Effects of Post-Stroke Upper Extremity Assistance
Phase: NA
Conditions: Arm Weakness as a Consequence of Stroke
Sponsor: Stanford University

Study Protocol 
Effects of a Compliant Arm Support on Post-stroke Upper 
Extremity Range of Motion 
Principal investigator: 
Allison Okamura 
Professor 
Department of Mechanical Engineering 
Stanford University 
Stanford, CA, USA
ClinicalTrials.gov identification number
NCT03867838
Protocol identification number
IRB-49194
Author
Cole Simpson 
Redwood City, CA, USA
Version 
Date
Draft 0.3 
8 January, 2021
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Signature page 
Principal investigator: 
____________________________ 
Allison Okamura 
Author
____________________________ 
Cole Simpson
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Table of contents 
I. Introduction 
4 
II. Aims and objectives 
4 
III. Study design 
4 
III.a. Participant recruitment 
4 
III.b. Study protocol 
5 
IV. Analyses 
6 
IV.a. Reachable workspace area computation 
6 
IV.b. Estimate of flexor synergy activation (biceps electromyography) 
6
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I. Introduction 
The aim of this study is to test in a single-center self-controlled study whether a custom 
lightweight, low-cost compliant exoskeletal arm support assists stroke survivors to achieve a 
greater reachable workspace area with the impaired arm and whether any such effect might 
persist when the device is no longer in use.  
This protocol and statistical analysis plan will give more detailed descriptions of the 
methodology, analyses, and endpoints of this study. 
II. Aims and objectives 
The aim of this study is to test the efficacy of an experimental compliant arm support designed to 
support shoulder abduction in human users. We consider two ways in which such a device might 
be helpful for stroke survivors: (1) improved functionality while using the device and (2) residual 
benefits that persist after use of the device. In Section III, we describe the protocol we developed 
to examine whether our device increases the reachable workspace area and whether any 
improvements persist for a short period of time after an intervention. 
III. Study design 
The study is a single-arm pilot study designed to assess whether an experimental compliant arm 
support (1) assists stroke survivors to achieve a larger reachable workspace area and (2) whether 
a short assisted exercise trial causes a residual increase in reachable workspace area caused by a 
reduction in flexor synergy activation.  
III.a. Participant recruitment 
Candidate participants will be identified in one of the following manners: 
(1) referral from treating physician through the Stanford Neurology & Neurological Sciences and 
Physical Medicine & Rehab clinics (both outpatient). Patients with clinic appointments and 
history of stroke will be screened under a waiver of authorization for recruitment, guided by 
inclusion/exclusion criteria. The physician will discuss the study with the patient and if the 
patient agrees, a physician or coordinator from the study team will approach the patient after the 
patient's clinic appointment. 
(2) through a database in which stroke survivors from the community have indicated their 
interest in participating in Stanford stroke research studies and filled out a form to add 
themselves to a database. Study personnel may contact individuals directly from that list. 
(3) from a list of subjects who enrolled in other stroke research studies at Stanford and indicated 
that they are interested in participating in more stroke studies. These are current patients of the 
study physicians. Study personnel may contact these individuals directly. 
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Once identified, candidate participants will be contacted via phone call and asked to answer a 
few questions to establish eligibility and interest. Participants will be scheduled only if they 
express interest and meet the inclusion criteria determined during the phone screening. 
To be included in the study, all participants must: 
- be at least 18 years of age 
- be greater than 6 months post stroke 
- exhibit passive abduction to 90 degrees at shoulder 
- exhibit reduced active (retro)flexion/extension at shoulder when abducted to 90 degrees 
- exhibit reduced active flexion/extension at the elbow 
Participants will be excluded from all assessments if they: 
- are unable to give informed consent 
- are unable to comprehend and follow instructions 
- have a condition (other than stroke) affecting sensorimotor function 
- show evidence of unilateral spatial neglect 
- are unable to sit in a chair (without armrests) for at least 2 hours (transfer from wheelchair 
acceptable) 
We do not have pilot data to power our study. However, previously published studies using 
similar methods have typically examined 6-12 participants. We aim to enroll up to 10 
participants. 
III.b. Study protocol 
When a participant arrives for the study session, time will first be allocated to review the consent 
document and answer any questions. Once participants have granted their informed consent, non-
invasive clinical assessments will be administered by the study personnel for demographics 
purposes. These assessments include: the Upper Extremity portion of the Fugl-Meyer 
Assessment (FMA) and simple tests for joint range of motion, visual/tactile neglect, and scapula-
humeral rhythm. 
Our protocol consists of a set of assessments performed with each of 2 support conditions: (1) 
unassisted and (2) using our experimental device. In each assessment, we will measure the 
reachable workspace area and a proxy for flexor synergy activation. To assess reachable 
workspace area, participants will be coached to individually flex and extend the elbow and 
shoulder to trace the largest possible circle while keeping the hand and elbow raised to the height 
of the shoulder while arm kinematics are measured using an optical motion capture system 
(Phasespace Impulse X2E, San Leandro, CA, USA). Participants will trace 6 circles per 
measurement, 3 in each direction (clockwise or counterclockwise) with the order randomly 
determined. As a proxy measurement for flexor synergy activation, the arm will be placed in a 
configuration known to activate the flexor synergy — arm raised to shoulder height with the 
elbow bent 90˚ with the hand placed directly in front of the sternum — while the activation of 
the biceps muscle is recorded using electromyography (Delsys Bagnoli 2 system, Natick, MA, 
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USA). Each participant will complete the first set of assessments unassisted to establish baseline 
measurements. Participants will then complete a trial while wearing our experimental device. A 
trial consists of a workspace and flexor synergy evaluation with the assigned support followed by 
a ten-minute intervention trial. In this intervention trial, participants will perform the same 
clockwise and counterclockwise circular movements with the hand used to measure the 
reachable workspace. The direction of the circular movements will be randomly determined and 
repeated for 1 minute. Up to three 1-minute rest periods will be allowed as needed. The support 
will then removed and participants will perform another workspace and flexor synergy 
assessment with no support to test for any effects of the exercise. Participants will then rest for 
30 minutes before performing another workspace and synergy assessment to determine whether 
any exercise effects have worn off. 
IV. Analyses 
The subsections below will describe data processing and analyses performed to compute the 
primary outcome measures.  
IV.a. Reachable workspace area computation 
Motion capture data is low-pass filtered at 20 Hz using an 8th order, zero-phase shift Butterworth 
filter. Any gaps in the marker trajectories caused by temporary occlusions (less than 0.2 seconds) 
of the marker are filled using cubic interpolation. Any occlusions lasting longer than 0.2 seconds 
are ignored in our analyses rather than interpolated to avoid generating incorrect data. We 
compute the reachable workspace area of the hand using the boundary function in Matlab, which 
computes a concave boundary around the input data and returns the area of that boundary. We 
disregard datapoints in which the hand (defined as the marker on the ulnar epicondyle) or elbow 
(defined as the marker on the lateral humeral epicondyle) fall below 20 cm below the height of 
the shoulder (defined as the marker on the acromion). 
IV.b. Estimate of flexor synergy activation (biceps electromyography) 
Recorded electromyograms (EMG) are high-pass filtered with a cutoff frequency of 30Hz, 
rectified, and then low-pass filtered with a cutoff frequency of 6Hz to create linear envelopes. All 
filters are 8th order, zero-phase shift Butterworth filters. We use the average of this linear 
envelope as the estimate for flexor synergy for a given trial. 
 
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