBI; 1) poor compliance and quality of performance of home exercise program (standard of care after 
mTBI for balance rehabilitation) and 2) lack of important feedback during training of balance and vestibular 
exercises on head and trunk movement during movement. In this proposal, we aim to improve home exercise 
program and improve training in the clinic; both using novel wearable sensor technology. 
 
Home monitoring: Vestibular and balance rehabilitation after mTBI relies heavily on a home exercise program 
and repetition is essential for recovery (Shepard and Telian 1995). We recently published a paper showing that 
home exercise program is the least effective way to address balance deficits in people with Parkinson’s disease 
compared to a group class or individualized physical therapy (King, Wilhelm et al. 2015). This finding was 
particularly true is if a person had common comorbidities such as depression or mild cognitive impairment, also 
commonly seen after mTBI. Despite this, a home exercise program remains an important part of care after mTBI 
and, in fact, all patients with mTBI in our rehabilitation clinic are prescribed a home exercise component to 
address imbalance and dizziness. The average time they are seen by physical therapy is only 1x/week. However, 
we believe that home exercise can be improved using wearable sensors to monitor compliance and performance 
at home.  
 

 
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The slow progress in balance rehabilitation may be partially due to an inability of people with mTBI to correctly 
perform the prescribed rehabilitation exercises on their own. There is evidence that people with vestibular 
pathology have impaired perception of body position such as head in relationship to trunk and may limit head 
velocity and head in relation to trunk to minimize symptoms (Borel, Harlay et al. 2002). After mTBI, participating 
in a home exercise program that emphasizes head movement may be particularly difficult to comply with and 
may explain slow or delayed recovery. Vestibular and balance rehabilitation relies on progressively increasing 
head movement amplitude and velocity during static and dynamic balance tasks while maintaining a stable trunk 
(Konrad, Tomlinson et al. 1992, Kang and Tusa 2013). Further, other comorbidities such as depression could limit 
compliance and determination to perform the home portion of rehabilitation. 
 
Training in the physical therapy clinic: One of the most important components of motor learning is feedback of 
performance, yet this important feature is hard to implement objectively in balance rehabilitation. For example, 
orthopedic physical therapy focuses on objective measures of joint angles, peak torques and gait speed during 
task acquisition. Rehabilitation of balance deficits is more difficult to quantify and to provide feedback around a 
training task. Subtle movements, such as postural sway and head and trunk synchronicity are often not detected 
visually. Furthermore, people with mTBI show more deficits during complex mobility tasks, yet we do not 
objectively evaluate and provide feedback on complex tasks in the clinic. For example, an average individual turns 
over 800X/ day (Mancini, El-Gohary et al. 2015) and 35-45% of all steps during daily locomotion are not straight 
(Glaister, Bernatz et al. 2007). A stereotyped multi-segmental sequence of reorientation occurs during turning, 
whereby vision is realigned with the new direction of travel and closely followed by the head then trunk and 
pelvis (Authié, Hilt et al. 2015). The anticipatory lead of the head and “top-down” reorientation is necessary to 
maintain gaze stabilization in the new direction of movement (Akram, Frank et al. 2010). Yet, individuals with 
recent mTBI show more variable reorientation sequencing (Powers, Kalmar et al. 2014). Independent eye 
movement, head rotation, and trunk rotation, is important for everyday mobility to integrate visual, vestibular, 
and somatosensory information and may be impaired after mTBI. Even during straight ahead gait, the role of 
head stability is critical to maintain a stable visual field. Less independent oculomotor control has been 
associated with poorer balance performance in athletes with mTBI (Murray, Ambati et al. 2014). A recent study 
using Motion Analysis showed a lack of head and trunk synchronicity during gait on a treadmill in people with 
vestibular deficits and TBI (Sessoms, Gottshall et al. 2015) and such asynchronicity may lead to avoidance 
behavior and decreased quality of life, and delayed return to previous levels of function (Shepard and Telian 
1995). We believe it is critical to evaluate and treat complex balance skills and to incorporate performance 
information objectively into training and rehabilitation.  
 
Biofeedback is a clinical technique that provides physiologic information that would otherwise be unknown to 
patients and may improve outcomes after mTBI. Biofeedback complements the patients’ internal feedback 
(visual, auditory, and proprioceptive) and reinforces patients’ weaker or absent sensory signals. Different forms 
of biofeedback have successfully been used in laboratories for the treatment of gait abnormalities in patients 
with Parkinson's disease (McIntosh, Brown et al. 1997, Nieuwboer, Kwakkel et al. 2007, Horak, Wrisley et al. 
2009), Multiple Sclerosis (Baram and Miller 2006, Baram and Miller 2007), Stroke (Glanz, Klawansky et al. 1997, 
Thikey, Grealy et al. 2012), Amputation (Lee, LIN et al. 2006), and Spinal Cord Injuries (Jensen, Barber et al. 2009). 
We have also shown significant benefits of practicing tandem gait with vibrotactile biofeedback in people with 
unilateral vestibular loss (Horak, Dozza et al. 2009) and auditory biofeedback to improve postural sway during 
standing in subjects with bilateral vestibular (Dozza, Chiari et al. 2006, Dozza, Wall Iii et al. 2007). Biofeedback has 
also been successfully used in the laboratory to reduce leg loading after total hip arthroplasty (Pataky, Rodriguez 
et al. 2009), increase knee motion symmetry after total knee arthroplasty (McClelland, Zeni Jr et al. 2012), and to 
modify gait and reduce knee joint loads (Dowling, Fisher et al. 2010). While electroencephalography biofeedback 
has been explored to rehabilitate cognition (Thornton and Carmody 2009) and others have described the 
potential of biofeedback to improve balance and gait in the mTBI population (Lawson and Rupert 2010, Collins, 
Markham et al. 2015, Mortimer, McGrath et al. 2015, Sessoms, Gottshall et al. 2015), we are unaware of any 

 
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study that has examined the use of biofeedback to improve the compliance and performance of prescribed 
rehabilitation exercises for mTBI. 
 
There are no commercially available systems to provide the physical therapist and/or patient objective 
information on the quality of head movements during training of rehabilitation tasks that involve balance and 
walking. Despite evidence that people with vestibular deficits and TBI may have impaired perception of head 
movement (Borel, Harlay et al. 2002), we currently have no easy way to quantify or provide feedback during 
therapy on these important aspects during functional mobility. Computerized dynamic visual acuity testing is 
available to measure 1) changes in visual acuity at head velocities associated with the Vestibulo-Ocular Reflex 
(VOR) and 2) the maximum head velocity the patient can achieve while maintaining accurate vision during a gaze 
stabilization test (Herdman, Tusa et al. 1998). While this system provides a quantitative assessment of gaze 
stabilization with head movement, it is limited to stationary, in-clinic use. Since home exercise programs are an 
integral part of rehabilitation care after mTBI, a portable system for monitoring head movements and one that 
can assess head movement in walking conditions is needed. The ideal system would be wearable and portable for 
both clinic and home use and would combine biofeedback with monitoring capabilities. Our intention is to design 
and build a wireless biofeedback system to allow therapists to select among a variety of exercises that target 
balance and vestibular function. This system will (1) enable physical therapists to teach their patients to perform 
the exercises correctly, (2) monitor quality and rate of improvement in home exercise performance, and (3) 
enable patients to monitor their own progress and increase their adherence to home exercise regimen. 
 
Relationship to other funded studies: Our group has extensive experience running clinical trials and studies 
related to gait, balance and rehabilitation in people with mTBI. This proposal is a natural continuation of previous 
funding. In 2012 we were awarded a pilot grant (Center for Translation of Rehabilitation Engineering Advances 
and Technology; King PI) to develop a protocol for instrumented balance testing which was tested on people with 
chronic post-concussion syndrome (King, Horak et al. 2014). From there, we moved the instrumented balance 
testing to onsite assessment at 6 local Universities (NIH; Oregon Clinical Translational Research Center (OCTRI) 
KL2 Award and National Institute of Health KL2TR000152; R21 NIH R21HD080398; King PI) to explore the 
usefulness of wearable sensors in acutely injured athletes and to determine trajectory of balance recovery after 
concussion. We enrolled 50 people with mTBI and 75 controls (results are under review). Most recently, we 
received funding from the DOD (King PI-W81XWH-15-1-0620) to investigate central sensorimotor integration and 
vestibular deficits in people with chronic non-resolving balance deficits after mTBI. With that funding we have 
developed new methodology to assess central sensorimotor integration (CSMI test) using a commercially 
available Neurocom platform and are currently executing that study. We will use the CSMI test in the proposed 
study as an impairment level outcome measure. 
 
PRELIMINARY STUDIES 
Pilot data for Aim I 
The primary goal of Aim I is to determine the role timing plays in rehabilitation efficacy after mTBI. To accomplish 
this goal, we will randomize people into early physical therapy (within first two weeks of physician visit) or late 
physical therapy  (standard of care; 8 weeks from first physician visit). We will use both recommended Common 
Data Elements (CDE) outcome measures alongside innovative objective measures to quantify balance control and 
change after rehabilitation. In preparation for this proposal, we have investigated current rehabilitation practice 
at our University and summarized our ongoing and published research demonstrating the value of objective 
balance and gait measures for mTBI. 
 

 
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Despite evidence of early intervention being a critical aspect of rehabilitation for many balance problems, people 
with mTBI are not being seen early by physical therapy. Our 
University has a comprehensive mTBI rehabilitation program 
that incorporates physical therapy recommendations from 
recent guidelines to include work on vestibular dysfunction, 
high-level balance dysfunction, attention and dual-task 
performance deficits (Weightman, Bolgla et al. 2010). 
However, even at our specialized mTBI clinic, the referral 
patterns for physical therapy are late and inconsistent. We 
randomly sampled 40 patients who were seen in OHSU 
Rehabilitation Center between October 2014 and September 
2016. The average age of this population was 37.5 ±12 years. Figure 1 shows the average timeline for patients 
seeking care after mTBI. On average, people were seen by the primary care physician on average 10 days after 
injury. In this group, 80% had complaints of imbalance and/or dizziness at their first physician office visit and yet 
the average time to see physical therapy was on average 61 days later.  
 
The lack of guidelines after the initial ‘rest period’ leads to inconsistent rehabilitation care. In the same 40 mTBI 
patients, we found that, unlike the initial physician visit, the timing for the initial physical therapy visit was 
extremely varied and unrelated to patients’ symptoms     (r = 
-0.049, p = 0.32). Figure 2 compares the right-skewed 
distribution of the time from injury to the first physician visit, 
with the delayed and variable distribution of the time from 
injury to the first physical therapy visit. The people who were 
seen early in physical therapy were the small 
percentage of people who had a direct 
referral from the OHSU Concussion Clinic. 
Similarly, we found that a random sampling of 
20 Veterans with mTBI seen at our Portland 
VA in Sept 2016, 60% (12/20) had subjective 
complaints of imbalance and/or dizziness and 
the average length of time to be seen by 
physical therapy for the first visit for Veterans 
was approximately 48 days from that 
physician visit. However, this group 
represented a more chronic population and 
had likely been seen outside the VA prior to 
the first physician visit at the Portland VA.  
 
We have data indicating that mTBI subjects 
with chronic balance complaints demonstrate 
abnormal sensorimotor weighting strategies 
for balance control. We tested 6 subjects with 
Figure 2. Histograms showing distribution of time from injury until 
the first physician visit and until the first physical therapy visit. 
Figure 1. Average time from injury to first visit with a physician and 
time from first physician visit to first visit with a physical therapist 
 
Figure 3. Central Sensorimotor Integration (CSMI) test. A. Balance 
control model used to interpret experimental body sway evoked by 
surface and/or visual tilt stimuli. B. Example results showing mean CoM 
body sway across 11 stimulus cycles evoked in a control subject and an 
mTBI subject by a surface tilt stimulus during eyes closed stance. C. 
Sensory weighting factors from control subjects (mean±sd) and 
individual mTBI subjects from 4 test conditions. 
 

 
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chronic mTBI and 16 healthy control subjects using a novel Central Sensorimotor Integration (CSMI) test. This 
data was obtained from currently funded DOD project # W81XWH-15-1-0620. The CSMI test evokes body sway in 
response to continuously applied pseudorandom wide-bandwidth, low-amplitude rotations of the stance surface 
and/or the visual scene viewed by the subject (Fig. 3B). The Center of Mass sway responses are interpreted with 
reference to a mathematical model (Fig. 3A) of the balance control system by adjusting model parameters to 
optimally account for the experimentally observed body sway. The identified model parameters are 
physiologically meaningful and include ‘sensory weights’, which quantify the proportional contributions of 
sensory systems to balance control, neural controller parameters, which quantify the amount of corrective action 
(ankle torque) generated to control balance, and the time delay in initiating corrective actions (Peterka 2002).  
Four of 6 chronic mTBI subjects tested to date showed abnormalities in sensory weighting scores on at least 1 of 
4 test conditions indicating increased abnormal reliance on proprioception and/or vision for balance control (Fig. 
3C). Additionally, 4 of the 6 mTBI subjects also showed reduced corrective action in one or more test conditions 
(not shown). Abnormally high sensory weights in a given test condition correspond to a greater disruption of 
balance in response to balance disturbances and balance is further disrupted when corrective actions are weaker 
than normal.  
 
Our preliminary results demonstrate that major sensorimotor integration deficits are present in many mTBI 
subjects with chronic balance complaints and that CSMI testing can characterize these deficits in individual 
subjects. The identified abnormal balance control (i.e. decreased weighting on vestibular information) strategies 
may be responsive to rehabilitation. Therefore, CSMI testing has the potential to track the effectiveness of 
rehabilitation in restoring normal balance control strategies. It is currently unknown if the abnormal strategies 
observed in chronic mTBI are due to maladaptive compensation that may be avoided with early intervention.  
We have recently demonstrated that instrumented tests of balance and gait are more senstive to mTBI than the 
clinical BESS. Balance impairment is most commonly assessed with a subjective question on imbalance 
(Guskiewicz, Register-Mihalik et al. 2013) and, sometimes, a clinical assessment such as the BESS (Shumway-Cook 
and Horak 1986, Riemann and Guskiewicz 2000). The low sensitivity (< 
64%) (Finnoff, Peterson et al. 2009) of the BESS may contribute to 
inconsistent referrals. We have shown that wearing an inertial sensor on 
the waist while performing the BESS significantly improves its sensitivity 
to mild impairments (Mancini, Salarian et al. 2012, King, Horak et al. 
2014). Specifically, mediolateral (ML) root-mean-squared (RMS) 
acceleration during double stance with eyes closed was more sensitive 
to classifying mTBI than clinical error counts when comparing the areas 
under the receiver operator characteristic curves (ROC) (AUC = 0.74 vs, 
0.61) from 128 college athletes; 50 with acute mTBI at approximately 2 
days post-injury (Fig. 4). While wearable sensor data is not currently 
used for balance assessment in the clinic, we have found it feasible for a 
trained assistant to perform instrumented tests of static and dynamic 
balance in patients with mTBI presenting to our clinic. Wearable sensor 
technology is commercially available and could readily be adopted for 
use in rehabilitation of balance disorders in mTBI patients presenting with imbalance. In this proposal we will 
develop and refine test protocols that can be used specifically for mTBI. Increasing the sensitivity of clinical 
balance testing may improve the consistency of referrals for physical therapy 
 
Pilot data for Aim II  
The primary goal of Aim II is to improve the compliance and quality of the rehabilitation exercises after mTBI by 
monitoring and reporting the performance of a home exercise program while using wearable sensors during self-
directed exercise at home. Here, we summarize preliminary data showing that head control is abnormal after 
mTBI which presents a challenge to consistently high quality exercises that target impairment. 
 
Figure 4. ROC curves for Instrumented and non- 
instrumented BESS 

 
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We have preliminary data showing that individuals with mTBI do not perform balance rehabilitation exercises in 
the same way as controls, despite similar instructions and ability to perform the task while working with the 
physical therapist. In our Rehabilitation Clinic, a physical therapist instructed 2 people with mTBI and 2 control 
subjects to perform a series of 3 common balance and vestibular exercises: gaze stabilization while standing, 
walking with head turns and quiet stance on foam with head turns. After all 4 people had learned the exercises, 
we later tested them, without coaching and without feedback, to perform the exercises, as they were meant to 
do at home. All participants wore a head-mounted Opal inertial sensor while performing the exercises. The two 
participants with mTBI had smaller peak-to-peak amplitudes and greater variability of rotational head velocity 
while performing the task compared to the control subjects (Fig. 5).  
Head turns while walking may be a good indicator for recovery after mTBI. We have data on 25 young athletes 
with a sport-related mTBI (2 days post-injury) and 25 matched healthy controls. Adapting the protocol for the 
Dynamic Gait Index (DGI), participants were asked to turn their head side to side while walking. Using an Opal 
inertial sensor affixed to the head with an elastic headband, we found that individuals with acute mTBI rotated 
their heads with less velocity (3.7 rad/s versus 4.3 rad/s; p = 0.07) and had smaller head movements (0.91 rad 
versus 1.0 rad; p = 0.06) during this common rehabilitation and everyday task at the initial assessment (Fig 6). 
Following the resolution of their symptoms, participants improved and executed the head turns at a similar 
angular velocity compared to controls. These preliminary results suggest symptomatic individuals with mild mTBI 
preferentially choose slower rotational head velocities and can improve over time. We similarly expect 
participants in Aim II to be capable of rotating their heads faster than they preferentially choose. We expect they 
are capable of increasing the speed and amplitude of head rotation when quantitative feedback is provided to 
the physical therapist about their performance at home. The individuals presented in Fig 6 were very mild and all 
returned to their sport without the 
need for a physician visit or 
rehabilitation. In contrast, we 
expect the participants in our 
proposed study will be more 
impaired since they are seeking out 
physician evaluation of their 
symptoms.  
 
Head coordination is altered during 
functional tasks of everyday living, 
such as walking and turning. We 
have preliminary data from 3 
individuals with chronic mTBI and 
ongoing complaints of imbalance 
and 17 healthy controls walking around a marked course 
containing left and right turns of 45, 90, and 135 degrees (Data 
Figure 5. Head rotational velocity of participants with complex mTBI and controls when instructed to rotate their head left and right while standing 
on a foam surface with eyes closed. Left shows raw data from gyroscope on the head and right shows means + SD 
Figure 7. Angular velocity of the head during left 
and right turns of various angles. Controls shown 
with mean ± SD. The individuals with mTBI (green) 
exhibited consistently less peak angular velocity of 
the head despite similar overall gait speed 
compared to controls. Two 90° turns were 
examined (King et al., pilot data) 
Figure 6. Peak rotational velocities of the 
head during walking with head turns. When 
symptomatic, concussed athletes had slower 
angular velocities than controls. Peak 
rotational velocities increased to normal 
levels once symptoms resolved. (King et al., 
presented at Society for Neuroscience, 2016) 

 
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obtained from currently funded DOD project # W81XWH-15-1-0620). While turning, the subjects with mTBI 
consistently rotated their heads slower than control subjects (Fig. 7) despite similar lumbar rotational velocities 
and overall speed of walking during a complex walking (navigation) task as quantified by inertial sensors affixed 
on the head, sternum, and lumbar area. These preliminary results suggest that mTBI influences the reorientation 
of the head during common ambulatory activities such as turning which could explain complaints of altered 
balance during complex everyday activities. 
 
Combined, these results suggest that symptomatic people with mTBI show abnormal head movements during 
prescribed head turning tasks as well as in everyday mobility tasks such as walking in complex environments. 
Further, they show an inability to perform head exercises directed at increasing head movement during various 
activities suggesting insufficient vestibular recovery and poor ability to perform a home exercise program. We 
propose that recovery may be improved by objectively monitoring the quality of prescribed balance exercises. In 
Aim II, we expect that increasing the angular velocity and amplitude of the head movement through home 
monitoring of prescribed balance and vestibular rehabilitation exercises will improve functional mobility during 
complex locomotor tasks such as walking and turning. 
 
Pilot data for Aim III  
The primary goal of Aim III is to develop a novel sensor-based biofeedback system to provide real-time 
information to the physical therapist regarding head (amplitude and velocity) and trunk stability during the 
training phase of rehabilitation. To accomplish this goal, we will work closely with 1) APDM (a local small 
company that develops and commercializes inertial sensor systems to quantify human movement), 2) physical 
therapists from local practices (OHSU Outpatient Clinic, the Portland VA Rehabilitation Center and community 
practices) and 3) mTBI patients to develop clinically-useful tools for balance rehabilitation after mTBI.  
 
APDM has experience in adapting wearable sensors for real time feedback on gait (i.e. step length and arm 
swing). APDM, together with our Balance Disorders Laboratory, has a current grant to support developing a 
biofeedback system for gait training (Phase I SBIR Grant R43AG056012; NIA). For this project, patients wear 
sensors on the feet, wrists and trunk while walking using a non-portable, laptop-based, biofeedback prototype 
(Fig. 8). APDM has developed and validated various innovative algorithms that use wearable inertial sensors to 
provide objective measures of gait and balance in patients with movement 
disorders. These algorithms have been developed to automatically collect 
and then analyze data offline. The algorithms use inertial sensors attached 
to the feet and lumbar segment to identify temporal events of the gait cycle 
including loading response, mid/terminal stance, pre-swing, and swing 
phases. In addition to gait events, the algorithm characterizes gait and 
dynamic balance with more than 20 spatial and temporal metrics. During 
Aim III of this project, we will develop and validate new algorithms to 
characterize head and trunk kinematics during movement without a laptop 
(Fig. 8).  
 
4. Study Design 
This study is an interventional study on people with mTBI with two nested arms. Arm 1 examines whether 
initiating interventional physical therapy earlier improves outcomes compared to the standard of care. Arm 2 is 
nested within Arm 1, and examines whether added information about the quality of prescribed exercises 
performed at home and obtained from inertial sensors further improves outcomes. A third arm of the study is to 
develop a system capable of delivering real-time feedback on the quality of prescribed exercises to improve 
outcomes. 
 
Figure 8. Current APDM feedback 
prototype using a laptop with auditory 
feedback. 

 
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5. Study Population 
The proposed interventional study (Aims I and II) will involve 160 human participants for intervention, all of 
whom who have sustained a mild traumatic brain injury (mTBI) and have complex, multisensory system 
impairment and complaints of imbalance and 10 subjects for validation. Aim III will involve a total of 80 human 
participants: 25 subjects who have sustained an mTBI with balance and/or vestibular deficits and 50 healthy 
control subjects and 5 physical therapists. The Oregon Health & Science University (OHSU) Concussion 
Management Clinic currently sees 1,200 new concussion patients per year and the primary care clinics at OHSU 
see approximately 3,000 mTBI patients per year. 
 
a. Number of Subjects 
The proposed interventional study (Aims I and II) will involve 160 human participants for intervention, all of 
whom who have sustained a mild traumatic brain injury (mTBI) and have complex, multisensory system 
impairment and complaints of imbalance and 10 mTBI subjects for validation. Aim III will involve a total of 80 
human participants: 25 subjects who have sustained an mTBI with balance and/or vestibular deficits and 50 
healthy control subjects and 5 physical therapists. A subset of (approx. 100) healthy adults will be tested to 
validate and provide normative data with the updated testing protocol.  
 
b. Inclusion and Exclusion Criteria 
Inclusion criteria for Aims I and II: Participants may be either Veterans or non-Veterans and must: 1) have a 
diagnosis of mTBI based upon VA/DoD criteria (Control and Prevention 2014, Defense 2015), 2) be between 18-
60 years-old, 3) be within the acute or post-acute stage (< 12 weeks post-concussion) according to the VA/DoD 
clinical practice guidelines (Group 2016),  4) be able and willing to come to OHSU for physical therapy and 
perform home exercise program daily for 6 weeks, 5) have no or minimal cognitive impairment; a score between 
0 and 9 on the Short Blessed test, and 6) have a SCAT sub score of 1 or higher on balance, dizziness, nausea, 
headache, or vision AND a minimum total score of 15. 
 
Inclusion criteria for Aim III: The physical therapists we will recruit to test and provide feedback on the system will 
1) have experience in neurologic rehabilitation and 2) be naïve to the APDM mobility Lab system. The patients 
with mTBI may be either Veterans or non-Veterans and must: 1) have a diagnosis of mTBI based upon VA/DoD 
criteria (Control and Prevention 2014, Defense 2015), 2) have continued complaints of imbalance, 3) be any time 
point out since mTBI, 4) be able and willing to test the system and provide structured feedback. The control 
subjects we will include may be either Veterans or non-Veterans and must be between the ages of 18-60 years-
old.   
 
Exclusion criteria for all categories: Participants must NOT: 1) have had or currently have any other injury, 
medical, or neurological illness that could potentially explain balance deficits (e.g., CNS disease, stroke, greater 
than mild TBI, lower extremity amputation), 2) meet criteria for moderate to severe substance-use disorder 
within the past month, as defined by DSM-V, 3) display behavior that would significantly interfere with validity of 
data collection or safety during study, 4) be in significant pain during the evaluation (5/10 by patient subjective 
report), 5) be a pregnant female (balance considerations), 6) have past history of peripheral vestibular pathology 
or ocular motor deficits, 7) be unable to abstain for 24 hours in advance of testing in the use medications that 
might impair their balance, and 8) any condition or behavior that would interfere with comprehending the 
consent form and/or following directions.  
 
c. Vulnerable Populations 
No vulnerable populations (pregnant women, fetuses, neonates, children, or prisoners) will be included in this 
study. 
 

 
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d. Setting 
All aims will take place at OHSU and at the VAPORHCS and recruitment may also occur at community clinics 
around Portland. VA and OHSU activities:  All data collected at the VA will be collected at the National Center for 
Rehabilitative Auditory Research by a VA investigator including an audiologist and/or a research assistant. OHSU 
data will be collected at the Balance Disorders Laboratory, School of Nursing and Vestibular clinic by an OHSU 
investigator including an audiologist and/or a research assistant.  All OHSU work will be done on OHSU time, 
under the OHSU portion of the approved protocol.  The rehabilitation intervention will be done in the Balance 
Disorders Laboratory.  
 
Adaptation during COVID- 19 restrictions: During this time we will implement virtual visits or over the phone 
visits instead of in-person. This includes recruitment, screening, and all modified testing and rehabilitation 
sessions. No VA participants or VA data will be collected during this time.   
 
e. Recruitment Methods 
Aim I & II: Participants will be recruited from 3 primary sources; 1) OHSU Family Medicine clinic, 2) OHSU 
Concussion Clinics, and 3) community clinics.  Subjects will be screened for Aim I & II through medical records by 
RA’s and MA’s for upcoming visits to clinics. Subjects interested in participating will receive a phone screening to 
determine basic eligibility. After passing initial eligibility screening they will be invited to come in for consent and 
comprehensive medical history screening. This study will use an Epic BestPractice Advisory (BPA) to recruit 
potential participants. Researchers will work with ITG to identify potential participants based upon the above 
eligibility criteria. Researchers will provide the list of inclusion and exclusion criteria and ITG will build the BPA in 
Epic based on these criteria. During a clinical interaction in Epic, if a patient meets the criteria built into the BPA, 
an Epic In Basket message will be sent to the study contact containing a link to the patient’s medical record.  
Study staff will contact identified patients to determine if they are interested in participating in the study.  Once 
the BPA has identified a patient, it will not fire again for that same patient. Recruitment methods may include 
websites such as the OHSU Study Participants Opportunities page; newsletters; advertisements; flyers and other 
printed study materials; social media; institutional communication and events; presentations; and outreach at 
community events.  
Prep to Research:  
Epic records for patients identified through the Epic BPA will be queried for eligibility and will be contacted by 
study personnel about the study. ResearchMatch.org will be used as one of the recruitment tools for this 
research study/protocol. ResearchMatch Volunteers will be contacted through ResearchMatch.org. Included 
with this submissions is a study recruitment message that will be sent to potential study volunteers."Aim III: 
Participants (physical therapists, mTBI patients and control subjects) will be recruited from 4 primary sources; 1) 
OHSU Rehabilitation Center 2) VAPORHCS (Rehabilitation and NCRAR Departments) 3) local outpatient physical 
therapy clinics in Portland and 4) the community (non-VA clinics). Physical therapists will be recruited from 
OHSU, the VA and the community. Once physical therapists from OHSU, the VA and the greater community have 
been recruited, they will be the ones to identify the potential mTBI patients for this Aim. To do this they will ask 
the patient if they are interested in learning more about participating in a 1-hour session to try the biofeedback 
sensor system. If the subject is interested, the physical therapist will give the subject the research assistants 
contact information and the subject will directly contact the research assistants. For all Aims, once potential 
subjects have been identified, research assistants will be responsible for the rest of the recruitment process, 
including further explanation of study details, screening and obtaining informed consent. The research assistant 
will ask prescreening questions on the phone to determine if the person is an appropriate candidate for the 
study. If the person meets all inclusion and exclusion criteria, the research assistant will schedule the candidate 
for the initial 1-hour appointment with the physical therapist and this will occur at OHSU in our Balance 
Disorders Laboratory. This 1-hour session will occur outside of the PTs regular clinical hours. Healthy controls 
will be recruited from the community and OHSU, using posted flyers. These flyers will be posted at community 
centers, fitness centers, and around the OHSU area. No flyers will be posted at the VAPORHCS. 
 

 
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Aim I & II: subjects will be compensated on a graduated scale to encourage retention. The first visit 
consisting of vestibular and oculomotor tests will be compensated $40. The second session, consisting of 
the baseline mobility and further oculomotor tests, will be compensated $60. The post-therapy mobility 
and oculomotor session will be compensated $80, and the retention mobility and oculomotor session 
will be compensated $100. Participants will be compensated $10 dollars per visit for each rehabilitation 
session. There is a maximum of 5 testing sessions, and approximately eight rehabilitation sessions. 
Subjects randomized into the standard of care intervention will be tested for mobility and oculomotor at 
both baseline and prior to starting their physical therapy. Therefore, the standard of care group will 
have an additional session for which they will be compensated $60. If a subject does not complete all 
parts of a session they will be compensated a prorated amount for their time based on the 
compensation for that session. People who complete all sessions for Aim I & II will be compensated 
$275 if they are randomized into the early intervention group, or $335 is they are randomized into the 
standard of care group.  
 
Adaptation during COVID- 19 restrictions: Participants will be compensated $10 for rehab, $20 for 
modified Day 1, and $30 for modified follow up testings. People that complete all modified sessions will 
be compensated up to $190.  
 
Home monitoring: Participants will be compensated $10/per day for approx. 7 days= $70.  This will take place at 
two different time points during the study for a maximum compensation of $140.   
 
Aim III: Physical Therapists will be compensated $100 for their time in training as well as testing. Both 
people with mTBI and healthy controls will be compensated $25 for the 60-minute long session  
 
f. Consent Process 
After a phone screening for inclusion/exclusion criteria by our research assistants, subjects who come in 
for testing will be presented with the appropriate consent form (either for Aims I & II, or for Aim III) that 
explains the nature of the study and the possible risks and benefits of the experiment, as well as Health 
Insurance Portability and Accountability Act (HIPAA) privacy information. The consent form also informs 
the subjects that they may withdraw from the study at any time without penalty. Subjects will be given 
privacy and ample opportunity to read, ask questions, and when satisfied document their consent to 
participate by signing the informed consent form. Consenting will take place at the subjects’ respected 
location depending on their status as a Veteran or civilian. We will obtain a joint OHSU/ VAPORHCS 
Institution Review Board (IRB) to facilitate the process between sites. 
 
Adaptation during COVID- 19 restrictions: We will provide consents to eligible participants through the 
Docu-Sign System.  A link with the OHSU informed consent form (ICF), OHSU repository consent, and 
OHSU HIPAA authorization will be sent to the participant’s preferred email address. A study team 
member will call the participant and discuss study details within the forms just like they would in-
person.  The study team member obtaining consent will be able to answer any questions the participant 
may have during this time.  After the participant has signed all forms the person obtaining consent will 
also be sent a Docu-Sign link to sign as well.  Once both parties have signed the documents the study 
coordinator will receive an email and will save these documents to a secure OHSU server.  The 
participant will also receive a copy of the signed documents.   
 
Mental Capacity: 
Subjects suffering from mTBI may have minimal cognitive impairment but must be able to follow 
instructions and comprehend the consent form. Control subjects will be excluded if they are cognitively 
impaired. 
 

 
Page 13 of 22 
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Ongoing Consent: 
Due to the length of this study, ongoing consent will not be considered for individuals participating. 
 
Consent for individuals with Legal Authorized Representative (LAR): 
Subjects with an LAR must be meet all inclusion criteria to participate in the research study. If all inclusion 
criteria are met the Legal Representative must complete an IRB approved ‘Application & Certification for 
Waiver or Alteration of the HIPPA Authorization requirement’ prior to participation in the study. This 
study will follow all rules and regulations of Title 10 United States Code Section 980 (10 USC 980).  
 
6. Procedures Involved 
Aim I & II 
 
We will ask subjects their preferred contact method for appointment reminders (email, text message, or phone 
call).  We will send participants IRB approved text/email templates for each appointment dependent on where 
their testing location is (VA or OHSU). 
 
All testing visits will take approximately 3-4 hours and will take place at either OHSU or at the Portland VA 
(NCRAR). During the first two initial testing sessions over two days, participants will complete questionnaires to 
help identify how they perceive their problems, as well as undergo clinical tests of vestibular function and 
balance and gait. We will place five small (Apple Watch size) motion sensors on their waist, feet, trunk and head 
to measure balance and gait, and then will use a Neurocom platform to measure balance during a variety of 
sensory conditions. The platform moves and the participant stands as still as they can. They will be secured in a 
harness to eliminate the chance of falling. We will then have you perform several balance and gait assessments 
such as standing on one leg, tandem stance and feet together as well as walking tests such as continuously 
walking for approximately two minutes. If rehabilitation does not begin immediately, there will have one 
additional balance and gait testing session just prior to beginning rehabilitation. The two follow up testing 
sessions after the conclusion of rehabilitation will include the balance and gait testing but not the vestibular 
testing. The first follow up session will occur immediately after the 6 weeks of rehabilitation and the second 
follow up session will be an additional 6 months later.  
 
Vestibular and cognitive testing session: 
The vestibular and cognitive testing session will involve a standard clinical battery of vestibular and oculomotor 
tests. All vestibular testing will be performed by an audiologist. Vestibular testing is a part of standard training of 
audiologists and testing as described here will be performed by a practitioner with a particular specialization and 
experience in vestibular testing. These tests will include: 
 
Hearing Tests: 
Your ears will be examined with an ear light to check for wax, substances or other conditions that might 
interfere with the tests to be conducted. Next a soft ear-tip will be placed in your ear canal opening and you will 
sit quietly while small changes in ear canal pressure are made. You will then be asked to listen very carefully and 
respond to tones of different pitches and loudness levels. These tests will take approximately 15 minutes to 
complete. 
 
Oculomotor, positional and other vestibular tests:  
Some vestibular tests require you to wear electrodes on your neck and face and listen to relatively loud sounds 
for short amounts of time while contracting your neck or eye muscles. For the other vestibular tests you will 
wear video eye goggles that track your eye movements either while you are seated in an upright chair that 
rotates from left to right or while being positioned laying down on an exam table. During the laying down 
positioning tests you will guided to move from sitting to laying down while the audiologist monitors your eye 
movements with the video goggles. For testing in the chair, you will be in a lightproof booth wearing video 

 
Page 14 of 22 
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goggles and first asked to follow a red dot as it moves in different ways. You will wear a seatbelt and be provided 
with a headset so you can communicate with the examiner outside the booth. The final chair tests involve it 
moving back and forth at different speeds while the examiner monitors your eye movements. Together these 
tests will take approximately an hour and a half to complete. 
  
Cognitive Testing:  
Participant will complete the Automated Neuropsychological Assessment Metric test, a computerized 
neurocognitive test. This test will take about 40 minutes to complete. 
 
Mobility and Coordination testing session: 
The following tests and procedures will be performed a maximum of 4 times, depending on which physical 
therapy group participants were randomized into. Throughout this session, participants will wear 5 inertial 
sensors: 2 at the feet, 1 on the waist, 1 on the trunk, and 1 on the head to record the movements of each body 
segment. The sensors record accelerations, angular velocities, and orientation data and wirelessly transmit 
these data to a computer located across the room. No PHI / PII or identifiable data is included in this 
transmission. 
 
Clinical and dynamic measures of balance, mobility and coordination: Participants will perform the Balance Error 
Scoring System consisting of 30 seconds of standing quietly in various conditions. They will also perform the 
mini-BEST, a standard clinical test of mobility that measures different elements of balance such as walking and 
going from sit to stand. They will also complete a complex turning task that involves motions similar to everyday 
movements around a home, where they will perform several walking turns in order to navigate a marked path 
multiple times. The time taken to complete the course will be recorded, and inertial sensors will record body 
movement. Eye tracking glasses will be worn and record the motion of the eyes during turning. Additionally, a 2-
minute walk test will be performed at 1) a comfortable pace, 2) a comfortable pace while performing a 
secondary cognitive task. Clinical and instrumented assessment will occur simultaneously using a stopwatch and 
the inertial sensors. Participants will also wear eye tracking glasses to monitor the stability of their vision with 
respect to body movements. These tests will take approximately one and a half hours.  
 
Oculomotor function and coordination: The coordination between participant’s eyes and head will be assessed 
using a clinical assessment of vestibular and oculomotor function (Vestibular/Ocular-Motor Screening for 
Concussion – VOMS). Participants will wear the inertial sensors described above and the eye tracking glasses 
described above and then be asked to follow the researcher’s finger in various configurations. Your vision will be 
screened using eye charts to test how clear letters are on a chart while seated and while moving your head. The 
researcher will ask then to report symptoms after each test. These tests will take approximately 15 minutes to 
complete.  
 
Central Sensorimotor Integration (CSMI) Testing: Participants will be tested on a modified Research NeuroCom 
platform where they will stand on a force plate to record postural sway. The surface and / or visual surround will 
move while the participant is instructed to maintain their balance. Participants will wear a safety harness 
attached above to prevent a fall in case a loss of balance occurs. Participants will complete several trials of 
different perturbations (e.g., visual surround moving, platform moving, both moving). This test will take 
approximately 40 minutes to complete.  
  
Questionnaires:  These tests help to identify how participants perceive their problems. 
 
Short Blessed Test (SBT): This questionnaire takes approximately 5 minutes and evaluates basic cognition and 
memory. 
 

 
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PROMIS Item Bank v1.0 (Satisfaction with Participation in Social Roles – Short Form 4a): This questionnaire asks 
four questions related to how satisfied they are with social roles in the past 7 days.  It takes approximately 2 
minutes and will be given at the same time as the SCAT-2.   
 
IPAQ (International Physical Activity Questionnaire- Short Form): This questionnaire takes approximately 5 
minutes and asks intensity and type of physical activity performed in the last 7 days.   
 
Dizziness Handicap Inventory (DHI): This questionnaire takes approximately 10 minutes and asks if   participants 
become dizzy while performing various tasks. 
 
PTSD Checklist (military or civilian version depending on service): This questionnaire takes approximately 10 
minutes and is a list of problems and complaints some people have in response to stressful life experiences. 
 
Sports Concussion Assessment Tool – 2 (SCAT-2): This questionnaire and balance screen takes approximately 10 
minutes and asks people to rate 22 different symptoms on a scale between zero and six. This symptom 
questionnaire will be administered weekly by survey (REDcap) or by telephone, depending on the participant 
preference. 
 
Neurobehavioral Symptom Inventory (NSI): This questionnaire takes approximately 10 minutes and goes 
through commons symptoms after traumatic brain injury (such as nausea and blurred vision) and asks them to 
rate symptoms. 
 
Insomnia Severity Index (ISI): This questionnaire quantifies a participant’s difficulties sleeping in the last two 
weeks on a scale of 0-4. It takes approximately five minutes. 
 
Headache Impact Test- 6 (HIT-6): This questionnaire measures one’s ability to function in everyone life (work, 
school, home and social situations). This questionnaire takes five minutes. 
 
Quality of Life After Brain Injury (QOLIBRI): This questionnaire takes approximately 10 minutes and will ask them 
to rate your quality of life before and after concussion. 
 
Concussion Symptom Subtype Inventory (CSSI): This questionnaire takes approximately 10 minutes and asks you 
to rate if you have had specific symptoms within eight categories at two points in time – before your injury and 
now.  
 
Patients Global Impression of Change (PGIC): This single questionnaire takes approximately 1 minute and will ask 
people to rate how they perceive their health has changed over the course of treatment on a scale of 1-7.  
 
Home monitoring: A subset of participants will be given an inertial sensor to wear at home for a period of time 
(i.e. 7 days) to follow their activity recovery at home.  
 
Adaptation during COVID- 19 restrictions: Modified procedures during this time will be for study team members 
to ask questionnaires (listed above) over the phone or through a virtual visit. Participants will be emailed a PDF 
of the questionnaires for them to review while the study team member asks them to subjectively rate their 
symptoms.  
 
Intervention: After participants are enrolled in the study, they will be randomly assigned to begin physical 
therapy immediately (approximately 2 weeks after their physician appointment) or within the standard of care 
timeline (approximately 8 weeks after their physician appointment). This randomization will be found on a pre-
assigned list that was generated prior to their enrollment. This randomization will be performed in RedCap by a 

 
Page 16 of 22 
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statistician using the Randomization Module to ensure half the participants receive the early intervention and 
half receive the standard of care timeline. Rehabilitation will last for 6 weeks with approximately one physical 
therapy session per week. During these sessions, the participant will be evaluated by the physical therapist and 
will perform exercises around commonly impaired areas such as balance performance, head movement, and 
aerobic exercise capability. They will be expected to do a home exercise program that is tailored to their ability 
level and you will either do this home portion as it is commonly prescribed or while using a wearable sensor to 
track head and trunk movements. They will be progressed in their rehabilitation program according to standard 
practice and by ability level. See appendix for specific details of intervention. 
 
Functional Near Infrared Spectroscopy: 
Functional Near Infrared Spectroscopy (fNIRS) is a noninvasive, mobile 
brain imaging modality that allows for reliable measures of cortical 
activity. Prefrontal cortex activity data will be collected on a subset of 
participants using a wireless portable, continuous-wave, functional 8-
channel fNIRS system (OctaMon, Artinis Medical system) on the first and 
last rehabilitation session when performing aerobic exercise on the 
treadmill (Figure 9). 
 
Adaptation during COVID- 19 restrictions: A study team member will send 
or deliver the wearable sensor technology to the subject’s home.  No 
physical contact will occur with patient. The physical therapist will do all 
rehabilitation intervention through a virtual visit.  The home exercise 
program will be tailored to their ability and level.   
 
Post testing: After the conclusion of physical therapy, subjects will be 
retested two times on the gait and balance testing but not the vestibular testing. The posttest session will occur 
after the 6 weeks of physical therapy. The follow-up session will be an additional 6 months later and will 
encompass the same testing protocol as the posttest session. 
 
Home Monitoring: 
Participants may be sent home with wearable sensors at pre-physical and post-physical therapy time points and 
wear the sensors for approx. 1 week. The wearable sensors will be worn for a minimum of 8 hours each day and 
collect the participant’s activity and mobility metrics. 
 
Videotaping: Testing session may be videotaped for use in data checking and educational purposes. We will not 
videotape if the participant requests not to be videotaped. It is not a requirement of the study. We will use the 
photographs and videos in research publications and educational materials, in these cases we will use a black 
box over the participants face to hide their identity.  
 
Aim III   
 
Physical therapists will be trained to use the biofeedback sensor system and will be asked to try the system and 
provide feedback to the researchers and company (APDM). They will also be asked to evaluate the system with 5 
of their patients who have balance deficits and mTBI. Specifically, they will use the device to provide feedback 
during 3 specific vestibular exercises: gaze stabilization (head turns), walking with head turns and standing on 
foam with eyes closed and turning the head.  Feedback will be either auditory or visual from the motion of the 
head and/or trunk. People with mTBI will be asked to try the biofeedback system and provide feedback to the 
researchers and company (APDM).  People without mTBI will be asked to perform specified exercises that 
require head movements during standard balance and vestibular exercises in order to obtain normative values 
Figure 9. fNIRS measurements during
rehabilitation 

 
Page 17 of 22 
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to incorporate into the patient report forms. All of these sessions will occur at OHSU in the Balance Disorders 
Laboratory. 
 
Questionnaires: 
Health Screening Questionnaire: This questionnaire will take approximately 15 minutes to complete, containing 
questions about participant age, sex, race/ethnicity, and a comprehensive look at health history and symptoms. 
 
mTBI (concussion) Screening Questionnaire: This questionnaire will take approximately 15 minutes to complete 
and contains questions about injury, severity, treatment and history to determine eligibility. 
 
Physical Therapists Questionnaires:  
System Usability Questionnaire: This questionnaire takes approximately 5 minutes and ask them to rate the 
APDM Mobility Lab system for ease of use and user friendliness.  
 
We will ask Physical Therapists about their general practice and experience. 
 
7. Data and Specimens 
a. Handling of Data and Specimens 
Data on gait, balance, eye movements, vestibular and oculomotor function, and questionnaires will be collected 
and stored on our secure OHSU database. All data will be entered by research personnel and stored indefinitely. 
 
b. Sharing of Results with Subjects 
The results generated in this study are experimental in nature and will not be shared with study subjects. 
 
c. Data and Specimen Banking 
Laboratory Evaluations:  Not applicable. This study does not propose to collect or store human 
specimens. 
Data will be de-identified with a unique subject ID that on the PI and RA will be able to link the ID to the person. 
Subject information and study data will be stored behind a locked office in a locked cabinet at OHSU (if paper) or 
behind a secure Oregon Health & Science University (OHSU) firewall on network drives requiring password 
authentication (if electronic). If being stored at the VA, it will be kept on the secure VAPORHCS network folder 
(King17370) or in locked cabinets in locked office P5F-153 bldg 104 (if paper). Data will be stored at OHSU in our 
secure database and may be used for future research. We will also ask permission from our subjects to be 
maintain their data in our Balance Disorders Laboratory repository (eIRB# 7797). 
As required by the DOD, we will upload de-identified data to Federal Interagency Traumatic Brain Injury Research 
Informatics System (FITBIR) quarterly. The data will have no PHI uploaded and only quantitative data will be 
uploaded.  
 
8. Data Analysis 
 
Analysis of oculomotor data: We will use eye tracking along with inertial sensors on the head and trunk to 
examine how well the subjects is able to maintain a stable gaze, particularly in the horizontal and vertical VOR 
conditions, by examining average eye velocity throughout the condition. Secondary measures will be the cross-
covariance between eye velocity and head angular velocity. 
 
Analysis of postural sway data: Postural sway will be automatically quantified in the ML direction using APDM 
software during each stance condition by calculating the RMS around the mean acceleration (acc), a metric 
representing sway dispersion (APDM 2013). Our primary measure for this test will be the averaged ML RMS 
during the Instrumented Modified BESS using an inertial sensor to measure linear acceleration of the body since 

 
Page 18 of 22 
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this test could classify mTBI best in our previous study (King et al., under review). Other temporal and spatial 
metrics such as sway velocity, frequency and jerkiness will be simultaneously collected for secondary analysis. 
Analysis of head stability during gait: Our primary measure during gait will be the lumbar to head attenuation of 
acceleration quantified by the attenuation coefficient (Iosa, Mazzà et al. 2010). The attenuation coefficient 
quantifies the amount of acceleration that is dissipated when moving from inferior to superior body segments. It 
is calculated using the ratio of head RMS acceleration to lumbar RMS acceleration, with a larger attenuation 
coefficient indicating more acceleration was dissipated from the lumbar to the head. Wireless eye tracking 
goggles during each trial will be analyzed to obtain secondary measures including the cross-correlation and time 
lag between eye, head, and trunk rotational velocities. The eye tracking glasses and head sensor will be used to 
quantify change in visual field and the quality (amplitude, symmetry, smoothness of head movement) of 
purposeful head turning, respectively, when participants are asked to walk while performing head turns. 
 
Analysis of complex turning: Head, sternum, and lumbar mounted inertial sensors will quantify the angular 
velocity of reorienting segments, specifically of the head, trunk, and pelvis. The primary outcome will be the peak 
axial angular velocities head for each turn. Mobile eye tracking glasses will quantify the reorientation velocity and 
timing of the eyes with respect to the head. Eye-to-head, head-to-trunk, and head-to-lumbar sequential timing, 
along with peak axial angular velocities of the trunk and pelvis, will be calculated from the inertial sensors as 
secondary outcomes. 
 
Analysis of CSMI data: The primary outcome measures are the parameters derived from a model-based 
interpretation of CoM sway evoked by pseudorandom stimuli (Table 4). The procedure for calculating these 
parameters is to (1) calculate CoM angular displacement from experimental measures of hip and shoulder 
displacement on each test trial, (2) use Fourier methods to calculate a frequency response function, FRF (Pintelon 
and Schoukens 2001), and (3) adjust parameters of a model of the balance control system using a constrained 
optimization algorithm until the model-derived FRF optimally matches the experimental FRF (Peterka 2002, 
Peterka 2003). 
 
Sample size calculation for Aims I and II: 

 
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 Sample size estimation for the efficacy of early versus later physical therapy intervention on patient-reported 
outcomes (Aim I) was derived from a published study evaluating the effects of early initiation of balance exercises 
after acute, peripheral vestibular balance disorders as measured by the Dizziness Handicap Inventory (DHI) 
(Jacobson and Newman 1990, Bamiou, Davies et al. 2000). Patients who presented for treatment within six 
months of the onset of vertigo had lower DHI scores following physical therapy compared to those who waited 
longer (22 versus 51, Mann-Whitney, p=0.007, Cohen’s d=0.432). This significant difference in symptomatic 
outcome based on the effect of physical therapy latency is expected to be at least as profound in the proposed 
cohort given this study investigates the effects of an even earlier initiation of physical therapy, than the six or 
more-month latency of the described study. Assuming the effect size 
between early and late therapy initiation observed in the literature is 
equivalent in magnitude to the effect size expected in the proposed 
cohort, a significant effect of time would still be observed at α=0.05 with 
80% power with a sample size of 36 per group, for both the wearable 
sensor group and standard physical therapy regimens.  
We demonstrated the resolution of symptoms in very mild mTBI was 
associated with increased head rotation during walking with head turns 
(Fig. 6). Power analysis for the secondary outcome (head-turn velocity) 
was derived from our pilot data assessing improved head velocity over 
time. In an mTBI cohort, a significant rate of change was observed with 
increasing head-turn velocity over time (N=26, t=4.07, p<0.001, Cohen’s 
d=0.798, Fig. 6). With the same sample size of 36 per group, a significant 
effect of early versus later intervention would still be observable at 
α=0.05 with 80% power, if there is at least a 56% difference in the effect 
size (d=0.446) between the two time-course arms for either intervention 
group. Similarly, this effect size could also be observed to be statistically 
significant between the feedback-enhanced intervention and standard 
exercise regime within either the time to rehabilitation cohorts. Assuming 
a dropout rate of ~20% over the study period, the expected effects sizes 
would be found to be significant with a final recruitment of 40 subjects 
for each of the four groups; totaling 160 people with mTBI for aims I and 
II combined. 
Primary outcome: DHI   The final sample for Aims I and II will consist of four distinct groups: A) early 
rehabilitation using wearable sensors at-home, B) early intervention with traditional at home exercise 
program, C) late rehabilitation using wearable sensors at-home, and D) late intervention with traditional 
at home exercise program. Linear mixed-effects models will be used in an intention-to-treat design to 
assess the continuous rate of change in DHI over time in each group. Mixed-effects models will be used 
to account for within-subject correlation in the repeated measurements across time while addressing any 
missing data due to dropouts or absentee visits. An on-treatment comparison will also be leveraged, 
using ordinary least squares to model to bulk change in study outcomes from baseline to study exit for all 
subjects completing the study.  
To compare the effect of early versus late intervention, the main effect of time (Aim I, comparing groups 
AB to CD) will be assessed in the mixed-effects model. To compare the effect of rehabilitation with home 
monitoring versus standard-of-care rehabilitation, the main effect of treatment will be assessed in the 
mixed-effects model (Aim II, comparing groups AC to BD). To compare whether the effect of at-home 
monitoring is different between early and late rehabilitation, the interaction between time and 
treatment will be evaluated using the mixed-effects model. Beyond the main effects of time, treatment 
and their interaction, individual contrasts among groups will be considered using an ANOVA framework 
to compliment mixed-effects regression model.  
 
Study design for Aims I and II 

 
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Mixed-effects models will also incorporate covariates found to influence study outcomes, including, but 
not limited to, age, gender, vestibular function. For the intention-to-treat mixed-effects models, an 
unstructured error covariance structure will be utilized and parameters will be estimated using restricted 
maximum likelihood procedures. Missing data points in the analytical sample are considered missing at 
random and the above approach is sufficient under this assumption. Results will be considered significant 
at α=0.05 with Holm-Bonferroni adjustments to correct for multiple comparisons among the various 
outcome measures. Model fit and integrity will be examined using a combination of formal fit criteria and 
visual inspection of residual plots. 
Secondary Outcome measures will be assessed using the mixed-effects models as described above to determine 
the effect of time and treatment on each outcome. To determine the meaningful change of head stability metrics 
after rehabilitation, the minimal detectable change of our novel outcome measures presented in Table 2 such as 
attenuation coefficient, cross-covariance of eye, head, and lumbar movements, peak axial rotational velocities, 
and sequential timing of reorientation will be calculated. Minimally clinically important difference for these novel 
measures will also be calculated using an anchor-based approach where clinically meaningful difference is based 
on PGIC. 
 
9. Privacy, Confidentiality, and Data Security 
Identifiers: Subjects will be assigned a coded study identification (ID) number generated after written informed 
consent has been obtained.  The subjects’ name and unique ID number will be recorded in an electronic file, 
stored on a password-protected secure drive. Research records will be stored in a confidential manner so as to 
protect the confidentiality of subject information. Data collection forms will be labeled using unique study ID 
numbers and will not have personal identifiers. 
 
Confidentiality:  To ensure and protect the privacy of the study subjects and to maintain confidentiality of the 
data, the following activities for data and safety monitoring will be in place for the study: 1) A detailed plan will 
be approved by the Institutional Review Board (IRB) before recruitment begins, 2) Data will be coded upon 
collection with the key to the code held separately from the data and accessible only to IRB approved study 
personnel who need to know. Subject information and study data will be stored behind a locked office in a 
locked cabinet at OHSU (if paper) or behind a secure Oregon Health & Science University (OHSU) firewall on 
network drives requiring password authentication (if electronic). If being stored at the VA, it will be kept on the 
secure VAPORHCS network folder (King17370) or in locked cabinets in locked office P5F-153 bldg 104 (if 
paper). The representatives of the US Army Medical Research and Material Command (USAMRMC) are eligible 
to review study records. The persons who are authorized to use and disclose the data from this study are the 
approved investigators, other research professionals at OHSU who are participating in the conduct of this 
research protocol, and the OHSU/Veteran Affairs (VA) IRB. All data will be safeguarded in accordance with 
Health Insurance Portability and Accountability Act (HIPAA). The knowledge of any pending compliance 
inspection/visit by the USAMRMC, or other government agency concerning clinical investigation or research, the 
issuance of Inspection Reports, warning letters, or actions taken by any Regulatory Agencies, including legal or 
medical actions, and any instances of serious or continuing noncompliance with the regulations or requirements 
will be reported immediately to OHSU and/or the Portland VA Human Research Protection Office, and to the 
Department of Defense and/or USAMRMC. Representatives from USAMRMC are eligible to review study records 
upon request. Data collected in this study do not include any sensitive information, such as history of 
communicable diseases that are required to be reported to state or local authorities. 
  
Data capture, verification and disposition: Data will be gathered from questionnaires and instrumented 
assessments, and entered into the web-based Research Electronic Data Capture system (REDCap) and into the 
OHSU Balance Disorders database. REDCap is a secure electronic database administered by OHSU. Hard copies 
of these records will be stored behind a locked office in a locked cabinet at OHSU or if at the VA on the secure 
VAPORHCS network folder (King17370) or in locked cabinets in locked office P5F-153 bldg 104 (if paper). The de-
identified Mobility Lab data will be collected on a password-protected and data-encrypted laptop computer and 

 
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uploaded after each test session to an OHSU secure server, where the Balance Disorders database is located. 
The computer that will store the project database will be protected by current network security behind OHSU 
firewall. An institutional computer account and password will be required to access the computer storing the 
recruitment database and the images. In addition, the REDCap database is password protected, and only project 
personnel approved by Dr. King will be given access. Any hard-copy research records and consent forms will be 
stored in a locked file cabinet within a locked, secure office. Hard-copy and electronic research records will be 
kept for seven years, in compliance with HIPAA, or one year after publication, whichever is longer. VA record will 
be keep indefinitely or as directed by the VA standards. All identifiers will be removed at the completion of the 
study and it will not be possible to link the data to individuals after that time. 
 
Adaptation during COVID- 19 restrictions: All data collected over the phone or through virtual visit will be 
recorded on REDCap and stored on a secure OHSU server, which only study team members have access to.  
The study team member and participant will do all remote virtual visits over a secure Wi-Fi network.  
10. Provisions to Monitor the Data to Ensure the Safety of Subjects 
See the Data and Safety Monitoring Plan form for details.   
 
11. Risks and Benefits 
 
a. Risks to Subjects 
Information that identifies participants will be used in this study and shared with research staff and non-VA 
researchers. A breach in confidentiality and a resulting loss of privacy could result in monetary loss due to 
identity theft. However, the research team will make every effort to protect private health information and 
guard against any loss of privacy. 
 
Musculoskeletal injury -There is a low risk of joint, tendon, or muscle pain, inflammation, or swelling during or 
after a testing session of gait and balance. The risk is reduced by use of well-trained assistants and also by the 
mild nature of the gait, balance and vestibular testing. 
 
Exacerbation of symptoms - There is a low risk that existing symptoms such as dizziness will become worse by 
performing the tests and performing rehabilitation. 
 
Emotional Distress- Some of the questions asked may be personal or embarrassing. People may refuse to 
answer them if they don’t want to. Also, they may learn information about their balance and walking and that 
could be upsetting to them. 
 
Falls- The balance and walking tasks may cause them to lose their balance or fall. However, our trained 
research assistants will walk alongside them at all times for safety.  All safety measures will be taken to ensure 
a secure and comfortable environment. People will be allowed to take a break from the balance and walking 
tasks whenever necessary. For balance testing on the force plate, people will be secured in a harness for 
safety. 
 
Nausea- There is a risk during some of the vestibular testing that some people will experience nausea and or 
dizziness, in which case we stop the test immediately. 
 
Wearable sensor system- The wearable sensors worn on the body are commonly used in other laboratory 
studies assessing balance and gait. There is no identifiable information stored on these sensors. These sensors 
are non-invasive and may cause minimal discomfort, no greater than wearing a headband, wristwatch or belt. 
 

 
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Biofeedback sensor system- These sensors used for biofeedback are the same as the sensors in the wearable 
sensor system. There is no identifiable information stored on these sensors. These sensors are non-invasive 
and may cause minimal discomfort, no greater than wearing a headband, wristwatch or belt. 
 
Other Risks:  There is a small risk that people may experience some ear discomfort when having your ears 
examined and with wearing earphones during testing. Possible temporary discomfort may be experienced 
during preparation and placement of the electrodes on their skin. This is rare and lasts only a short period of 
time. Some tests require wearing video goggles over the eyes, these may also cause discomfort. 
All sounds will be presented at levels where there is minimal risk of damage or discomfort. The vestibular-
evoked potential tests involve the presentation of brief but loud sounds, if they find the sounds too loud we 
will stop the tests.  
 
b. Potential Benefits to Subjects 
Subjects and physical therapist will be compensated for their participation in this study. Subjects who 
participate in Aim I and Aim II will receive free physical therapy. Subjects may or may not personally benefit 
from being in this study. However, by serving as a subject, they may help us learn how to benefit patients in 
the future. All rehabilitation will be provided free of charge. 
 
Short-term impact: Anticipated outcomes in the short term are to facilitate evidence-based recommendation 
for timing of physical therapy intervention for mTBI, particularly for those with complaints of imbalance. 
Based on results from this project and the expected benefits of early physical therapy, we expect patients 
with mTBI will have faster and more consistent referrals to physical therapy, thereby facilitating faster 
recovery. We expect the short-term impact will be immediately addressed within OHSU clinics who see 
patients with mTBI. Another short term impact will be mTBI-specific protocols implemented into the 
commercially available APDM Mobility Lab system. These test protocols will be readily available for 
researchers and clinicians.  
 
Long-term impact: Our long term goals for this project are to produce more evidence-based rehabilitation and 
to ultimately improve care after mTBI. We believe that implementation of the findings from this research can 
be readily adopted into military protocols for post-mTBI care and have the potential to produce more long-
term efficacious balance rehabilitation. An important long term impact of this work could clarify best practices 
for the rehabilitation of balance deficits by providing evidence regarding when to initiate rehabilitation and by 
producing protocols for utilizing wearable sensors in assessing and treating balance deficits after mTBI. We 
expect the use of wearable, inertial sensors will progressively increase throughout clinical, field-side or in-
theatre environments as technology becomes less expensive and more widely accepted. This project will 
result in a portable, wireless, and easy-to-use product for physical therapists to use when training complex 
balance and vestibular rehabilitation exercises. The use of wearable sensors, as proposed in our project, is 
gaining momentum in the civilian and military populations as a method to detect mTBI. Yet, the use of inertial 
sensors in rehabilitation settings for clinical care is still lacking. This project will produce a system with 
wearable sensors to augment rehabilitation by providing feedback on the quality of head and trunk 
movements that are difficult to quantify visually. We anticipate that implementing this system will significantly 
improve the efficacy of rehabilitation following mTBI, reduce the chronic effects of mTBI and improve quality 
of life after mTBI.  More effective rehabilitation will also lower the economic burden of mTBI on health care 
costs.