The findings are published in the January issue of the journal PLoS ONE.
Although the therapy has been studied in some patients soon after they experienced a stroke, this is the first study to look at the therapy in patients in the "late-chronic phase" after the stroke, the researchers said.
All participants in this study had suffered an ischemic or hemorrhagic stroke between six and 36 months earlier, and none had shown improvements in their condition for at least a month.
Half of the group received 90-minute sessions of oxygen therapy five days a week for two months while the other half received no treatment for two months and then started the oxygen therapy.
Brain imaging done before and after oxygen therapy showed improvements in brain activity after the therapy was completed, and some patients showed impressive functional improvements.
There were a few patients for whom improvements were marginal, said study co-author Eschel Ben-Jacob, a physicist with Tel Aviv University's School of Physics and Astronomy and the Sagol School of Neuroscience.
Side effects were fairly minimal: Six participants experienced ear troubles due to pressurization and two patients with a history of seizures had mild convulsions.
Two years after the treatment ended, the improvements held.
"The rationale is that once the damaged brain area has been reactivated, there is no going backward unless there is another insult," said Efrati, who also is head of the Hyperbaric Institute at Assaf-Harofeh Medical Center in Israel.
Ben-Jacob said high levels of oxygen allow neurons that have been damaged but are not destroyed to become active again, reconnecting with other neurons and firing the signals needed to maintain healthy brain function.
The researchers believe oxygen therapy also may be able to help people with other neurological conditions, such as Alzheimer's, and are currently studying it in patients with traumatic
All rights reserved