In a study of 120 patients with chronic multiple sclerosis the effects of treatment with 100% oxygen at 2 atmospheres absolute for 90 min daily for a total of 20 exposures were compared with those of normal air at normal pressure for a similar length of time within the same compression chamber. No patient in either group showed any improvement on the Kurtzke disability status scale. 12 of 51 patients in the hyperbaric-oxygen group and 3 of 47 control patients improved on the Kurtzke functional systems scale on the subjective bowel/bladder parameter only. Such a degree of improvement can also be achieved with medication for urinary symptoms, but none of the patients in this study received such medication. The short-term results of this trial do not support the claims made for hyperbaric oxygen in the management of multiple sclerosis.

Barnes, Bates, Cartlidge, French, Shaw (1985). Hyperbaric oxygen and multiple sclerosis: short-term results of a placebo-controlled, double-blind trial. Lancet (London, England), 1985 Feb;1(8424):297-300. https://www.ncbi.nlm.nih.gov/pubmed/2857361