Method and apparatus for determining relative positioning between neurostimulation leads

A medical system, comprising:

• a first lead configured for being placed adjacent tissue of a patient, the first lead carrying a first electrode and a reference electrode;
• a second lead configured for being placed adjacent the tissue of the patient, the second lead carrying a second electrode;
• a controller configured for activating the first electrode to generate an electrical field within the tissue;
• monitoring circuitry configured for measuring an electrical parameter in response to the generated electrical field at the second electrode, and measuring a reference electrical parameter in response to the generated electrical field at the reference electrode, wherein a reference distance between the first electrode and the reference electrode is known prior to generation of the electrical field;
• and
• at least one processor configured for computing a ratio between the measured electrical parameter and the measured reference electrical parameter, and computing a distance between the first and second electrodes as a function of the computed ratio and the reference distance.