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When less is more

Reducing oxygen to mountain-peak levels benefits patients with spinal cord injuries

By Kay Torrance

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Friday the 13th did prove unlucky, even devastating, for Danny Jackson.

On March 13, 2009, the North Carolina sheriff's deputy was responding to a call when his car went off the road and hit a tree. Since then, he had been confined to a wheelchair.

While undergoing physical therapy in Atlanta, he heard about an Emory study for people with incomplete spinal injuries, in which participants might improve their walking ability by temporarily reducing their oxygen supply. It sounded counterintuitive to Jackson. "I said yeah, right," he says. "But it changed everything—dramatically. I wish this treatment was FDA-approved."

For patients with spinal injuries that are not absolute, pathways in the nervous system are capable of functioning but often work only minimally, making for modest gains in mobility. Most do not return to walking unassisted even after years of physical therapy.

Jackson, 32, and other participants breathed 90 seconds of reduced oxygen (9%) followed by a minute of normal oxygen, repeated 15 times for five days, and did walking therapy. (The 9% rate of oxygen is the equivalent of standing on Mount McKinley at 26,000 feet.) The lack of oxygen causes the brain to release serotonin, which acts on receptors within the spinal cord. The receptors help increase the production of an important protein, brain-derived neurotropic factor, which in turn increases the excitability of neurons in the leg muscles, causing movement, and in the diaphragm muscle, increasing the patient's breathing capacity.

Of the 19 participants, 70% walked faster and farther after the treatment, including Jackson, who now uses a walker instead of a wheelchair. "Functional recovery after spinal injury is slow, variable, and frustratingly limited," says Randy Trumbower, a researcher in Emory's Division of Physical Therapy, who led the study. "There is a need for therapies that can help patients be more independent. Even small improvements that enable someone to stand, walk within the home, or negotiate spaces not accessible to wheelchairs can translate into significant health benefits and improved quality of life."

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