In a double blind, placebo-controlled study to assess the prophylactic effect of hyperbaric oxygen therapy on migraine, 40 patients were randomly assigned to a treatment group receiving three sessions of hyperbaric oxygen, or a control group receiving three hyperbaric air treatments. The patients were instructed to keep a standardized migraine diary for eight weeks before and after the treatment. Thirty-four patients completed the study. Our primary measure of efficacy was the difference between pre- and post-treatment hours of headache per week. The results show a nonsignificant reduction in hours of headache for the hyperbaric oxygen group compared to the control group. Levels of endothelin-1 in venous blood before and after treatment did not reveal any difference between the hyperbaric oxygen and control groups. We conclude that the tested protocol does not show a significant prophylactic effect on migraine and does not influence the level of endothelin-1 in venous blood.

Eftedal, Lydersen, Helde, White, Brubakk, Stovner, , , (2004). A randomized, double blind study of the prophylactic effect of hyperbaric oxygen therapy on migraine. Cephalalgia : an international journal of headache, 2004 Aug;24(8):639-44. https://www.ncbi.nlm.nih.gov/pubmed/15265052