I found this mysterious device on my wife's nightstand that I think she uses to massage her neck. Since I am suffering from a mild case of 'trigger finger' that is threatening to turn CTS, I had a crazy idea to massage the palm of my hand and wrist with it at night. I think it is working quite well. I'm not a therapist but I would say that it stimulates blood circulation, reducing the numbness I feel in the morning. Of course, it is not advisable to abandon physical therapy exercises but I think that as a complement, it is quite good. Warning: don't use it at full speed and stop if it's painful.
I wouldn't do anything like this without consulting your doctor first since while it could be beneficial at first, it could make things worse further along. But I do hope it helps.
My bet is that if it doesn't produce any harm on other spots, it will probably won't harm a few swollen tendons if used in moderation. I'll take care, don't worry.