COMPUTERIZED DYNAMIC POSTUROGRAPHY COMPARING THE …

ABSTRACT

COMPUTERIZED DYNAMIC POSTUROGRAPHY COMPARING THE BERTEC BALANCE ADVANTAGE™ AND NEUROCOM

SMART BALANCE MASTER® IN ASSESSING POSTURAL STABILITY IN HEALTHY ADULTS

Purpose: The purpose of this study is to establish the validity of postural

stability measures between a new computerized dynamic posturography (CDP)

system Bertec™ using an immersive virtual environment to the gold standard sway-

referencing of NeuroCom®. Methods: 50 healthy adults aged 20-69 years old were

tested on the 3 protocols for CDP: Sensory Organization Test (SOT), Motor Control

Test (MCT), and Adaptation Test (ADT). Results: Strong to moderate correlation

values between Bertec™ and NeuroCom® on the SOT's Conditions 1-6 and

Composite and MCT indicating good concurrent validity. Poor correlation values for

ADT toes up and toes down indicating poor concurrent validity. Condition 1, 4, 6 and

SOT composite equilibrium scores were significantly lower in Bertec™ MCT

composite latency scores were significantly longer and ADT toes up and toes down

sway energy scores were significantly higher on Bertec™. All scores indicated less

stability observed on the Bertec™ versus the NeuroCom® The largest clinically

important difference was found in Condition 4 on the SOT and the ADT. Conclusion:

CDP tests of SOT and MCT showed high levels of concurrent validity indicating that

both Bertec™ and NeuroCom® are valid measures of postural stability. With

somatosensory and vestibular ratio scores comparable, it gives clinicians confidence

both devices are reliable in measuring somatosensory and vestibular cues for balance.

Significantly lower vision ratio scores on Bertec™ as compared to NeuroCom®,

suggest the immersive virtual environment of Bertec™ may provide a more sensitive

analysis of visual input into postural stability.

Carolyn Bentley May 2017

COMPUTERIZED DYNAMIC POSTUROGRAPHY COMPARING

THE BERTEC BALANCE ADVANTAGE™ AND NEUROCOM

SMART BALANCE MASTER® IN ASSESSING POSTURAL

STABILITY IN HEALTHY ADULTS

by

Carolyn Bentley

A project

submitted in partial

fulfillment of the requirements for the degree of

Doctor of Physical Therapy

in the Department of Physical Therapy

College of Health and Human Services

California State University, Fresno

May 2017

APPROVED

For the Department of Physical Therapy:

We, the undersigned, certify that the project of the following student meets the required standards of scholarship, format, and style of the university and the student's graduate degree program for the awarding of the doctoral degree. Carolyn Bentley

Project Author

Peggy Trueblood (Chair) Physical Therapy

Monica Rivera Physical Therapy

Nancy Wubenhorst Physical Therapy

For the University Graduate Committee:

Dean, Division of Graduate Studies

AUTHORIZATION FOR REPRODUCTION

OF DOCTORAL PROJECT

X I grant permission for the reproduction of this project in part or in

its entirety without further authorization from me, on the

condition that the person or agency requesting reproduction

absorbs the cost and provides proper acknowledgment of

authorship.

Permission to reproduce this project in part or in its entirety must

be obtained from me.

Signature of project author:

ACKNOWLEDGMENTS

I would like to thank my family including my mother Theresa and brothers

Derek and Kevin for all the support provided. I would also like to thank the Fresno

State Graduate Net Initiative Research Fellowship program for the workshops

provided as well as a travel opportunity. Lastly, I would like to thank my project

chairs for all their help in creating a positive learning environment including Dr.

Peggy Trueblood, Dr. Monica Rivera and Nancy Wubenhorst.

Thank you to everyone who has helped me these past 3 years in pursuing a

Doctor of Physical Therapy degree at California State University, Fresno.

TABLE OF CONTENTS

Page

LIST OF TABLES ................................................................................................. vii

LIST OF FIGURES ............................................................................................... viii

INTRODUCTION .................................................................................................... 1

METHODS ............................................................................................................... 5

Participants and Enrollment .............................................................................. 5

Testing Procedures ............................................................................................ 5

Data Analysis .................................................................................................... 7

RESULTS ................................................................................................................. 8

Sensory Organization Test & Sensory Ratio Scores ......................................... 9

Motor Control Test .......................................................................................... 10

Adaptation Test ............................................................................................... 10

DISCUSSION ......................................................................................................... 12

Statistical Findings .......................................................................................... 12

Limitations ...................................................................................................... 18

Future Research ............................................................................................... 20

Conclusion ....................................................................................................... 22

REFERENCES ....................................................................................................... 23

TABLES ................................................................................................................. 28

FIGURES ............................................................................................................... 35

APPENDICES ........................................................................................................ 41

APPENDIX A: STANDARDIZED TESTING INSTRUCTIONS ........................ 42

APPENDIX B: CONDITIONS 1-6 OF THE SOT ................................................ 47

APPENDIX C: MOTOR CONTROL TEST.......................................................... 49

Page

vi vi

APPENDIX D: ADAPTATION TEST .................................................................. 51

APPENDIX E: HEALTH QUESTIONNAIRE ..................................................... 53

APPENDIX F: INFORMED CONSENT ............................................................... 56

LIST OF TABLES

Page

Table 1: Subject Characteristics ............................................................................. 29

Table 2: Pearson's Correlation Coefficients for SOT, MCT & ADT ..................... 30

Table 3: Equilibrium Scores for SOT Conditions 1, 2, 3 and 4 across Age Groups ...................................................................................................... 31

Table 4: Equilibrium Scores for SOT Conditions 5, 6 and Composite Score Across Age Groups .................................................................................. 32

Table 5: Somatosensory, Vision, Vestibular & Preference Ratio Scores across Age Groups .............................................................................................. 33

Table 6: MCT Latency and ADT Toes Up & Down Trial 1 and 5 Sway Energy Difference Across Age Groups ................................................................ 34

LIST OF FIGURES

Page

Figure 1: Bertec™ Balance AdvantageTM (a) and NeuroCom® Equitest (b) ........ 36

Figure 2: Pearson's Correlation coefficient for Bertec™ and NeuroCom® for SOT conditions 1-6 and SOT composite. ............................................... 36

Figure 3: SOT conditions 1-6, composite equilibrium score for all subjects ......... 37

Figure 4: SOT composite equilibrium score across age groups ............................. 37

Figure 5: MCT latency composite scores comparing age groups .......................... 38

Figure 6: MCT composite latency scores across age groups ................................. 38

Figure 7: ADT toes up & down sway energy for the mean difference between Trials 1 and 5 ..................................................................................... 39

Figure 8: ADT toes up sway energy across age groups ......................................... 39

Figure 9: ADT toes down sway energy across age groups .................................... 40

Figure 10: Condition 4 equilibrium scores for Trials 1-3. ..................................... 40

INTRODUCTION

Balance or dizziness impairments are common in the adult population1. It

has been estimated that 40% of the population in the United States will experience

some form of balance or dizziness impairment over the course of a lifetime1.

Falling can be a direct consequence of dizziness and balance impairments

especially in people over 65 years of age compounded by other neurologic deficits

and chronic medical problems2,3. Falls are the leading cause of death and injury in

patients that are 65 years and older resulting in direct medical costs over $31

billion annually2,3. More than 2.8 million older adults are treated in the emergency

department for fall injuries each year4. Therefore, it is important to seek valid and

reliable postural control stability measures that identify individuals with functional

impairments and those that may be at increased risk for falls.

Postural stability is a person’s ability to correctly perceive their

environment through peripheral sensory systems and maintain their upright stance.

The brain relies on the sensory input from the somatosensory, visual and

vestibular systems in order to maintain the body's center of gravity over its base of

support. When these 3 sensory systems are affected they relay altered information

to the brain and the individual is unable to organize the sensory input correctly.

This results in postural instability with difficulty in controlling their body's sway

leading to falls and imbalance5,6. Postural instability has been shown to be a high

predicting factor of a patient’s fall risk in both computerized and non-

computerized measurements5,6. There are a multitude of reliable and valid methods

to subjectively and objectively measure postural stability.

Current postural control and fall risk assessment techniques include Berg

Balance test, Modified Clinical Test of Sensory Interaction and Balance

2 2

(mCTSIB), Timed Up and Go, Functional Reach, among others7-10. Although

these tests are valid and easily conducted in the clinical setting, they have potential

drawbacks including variability in test performance, biases in the subjective nature

of the scoring system and decreased sensitivity to small changes11,12.

Computerized Dynamic Posturography (CDP) was developed to diminish these

drawbacks by providing a consistent quantitative postural control assessment11,12.

Computerized Dynamic Posturography is a computerized device used to

quantify an individual’s postural control through the movement of the body’s

center of gravity using dynamometric platforms12. It is an integral component in

the diagnostic workup of balance impairments to help identify the underlying

sensory and motor control impairments12,13. Developed in the 1980s, NeuroCom®

International provided the EquiTest system involving the Sensory Organization

test (SOT), Motor Control test (MCT) and Adaptation test (ADT)14 (Figure 1).

This system is the gold-standard assessment technique used to quantify and

differentiate the sensory, motor, and central adaptive impairments in balance

control through postural sway-referencing. Sway-referencing refers to tilting of the

support surface and/or visual surround to directly follow the patient’s anterior to

posterior body sway. This effectively eliminates the subject’s use of visual and

proprioceptive information for orientation thereby creating a sensory conflict

situation. This is performed to quantify vestibular balance control and to stress the

adaptive response of the central nervous system in order to diagnostically

determine balance impairments15.

NeuroCom® has been extensively studied utilizing the SOT which

performs a set of 6 postural sway examinations identifying visual, balance and

vestibular impairments. A SOT composite score is then compiled, providing a

baseline objective measurement of postural stability. The SOT composite score

3 3

has been found to be a valid assessment in healthy older adults, as well as a wide

array of pathologies peripheral neuropathy, people with Parkinson's Disease,

Multiple Sclerosis among other neurological and musculoskeletal disorders.16-18

More recently the Bertec Balance AdvantageTM a dynamic CDP utilizing

an immersive virtual environment in a specially modified dome was created to

objectively identify postural instability (Figure 1). The incorporation of the static

and dynamic properties of the optic surround, a series of concentric ovals leading

to a grey oval shape creates the perception of a tunnel with no definable end or

horizon. This has the ability to enhance the visual stimulus for postural control in

order to evaluate and provide interventions that closely reflect conditions found in

the physical world19,20. The computer interactive display technology of Bertec™

as opposed to sway-referencing, creates an environment where the subjects will be

completely engaged in a virtual surround, therefore their responses to the images

will be similar to those in the real world. This strong immersive environment the

subject experiences is needed in order to engage and interact with the higher level

processes of the central nervous system that influence postural control19,21. As

complex visual environments are difficult to reproduce in the clinical setting, the

immersive virtual environment creates a real life scenario to accurately identify

impairments of balance and provide for enhanced balance training.

While sway-referencing CDP has been studied extensively with balance

assessment, there are limited studies available incorporating the effectiveness of

assessing postural control in an immersive virtual environment. Furthermore, there

are no published quantitative comparisons between Bertec™ and NeuroCom®20.

Given these factors, this study examines Bertec™ CDP system incorporating an

immersive virtual environment projected in a specially modified dome and

comparing this data with the sway-referencing used by EquiTest systems

4 4

developed by NeuroCom®Incorporated. The purpose of this study is to validate

the ability of Bertec Balance AdvantageTM to assess postural control as compared

to the gold-standard NeuroCom® Equitest. The null hypothesis is that there will

be no differences between the immersive virtual environment of Bertec™ and

sway-referencing of NeuroCom® in any of the 6 conditions. The alternative

hypothesis is that the 2 devices will be comparable for all tests with the exception

of Conditions 3 and 6 of the SOT, when visual conflict is utilized. During

Conditions 3 and 6 of the SOT, the alternative hypothesis is that the equilibrium

scores will be significantly lower in the Bertec™ as compared to the NeuroCom®

due to the stronger visual stimulus of an immersive virtual environment in

Bertec™ in the 2 conditions. The final alternative hypothesis is that the MCT and

ADT toes up and toes down will be comparable between Bertec™ and

NeuroCom® as the visual surround is static.

METHODS

Participants and Enrollment

Fifty healthy adults (33 females and 17 males) were voluntarily recruited

through flyers, emails and oral communication. The subjects were stratified into 5

age groups with an N of 10 for each group. Group 1 (20-29 years), group 2 (30-39

years), group 3 (40-49 years), group 4 (50-59 years) and group 5 (60-69 years)

(Table 1).

The study was approved by the California State University, Fresno

Committee on the Protection of Human Subjects. An informed consent, a Medical

Research Patient’s Bill of Rights and a subjective history were obtained from all

subjects.

Inclusion criteria were healthy adults aged 20-69 years old with the

exclusion criteria of: 1) dizziness, inner ear, or other balance or vestibular

disorder; 2) closed or open head injury resulting in any neurological symptoms; 3)

cervical injury; 4) assistive device use or inability to stand for 20 minutes; 5)

visual impairment; 6) concussion with complaints of headache and/or other

symptoms; 7) diabetes; 8) peripheral vascular disease; 9) any significant lower

extremity joint disorder or injury that would interfere with balance, and/or 10)

persistent motion sickness/sensitivity.

If the subject did not respond to these criteria, he or she was eligible for the

study. The details of the study were described, written informed consent was

obtained and subjects were free to withdraw from the study at any time.

Testing Procedures

The subjects were provided standardized instructions prior to the start of

each test condition (Appendix A). Testing was completed in a quiet room, the

6 6

subject was fit with an appropriate-sized restraining harness and the investigator

remained in close proximity in case they lost their balance. The subject was tested

barefoot without shoes and socks. The investigator aligned the subject’s feet

according to predetermine guidelines22. The malleoli were aligned with the

horizontal line on the force plate and the lateral calcaneus was aligned with the

size line according to the subject’s height. The angular alignments of the feet were

positioned for patient comfort. Measurements were taken of the feet placement

from the calcaneus to the end of the platform, to ensure correct alignment of the

feet if a fall were to occur. Correct foot alignment was monitored and maintained

throughout testing.

The subject underwent testing on the 2 computerized systems, each using 3

different tests to measure balance: SOT, MCT and ADT. The subject first

performed testing on the Bertec™ system (Figure 1) by Researcher 1, followed by

a 15 minute rest, then NeuroCom® (Figure 1) testing by Researcher 2. Researcher

1 completed all Bertec™ testing, and Researcher 2 completed all NeuroCom®

testing.

The Sensory Organization Test (SOT) measured the subject's center of

gravity during 3 trials of 6 conditions. Condition 1: eyes open, fixed environment.

Condition 2: eyes closed in fixed environment. Condition 3: eyes open, fixed

platform, moving visual environment. Condition 4: eyes open, moving platform,

fixed visual environment. Condition 5: eyes closed, moving platform, fixed visual

environment. Condition 6: eyes open, moving platform and visual environment

(Appendix B).

Sensory analysis ratios are calculations provided through the 6 conditions

of the SOT. Somatosensory analysis ratio is Condition 2 divided by Condition 1.

Visual analysis ratio is Condition 4 divided by Condition 1. Vestibular analysis

7 7

ratio is Condition 5 divided by Condition 1. Preference analysis ratio is sum of

Condition 3 and 6 divided by the sum of Condition 2 and 5.

The Motor Control Test (MCT) measured the subject’s reaction time in 3

trials of 6 conditions. Condition 1: small translation forward. Condition 2: medium

translation forward. Condition 3: large translation forward. Condition 4: small

transition backward. Condition 5: medium transition backward. Condition 6: large

transition backward. Data was only analyzed for the MCT composite of medium

and large translations (Appendix C).

The Adaptation Test (ADT) measured the subject’s center of gravity and

reaction time in 5 trials of 2 conditions. Condition 1: Platform moved in toes up

direction. Condition 2: platform moved in toes down direction. Data were

analyzed for the difference of trial 1 and 5 for both toes up and toes down

(Appendix D).

Data Analysis

Data was entered in the IBM SPSS Version 24 System. Pearson Product

Correlations (r) were used to determine the strength of the relationship of Bertec™

and NeuroCom®. An r-value larger than .75 was considered good, .50 - .75 as

moderate and less than .50 as a poor correlation23. Repeated measures analysis of

variance (ANOVA) were used to analyze the differences between Bertec™ and

NeuroCom®. Data was analyzed for all 50 subjects and across each age group

including the composite and average of 3 trials of the 6 conditions of the SOT,

sensory ratio scores, composite MCT scores and ADT differences of trials 1 and 5.

A 2 x 5 factor analysis, 2-way utilized for comparison of devices and 5-way for

differences of age groups. A p-value less than .05 was considered significant.

RESULTS

A total of 56 subjects were tested, however, 6 subjects were excluded from

our analysis due to not meeting the inclusion criteria. The 6 subjects that were

excluded had 1) a history of a recent concussion with residual symptoms (2/6); 2)

ACL surgical procedure (2/6); 3) cervical fusion with metal plate in the ankle (1/6)

and 4) a prior non-specified lower back surgery (1/6). One subject included in the

40-49 years old had a concussion 10 years prior due to skiing injury however they

were not excluded as they had no residual symptoms nor other significant medical

history. Two subjects in the 30-39 years old had prior knee arthroscopy due to

meniscal involvement, however, the surgery was noninvasive and occurred more

than 3 years prior with no subjective knee complaints and therefore not excluded.

Although 17/50 subjects had reported visual impairments they were all corrected

with glasses. 10/50 subjects indicated they had motion sickness sometime during

their life, however it was not considered significant to interfere with testing as

none of them had symptoms. 23/50 subjects reported a prior lower extremity (LE)

injury and/or surgical intervention including stress fracture, knee arthroscopy,

hysterectomy, caesarian section and appendectomy, however they were not

considered significant. 18/50 subjects reported use of over the counter and/or

prescription drugs. Subjects ranged from taking 0 to 4 medications with 1 person

on 4 prescribed medications. The over the counter drugs included vitamins,

analgesics and allergy medications. Prescription medications include

bronchodilators, gastrointestinal disorders, thyroid involvement, cholesterol,

hypertension, diuretics and hormonal treatment. Dosages and medication time

lines of the subjects were unknown, however it was considered not significant to

interfere with testing as most were over the counter type medications and there

9 9

were no reports of any symptoms of dizziness or impaired balance prior or during

testing. Table 1 describes the characteristics of the 50 subjects included for the

analysis. See Appendix E for the health questionnaire used in the study, and

Appendix F for the informed consent.

Sensory Organization Test & Sensory Ratio Scores

There was a strong positive correlation between Bertec™ and NeuroCom®

SOT Composite scores (r=.81, N=50, p<.001). Conditions 2, 4, 5 and 6 were

moderately correlated (r=.65, p<.001; r=.57, p<.001; r=.61, p<.001; r=.65, p<.001

respectively), whereas, Conditions 1 and 3 were poorly correlated (r=.34, p<.02;

r=.40, p<.001; respectively) (Figure 2) Vision and vestibular ratio scores were

moderately correlated (r=.53, p<.001; r=.60, p<.001; respectively). Somatosensory

and preference ratio scores were poorly correlated (r=.34, p<.02; r=.09, p<.56;

respectively) (Table 2).

There was a significantly lower mean average in the SOT Composite

equilibrium (EQ) score for Bertec™ as compared to NeuroCom® for all subjects

(75.36 ± 6.05, 79.28 ± 5.31 respectively, p<.001) (Figure 3). When individual

conditions were compared, EQ scores were significantly lower on Bertec™ as

compared to the NeuroCom® in Conditions 1,4 and 6 (mean differences were 2-13

points), with Condition 4 showing the greatest mean difference (mean EQ score

71.92 vs 84.89, for Bertec™ and NeuroCom® respectively). Condition 2 was

slightly higher on the Bertec™ (92.08 and 91.15, p<.001) and Condition 3 and 5

were not significantly different (p<.61, p<.44 respectively) (Table 3 and 4).

Consistent with these findings the calculated visual and preferences ratio scores

were also significantly lower (mean EQ score difference of 12.31 and 4.95

respectively). The somatosensory ratio score was slightly higher on the Bertec™

10 10

as compared to the NeuroCom® (mean EQ score 99.40 vs 96.38, p<.001).

Whereas, the vestibular ratio score was not significantly different between

Bertec™ and NeuroCom® (p<.07) (Table 5).

The significant differences found between Bertec™ and NeuroCom® on

SOT conditions, composite and sensory ratio scores were found to not differ

between age groups. The p-value for between-subject age-groups were greater

than .05 for all the above testing scenarios indicating no significant difference

(Figure 4). Therefore the post-hoc Tukey Honest Significant Difference (HSD)

was not analyzed.

Motor Control Test

The MCT composite latency score had a good correlation between devices

(r=0.67, p<.001) (Table 2). There was a significantly slower latency on the MCT

composite score on Bertec™ as compared to the NeuroCom® for all subjects

(mean difference of 3.2 msec p<.001) (Figure 5, Table 6). The p-value for within-

systems was found to be significant with a p-value of .004. The between-subjects

age groups were not significant with a p-value of .083. However, there was an

interaction for system and age group (p=.046) indicating the difference in devices

was dependent on age groups (Figure 6, Table 5). Overall larger mean differences

were found in the younger groups (age 20-29 and 30-39) compared to the older

groups (age 50-59 and 60-69) (6-7 msec vs 1-3 msec).

Adaptation Test

There was a poor correlation between ADT toes up and toes down Trial 1

and 5 difference between Bertec™ and NeuroCom® (r =.08, p<.57; r=.09, p<.54)

(Table 2). The toes up average differences of Trial 1 and 5, Bertec™ sway energy

differed by 21.84 while NeuroCom® differed by 8.66. In toes down average

11 11

differences of Trial 1 and 5, Bertec sway energy differed by 24.90 while

NeuroCom® differed by 9.90 (Figure 7, Table 6). There was a significantly

greater sway energy score indicating less stability in the Trial 1 and 5 difference of

ADT toes up and toes down sway energy scores for Bertec™ as compared to

NeuroCom® for all subjects (Sway energy scores differed by 13.18 and 15.00

points, p<.001,p <.00; respectively). The toes up between-subjects age groups and

the interaction between device and age group had a p-value of >.05 indicating the

differences in devices was not dependent on the 5 age groups (Figure 8). The toes

down between age groups p-value of .719 indicates there is no difference in age

groups. (Figure 9, Table 5).

DISCUSSION

Statistical Findings

The Bertec Balance AdvantageTM system has high concurrent validity in

association with the gold-standard NeuroCom® Equitest. Both the MCT and SOT

composite and conditions 2, 4, 5 and 6 exhibited moderate to good correlation

(Figure 2). ADT toes up and toes down test had poor correlations and therefore

determined to have poor concurrent validity. The strong to moderate correlations

of SOT and MCT indicate that both the Bertec™ and NeuroCom® are comparable

and valid measures of postural stability.

A clinical important difference is indicated by a greater than 8 point change

in the SOT Composite, greater than a 5 point change in SOT Conditions 1-2, a

greater than 10 point change in Conditions 3-6, a greater than 10 msec difference

in MCT Composite and a greater than 10 sway energy in ADT24. This study was

able to accept parts of the null hypothesis indicating there is a clinical difference

between the 2 CDP systems of Bertec™ and NeuroCom®. Condition 3 was not

statistically nor clinically different and Condition 6 not clinically different,

rejecting the alternative hypothesis that those conditions with a dynamic

immersive virtual environment in Bertec would show the greatest differences. The

alternative hypothesis indicating MCT was comparable between devices was

accepted as the 3.2 msec difference is not clinically relevant. The alternative

hypothesis indicating ADT was comparable between devices was rejected as there

were large statistical differences between the 2 systems with Bertec™ having

larger sway energy differences, suggesting less stability. This prospective study

and results was able to add to the psychometrics of these devices.

13 13

Although the CDP devices exhibited statistically significant differences in

SOT composite, Conditions 1, 2, 4 and 6, MCT the differences were very small

and therefore the clinical interpretation would still be the same for each device.

The only clinical significant difference was found in Condition 4 and the visual

ratio score of the SOT and ADT toes up and toes down.

These results do not support the hypothesis that the immersive virtual

environment of Bertec™ provides a differing balance analysis than the sway-

referencing system of NeuroCom® during Conditions 3 and 6. Bertec™

equilibrium means are similar to NeuroCom® in analyzing vestibular and

somatosensory cues for balance but differ when analyzing visual cues. It can be

proposed that Bertec™ is comparable to NeuroCom® in analyzing vestibular and

somatosensory postural control but may be able to detect more subtle postural

abnormalities especially those related to visually sensitive deficits.

Sensory Organization Test

Overall the SOT composite scores were considered not clinically relevant

as Bertec™ had a score of only 4 points lower than NeuroCom®, this was found

to be consistent across all age groups (Figure 4). Wrisley et al. found that a

composite score of 8 points or greater would indicate change from rehabilitation24.

This concludes that the SOT composite scores are comparable between both

devices.

Conditions 1 and 2 are baseline measurements of static standing of eyes

open and eyes closed. Both of these conditions only differed by 1-2 points

indicating no clinically significant findings. This is important to conclude that both

devices are comparable in baseline measurements of postural control.

14 14

The lower value on Condition 3 in the Bertec™ was not statistically

significant compared to NeuroCom®. To further clarify, Condition 3 provides a

conflicting visual stimulus in which the individual has to rely on their

somatosensory input. In a sensory weighted environment with a stable surface, the

normal individual relies 70% on their somatosensory input, 20% on vestibular and

10% on vision25. Due to this very high somatosensory input and low visual input,

both the Bertec™ and NeuroCom® produce similar results25. Therefore these

findings suggest the immersive virtual environment provided in the Bertec™ is

comparable to the sway referencing in NeuroCom®.

The greatest change was observed between Bertec™ and NeuroCom® was

during Condition 4 (71.92 vs 84.89 mean EQ scores). Condition 4 is eyes open

dynamic support surface where an individual is unable to use their somatosensory

system and needs to rely on vision for balance. Initially looking at the 3 trials of

Condition 4, subjects scored on average 21 points lower on Bertec™ for Trial 1,

while Trial 2 and 3 only differed by 11 and 7 points. To determine if the difference

seen in Condition 4 is due to the lower score on Trial 1 score as subjects need a

period to learn and adapt, the average of Trials 2 and 3 were analyzed. When

comparing the average of Trials 2 and 3, Bertec™ continued to be statistically

significantly lower (p<.05) by 9 points (Figure 6). This indicates that although

there was a large disparity on Trial 1, it did not affect the overall equilibrium score

of Condition 4. Another explanation for the increase challenge during Condition 4

could be that Bertec™, as compared to NeuroCom® provides no compensatory

visual strategy. For example, there is no visual cue in the Bertec™ since it is an

immersive virtual environment, whereas in the NeuroCom®, individuals can

reference to the horizon and images in the scene, the colorful scenario and/or the

computer monitor. Therefore, people with visual impairments in Condition 4

15 15

would more likely be identified using the Bertec™ as opposed to NeuroCom®.

Although both devices provide different visual conflicts depending on the

surround there are no significant differences between devices in assessing

vestibular cues for balance.

Condition 5 has a dynamic support and eyes closed therefore eliminating

the immersive virtual environment. As there is no visual stimulus to provoke the

individual, this tests the use of the vestibular system. It has been previously shown

in people susceptible to seasickness had poor results in Condition 5 and vestibular

ratio scores, indicating they may be more dependent on somatosensory and visual

input to maintain balance26. As both devices are comparable in analyzing postural

cues, with the more challenging visual environment in Bertec™ it may have

greater accuracy at identifying persons with motion sensitivity or more subtle

visual dependency impairments. As both devices are similar in Condition 5, this

can conclude that Bertec and Neurocom are comparable in assessing vestibular

cues for postural control.

Although Condition 6 was significantly lower in the Bertec™, the mean

differences was relatively small (61.39 vs 67.05 mean EQ scores). Condition 6

eyes open dynamic support and surround was considered statistically different

between the devices but not clinically different as they only differed by 6 points.

This condition aims to test the preference of sensory system use by providing

altering visual and somatosensory cues. Preference indicates the amount to which

the subject relies on visual information to maintain balance even if conflicting

visual cues are provided27. The Condition 6 findings help to conclude that the

immersive virtual environment of Bertec seems to be comparable to sway-

referencing on NeuroCom®.

16 16

Sensory Ratio Scores

The somatosensory ratio is a ratio of Condition 2 to 1 indicating no clinical

difference as they only differed by 3 points (99.40 vs 96.38 EQ). This is consistent

with Condition 2 and 1 equilibrium scores and helps to conclude the devices are

comparable in assessment of somatosensory cues.

The contrast in the device's visual array coincides with the visual ratio score

large difference of 12 points. Visual ratio score is the ratio of Condition 4 to 1 and

found to be clinically lower on Bertec™ (77.42 vs 89.73 mean EQ scores). This

coincides with Condition 4 indicating Bertec may be more sensitive in assessing

visual cues for balance.

The vestibular ratio score of Condition 5 to 1 also was not statistically and

not clinically different agreeing with the Condition 5 results (71.16 vs 68.71 EQ).

This finding is important as clinicians can be confident the 2 posturography

systems are similar in assessing vestibular cues for postural control.

The preference ratio between the devices differed by 5 points and

determined to not be clinically relevant as they differed by less than 10 points

(96.50 vs 101.45 EQ scores). This is a calculated ratio comparing conditions 3

and 6 to 2 and 5 which was also statistically different (p<0.05). This coincides

with the differences in equilibrium scores Condition 6 on the 2 devices as not

clinically relevant.

Motor Control Test

The Motor Control test (MCT) provides a composite score utilizing the

medium and large forward and backward translations. This attempts to mimic a

real-life environment by assessing how quickly a subject can recover from

unexpected external perturbations. The composite scores were strongly correlated

between Bertec™ and NeuroCom® for both forward and backward translations.

17 17

The MCT latency scores were statistically slower on Bertec™ for both

forward and backward perturbations and the composite score had an insignificant

clinical change of 3.2 msec as it is less than a 10 msec difference (Figure 7). This

significant difference can be due to the higher sampling rate of Bertec™ at 1000

Hz as compared to 100 Hz on NeuroCom®28,29. As NeuroCom® samples at a 10

msec resolution, and only valid up to a 10 msec difference. It was also found that

individuals with bilateral vestibular loss had normal MCT latencies and it was not

influenced by vision30. This supports the immersive virtual environment of

Bertec™ does not influence the MCT results and we can conclude this test is

comparable between devices.

Adaptation Test

The Adaptation test (ADT) examines a patient’s ability to adapt and sustain

proper balance with minimal sway when exposed to equivalent surface

irregularities. A normal response involves the subject expending a decreasing

effort to return to the center of gravity following subsequent rapid changes to the

surface secondary to adaptation. This is measured by the amount of anterior-

posterior sway after a toes up and toes down perturbation, referred to as sway

energy.

The poor correlation values provides poor concurrent validity, indicating

both systems are poorly comparable in assessing the ability to adapt. The

significantly higher average sway energy scores on Bertec™ as compared to the

NeuroCom® for both toes up and toes down suggests less stability. This

significant difference can be due to the higher sampling rate of Bertec™ at 1000

Hz as compared to 100 Hz on NeuroCom®28,29. As NeuroCom® samples at a 10

point resolution, and only valid up to a 10 point difference, the ADT scores

18 18

difference of 13.18 and 15 sway energy scores indicate a large clinically different

results. While the platform is moving 5 times in 1 direction there are many factors

influencing the results including reliance on visual cues of which the Bertec™

does not provide, ankle ROM, strength and biomechanical alignment. In the 50

subjects utilized 48% had a form of musculoskeletal involvement, of which

Bertec's™ higher sampling rate may be more sensitive to pick up subtle

impairments. It is important for this test to have concurrent validity as a decrease

performance in the toes up direction has a direct correlation into the frequency of

falls31.

Limitations

This current study had several limitations. The 50 person overall sample

size is effective, however 10 in each group is considered a small sample size. As

the smaller sample size creates a bias this can alter the results when comparing

between the 5 age groups.

Another limitation was the testing procedure. Subjects were recruited

through a sample of convenience and were tested on the Bertec™ prior to the

NeuroCom® introducing a possible order bias and a learning effect. As subjects

had better stability on all tests on NeuroCom®, this could possibly be due to a

learning effect as it is no longer a novel experience (Figure 1). However a one-

sample t-test comparing published normative data for the SOT Composite using

the NeuroCom® were compared to our results. The results suggests our subject’s

SOT Composite scores were not affected by the previous tests on the Bertec™

(p<.810) which may eliminate the effect of testing order bias as a factor29. Also the

largest difference was found in Condition 4, a study by Wrisley et al. found that

repeated administration of the SOT had significant learning effects in Condition 4,

19 19

however if you look at the raw equilibrium score of Condition 4 from session 1 to

2 there was only a 1.5 point increase24. The large difference of 12 points on

Condition 4 can help eliminate the testing order bias and indicates a true

difference between devices.

Although both researchers were not blinded, it was attempted to eliminate

subjective bias and/or tester scoring differences by using one researcher per

device. CDP aids in eliminating this bias by providing good test-retest reliability

and minimizes inter-rater variability11,12.

Another possible limitation is the variability of subject characteristics in our

sample. Overall 56 subjects were tested, 50 of which made the inclusion criteria. 6

subjects were excluded due to not meeting our inclusion criteria. Of the 50

subjects included, 33 were female and 17 were male, age range of 24-69 years old

with an average age of 44 years old. 7 out of 10 60-69 year olds were on at least 1

prescribed medication. There was a wide range of medications listed some of

which have the possible side effects of imbalance and dizziness. It is difficult to

find elder adults with no medications as 87.7% of community-dwelling adults

aged 62-85 years old are on at least 1 medication32. To minimize this effect we

ensured each subject did not have any subjective complaints of dizziness from any

of their medications or throughout testing. Another confounding factor was 24 out

of 50 subjects reported prior surgeries. Surgeries were considered benign and

included appendectomy, caesarian section, wisdom teeth removal, face lift,

tonsillectomy, cholecystectomy, shoulder arthroscopy and hysterectomy. These

surgeries were deemed to not affect the lower extremities nor balance and were

performed a minimum of a year prior with no complaints the day of testing. 13

subjects reported motion sickness which included air, sea, car and motion. None of

these subjects reported any sickness throughout testing on both machines and

20 20

therefore were not excluded. People with motion sensitivity have more difficulty

using vision for balance and could possibly be an explanation for people having

more difficulty with Condition 4. However, when we compared subjects with and

without a report of motion sensitivity there was no significant difference in the

equilibrium scores on Condition 4 for Bertec™ or NeuroCom®. 18 subjects had

reported visual impairments that were all corrected with glasses. From the variety

of subjects although considered healthy as they met the inclusion criteria can pose

a limitation to the collected data (Table 1).

Future Research

This prospective study helped to add to the psychometrics by determining

concurrent validity and correlation between the Bertec™ and NeuroCom® CDP

analysis. Clinicians can be confident when performing CDP in the new Bertec™

system, as test results are comparable to that found with the NeuroCom® Equitest

system. Normative values for Bertec™ are reported in a separate paper. Future

research using the Bertec™ with patient populations will be important to further

identify the usefulness of this system for testing postural stability.

The gold-standard NeuroCom® has been extensively used to detect balance

deficits, and help to assess abnormal conditions. It is also used in the treatment of

vestibular rehabilitation, traumatic brain injury including a sports-related

concussion and neurological diseases including multiple sclerosis and Parkinson's

disease16,18. In contrast, Bertec'sTM spherical dome immerses the subject and

provides a visually provoking environment. Similar to this dome, it been shown

people with mal de debarquement syndrome can significantly improve their

function by utilizing an optokinetic stimulator to readapt the vestibulo-ocular

reflex33. This prior knowledge and the findings of this study indicate that Bertec™

21 21

may be most sensitive in detecting postural instability and more specifically visual

cues for balance. Future research needs to be conducted on Bertec'sTM ability to

detect subtle postural changes. One day post-concussive subjects demonstrated a

decline in postural stability using the NeuroCom® including a significant decline

in SOT composite score, visual and vestibular ratio scores34. With Bertec™ being

comparable in vestibular ratio scores but more sensitive in assessing visual ratio

scores with Condition 4, future research needs to determine if the immersive

visual environment is more sensitive for return-to-play assessment post-

concussion. As a concussion can affect both visual and vestibular inputs, it was

suggested that vision may play an important role in weakening the vestibulo-

ocular reflex and influence an individual's balance and vestibular system34,35. It is

important to further determine how individuals with visual impairments can

impact vestibular balance and develop improved fall prevention strategies for

those with inadequate visual inputs.

As this research helps to add to the current literature of the effectiveness

and increased sensitivity of an optic environment, future research should continue

to determine treatment options and its advantages. Research should be towards a

more clinical and treatment relevance by determining if Bertec™ can differentiate

between fallers and non-fallers to better determine the magnitude of a person's fall

risk. As individuals age they rely more on their visual environment, therefore it

will be important for future research to determine the sensitivity and specificity of

the quality of visual input on balance in the elderly population.

The findings of this study help to determine the concurrent validity of

Bertec™, it is now important to determine the predictive validity. Predictive

validity is important to establish to determine if the Bertec™ is valid day-to-day in

order to utilize it for pre and post-test intervention measures. As the CDP devices

22 22

and NeuroCom® provides extensive objective data it helps to reduce the bias of

low inter and intra rater reliability. Future research can establish more

psychometrics including inter and intra-rater reliability.

Conclusion

The Bertec™ and NeuroCom® composite test scores were correlated for

SOT, MCT and during CDP assessment in healthy adults aged 20-69 years old.

Overall, the Bertec™ system was more challenging for subjects during all 3 CDP

tests, however vestibular, somatosensory and preference ratio scores were

comparable between the 2 systems, as there were no clinical differences. This

concludes that Bertec™ and NeuroCom® are valid measures of balance giving

clinicians confidence they are comparable for postural control measures. However,

visual ratio scores were significantly lower when tested with the Bertec™ system.

This could prove that Bertec™ may provide a more sensitive test for subjects with

poor use of vision during balance such as people with motion sensitivity or post

concussion or mild TBI.

REFERENCES

REFERENCES

1. National Institute on Deafness and Other Communication Disorders

(NIDCD). 2014.

2. Shumway-Cook A, Ciol MA, Hoffman J, et al. Falls in the Medicare

Population: Incidence, Associated Factors, and Impact on Health Care.

Phys. Ther. 2009; 89(4): 324-332.

3. Burns EB, Stevens JA, Lee RL. The direct costs of fatal and non-fatal falls

among older adults—United States. J Safety Res 2016:58.

4. Centers for Disease Control and Prevention, National Center for Injury

Prevention and Control. Web–based Injury Statistics Query and Reporting

System (WISQARS) [online]. Accessed August 5, 2016.

5. Bigelow K & Berme N. Development of a protocol for improving the

clinical utility of posturography as a fall-risk screening tool. J Gerontology

A Biol Sci Med. 2011; 66(2): 228.233.

6. Melzer I, Benjuya N, Kaplanski J. Postural stability in the elderly: a

comparison between fallers and non-fallers. Age Aging. 2004; 33: 602-607.

7. Rehab Measures: Berg Balance Scale. http://www.rehabmeasures.org/Lists/

RehabMeasures/DispForm.aspx?ID=888. Published 1989. Accessed March

2017.

8. Rehab Measures: Modified Clinical Test of Sensory Interaction on Balance.

http://www.rehabmeasures.org/Lists/RehabMeasures/DispForm.aspx?ID=1

180. Accessed March 2017.

9. Rehab Measures: Timed Up and Go.


03. Published 1991. Accessed March 2017.

10. Rehab Measures: Functional Reach Test.


50. Published 1990. Accessed March 2017.

11. Visser JE, Carpenter MG, van der Kooij H, Bloem The clinical utility of

posturography BR. Clin Neurophysiol. 2008 Nov; 119(11):2424-36.

http://www.cdc.gov/injury/wisqars

http://www.cdc.gov/injury/wisqars

25

12. Mancini M, Horak FB. The relevance of clinical balance assessment tools

to differentiate balance deficits. Eur J Phys Rehab Med. 2010;46(2):239-

248.

13. Faraldo-Garcia A, Santos-Perez S, Crujeiras R, Labella-Caballero T, &

Soto-Varela A. Comparative study of computerized dynamic posturography

and the SwayStar system in healthy subjects. Acta Oto-Laryngologica.

2012; 132: 271-276.

14. Ferber-Viart C, Ionescu E, Morlet T, Froehlich P, & Dubreuil C. Balance in

healthy individuals assessed with Equitest: Maturation and normative data

for children and young adults. Int J Pediatr Otohinolaryngol. 2007; 71:

1041-1046.

15. Computerized Dynamic Posturography. NatusR Balance & Mobility.

Website http://balanceandmobility.com/for-clinicians/computerized-

dynamic-posturography/cdp-protocols/. Accessed October 11, 2016.

16. Colnat-Coulbois S, Gauchard GC, Maillard L, Barroche G, Vespignani H,

et al. (2005) Bilateral subthalamic nucleus stimulation improves balance

control in Parkinson's disease. J Neurol Neurosurg Psychiatry 76(6): 780–

787

17. Reid VA, Adbulhadi H, Black KR, Kerrigan C, Cros D (2002) Using

posturography to detect unsteadiness in 13 patients with peripheral

neuropathy: a pilot study. Neurol Clin Neurophysiol 2002 (4) 2–8

18. Whitney, S. L., Marchetti, G. F., et al. (2006). "The relationship between

falls history and computerized dynamic posturography in persons with

balance and vestibular disorders." Arch Phys Med Rehab. 87(3): 402-407.

19. Keshner E, & Kenyon R. Postural and spatial orientation driven by virtual

reality. Stud Health Technol Inform. 2009; 145: 209-228.

20. Pickerill M & Harter R. Validity and Reliability of Limits of Stability

Testing: A Comparison of 2 Postural Stability Evaluation Devices. J Athl

Train. 2011; 46(6): 60-606.

21. Sadowski W, Stanney K. Prescence in Virtual Environments. Handbook of

Virtual Enviornments: Design, Implementation and Applications. London:

Lawrence Erlbaum Associates, Inc; 2002; 791-806.

22. Bertec Workbook Program Documentation. 2014.

26

23. Portney L, Watkins M. Foundations of Clinical Research: Applications to

Practice. Upper Saddle River, N.J: Pearson/Prentice Hall; 2009.

24. Wrisley, D. M., Stephens, M. J., et al. (2007). "Learning effects of

repetitive administrations of the sensory organization test in healthy young

adults." Arch Phys Med Rehab. 88(8): 1049-1054

25. Peterka, R. and P. Loughlin (2004). "Dynamic regulation of sensorimotor

integration in human postural control." J Neurophysiol 91.

26. Shalal B, Nachum Z, Spitzer O, Ben-David J, Duchman H, Podoshin, L et

al. Computerized dynamic posturography and seasickness susceptibility.

Laryngoscope. 1999; 109(12): 1996-2000.

27. Pickett T, Radfar-Baublitz L, McDonald S, Walker W, & Cifu D.

Objectively assessing balance deficits after TBI: Role of computerized

posturography. JRRD. 2007; 44(7): 983-990.

28. Digital Acquire 4: Program Documentation. Bertec Balance Manual.

Website.

http://bertec.com/uploads/pdfs/manuals/Digital%20Acquire%204.pdf

Published Jan 2013. Accessed Jan 2017.

29. Designed for the Clinical Researcher. NeuroCom® Clinical Research

System (CRS). NeuroCom® Manual. Website.

http://www.natus.com/documents/014320A_lo-res_for%20web.pdf

Published 2014. Accessed Jan 2017.

30. Schupert C, Black F, Horak F, Nashner L. Coordination of the head and

body in response to support surface translations in normals and patients

with bilaterally reduced vestibular function. Posture and Gait:

Development, Adaptation and Modulation. 1988: 281-289.

31. Paquette C, Franzen E, & Horak Fay. More falls in cerebellar ataxia when

standing on a slow up-moving tilt of the support surface. Cerebellum. 2016;

15(3): 336-342.

32. Qato D, Wilder J, Schumm L, Gillet V, & Alexander G. Changes in

Prescription and Over-the-Counter Medication and Dietary Supplement

Use Among Older Adults in the United States, 2005 vs 2011. JAMA Intern

Med. 2016; 176 (4): 473-82.

33. Dai M, Cohen B, Smouha E, & Cho C. Readaptation of the vestibulo-ocular

reflex relives the mal de debarquement syndrome. Frontr Neurol. 2014.

27

34. Guskiewicz KM, Ross SE, Marshall SW. Postural Stability and

Neuropsychological Deficits After Concussion in Collegiate Athletes. J

Athl Train. 2001;36(3):263-273.

35. Willis J, Vitale S, & Agrawal Y. Visual impairments, uncorrected refractive

error, and objectively measured balance in the United States. JAMA

Ophthalmol. 2013; 131(8): 1049-1056.

TABLES

29

Table 1: Subject Characteristics

*% indicates the percentage of subjects who indicated 'Yes' on the health

questionnaire form seen in Appendix E.

Past Medical History Subjects (n=50)

(%)*

Age 44.10 ± 14.33

Males (17) 34 %

Females (33) 66 %

Dizziness 6 %

Visual Impairments 34 %

Motion Sickness 20 %

Concussion > 10 yrs 2 %

Consumed Alcohol in Past

12 Hours <1 Glass

4 %

Medications 36 %

History of Surgeries 48 %

Appendectomy 8 %

Hysterectomy 16 %

Caesarian Section 8 %

Orthopedic Problems

Cervical Injury 2%

LE Injury 14 %

Knee Arthroscopy 10%

30

Table 2: Pearson's Correlation Coefficients for SOT, MCT & ADT

r-value p-value

Condition 1 .34 .020






SOT Composite .81 .001

Somatosensory Ratio Score .34 .020

Vision Ratio Score .53 .001

Vestibular Ratio Score .60 .001

Preference Ratio Score .09 .560

MCT Composite .67 .001

ADT Toes Up Difference .08 .570

ADT Toes Down Difference .09 .540

31

Table 3: Equilibrium Scores for SOT Conditions 1, 2, 3 and 4 across Age Groups

Age

Groups

Bertec™ NeuroCom® Bertec™ NeuroCom® Bertec™ NeuroCom® Bertec™ NeuroCom®

Condition 1 Condition 2 Condition 3 Condition 4

Mean ± sd Mean ± sd Mean ± sd Mean ± sd

20-29 92.46 ± 2.20 94.73 ± 2.01 92.97 ± 1.32 92.70 ± 1.69 91.70 ± 1.67 92.10 ± 2.61 76.64 ± 5.60 87.47 ± 5.79

30-39 93.38 ± 1.74 95.43 ± 1.16 92.83 ± 2.18 91.60 ± 2.46 92.10 ± 2.30 92.47 ± 2.02 73.13 ± 9.68 84.07 ± 7.77

40-49 92.27 ± 1.89 94.57 ± 1.56 92.30 ± 1.09 90.50 ± 2.88 90.10 ± 4.48 91.57 ± 1.30 70.67 ± 11.30 85.13 ± 5.76

50-59 92.98 ± 1.48 94.07 ± 1.81 90.50 ± 2.43 90.17 ± 2.56 89.03 ± 4.19 89.53 ± 4.07 68.77 ± 9.50 83.90 ± 7.85

60-69 92.33 ± 1.67 94.10 ± 1.14 91.80 ± 1.93 90.77 ± 2.05 91.36 ± 2.85 89.93 ± 3.62 70.40 ± 5.56 83.87 ±3.82

All Ages 92.68 ± 1.79 94.58 ± 1.59 92.08 ± 2.00 91.15 ± 2.51 90.86 ± 3.35 91.12 ± 3.03 71.92 ± 8.74 84.89 ± 6.26

32

Table 4: Equilibrium Scores for SOT Conditions 5, 6 and Composite Score Across Age Groups

Age

Groups

Bertec™ NeuroCom® Bertec™ NeuroCom® Bertec™ NeuroCom®

Condition 5 Condition 6 SOT Composite

Mean ± sd Mean ± sd Mean ± sd

20-29 70.50 ± 10.52 68.80 ± 11.12 68.50 ± 9.45 74.83 ± 10.23 79.18 ± 4.67 82.60 ± 5.21

30-39 67.10 ± 11.30 68.23 ± 9.21 60.47 ± 13.17 69.77 ± 10.78 76.05 ± 7.06 80.70 ± 5.60

40-49 62.86 ± 10.47 63.93 ± 9.86 54.17 ± 9.60 60.50 ± 10.36 72.58 ± 6.09 77.70 ± 4.27

50-59 63.93 ± 9.38 64.33 ± 8.65 61.50 ± 9.86 65.47 ± 14.24 73.85 ± 6.62 78.20 ± 6.60

60-69 65.27 ± 8.41 59.63 ± 8.38 62.33 ± 10.23 64.70 ± 7.18 75.12 ± 4.32 77.20 ± 3.19

All Ages 65.93 ± 10.02 64.99 ± 9.70 61.39 ± 11.12 67.05 ± 11.46 75.36 ± 6.05 79.28 ± 5.31

33

Table 5: Somatosensory, Vision, Vestibular & Preference Ratio Scores across Age Groups

Age

Groups

Bertec™ NeuroCom® Bertec™ NeuroCom Bertec™ NeuroCom® Bertec™ NeuroCom®

Somatosensory Vision Vestibular Preference

Mean ± sd Mean ± sd Mean ± sd Mean ± sd

20-29 100.60 ± 2.55 97.89 ± 2.52 82.90 ± 5.36 92.31 ± 5.34 76.5 ± 11.60 72.68 ± 11.91 98.30 ± 6.62 103.61 ± 7.50

30-39 99.40 ± 2.17 95.98 ± 2.15 78.40 ± 9.37 88.10 ± 8.15 71.90 ± 11.51 71.50 ± 9.55 95.40 ± 4.45 101.49 ± 3.48

40-49 100.10 ± 1.79 95.71 ± 2.84 75.80 ± 13.31 90.03 ± 5.99 68.10 ± 10.59 67.68 ± 10.95 93.30 ± 5.62 98.84 ± 8.22

50-59 97.40 ± 2.12 95.87 ± 3.09 73.80 ± 9.22 89.14 ± 7.56 68.70 ± 9.33 68.34 ± 8.64 97.50 ± 4.09 100.34 ± 9.01

60-69 99.50 ± 1.35 96.48 ± 2.70 76.20 ± 5.33 89.10 ± 3.26 70.60 ± 8.77 63.35 ± 8.66 98.00 ± 4.74 102.95 ± 5.64

All Ages 99.40 ± 2.24 96.38 ± 2.69 77.42 ± 9.20 89.73 ± 6.21 71.16 ± 10.44 68.71 ± 10.16 96.50 ± 5.32 101.45 ± 6.98

34

Table 6: MCT Latency and ADT Toes Up & Down Trial 1 and 5 Sway Energy Difference Across Age Groups

Age

Groups

Bertec™ NeuroCom® Bertec™ NeuroCom® Bertec™ NeuroCom®

MCT Composite ADT Toes Up Difference ADT Toes Down Difference

Mean ± sd Mean ± sd Mean ± sd

20-29 130.50 ± 5.91 123.80 ± 8.43 30.00 ± 25.64 11.10 ± 21.71 17.50 ± 7.69 8.20 ± 23.66

30-39 125.50 ± 3.89 119.60 ± 9.79 24.10 ± 43.67 2.90 ± 10.02 26.10 ± 18.30 10.20 ± 21.19

40-49 132.80 ± 7.51 128.00 ± 7.06 21.60 ± 24.38 8.50 ± 10.07 37.70 ± 17.30 3.30 ± 24.24

50-59 130.90 ± 8.18 133.50 ± 15.44 11.30 ± 31.77 6.80 ± 25.54 23.50 ± 26.71 20.70 ± 14.40

60-69 128.20 ± 7.21 127.00 ± 8.51 22.20 ± 36.58 14.00 ± 13.07 19.70 ± 31.04 7.10 ± 25.40

All Ages 129.58 ± 6.92 126.38 ± 10.89 21.84 ± 32.38 8.66 ± 17.01 24.90 ± 22.05 9.90 ± 22.02

FIGURES

36

a) b)

Figure 1: Bertec™ Balance AdvantageTM (a) and NeuroCom® Equitest (b)

Figure 2: Pearson's Correlation coefficient for Bertec™ and NeuroCom® for

SOT conditions 1-6 and SOT composite.

Note: Moderate to good positive r-values for SOT Conditions 2, 4-6. Asterisk

indicates p<.05.

0

0.2

0.4

0.6

0.8

1

Cond 1* Cond 2* Cond 3* Cond 4 * Cond 5* Cond 6* SOT

Comp*

Pea

rso

n P

rod

uct

Co

rrel

ati

on

(r) Pearson Product Coefficient for SOT

Bertec vs Neurocom

Linear (Bertec vs

Neurocom)

37

Figure 3: SOT conditions 1-6, composite equilibrium score for all subjects

(N=50).

Note: The scores for Conditions 1, 4, and 6 of Bertec™ were significantly lower

compared to NeuroCom® with Condition 4 having the greatest 12.97 point mean

difference.

Figure 4: SOT composite equilibrium score across age groups

0

20

40

60

80

100

120

Cond 1* Cond 2* Cond 3 Cond 4* Cond 5 Cond 6* SOT

Comp*

Eq

uil

ibri

um

Sco

res

SOT Condition 1-6 Equilibrium Scores

Bertec

Neurocom

66

68

70

72

74

76

78

80

82

84

20-29 30-39 40-49 50-59 60-69 All Ages

Co

mp

osi

te E

qu

ilib

riu

m S

core

SOT Composite Score Across Age Groups

Bertec

Neurocom

38

Figure 5: MCT latency composite scores comparing age groups

Note: The MCT composite latency scores were significantly slower on Bertec™

by 3.2 msec for all age groups.

Figure 6: MCT composite latency scores across age groups

-40

10

60

110

160

20-29 30-39 40-49 50-59 60-69 All AgesCo

mp

osi

te L

ate

ncy

(m

sec)

Age Group

MCT Composite Latency Across Age

Groups

Bertec

Neurocom

110

115

120

125

130

135

20-29 30-39 40-49 50-59 60-69 All Ages

La

ten

cy S

core

s (m

sec)

MCT Latency Scores

Bertec

Neurocom

39

Figure 7: ADT toes up & down sway energy for the mean difference between

Trials 1 and 5.

Note: The ADT Toes Up and Toes Down sway energy scores were slower and had

significantly larger differences on Bertec™ as compared to NeuroCom®. Error

bars indicated 1 sd.

Figure 8: ADT toes up sway energy across age groups

-20

-10

0

10

20

30

40

50

60

Toes Up* Toes Down*

Sw

ay

En

erg

yADT Sway Energy Mean Difference

Bertec

Neurocom

0

5

10

15

20

25

30

35

20-29 30-39 40-49 50-59 60-69 All Ages

Sw

ay

En

erg

y

ADT Toes Up Sway Energy Across Age

Groups

Bertec

Neurocom

40

Figure 9: ADT toes down sway energy across age groups

Figure 10: Condition 4 equilibrium scores for Trials 1-3.

Note the greater difference between devices during Trial 1 as compared to Trials 2

and 3 and equilibrium score.

0

50

100

Trial 1 Trial 2 Trial 3 Average

Eq

uil

ibri

um

Sco

res

Condition 4

Trials of Condition 4 Equilibrium

Score

Bertec

Neurocom

0

10

20

30

40

20-29 30-39 40-49 50-59 60-69 All Ages

Sw

ay

En

erg

y

ADT Toes Up Sway Energy Across Age

Groups

Bertec

Neurocom

APPENDICES

APPENDIX A: STANDARDIZED TESTING INSTRUCTIONS

43 43

SOT

We will be testing your balance during different conditions of eyes open,

eyes closed and with the floor moving or a visual stimulus.

You will be notified of the condition beforehand.

You will perform each condition 3 times.

As part of the test, I won’t be able to talk to you.

1) This first condition is with your eyes open with nothing moving.

-Your task is to stand with your arms to your side stay as steady as you can.

-Are you Ready?

-Testing...

-Testing Complete

2) This condition is with your eyes closed with nothing moving.


-Are you Ready?

-State: "Close your Eyes." "Testing"

-Once trial completed state 'Trial completed, open your eyes.'

3) This condition is eyes open with a visual stimulus.

-Your task is to stand with your arms to your side, stay as steady as you can.

-Are you Ready?

-Testing.

-Testing Complete

4) This condition is eyes open with the floor moving.


-Are you Ready?

-Testing.

-Testing Complete.

44 44

5) This condition is eyes closed with the floor moving.


-Are you Ready?

-State: "Close your Eyes." "Testing"

-Once trial completed state 'Testing complete, open your eyes.'

6) This condition is eyes open with the floor and surrounding moving.


-Are you Ready?

- Testing.

-This test is completed, would you like a break before the next test?

MCT

This is called a Motor Control Test

The platform will move backwards or forwards 3 times and will increase in

increments from small, medium to large.

1) The platform will move backwards 3 times of small intensity.


-Are you Ready?

- Testing Complete.

2) The platform will move backwards 3 times of medium intensity.


-Are you Ready?

- Testing.

-Testing Complete

3) The platform will move backwards 3 times of large intensity.


-Are you Ready?

45 45

- Testing.

-Testing Complete.

1) The platform will now move forwards 3 times of small intensity.


-Are you Ready?

-Testing.

-Testing Complete

2) The platform will move forwards 3 times of medium intensity.


-Are you Ready?

- Testing.

- Testing Complete

3) The platform will move forwards 3 times of large intensity.

-You task is to stand with your arms to your side stay as steady as you can.

-Are you Ready?

- Testing.

-Testing complete

-This test is completed, would you like a break before the next test?

ADT

This is called an Adaptation Test. The platform will move in a toes up and

toes down direction.

As part of the test, I can't tell you when the movements will happen.

1) You will feel the platform move in a toes up direction several times.


-Are you ready?

- Testing.

46 46

-Testing Complete

2) You will now feel the platform move in a toes down direction several times.


-Are you ready?

- Testing

-Your testing is now completed. (Thank subject for their participation.

APPENDIX B: CONDITIONS 1-6 OF THE SOT

APPENDIX C: MOTOR CONTROL TEST

APPENDIX D: ADAPTATION TEST

APPENDIX E: HEALTH QUESTIONNAIRE

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Subject Health Questionnaire:

1. Have you experienced dizziness or been diagnosed with inner ear or any other

balance or vestibular disorder?

[ ] Yes [ ] No

If Yes, please explain________________________________________________

2. Have you a prior head injury, open or closed?

[ ] Yes [ ] No

If Yes, please explain ________________________________________________

3. Have you had any prior cervical injury?

[ ] Yes [ ] No

4. Do you currently use an assistive device (e.g cane)?

[ ] Yes [ ] No

5. Are you able to stand unsupported for a minimum of 20 minutes?

[ ] Yes [ ] No

6. Do you have any visual impairments?

[ ] Yes [ ] No


7. Have you had a concussion after which you experienced headaches and/or other

symptoms?

[ ] Yes [ ] No


8. Have you been diagnosed with diabetes?

[ ] Yes [ ] No

9. Have you been diagnosed with peripheral vascular disease?

[ ] Yes [ ] No

10. Have you had any significant lower extremity joint disorder or injury?

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[ ] Yes [ ] No


11. Have you experienced any motion sickness or sensitivity?

[ ] Yes [ ] No

12. History of any neurological disease?

[ ] Yes [ ] No

13. Any history of surgeries?

[ ] Yes [ ] No


14. Any recent illnesses or ear infections?

[ ] Yes [ ] No


15. Have you consumed any alcohol in the past 12 hours?

[ ] Yes [ ] No

16. Please list (or provide) your current prescribed and/or over-the-counter

medications._________________________________________________

I, _____________________________, confirm that the above information is true

to my knowledge.

_______________________ _______________________

Participant Date

_______________________ _______________________

Witness to Signature Date

APPENDIX F: INFORMED CONSENT

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I.D.#

FRESNO STATE PHYSICAL THERAPY DEPARTMENT

PARTICIPANT CONSENT FORM

Project Title: Computerized Posturography using the Bertec in Healthy Adults

Principal Investigator: Peggy R. Trueblood, PhD, PT

Professor and Chair

Department of Physical Therapy

Co-Investigators: Marcia Thompson, DSc, DPT

Assistant Professor

Department of Physical Therapy

Leslie Zarrinkhameh, PT, DPT, GCS

Lecturer, Department of Physical Therapy

Toni Tyner, MHL, PT

Assistant Professor, Department of Physical Therapy

Student Investigators: Carolyn Bentley, SPT

Christian Lopez, SPT

PURPOSE OF RESEARCH

I have been informed that the overall purposes of this project are to collect normative data on a new

posturography system that measures a person’s balance and to compare this system to the gold standard

system, also measuring your balance or postural control. More specifically, we will 1) collect normative

data using the Bertec Computerized Dynamic Posturography (CDP) system using virtual reality with

images projected in a specially modified dome and 2) compare this data with the sway-referencing used by

EquiTest systems developed by NeuroCom International. The images used in the Bertec system are

controlled by the system’s computer and move in correspondence to your postural sway detected by a force

plate that you will stand on during the protocols. The image is concentric ovals leading to a grey oval

shape, creating the perception of a tunnel with no definable end or horizon during the Sensory Organization

test. In the case of the EquiTest system by NeuroCom, the dome is referenced by your postural sway on the

forceplate.

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I acknowledge that my participation is voluntary and will include a 60 minute collection period

(approximately 30 minutes with each system). The project will be conducted in McLane 104 and 111, the

Department of Physical Therapy at California State University, Fresno.

CRITERIA FOR PARTICIPATION

I am eligible to participate in this study if I meet the following criteria: 1) age 20-59 years old without any

significant medical history or known neurological or musculoskeletal disorder/impairment that can impact

my balance. I am aware that I will be ineligible to participate in this study if I do not meet the criteria

noted above and/or have a prior history of any of the following: 1) dizziness, inner ear, or other balance or

vestibular disorder, 2) closed or open head injury, 3) cervical injury, 4) assistive device use or inability to

stand for 20 minutes, 5) visual impairment (worse than 20/40 with corrective lenses), 6) concussion after

which I experienced headaches and/or other symptoms, 7) diabetes, 8) peripheral vascular disease, 9) any

significant lower extremity joint disorder or injury, 10) motion sickness/sensitivity.

PROCEDURE

I am aware that I will be:

1) Screened using a questionnaire to determine my eligibility before testing.

2) If eligible for testing, my name will be entered as a code name, eg Fresno 101, 102, etc into the

computerized systems that test your balance

3) My age, sex, height information will be entered in the systems. These parameters are used to

determine proper foot placement.

4) I will be provided standard instructions prior to the start of each test condition including the start

of each test. During the recordings, I will maintain a steady standing position.

5) I will be tested on two different computerized systems, each using 3 different tests to measure

balance: Sensory Organization Test (SOT); Adaptation Test (ADT) and the Motor Control Test

(MCT).

6) I will be tested without shoes. The investigator will align my feet properly at the beginning of the

tests.

7) I am allowed to rest as often as necessary throughout the testing.

8) During some of the tests the support surface and or the visual surround may move gently during

some of the recording trials. My task will be to remain as steady as possible. The investigator will

inform me when this may occur.

9) During all of the testing, I will be in a restraining harness and the investigator will remain in close

proximity in case I lose my balance.

10) The entire session will take approximately 30 minutes on each system. I will have a 15 minute rest

period between testing on the two balance systems.

11) I will first perform all of the standing balance tests on the Bertec System in the following order:

a) First, I will complete the Sensory Organization Test (SOT) This balance test systematically tests

our three sensory systems: vision, vestibular or inner ear, and somatosensory or our sensation of

our feet. During the SOT, I will complete 3, 20 second trials of six different test conditions (18

total trials) during the Sensory Organization Test. I will be allowed to rest between conditions as

needed. The order of testing is as follows:

i. Eyes open with a fixed (i.e. not moving) surface and visual surround

i. Eyes closed with a fixed surface

ii. Eyes open with a fixed surface

iii. Eyes open with a fixed surface and sway-referenced (i.e., moving) visual

surround

iv. Eyes open with a sway-referenced surface and fixed visual surround

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v. Eyes closed with a sway-referenced surface

vi. Eyes open with a sway-referenced surface and visual surroundings.

b) Next I will perform the Motor Control Test (MCT). This test is designed to assess my ability to

recover automatically from external perturbations or slight movements under my feet. The scale of

the movement is based on my height. This test will also include six different conditions, 3 trials

each, which are as follows:

i. Backward translation, small

ii. Backward translation, medium

iii. Backward translation, large

iv. Forward translation, small

v. Forward translation, medium

vi. Forward translation, large

c) The final test I will perform is known as the Adaptation test (ADT). This test measures my ability

to counteract a movement of the surface that I am standing on in a toes up or toes down direction.

I will be given 5 trials of each condition (toes up and toes down).

12) I will have a 15 minute rest period before repeating these tests on the NeuroCom System.

BENEFITS

I understand that there is no benefit in my participation in this project except to have my balance tested on

two different, but similar computerized systems. My participation will add to the normative database for a

new computerized balance system on the market and will help determine if there are differences in the

balance scores as compared to the gold standard system already in use.

RISKS AND DISCOMFORTS

Risks associated with the balance tests are minimal. I am aware that participation in this project may lead to

fatigue or dizziness. To avoid this, rest breaks will be allowed. I understand that there is a possibility that I

may lose my balance at times during the assessments. To prevent a fall or loss of balance, I will wear a

safety harness for all testing and will be guarded by trained investigators.

CONFIDENTIALITY

I understand that the findings of this study will be kept confidential and will be stored in a secure location.

Should the data be used for publication in medical literature or for teaching purposes, I understand that only

the investigators will know my identity and I will not be identified by my name in any publication. I

further understand that photographs and videotapes will be used only with my written permission.

REQUEST FOR MORE INFORMATION

I understand that I have the right to ask and have answered questions concerning this study at any time. Dr.

Peggy Trueblood, the principal investigator, is available to answer my questions or concerns at 278-3008. I

will receive a copy of this consent form to refer to for further reading or clarification if needed.

REFUSAL OR WITHDRAWAL OF PARTICIPATION

I understand that my participation is voluntary and that I may refuse to participate or withdraw consent and

discontinue participation in this study at any time. I also understand that the investigators may terminate

my participation in this study at any time after they have explained the reasons for doing so.

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INJURY STATEMENT

I understand that in the event of any physical injury resulting from my participation in this study, my

physician will be notified and treatment will be available at my own expense. There will be no form of

legal or monetary compensation available from the California State University, Fresno, my referring

physician, or the above listed investigators.

I have explained to ______________________________ the purpose of this study, the procedures, and the

possible risks and benefits to the best of my ability.

______________________________ ______________________

Investigator Date

CONSENT

I confirm that the investigators have explained to me the purpose of the project, interview process,

screening, and procedures that I will undergo. I also understand the possible risks and benefits that I may

experience as a result of this study. The procedures for this research have been reviewed and approved by

California State University, Fresno, Committee on Protection of Human Subjects. I have read and

understand this consent form. Therefore, I agree to give my consent to participate as a subject in this

project.

______________________________ ______________________

Participant Date

______________________________ ______________________


I do/do not authorize the taking of photographs or videotapes of myself for either publication or use as

educational materials.

_____________________________ ______________________

Participant Date

_____________________________ ______________________


I.D.#

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MEDICAL RESEARCH PATIENT’S BILL OF RIGHTS

California law requires that any person asked to take part as a subject in research involving a medical

experiment, or any person asked to consent to such participation on behalf of another, is entitled to receive

the following list of rights written in a language in which the person is fluent. This list includes the right

to:

1. Be informed of the nature and purpose of the experiment.

2. Be given an explanation of the procedures to be followed in the medical experiment and any drug or

device to be utilized.

3. Be given a description of any attendant discomforts and risks reasonably to be expected from the

experiment.

4. Be given an explanation of any benefits to the subject reasonably to be expected from the experiment,

if applicable.

5. Be given a disclosure of any appropriate alternative procedures, drugs, or devices that might be

advantageous to the subject, and their relative risks and benefits.

6. Be informed of the avenues of medical treatment, if any, available to the subject after the experiment if

complications should arise.

7. Be given an opportunity to ask any questions concerning the experiment or the procedures involved.

8. Be instructed that consent to participate in the medical experiment may be withdrawn at any time and

the subject may discontinue participation in the medical experiment without prejudice.

9. Be given a copy of the signed and dated written consent form.

10. Be given the opportunity to decide to consent or not to consent to a medical experiment without the

intervention of any element of force, fraud, deceit, duress, coercion, or undue influence on the

subject’s decision.

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