Hi @Outlander just wanted to welcome you to this forum and so sorry for this bad turn in your recovery. You have at least one kindred spirit here in @pando, I believe he’s a pianist too 
I only have a vague remnant of this spasticity in my right arm along with foot drop but I only had a mild stroke. There are others on here, included in the post below, who have more experience of what you are going through. You might want to check out that post as they’ve been experimenting with electrical devices to combat the effect of their spasticity.