Measuring the Neurological Benefits of Intermittent Hypoxia Therapy With MRI

Study Overview
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Brief Summary
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This study uses Magnetic Resonance Imaging to image the brain and spinal cord before and after an Intermittent Hypoxia intervention. Acquiring these scans in patients with chronic cervical spinal cord injury and uninjured controls will enable characterization of changes in neurovascular physiology caused by this promising new therapy.

Detailed Description
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Acute intermittent hypoxia (AIH) is an emerging, safe technique for facilitating neural plasticity in individuals with chronic spinal cord injury (SCI), demonstrating significant transient improvements in respiratory function, plantar flexion, locomotor function, and hand dexterity and strength. Although these studies observe some degree of success eliciting plasticity, we lack a framework for systematic optimization of the AIH protocol for individual patients. Better understanding of what physiological mechanisms drive AIH-induced neural plasticity in humans will directly inform the development of AIH as an effective treatment option in chronic SCI. This study applies magnetic resonance imaging (MRI) to test how AIH influences vascular and neural properties of the brain and spinal cord. Individuals with SCI and uninjured participants will be recruited to undergo two MRI scan sessions on one day. In between these scan sessions, participants will undergo a single 30-minute session of AIH. In each scan session, functional MRI will assess AIH-induced changes in neural activation patterns during motor tasks (unilateral isometric hand grasping tasks) and vascular reactivity to breath hold tasks (transient hypocapnia to induce vasodilation). Additional structural scans will be acquired to aid in image analysis.

Official Title
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Neurovascular Mechanisms of Intermittent Hypoxia Induced Neural Plasticity

Conditions
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Spinal Cord Injuries

Intervention / Treatment
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* Other: Acute Intermittent Hypoxia


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All participants must meet the following inclusion criteria: Between the ages of 18-60 years Safe to be scanned using MRI Able to communicate in English Ability to sign informed consent In addition, the participants recruited with SCI must meet the following criteria: History of a traumatic spinal cord injury, inclusive of levels C2-T1 At least 6 months since onset of spinal cord injury Cause of the spinal cord injury was non-progressive Ability to complete and comply with information within the informed consent Ability to close and open at least one hand without assistance Exclusion Criteria: MRI contraindications as indicated on MRI safety screening form Subjects with pacemakers, cochlear (in the ear) implants, or aneurysm clips or subjects who have worked with metal Women who are currently pregnant, nursing, or planning on becoming pregnant Individuals with severe claustrophobia Subjects unwilling or unable to give written informed consent in English Prisoners Frequent smokers (greater than 5 cigarettes per day) Blood pressure greater than 160/110 or less than 85/55. Individuals who report headaches, feeling dizzy or light-headed, or have heart palpitations on the day of the study. Diagnosis of any of the following comorbid conditions: congestive heart failure, cardiac arrhythmias, uncontrolled diabetes mellitus, chronic obstructive pulmonary disease, emphysema, severe asthma, previous myocardial infraction or known carotid/intracerebral artery stenosis, presence of active deep venous thrombosis, or cancer. Individuals who utilize mechanical ventilation or have a tracheostomy Individuals who utilize an intrathecal baclofen pump Orthopedic injury affecting upper extremities Currently participating in any other hypoxia related study.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 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: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Acute Intermittent Hypoxia<br>Both healthy participants and those with spinal cord injury will receive the acute intermittent hypoxia (AIH) intervention. All participants are imaged pre- and post-AIH intervention, and thus serve as a self-comparison to observe the hypothesized improvement in bilateral hand strength. | Other: Acute Intermittent Hypoxia<br>* Participants will wear a non-rebreathing face mask and alternate between breathing 9% O2 gas mixture for up to 1 minute, or until the target SpO2 of 85 percent is reached, and normal room air (21 percent O2) until 2 minutes are complete. This cycle will be repeated 15 times, resulting in a 30-minute protocol.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| BOLD fMRI activation in motor cortex during isometric hand grip tasks | Assess AIH-induced changes in %BOLD activation within the left and right motor cortices during unilateral isometric hand grasping tasks targeting submaximal force levels with real-time feedback. | Immediately before and   1-hour after AIH on the same day | 
| BOLD fMRI vascular reactivity to a breath-hold task | Measurements of breath-hold induced vasodilation (vascular reactivity, in units of %BOLD/mmHg end-tidal CO2) acquired via functional MRI in the brain and spinal cord. | Immediately before and   1-hour after AIH on the same day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Spinal Cord Injury, Acute Intermittent Hypoxia, Magnetic Resonance Imaging