Spasticity in SCI Following Acute Intermittent Hypoxia

Does the Administration of Acute Intermittent Hypoxia in Persons With Chronic Spinal Cord Injury Make Spasticity Worse?

This study aims to observe the effects of administration of a breathing intervention (Acute Intermittent Hypoxia (AIH)) on spasticity (tightness) in individuals with incomplete Spinal Cord Injury. It is hypothesized that hypoxia will decrease the reflex threshold of the biceps brachii, indicating an increase in spasticity following the AIH.

Study Overview

• Status: Recruiting
• Conditions: Spinal Cord Injuries (SCI)
• Intervention / Treatment: Device: Acute Intermittent Hypoxia (AIH)

Detailed Description

In the case of incomplete traumatic spinal cord injury, it is know now that muscular strength improves quickly after AIH administration, and this Increase in voluntary strength lasts from three to six hours. The Increase in strength, coupled with demonstrated improvements in spinal cord neural plasticity, makes AIH administration a potentially valuable new therapeutic intervention. AIH initially acts by releasing serotonin in the central nervous system, enhancing persistent sodium uptake (via the motor neuron soma) and activating voltage-gated calcium channels in motor neuron dendrites. There are also other effects of serotonin on motor neuron excitable channels. One potential complication of hypoxia is linked to the changes in motor neuron excitability in humans with SCI.

These issues may be relevant to our potential work on the Therapeutic efficacy of AIH in persons with incomplete spinal cord injury. In other words, if individuals are highly spastic, it may indicate that their neuronal receptor sites are inaccessible, and increasing spinal cord serotonin levels may not be beneficial.

• Study Type: Interventional
• Enrollment (Estimated): 10
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: William Z Rymer, MD, PhD; Phone Number: 312-238-3919; Email: w-rymer@northwestern.edu
• Study Contact Backup: Name: Alexander Barry, MS; Phone Number: 312-238-1435; Email: abarry@sralab.org

Study Locations

• United States
  • Illinois
    • Chicago, Illinois, United States, 60611
      • Recruiting
      • Shirley Ryan AbilityLab
      • Principal Investigator: William z Rymer, MD, PhD
      • Contact: Alexander Barry, MS; Phone Number: 312-238-1435; Email: abarry@sralab.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age >= 18
• Non-progressive spinal Cord injury at least 6 months prior
• Level of injury between C1-C8
• ISNCSCI ASIA classification C or D
• Measurable Spasticity

Exclusion Criteria:

• Pre-existing hypoxic pulmonary disease
• Positive Covid-Pneumonia diagnosis within 1 year of visit
• Uncontrolled hypertension >140/90 mmHg
• Individuals who are currently pregnant/nursing or planning on becoming pregnant
• Individuals with a tracheostomy or who utilize mechanical ventilation
• A botulinum toxin injection to upper extremity musculature within the past 3 months
• Currently taking Baclofen
• Congestive Heart Failure
• Cardiac arrhythmias
• Uncontrolled diabetes mellitus
• Chronic obstructive pulmonary disease
• Emphysema
• Severe Asthma
• Previous myocardial infarction
• Carotid/intracerebral artery stenosis
• Orthopedic injuries or surgeries that impact the ability to use the upper extremity
• History of Epilepsy

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: AIH intervention; In this Arm, participants will receive the Acute Intermittent Hypoxia Intervention. In this AIH, participants will breath alternating bouts of lowered oxygen and room air (approximately 60 seconds of each) for around 30 minutes.	Device: Acute Intermittent Hypoxia (AIH); This intervention involves breathing lowered levels of oxygen for 60 seconds, alternating with 60 seconds of room air breathing. Participants will be monitored and observed during the entire session for any changes in vital signs

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in reflex indentation threshold	Similar to a tendon tap that a doctor may perform, this study uses an automated tendon tapper to measure the level of indentation needed to elicit a reflex in the bicep muscle. The aim is to observe any changes in reflex threshold following the AIH intervention	Day 1 of Intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Modified Ashworth Scale - Elbow	The modified Ashworth scale is a measure of Spasticity, performed by a trained administrator. This test involves rapidly rotating the participant's arm and feeling the spastic muscle response. This assessment is scored from 0 to 4, with 0 indicating no spasticity, and 4 indicating a fully contracted limb	Day 1 of intervention
Grip Strength	Using a handheld dynamometer, maximum grip strength of participants will be measured	Day 1 of intervention

Collaborators and Investigators

• Sponsor: Zev Rymer
• Investigators: Principal Investigator: William Z Rymer, MD, PhD, Shirley Ryan AbilityLab

Study record dates

Study Major Dates

• Study Start (Actual): March 17, 2026
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): March 1, 2028

Study Registration Dates

• First Submitted: April 23, 2026
• First Submitted That Met QC Criteria: May 7, 2026
• First Posted (Actual): May 13, 2026

Study Record Updates

• Last Update Posted (Actual): May 13, 2026
• Last Update Submitted That Met QC Criteria: May 7, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Hypoxia; Reflex; Spasticity
• Additional Relevant MeSH Terms: Neurologic Manifestations; Musculoskeletal Diseases; Central Nervous System Diseases; Nervous System Diseases; Muscular Diseases; Muscle Hypertonia; Neuromuscular Manifestations; Wounds and Injuries; Signs and Symptoms, Respiratory; Trauma, Nervous System; Spinal Cord Diseases; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Muscle Spasticity; Hypoxia; Spinal Cord Injuries
• Other Study ID Numbers: STU00225515

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Upon request, we will provide de-identified study data to researchers. The ICF and Protocol will be uploaded upon completion of study procedures
• IPD Sharing Time Frame: At conclusion of the study, for up to 3 years following study closure
• IPD Sharing Access Criteria: The study team will provide de-identified files with study data upon specific request.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No