Need help in directing me to specific therapy to work on residual paralysis/weakness in my left hand due to a bout of Parsonage-Turner Syndrome. My grip is weaker but improving. The specific issue I'm having is in playing the guitar, which prevents me from forming a full or partial barre chord (where the first or first and second phalanges press multiple strings against the fretboard). Instead of being able to "hinge" my first joint, that is to lock or unlock it, I cannot lock it flat. It's hard to describe! Another way to understand what I can't do is to lightly take both of your hands and place the fingertips on the surface of a table in front of you. Now, bend your second joint on your fingers while holding the first joint (the one closest to the fingertips) flat. I have no problem doing this with my right hand, but on my left hand, unless I push down on the first joint of my middle, ring, or pinky fingers, they remain curved. My index finger works OK but is weak. I'd like to know exactly which muscles aren't working, and which nerves are involved. Any suggestions on therapy to regain function would be appreciated.