Hello Tristram,
I had some nerve damage in my right shoulder after getting Rituximab with the usual Cladribine. That was Nov, 22 2021, I was in the hospital for a high fever. On the 3-4th day I woke up not being able to use both shoulders. The left came back 1-2 days later. The neurologist told me I had about 2 inches of nerve damage. After a year I now have about 75-80 % recovery.
Good luck with your troubles.