METHOD AND SYSTEM FOR OPTIMIZING MULTIPOLAR STIMULATION IN NEVE STIMULATION PROTHESES

"Regarding multipolar stimulation, two types of strategies have been typically followed: electrode focusing and neural focusing. Electrode focusing tries to reduce electrode interaction from voltage spread associated with monopolar stimulation. These techniques include bipolar (BP), tripolar (TP), partial tripolar (pTP) and phased-array (PA), among others. In all of them, multipolar stimuli produce localized potential peaks that are sharper than monopolar stimuli. For the PA electrode focusing, the voltage pattern at the electrodes gives rise to a current pattern which is calculated by inverting the transimpedance matrix. In turn, neural focusing tries to achieve a sharper peak of the voltage distribution at the target neural pathway. Several studies have searched for a focusing strategy on this direction in order to maximize the effect of the electric currents delivered by an electrode in the specific location of said electrode while minimizing their effect anywhere else. However, in all of them, focusing was achieved at the expense of more power consumption if adequate loudness levels compared to monopolar stimulation were to be reached. Moreover, none of these focusing strategies employ an optimization procedure to calculate the configuration of input currents that increase spatial selectivity of neural excitation. Therefore, and in view of the strategies present in the state of the art, it would be necessary to provide a systematic and optimized approach to improve both the precision (focusing) of stimulation in specific areas of the target nerve (in particular of the auditory nerve) and the overall energy efficiency of the nerve stimulation implant. To overcome the above limitations, the invention proposes a novel approach to optimize the electric current profile delivered across an array of electrodes comprised in a multipolar nerve stimulation implant. "