Why is Hyperbaric Oxygen Therapy available to veterans in some states through the VA Health Care System, but not in Kentucky?

My husband suffered a TBI eight years ago in a traffic accident. After a short rehab period, the civilian neurologist that diagnosed him said there was nothing more that he could do for him and told him to go home and learn to live with it. After a couple of years, he lost his job and doubled his weight due to lack of ambition and a "what's the use" mentality toward exercise. He has progressed from a cane to a walker and now to a very large rollator. Doctors keep prescribing different medications and nothing has helped to relieve the pain. My husband and I are both Navy veterans and new to the VA Health Care System this year. The Kentucky Department of Veterans Affairs newsletter a few months ago mentioned Hyperbaric Oxygen Therapy (HBOT), a known therapy proven to relieve trauma pain and regenerate brain cells, is available to Kentucky veterans free of charge, yet no one in the VA can prescribe it. Can anyone explain why veterans in Kentucky cannot get these treatments while veterans in other states can?