A non-communicative lumen for electrode assemblies of medical implants, in particular prosthetic hearing implants, is provided by the present invention. The non-communicative lumen prevents the lumen within the cochlea from being able to transport fluids, cells, bacteria, tissue, etc., with the lumen outside the cochlea, and vise versa through the incision or cochleostomy. The lumen may have a cavity or slit that receives a stylet during insertion of the electrode assembly.