Study Effects of Intermittent Hypoxia on Restoring Hand Function Following SCI

The goal of the study is to examine the effects of repeated breathing episodes of mild
intermittent hypoxia (reduced oxygen) training on hand strength and grasping ability
following cervical spinal injury, and to determine whether these changes result in improved
hand function. If so, such changes may indicate hypoxia-induced spinal plasticity (ability
of the nervous system to strengthen neural pathways based on new experiences), which could
result in improvements in hand use for persons with spinal cord injury (SCI).

This idea stems from animal studies on respiration, in which investigators have shown that
intermittent hypoxia induces spinal plasticity, strengthening neural connections within the
spinal cord by a mechanism known as respiratory long-term facilitation. Exposure to mild
hypoxia triggers oxygen sensors in the nervous system resulting in a cascade of events,
including increased production of key proteins and, increased sensitivity of spinal cord
circuitry necessary for improved respiration.

Because previous work using animal models has shown that similar events occur along
non-respiratory pathways, the investigators propose to investigate whether a comparable
dosing scheme of daily, mild intermittent hypoxia can positively affect upper limb function
in persons with cervical SCI.

First, the investigators hypothesize that daily exposure of intermittent hypoxia training (7
consecutive days) will result in a sustained improvement in rat forelimb function that is
dose-dependent. To test this hypothesis, the investigators will quantify the effects of
variations in the number of intermittent hypoxia episodes on forelimb function in cervical
spinal injured rats.

Second, the investigators hypothesize that daily exposure of intermittent hypoxia training
will improve hand function in persons with cervical spinal injury. To test this hypothesis,
the investigators will quantify the effect of mild intermittent hypoxia exposure, using a
protocol derived from the animal model, on volitional grip strength and grasp function in
persons with cervical SCI.

The effects of mild intermittent hypoxia, known to increase spinal motor activity, will be
assessed as a possible therapeutic intervention to promote functionally useful hand
recovery. Results from this study will be valuable for identifying novel strategies to
control spinal neuron excitability and for improving motor function in persons with spinal
cord injury.

Inclusion Criteria:

- age 18 and 65 years

- medical clearance to participate

- lesion below the 5th cervical spinous process (C5) and above the first thoracic
spinous process (T1) with non-progressive etiology

- classified as motor-incomplete injury greater than 12 months

- independent breathing

Exclusion Criteria:

- Concurrent severe medical illness (i.e., infection, cardiovascular disease,
ossification, recurrent autonomic dysreflexia, unhealed decubiti, and history of
cardiac or pulmonary complications)

- Pregnant women because of the unknown affects of acute intermittent hypoxia on
pregnant women and fetus

- Concomitant acquired brain injury

- History of seizures, brain injury, and/or epilepsy

- Diagnosed with obstructive sleep apnea

- Undergoing concurrent physical therapy

- Any contraindications to EMG testing procedures (skin sensitivity)

- Any contraindications to passive movement of the limbs

- Score of < 24 on Mini-Mental Exam