AIH is a treatment where people breathe reduced amounts of oxygen (10% oxygen) for a short period of time alternating with normal oxygen levels (21%) through a facemask that is attached to an oxygen tank with 10% 02. Participants will undergo 6 AIH treatment sessions over 3-4 weeks.
AIH will be administered to 3 unique groups of people: 1) People with advanced MS disability who are no longer ambulatory, 2) People who experienced a disabling relapse within the past 4 weeks and 3) People with non-active, progressive MS who retain some ambulatory ability.
There will be one baseline and two post-treatment assessments (1 and 5 weeks following the last AIH session).