Implantable electrode positioning

A method of surgically positioning an electrode array at a desired implantation location relative to a nerve, the method comprising:

• implanting a temporary probe electrode adjacent to the nerve and at a location which is caudorostrally separate to the desired implantation location of the electrode array;
• temporarily fixing the implanted position of the probe electrode relative to the nerve;
• wherein the probe electrode is fixed by being temporarily anchored upon a vertebra, within the epidural space;
• during implantation of the electrode array, applying electrical stimuli from one of the temporarily fixed probe electrode and the electrode array, to evoke compound action potentials on the nerve;
• sensing, from at least one electrode of the other of the temporarily fixed probe electrode and the electrode array, the compound action potentials evoked by the stimuli;
• and
• determining from the sensed compound action potentials a position of the electrode array relative to the nerve.