Well, information seems to indicate that it is reversible, if it indeed is PRES. Now, if the symptoms subside, it may have been the prednisone. However, given the condition, a reversible side effect may be considered to be an acceptable risk given the overall fight. Now, prednisone is also an anti-cancer agent, and does stimulate the body's overall metabolism. It may have caused the reaction, or it may have exacerbated the PRES caused by the Velcade, thus leading them to discontinue it. This is one to ask the doctors about.