I use it and it works like a charm!!!!
I've also hear than a tens unit. Is very helful
I find massage and acupuncture helps. It's not always easy to find good therapists so don't be afraid to shop around.
I use one on my legs when they get tight, not for Parkinson's but when I overdo it running. It can feel really good. Just don't go near bone; stick to the fat/muscular parts.
They use it at therapy and it feels pretty good now this is back therapy