Apparently the cold injury that I suffered on Mt Shasta last year was actually immersion foot rather than frostbite. It has taken nearly a year for full feeling to return to the toe and for the random reappearance of numbness/pain/pressure to completely stop (it had no bearing on temperature).
I've been tentatively using my Nepal Evo climbing boots for climbing this winter where it was important to use them vs. plastics for climbing. I'm aware that the immersion foot makes the toe more susceptible to recurring cold damage, so I've been extra diligent on bringing extra socks & attempting to keep the toes from going numb for too long on climbs (both big toes have always repeatedly gone numb to some degree if I'm not in plastics, so I've just lived with minimizing the time and depth of the numbness by constant rethawing, toe wriggling etc. when I notice it creeping in). I've also been sleeping in camp booties rather than my climbing boots at camp or at bivys to get my feet out of cold, wet boots while I'm not active.
However, on my last climb I could not keep my feet dry due to all of the postholing, snow climbing, and creek crossings. Though my toes didn't feel any different on this trip vs. prior ones (if anything I was doing better about keeping them warm), once I got out of the mountains it was apparent that my old immersion foot injury had come back to haunt me. Now the toe is bleeding internally and blistering all around the old injury, with a re-emergence of my old symptoms reappearing over the days after the climb. Bad news
Does anyone here know of good sources for how to continue winter climbing while caring properly for immersion foot? I don't want to cause further damage, and trial and error experimentation is probably not the best way to learn here.
Web sites, reading materials, or climbers or doctors with experience with this injury would be great to consult. e.g. I'm wondering about whether vapor barrier socks worn on the inside or outside of my insulating socks would help by limiting the amount of moisture soaking into them, or whether that would be bad overall since my feet would be more wet more often.