I wish I knew this answer, but I can't find anything on it, either, and my guess is that there's not been enough large-scale medical research on cannabis and analgesia here in North America for anyone to be very knowledgeable.

My theory is that it must have something to do with the gradual desensitization of cannabinoid receptors that occurs. Or possibly, too, with its action as an early vaso-constrictor, followed by vaso-dilation, which might trigger spasms in some of your nerve pathways, worsening the inflammation (same mechanism by which it triggers headaches in some people). As you got more cannabis exposure, your body became less sensitive to it, and yet it still sent some of those vessels and nerves into spasms. This is just a guess, and it's not a very educated one.

I found some good information about neuropathic pain, which you may already have read. Doesn't have many mentions of cannabis or the question you asked here, but it comes from Canada. It said neuropathic pain is a hard thing to treat.
Neuropathic pain: a practical guide for the clinician -- Gilron et al. 175 (3): 265 -- Canadian Medical Association Journal

I had questions of my own for you. Did you by any chance change strains over the course of your smoking and perhaps later smoke a more Sativa-dominant strain instead of Indica? And when you've taken breaks from smoking and then returned to it, did you notice more analgesic relief after the break? I was curious about that.

When my sister Bess was sick, we noticed that cannabis did a lot more for her nausea, mood, and appetite than it did for her pain. She always found that prescribed medicines did the trick for pain a lot better than weed, but of course we didn't have much strain variety to choose from. She also had pain related to tumor growth as opposed to neuropathic pain, which was another difference.

Hope someone'll come along with a good answer here!
birdgirl73 Reviewed by birdgirl73 on . Could somebody PLEASE explain this to me....finally! There's something I've really been wondering about, but it seems nobody ever answers me when I mention it in other threads. I'm also wondering if it's typical of other people, or it's just me. A brief description of my condition; I have soft tissue damage throughout my upper and lower back, and in my neck. Nerve damage in 3 points in my spine, extremely painful needles that go down my arms (though that's gone since I got on lyrica), and sciatica + burning pain in my entire legs, all the way Rating: 5