AIH-induced Walking Recovery After Subacute SCI

The goal of the study is to determine whether repeatedly breathing mild bouts of low oxygen
for brief periods (termed acute intermittent hypoxia (AIH)) improves recovery of walking and
strength after spinal cord injury. This idea stems from animal studies on respiration, in
which investigators showed that mild AIH improves breathing in rats with spinal injuries.
These studies showed that AIH induces plasticity, strengthening neural connections by
increasing the production of key proteins and improving the sensitivity of spinal cord
circuitry. The ultimate goal of this research is to assess the potential of mild AIH as a
therapeutic approach not only in persons with chronic spinal cord injury but also in persons
with subacute injury. By applying AIH during early stages of recovery, the investigators hope
to expand the potential benefits of AIH to a broader range of persons with spinal injury,
thereby improving functional independence and quality of life for servicemen and civilians.

Inclusion Criteria:

- 18 to 70 years old

- medically stable with medical clearance from physician to participate

- spinal cord injury (SCI) at or below C4 (phrenic sparing) and above T12 with at least
motor function preserved below the neurologic level

- non-progressive etiology of spinal injury

- American Spinal Injury Association Impairment Scale (AIS) grade A-D

- 2-6 months post-injury (subacute)

Exclusion Criteria:

- severe concurrent illness or pain, including unhealed decubiti, severe neuropathic or
chronic pain syndrome, infection (e.g. bladder), hypertension, cardiovascular disease,
pulmonary disease, severe osteoporosis (history of fractures), active heterotopic
ossification in the lower extremities, or history of peripheral nerve injury in the
legs

- score less than 24 on Mini-Mental Exam

- severe autonomic dysreflexia

- history of cardiovascular/pulmonary complications

- pregnancy

- severe obstructive sleep apnea (OSA), characterized by uncontrolled hypoxia and sleep
fractionation

Specific inclusion/exclusion criteria for recruiting non-ambulatory subjects:

Participation in this group requires all of the above inclusion/exclusion criteria, as well
as being unable to complete any of the below measures:

- timed up-and-go (TUG) test

- 10-meter walk test (10MWT)

- 6-minute walk test (6MWT)

Specific inclusion/exclusion criteria for recruiting ambulatory subjects:

Participation in this group requires all of the above criteria, as well as successful
completion of at least one below measure:

- timed up-and-go (TUG) test

- 10-meter walk test (10MWT)

- 6-minute walk test (6MWT)