I'm going to comment because I'm probably one of the few people who've recently had bisphosphonate infusions for CRPS. My CRPS started abruptly March, 2013. After chasing many other diagnoses, I had a three phase bone scan in Dec, 2013 that confirmed the disease (along with other signs, symptoms and results). After messing around with a pain clinic for several months with no benefit my rheumatologist ordered the Padget's disease protocol for pamidronate infusions (30 mg of pamidronate per day over four hours for three days for a total of 90 mg of pamidronate). This was in May of 2014. I don't know if my bone scan would've still been showing abnormal uptake five months after the first test. However, I did have the normal positive side effects of cramping and having to take calcium throughout the day for a week or so, presumably because my bones where pulling calcium back into the bone from the peripheral blood. The infusions didn't cure me but they did help a lot of things. My rheumatologist has said he would be willing to repeat them but no more than once a year and only if my jaws where xrayed clear of osteo necrosis. He didn't say I needed a new bone scan.

Your question is a good one. The bisphosphonate should shut down abnormal osteoclast activity that's allowing breakdown of bone. I would think the bone scan would detect this.

As for the hot and cold. I think those are old classifications that still get used in the literature. My right ankle, where this all started, can be hot or cold at any given time since the beginning.