Plasmapheresis, also called plasma exchange, is a procedure in which the liquid portion of a child's blood is separated, replaced with donor plasma or a substitute, and returned to the body. The goal is to physically remove the harmful antibodies that researchers believe are attacking brain tissue in PANS and PANDAS. Unlike IVIG, which modulates the immune response, plasmapheresis directly filters out the problematic antibodies already present. It is generally discussed for children with severe or treatment-resistant presentations who have not responded adequately to antibiotics, anti-inflammatory treatment, and IVIG. It is performed at specialized centers with pediatric expertise, and the evidence base, while promising in some cases, is smaller than for other treatments. It is not a common first-line approach.