Not me but I've heard of a very few reports of it. Have you asked the doctor who did you your treatment? Did the numbness come on abruptly during the procedure, or not until a week later? Is numbness a symptom you have had before?
Possibilities could include vagus nerve being compressed during ballooning, unrelated MS relapse, new post-procedure redistribution of outflow from the brain leading to improved outflow in some areas but worse outflow in another area causing numbness, or ... any other possibilities?
One more possibility is that a clot has formed. This can be checked by any vein doctor, it does not have to be someone experienced in CCSVI. This is where I would start if I had a new symptom or loss of improvements in the early days after the procedure. Are you on any medications post-procedure?Did you have any improvements, or have improvements and lose them?