Too early to say how transient the effect is, it's very possible my symptoms return after a few weeks. There are conditions that HBOT can out right 'cure', the bends and carbon monoxide poisoning are the first to come to mind. So I don't think it's out of the question that it's effects can be permanent.

One of the causes of my symptoms will be straight up organ damage, and there's plenty of evidence HBOT speeds up the healing of tissue damage. So any progress in this area should be permanent.