Alissa, it's a procedure where they take small amounts of one's blood and cycle/separate it. The red cells and plasma are separated. The red cells are cycled back in and the patient's plasma is replaced with frozen plasma.

This procedure is supposed to help slow the affect mg has on the muscles. It's not a cure, but a treatment for relief.

Here's links to a more in depth definition: Plasmapheresis for MG and Plasmapheresis in detail

PS: My mom and sister live close to you. Sis is in Huntsville and mom is in Fayetteville.