Repetitive Acute Intermittent Hypoxia for Spinal Cord Repair

Study Overview
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Brief Summary
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Our goal is to enhance repeated exposure to acute intermittent hypoxia (rAIH)/training-induced aftereffects on upper and lower limb function recovery in humans with chronic spinal cord injury (SCI).

Detailed Description
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The experiments in this study will test the following: Hypothesis 1.1(Experiment 1) that rAIH will enhance corticospinal excitability and upper and lower limb function in humans with incomplete SCI. Hypothesis 1.2 (Experiment 2) that enhancing the aftereffects of rAIH with exercise training will further enhance upper and lower limb motor function in humans with incomplete SCI. Measurements of corticospinal, cortical, and motoneuron excitability will be tested to further understand the mechanisms of this induced-plasticity. Persons with chronic (>6 months) spinal cord injury between the levels of C2 and T2. SCI subjects must possess either the ability to produce a visible precision grip force with one hand, and/or the ability to perform some small wrist flexion and extension. Additionally, subject must possess the ability to perform a small visible contraction with dorsiflexion and hip flexor muscles. Controls must be right handed due to potential differences in the organization of the brain in right handed and left handed individuals.

Official Title
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Repetitive Acute Intermittent Hypoxia for Spinal Cord Repair

Conditions
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Spinal Cord Injuries

Intervention / Treatment
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* Other: Repeated exposure to acute Intermittent Hypoxia (rAIH)
* Other: Normal Room Air
* Other: Upper-limb Training by Research Staff
* Other: Lower-limb Training by Research Staff


Participation Criteria
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Eligibility Criteria
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Inclusion criteria for SCI: Males and females between 18-85 years Chronic SCI (≥ 6 months post injury) SCI at or above L2 ASIA A, B, C, or D, complete or incomplete Possess the following: The ability to produce a visible precision grip force with one hand, and/or the ability to perform some small wrist flexion and extension. The ability to perform a small visible contraction with dorsiflexion and hip flexor muscles. Inclusion criteria for controls: Males and females between 18-85 years Right-handed (Only right-handed individuals will be accepted into this group because of the potential differences in the organization of the brain in right handed and left handed individuals) Exclusion criteria for SCI and for controls: Uncontrolled medical problems including pulmonary, cardiovascular or orthopedic disease Any debilitating disease prior to the SCI that caused exercise intolerance Premorbid, ongoing major depression or psychosis, altered cognitive status History of head injury or stroke Metal plate in skull History of seizures Receiving drugs acting primarily on the central nervous system, which lower the seizure threshold such as antipsychotic drugs (chlorpromazine, clozapine) or tricyclic antidepressant Pregnant females Ongoing cord compression or a syrinx in the spinal cord or a spinal cord disease as spinal stenosis, spina bifida or herniated cervical disk. AIH exclusion criteria (in addition to the above listed exclusion criteria) Resting heart rate ≥120 BPM Resting systolic blood pressure >180 mm Hg Resting diastolic Blood Pressure >100 mmHg Self-reported history of unstable angina or myocardial infarction within the previous month Resting SpO2 ≥ 95% Cardiopulmonary complications such as COPD

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: rAIH + training by research staff<br>Participants will receive repeated exposure to acute Intermittent Hypoxia (rAIH) and training by research staff. | Other: Repeated exposure to acute Intermittent Hypoxia (rAIH)<br>* Participants will be fitted with a mask that will be placed over mouth and nose. Tubing will be attached to the front of the mask. The session will last approximately 30-45 minutes with 60-90 seconds of lower oxygen (tubing attached, 9-10% oxygen level), alternating with 60-90 sec of normal room air (no tubing attached).<br>Other: Upper-limb Training by Research Staff<br>* Training sessions will last for approximately 30 minutes, with additional time for set up. During these sessions, participants will be asked to complete a variety of tasks related to general arm/hand movement, gross grasping, fine grasping, and hand cycle using an arm ergometer. The number of repetitions will be monitored and adjust the difficulty to ensure appropriate task difficulty.<br>Other: Lower-limb Training by Research Staff<br>* Training sessions will last for approximately 30 minutes, with additional time for set up. During these sessions, participants will be asked to complete a variety of tasks related to general leg/foot movement, over-ground walking, treadmill walking, stair climbing training, leg cycling, standing frame, and NuStep. The number of repetitions will be monitored and adjust the difficulty to ensure appropriate task difficulty.<br>|
| Sham Comparator: sham rAIH + training<br>Participants will sham receive repeated exposure to acute Intermittent Hypoxia (rAIH) and training by the research staff. | Other: Normal Room Air<br>* Participants will be fitted with a mask that will be placed over mouth and nose. Tubing will be attached to the front of the mask. The session will last approximately 30-45 minutes with 60-90 seconds of normal room air (with tubing attached to the mask) and 60-90 sec of normal room air (without the tubing attached to the mask).<br>* Other names: Sham repeated exposure to acute Intermittent Hypoxia (rAIH);Other: Upper-limb Training by Research Staff<br>* Training sessions will last for approximately 30 minutes, with additional time for set up. During these sessions, participants will be asked to complete a variety of tasks related to general arm/hand movement, gross grasping, fine grasping, and hand cycle using an arm ergometer. The number of repetitions will be monitored and adjust the difficulty to ensure appropriate task difficulty.<br>Other: Lower-limb Training by Research Staff<br>* Training sessions will last for approximately 30 minutes, with additional time for set up. During these sessions, participants will be asked to complete a variety of tasks related to general leg/foot movement, over-ground walking, treadmill walking, stair climbing training, leg cycling, standing frame, and NuStep. The number of repetitions will be monitored and adjust the difficulty to ensure appropriate task difficulty.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Upper limb functional measurement | The Graded Redefined Assessment of Strength, Sensibility and Prehension (GRASSP) will be used to assess sensation, strength, and prehension. | 45 minutes to 1 hour | 
| Lower limb functional measurement | 10-meter walk test will be used to assess walking speed | 5-10 minutes | 
| MEP/CMEP recruitment curves using TMS | Ten Transcranial magnetic stimuli (TMS) will be delivered to plot the mean peak-to-peak amplitude of the motor and cervicomedullary evoked potentials (MEPs and CMEPs, respectively) from the non-rectified response against the TMS intensity in each subject (MEP/CMEP recruitment curves). | 30 minutes to 1 hour | 
| EMG and force voluntary output | EMG surface electrodes will be placed over target muscles (deltoid, biceps brachii, first dorsal interosseous, abductor pollicis brevis, quadriceps femoris, tibialis anterior and/or soleus) to measure maximum voluntary contraction (MVC) | 30 minutes to 1 hour | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Acute Intermittent Hypoxia, Transcranial Magnetic Stimulation