A stroke is a disturbance in the blood flow to the brain. It can be caused by a blockage or by excessive bleeding but either way, it’s bad news for the effected area. Israeli researchers led by Shai Efrati of Tel-Aviv University and Assaf Harofeh Medical Center wondered if Hyperbaric Oxygen Therapy (HBOT) could help alleviate some of the symptoms of stroke.
The theory behind using HBOT is that brain tissues damaged by stroke are depleted in oxygen. This both decreases neuronal activity and prevents regrowth and repair. By pumping extra oxygen under higher pressure into the body, you increase the amount of oxygen dissolved in the blood stream and consequently the amount that passes into the brain. It was hoped that this in turn would stimulate the damaged areas of the brain.
The researchers recruited 74 patients who had suffered strokes from six to thirty-six months prior to the study. All patients were treated with forty sessions of HBOT over a two-month period, each session consisting of breathing 100% oxygen at two atmospheres for ninety minutes. However, one group got HBOT immediately after recruitment, and the second were given no treatment for the first two months and then HBOT for the following two months. Each person was evaluated for neurological impairment at baseline and after HBOT. The people in the second group were also evaluated after the two-month no-treatment period but before starting HBOT.
Regardless of when HBOT was started (immediately or two months into the study), stroke victims showed significant improvement after the treatment. Remember, in some cases, the oxygen therapy was begun years after the initial stroke, and yet it still helped people recover function.
By the way, because the scientists did not want the subjects to know whether they were receiving HBOT, they put everyone in hyperbaric chambers to let their ears pop. This increased pressure results in increased dissolved oxygen even when using room air, but not by as much as when using 100% oxygen. Apparently, the increase in plasma oxygen without using HBOT was not enough to effect any changes.Efrati S, Fishlev G, Bechor Y, Volkov O, Bergan J, Kliakhandler K, Kamiager I, Gal N, Friedman M, Ben-Jacob E, & Golan H (2013). Hyperbaric oxygen induces late neuroplasticity in post stroke patients - randomized, prospective trial. PloS one, 8 (1) PMID: 23335971.