An implantable electrode arrangement for a cochlear implant system is described. The arrangement includes an electrode array with an outer surface having electrode contacts to apply cochlear stimulation signals to target neural tissue within an implanted patient cochlea. An electrode lead delivers the cochlear stimulation signals from an implanted signal processor to the electrode array. An electrode transition section includes a distal end portion of the electrode lead that is connected to a basal end portion of the electrode array. An electrode storage device contains the electrode transition section and is secured at an electrode opening in an outer surface of the patient cochlea. The electrode storage device is controllable after being surgically implanted to further insert an additional section of the electrode array from the electrode storage device into the patient cochlea and thereby implant a greater portion of the electrode array more deeply into the patient cochlea.
