A mediastinoscopy is when they make a half-moon shaped incision in between your collarbones. A mediastinotomy is when they cut your chest along the sternum,- through some muscle, if you've got any there. The -oscopy, you were told, would be definitive. The -otomy, you are told, will be definitive. The -oscopy hurt a little, the -otomy will hurt a little more. The -oscopy took 8-10 BB-sized pieces from your lymph nodes, and the -otomy will take a golf ball-sized chunk. The -otomy is also known as the Chamberlain procedure. The Chamberlain procedure is tomorrow at 1 pm.