The idea to use oxygen as a treatment for MS began over 45 years ago. In 1970, two Romanian doctors, Boschetty and Cernoch, treated patients with brain injuries with pressurised oxygen to help more oxygen enter their tissues – oxygen helps protect nerve cells from damage and maintains the integrity of the blood-brain barrier. In a study of MS patients, they found that symptoms in 15 out of 26 volunteers improved. This led to further interest in the use of hyperbaric oxygen to treat MS specifically.
https://www.nejm.org/doi/full/10.1056/NEJM198301273080402 (The famous Fischer study, the most rigorous of all studies performed on HBOT in MS. Strongly positive results).
P.B. James, Oxygen Treatment for Multiple Sclerosis Patients, Chapter 22, Textbook of Hyperbaric Medicine, Sixth Edition, Editor: K.K. Jain, Springer Publisher, Cham, Switzerland, 2017.