Locomotor Function Following Acute Intermittent Hypoxia (AIH) and Transcutaneous Electrical Spinal Cord Stimulation (tSCS) With Gait Therapy Versus Traditional Gait Therapy in Individuals With Spinal Cord Injury
Phase: NA
Conditions: Spinal Cord Injuries, Spinal Cord Diseases
Sponsor: Shirley Ryan AbilityLab

Title: Locomotor Function Following Acute Intermittent Hypoxia (AIH) and Transcutaneous 
Electrical Spinal Cord Stimulation (tSCS) With Gait Therapy Versus Traditional Gait Therapy in 
Individuals With Spinal Cord Injury   
 
NCT03922802 
 
6/13/2022 
 
 

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PROTOCOL TITLE: Locomotor function following acute intermittent hypoxia and 
transcutaneous electrical spinal cord stimulation with gait therapy versus traditional gait therapy 
in individuals with spinal cord injury 
 
PRINCIPAL INVESTIGATOR: 
Arun Jayaraman PT, PhD 
Max Nader Center for Rehabilitation Technologies and Outcomes, Center for Bionic Medicine 
312-238-6875 
a-jayaraman@northwestern.edu  
 
VERSION NUMBER: 
9 
 
VERSION DATE: 
6/13/2022 
  
STUDY SUMMARY: 
 
Investigational Agent(s)  
(Drugs or Devices) 
Biostim-5 Spinal Stimulator 
IND / IDE / HDE #  NSR  
Indicate 
Special Population(s) 
Children  
 Children who are wards of the state  
 Adults Unable to Consent   
 Cognitively Impaired Adults  
 Neonates of Uncertain Viability  
 Pregnant Women  
 Prisoners (or other detained/paroled individuals)  
 Students/Employees  
Sample Size 36 (up to 75 screened) 
Funding Source Max Nader Center, Craig H. Nielsen Foundation, and the 
Shirley Ryan AbilityLab Catalyst Grant Program 
Indicate the type of consent 
to be obtained 
Written  
Verbal/Waiver of Documentation of Informed Consent 
Waiver of HIPAA Authorization  
 
Waiver/Alteration of Consent Process   
Site 
 Lead Site (For A Multiple Site Research Study) 
 Data Coordinating Center (DCC) 
Research Related 
Radiation Exposure 
Yes  
 No  
DSMB / DMC / IDMC 
Yes  
No 
 
 
OBJECTIVES: 
• 
To determine whether acute intermittent hypoxia therapy (AIH) combined with 
transcutaneous spinal cord stimulation during ambulation training modulates spinal 
locomotor networks in individuals with spinal cord injury 

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• 
To determine whether acute intermittent hypoxia therapy (AIH) combined with 
transcutaneous spinal cord stimulation during ambulation training improves locomotor 
function in individuals with spinal cord injury 
• 
To determine whether ambulation efficiency (improved cardiovascular conditioning) 
improves with training combination of AIH, transcutaneous spinal cord stimulation and 
ambulation training in individuals with spinal cord injury  
 
STUDY ENDPOINTS: 
Primary endpoints: 
• 
Change in locomotion efficiency as measured by the 6-Minute Walk West (6MWT) 
 
Secondary endpoints 
• 
Change in Ten Meter Walk Test (10MWT) at self-selected velocity and fastest (safe) 
velocity 
• 
Change in maximum volitional isokinetic and isometric ankle and knee torque as 
measured by the Biodex dynamometer strength assessment 
• 
Change in transfers 
• 
Change in bilateral lower extremity strength 
 
STUDY INTERVENTION(S) / INVESTIGATIONAL AGENT(S): 
Transcutaneous Spinal Cord Stimulation: A Transcutaneous Spinal Cord Neurostimulator 
(BioStim-5 or NeuroEnabling Stimulator System) will deliver transcutaneous electrical spinal 
cord stimulation.  It provides constant current stimulation with a range of 0-250 mA through self-
adhesive electrodes (ValuTrode, Axelgaard Ltd., USA) with a diameter of 3.2 cm placed as 
cathodes on the skin between the spinous processes of the vertebrae. In addition, two 7.5 × 13 
cm self-adhesive electrodes serving as anodes (ValuTrode, Axelgaard Ltd., USA) will be placed 
symmetrically on the skin over the iliac crests. A foam rubber pad will be placed over the 
cathodes and secured using adhesive tape, and an elastic belt will be wrapped tightly around 
the trunk above the waist to ensure a constant pressure between the electrodes and the skin. 
The stimulation waveform will consist of monophasic or biphasic, rectangular 1-ms pulses at a 
frequency ranged between 0.2 and 40 Hz, with each pulse filled with a carrier frequency of 5 to 
10 kHz. The stimulation intensity will vary from 10 to 250 mA and be determined based on 
participant threshold and maximum motor outputs.   
 
Acute Intermittent Hypoxia (AIH): Intermittent hypoxia will be administered within a clinical 
research laboratory.  Subjects will be fitted with a latex-free full non-rebreather mask with a 
custom neoprene head strap [Hypoxico Inc., New York, NY, USA].  This mask and oxygen 
delivery system are commonly used for altitude training.  The mask will first provide a normoxic 
air (room air) mixture (FiO2 = 0.21) via the mask. The mask is designed to couple with a 
universal mask circuit connecting to the air mixture system. The purpose of the mask will be to 
minimize room air entrainment. The non-rebreather mask has an attached reservoir bag where 
the controlled air mixture (FiO2 = 0.08 - 0.95) from the generator fills in between breaths, and a 
valve that largely prevents the inhalation of room or exhaled air.  Delivery of air mixtures will be 
done through adjustment of one-way valves attached to the delivery cylinders. Tubing will 
extend from the reservoir bag directly to the machine.  
 
 
Once fitted with the mask, initial recordings of heart rate, blood pressure, and arterial oxygen 
saturation (SpO2) will be taken.  The sequence of hypoxia will consist of up to 60- 90 seconds of 
9-10% O2 (FiO2 0.09), alternating with up to 60- 90 seconds of 21% O2 (normoxic air FiO2 0.21).  
The delivery of hypoxia and normoxic air mixtures will be repeated up to 18 times per session 

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each, for a total of up to 45 minutes, to maintain SpO2 at 80-90%. Hearth rate and pulse 
oximetry will be continuously monitored throughout, and recording will be taken at each 
alteration in sequence. Blood pressure will be taken upon completion of the total sequence. 
 
A pulse oximetry unit will provide continuous monitoring of heart rate and peripheral arterial 
oxyhemoglobin saturation (SpO2). SpO2 will be maintained at a goal of 80-90% during the 
hypoxic bouts, however, SpO2 as low as 75% will be accepted. If the SpO2 drops below 75%, 
we will terminate the hypoxia exposure immediately. 
 
Any subjective symptoms will be recorded and the subject will be monitored throughout the 
study period for any signs of cardiopulmonary distress.   
 
If there is a dangerous alteration in the cardiopulmonary parameters being assessed, the 
experiment will be stopped and appropriate care will be provided by the resident on call or 
nursing staff available at the Shirley Ryan AbilityLab. 
All research devices will remain at the Shirley Ryan AbilityLab in a secure research location.   
Only authorized research personnel will have access to the devices. 
All research procedures will be performed at the Shirley Ryan AbilityLab (SRALab) in the 
Research & Technologies Lab (RT&O). 
 
PROCEDURES INVOLVED: 
Study Design: A randomized, controlled crossover trial. We are evaluating the effectiveness of 
AIH prior to transcutaneous spinal cord stimulation during locomotor training on improving 
ambulation and standing balance among individuals with paraplegia or tetraplegia due to spinal 
cord injury. All participants will complete three arms of the study: 
 
1. AIH prior to transcutaneous spinal cord stimulation during locomotor training (AIH + 
tSCS) 
2. Sham AIH prior to sham transcutaneous spinal cord stimulation during locomotor training 
(SHAM + SHAM) 
3. Sham AIH prior to transcutaneous spinal cord stimulation during locomotor training 
(SHAM AIH + tSCS) 
 
Participants will complete a 4-week washout period between each arm. 
 
Prior to Visit 2, a medical clearance letter describing study procedures and risks will be sent to 
the subject’s physician or clinician to request medical clearance for the subject to participate in 
the study. Permission to contact the participant’s physician or clinician to obtain medical 
clearance will be obtained during the screening process.  
 
Visit 1: Initial screening session 
• 
Obtain voluntary and informed consent 
• 
Obtain medical clearance from subject’s physician  
• 
Inclusion/exclusion criteria checklist reviewed with patient  
• 
Medical history review 
• 
Patient name 
• 
Patient date of birth 
• 
Patient race (voluntary) 
• 
Patient gender 
• 
Emergency contact information 

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• 
Date of spinal cord injury 
• 
Type and location of spinal cord injury 
• 
AIS level 
• 
Assistive device use 
• 
Orthotic use 
• 
Recent surgery/injuries 
• 
Medications 
• 
Allergies 
• 
Medical History 
• 
Therapy history 
 
• 
Physical Function Assessment 
• 
Skin assessment 
• 
Active and passive range of motion (AROM/PROM) of bilateral lower extremities 
• 
Assessment of lower extremity spasticity using Modified Ashworth Scale 
• 
Manual muscle testing of bilateral lower extremities as an assessment of strength 
• 
Ten Meter Walk Test (10 MWT): Assesses subject walking speed in meters per 
second for 10 meters. Subjects will repeat each measure 3 times at their normal 
self-selected walking speed and 3 times at a fast speed while still able to 
maintain safety. The test may then be repeated without lower extremity orthotics 
and without assistive devices for a total of up to 18 trials.  
 
Baseline Assessments:  
• 
Standard evaluation of physical function 
• 
Active and passive range of motion of bilateral lower extremities 
• 
Assessment of lower extremity spasticity using Modified Ashworth Scale 
• 
Skin integrity screen  
• 
Assessment of maximum isometric voluntary ankle torque generation: Subjects will be 
instructed to contract, and for continued voluntary torque production will be encouraged 
using verbal commands for a period of approximately 5 seconds.  The hip will be flexed 
up to 90-100, the knee flexed up to 10 and the ankle at 0 plantar flexion, as described 
in previous studies (Shaffer, Okereke et al. 2000; Pathare, Walter et al. 2005). Axis of 
ankle rotation will be aligned with the axis of rotation of the dynamometer. The foot will 
remain secured to a footplate with straps placed at the forefoot and ankle. The knee will 
be braced to eliminate moments generated by hip adduction/abduction.  Subjects will 
exert constant endpoint forces against the dynamometer with the weight of the limb 
supported by the device.  
• 
Timed Up and Go Test (TUG): Assesses mobility, balance, walking ability and fall risk. 
The participant starts seated in a chair with his/her back against the chair back. On 
command, the participant rises from the chair, walks 3 meters, turns, walks back to the 
chair and sits down. Timing begins when the command to start is given and stops when 
the participant returns to a seated position. This test may be repeated up to 3 times 
during each assessment visit and during each training visit.  
• 
Six Minute Walk Test (6 MWT): The 6MWT is performed as an objective evaluation of 
functional exercise capacity. The 6MWT is easy to administer, well tolerated, and 
typically reflective of activities of daily living. The test measures the distance that the 
patient can walk on a flat, hard surface, indoors, in a period of 6 minutes. The walk test 
is self-paced and assesses the level of functional capacity. Patients are allowed to stop 
and rest during the test, however, the timer does not stop. If the patient is unable to 

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complete the time, the time stopped is noted and reason for stopping prematurely is 
recorded.  
• 
Ten Meter Walk Test (10 MWT): Assesses subject walking speed in meters per second 
for 10 meters. Subjects will repeat each measure 3 times at their normal self-selected 
walking speed and 3 times at a fast speed while still able to maintain safety.  
• 
Spinal Motor Evoked Potentials (MEPs) may be obtained at baseline and during all 
functional assessment visits while stimulating interspinous spaces with single pulses at 
each stimulation intensity. MEPs are the electromyographic responses of the peripheral 
muscles to electrical stimulation of the spinal cord. MEPs will be used to test the integrity 
of the motor pathways of the spinal cord. 
 
Treatment Sessions 
Each participant will complete 5 treatment sessions in each of the 3 arms of the study. 
Treatment sessions will take place 5 times per week. 
 
Each treatment session may include: 
• 
Arm 1: AIH + tSCS 
o May receive up to 45 minutes of AIH and 30 min of locomotion training with 
transcutaneous spinal cord stimulation.   
• 
Arm 2: SHAM + SHAM 
o May receive up to 45 minutes of sham AIH and 30 min of locomotion training 
with sham transcutaneous spinal cord stimulation.   
• 
Arm 3: SHAM AIH + tSCS 
o May receive up to 45 minutes of sham AIH and 30 min of locomotion training 
with transcutaneous spinal cord stimulation.   
 
Under all of the conditions, the goal during locomotor training is to generate smooth and 
symmetrical stepping movements.  The trained research personnel will provide cues (verbal, 
visual and tactile) to improve symmetry of gait and avoid compensatory mechanisms.  The 
progression in training refers to gradually increasing gait speed while maintaining improved gait 
kinematics. Electromyographic (EMG) activity will be collected from the lower extremity muscles 
bilaterally during maximum voluntary contractions and locomotor training.   
 
Functional Assessment Visits  
Occur after completion of each arm  
• 
Refer to Baseline Assessment Visits for repeat of assessments 
 
All visits will be conducted under the supervision of a trained researcher and clinician. Manual 
assistance or cueing will be provided as necessary for safety and balance. Clinicians will also 
utilize gait belts and overhead harness systems to ensure patient safety during physical activity. 
Vital signs will be monitored with use of our wearable sensors before, during and after physical 
exertion. All subjects will be permitted to stop physical activity or rest at any time during the 
study. In addition, the following patient reports will be used to assess patient participation and 
make adjustments as appropriate.  
• 
Rating of Perceived Exertion (RPE): The 15-grade Borg Scale during ambulation 
training (over ground, treadmill and gravity-eliminated) to monitor RPE. The intensity will 
be adjusted to ensure patients do not exceed a rating of 17 (very hard). 
• 
Pain scale: Visual Analogue Scale (VAS) for pain will monitor patient discomfort during 
non-invasive spinal cord stimulation and locomotion training parameters.  This is a 10-

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point scale. We will stop when the participant states pain that interferes with their safe 
participation in the research. 
 
Finally, any adverse reactions that result from participation in this study will be documented by 
the principal investigator on the subject’s data file and reported in writing to Northwestern’s 
Office for Protection of Human Subjects. 
 
Video recording and/or pictures of each participant during assessments may be taken during the 
training and testing sessions. These items may be used to help troubleshoot potential issues.  
They may also be used for presentations and training of other research personnel. All attempts 
will be made to ensure the images or videos used are devoid of any identifying information. 
Each subject may choose to limit if/how these items may be used, as indicated during their 
consent process. 
 
STUDY TIMELINES 
• 
One (1) screening visit 
• 
One (1) Baseline assessment visit prior to initiating each arm (3 total) 
• 
Fifteen (15) treatment/intervention visits, 5 per each intervention arms  
o The treatment sessions will be up to 5 times per week within each participants’ 
scheduling availability 
• 
One (1) Functional Assessment visit that occurs after all intervention sessions are 
complete for each arm (POST, 3 total) 
• 
One (1) Functional Assessment visit that occurs 1 week after all intervention sessions 
are complete for each arm (1 week follow up, 3 total) 
 
We anticipate an ongoing enrollment over 3 years. Investigators will complete this study 
(primary analyses) 5 years from start date (IRB approval date).  
 
INCLUSION AND EXCLUSION CRITERIA 
Inclusion Criteria: 
• 
Participants have been diagnosed with a spinal cord injury below level C2 
• 
ASIA Impairment Scale Grade A-D 
• 
Participants are 18 years of age or older 
• 
Participants are at least 6 months post spinal cord injury 
• 
Participants with paraplegia or tetraplegia secondary to a single spinal cord injury 
• 
Participants are able to provide informed consent 
• 
Participants are not currently receiving regular physical therapy services 
 
Exclusion Criteria 
 
• 
Individuals less than 18 years of age 
• 
Individuals less than 6 months post spinal cord injury 
• 
Individuals with cerebellar ataxia 
• 
Individuals with multiple spinal cord injury history 
• 
Pregnancy or nursing 
• 
Pacemaker or anti-spasticity implantable pumps 
• 
Active pressure sores 
• 
Unhealed bone fractures 
• 
Peripheral neuropathies 
• 
Painful musculoskeletal dysfunction due to active injuries or infections 

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• 
Severe contractures in the lower extremities 
• 
Active urinary tract infection 
• 
Clinically significant depression, psychiatric disorders, or ongoing drug abuse 
• 
Diagnosed with any of the following medical conditions: congestive heart failure, cardiac 
arrhythmias, uncontrolled hypertension, uncontrolled diabetes mellitus, chronic 
obstructive pulmonary disease, emphysema, severe asthma, previous myocardial 
infraction, or known carotid/intracerebral artery stenosis 
• 
Individuals with a tracheostomy or who utilize mechanical ventilation. 
• 
Individuals who are currently enrolled in another interventional research study or in 
therapy related to lower extremity function and/or walking. 
• 
Participants will be excluded if they have had a botulinum toxin injection to lower extremity 
musculature within the last 3 months. Participants will need to refrain from lower extremity 
botulinum toxin injections for the duration of the study. If participants wean off 
antispasticity medications to successfully complete the responsiveness to AIH screening 
session, they will need to refrain from the medications for the duration of the study.   
• 
Documented sleep apnea.  
• 
Orthopedic injuries or surgeries that would impact an individual’s ability to use the lower 
extremity.  
• 
Traumatic brain injury or other neurological conditions that would impact the study. 
 
We will not include the following populations: 
• Adults unable to consent, unless accompanied by a legally authorized representative. 
• Individuals who are not yet adults (infants, children, teenagers) 
• Pregnant women 
• Prisoners 
 
PARTICIPANT POPULATION(S) 
Accrual 
Number: 
Category/Group: 
(Adults/Children 
Special/Vulnerable 
Populations) 
Consented: 
Maximum Number to be 
Consented or 
Reviewed/Collected/Screened 
Enrolled: 
Number to Complete 
the Study or Needed 
to Address the 
Research Question 
Local 
Adults 
45 
36 
 
 
 
Study-wide 
Single-Center Study 
0 
0 
 
 
 
Total: 
 
45 
36 
 
STATISTICAL ANALYSIS PLAN:  
All functional gait outcomes will be assessed at three follow-up visits. We will use a linear mixed 
model with repeated measures to jointly assess changes at INT5, POST and 1WK relative to 
baseline within each arm as well as assess the changes between arms for each time point. The 
model will include time points (BL, INT5, POST, and 1WK as a categorical variable) and 
treatment arm (AIH + tSCS, SHAM AIH + tSCS, and SHAM + SHAM as categorical variable) as 
fixed effects and subject as a random effect. Linear mixed models provide a better mechanism 
for handling missing data by using all available data, rather than performing a complete case 

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analysis, if the data are assumed to be missing at random. The level of significance will be set 
at alpha = 0.05. Bonferroni corrections will be used to adjust for multiple comparisons.  
 
SAMPLE SIZE AND POWER CONSIDERATIONS:  
The sample size calculation will be based on a one-sided paired t-test comparing the changes in 
self-selected speed of the 10 meter walk test from pre- to 1 week post-treatment. Based on the 
minimum clinically important difference (MCID) for speed previously reported in SCI29, we want 
to detect a change in speed of 0.06 m/s. The standard deviation of the change from baseline to 
1 week post was 0.07 m/s. Therefore, using 0.857 as our effect size, a sample size of n=10 will 
provide a power of 80% with alpha = 0.05. 
 
References: 
1. National Spinal Cord Injury Statistical Center, Facts and Figures at a Glance. Birmingham, AL: 
University of Alabama at Birmingham, 2018 
2. Dimitrijevic MR, Gerasimenko Y, Pinter MM. Evidence for a spinal central pattern generator in 
humans. Ann NY Acad Sci 1998;860:360-376. 
3. Gerasimenko YP, Lu DC, Modaber M, et al. Noninvasive reactivation of motor descending control 
after paralysis. Journal of Neurotrauma. 2015. 32:1968-1980. Doi:10.1089/neu.2015.4008. 
4. Trumbower RD, Jayaraman A, Mitchell GS, Rymer WZ. Exposure to acute intermittent hypoxia 
augments somatic motor function in humans with incomplete spinal cord injury. Neurorehabil 
Neural Repair 2012;26(2):163–72. 
5. Hayes HB, Jayaraman A, Herrmann M, Mitchell GS, Rymer WZ, Trumbower RD. Daily 
intermittent hypoxia enhances walking after chronic spinal cord injury: a randomized trial. 
Neurology 2014;82(2):104–13. 
6. Labruyère, R. and H. J. A. van Hedel (2014). "Strength training versus robot-assisted gait training 
after incomplete spinal cord injury: a randomized pilot study in patients depending on walking 
assistance." Journal of NeuroEngineering and Rehabilitation 11: 4-4.