This study seeks to explore changes in the neural pathways and arm function following a breathing intervention in the multiple sclerosis (MS) population. The breathing intervention, known as Acute Intermittent Hypoxia (AIH), involves breathing brief bouts of low levels of oxygen. Research has found AIH to be a safe and effective intervention resulting in increased ankle strength in people with MS. Here, the study examines arm and hand function before and after AIH. In order to better understand the brain and spinal cord response to AIH, the investigators will measure muscle response, and signals sent from the brain to the arm muscles before and after AIH.
Diagnosis of relapsing-remitting MS according to the McDonald criteria, over 5 years ago
Relapse free for at least 6 months
Expanded Disability Status Scale (EDSS) ≤7
Index finger abduction strength <5 according to Medical Research Council Scale, or 9-Hole Peg Test score >20 seconds in at least one hand
Another diagnosis (e.g., peripheral neuropathies or orthopedic) affecting upper limb function
Mini-Mental State Examination (MMSE) score <24
Modified Ashworth Scale score >3 on elbow joint
Uncontrolled hypertension or hypotension (outside 140/90 and 85/55 mmHg)
Crossover
Acute Intermittent Hypoxia
Other interventionDuring AIH, the participant will be equipped with a non-rebreathing face mask, and provided with the AIH intervention. The AIH intervention involves alternating breathing cycles. One cycle involves breathing air with lower oxygen concentration (9-10% oxygen) for 30 and 90 seconds, followed by breathing normal room air (21% oxygen) for a similar duration. This cycle is repeated 15 times in one session. Blood oxygen and heart rate are monitored throughout.
Sham Acute Intermittent Hypoxia
Other interventionDuring Sham AIH, the participant will be equipped with a non-rebreathing face mask, and provided with the AIH intervention. The Sham AIH intervention involves alternating breathing cycles. One cycle involves breathing air closely resembling room air (\~21% oxygen) for 30 and 90 seconds, followed by breathing normal room air (21% oxygen) for a similar duration. This cycle is repeated 15 times in one session. Blood oxygen and heart rate are monitored throughout.
Motor Evoked Potentials (MEPs) in First Dorsal Interosseous (FDI)
The MEPs will be elicited by Transcranial Magnetic Stimulation (TMS), a procedure that uses magnetic fields to stimulate nerve cells in the brain.
Changes in Spinal Reflex Threshold
Spinal reflect threshold will be measured by calculating the average change in threshold length recorded from the biceps tendon's indentation. A linear motor will be used to impose precise tendon indentations of the biceps brachii.
Threshold For Detecting Passive Joint Movement
An assisted movement with enhanced sensation (AMES) will be used to rotate the participant's joint. The difference between the reference and matching joint angles is used to measure joint position sense. The investigators will present three target positions, and subjects will perform ipsilateral matching for each target 5 times.
Accuracy of Direction Estimation of Passive Joint Movement
An AMES will be used to rotate the participant's joint. The difference between the reference and matching joint angles is used to measure joint position sense. The investigators will present three target positions, and subjects will perform ipsilateral matching for each target 5 times.
Grip Strength
The participant will squeeze a calibrated dynamometer to measure grip strength.
Pinch Strength
The participant will pinch a calibrated pinch gauge to measure pinch strength.
Index Finger Abduction Force
Index finger abduction force will be measured using a load cell. We will also record surface EMG activity from the FDI muscle.
Nine-Hole Peg Test
A dexterity measurement involving placing 9 pegs in corresponding holes. Time to complete is measured.
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Shirley Ryan AbilityLab
Lead sponsor
National Multiple Sclerosis Society
Collaborator
