The Effect of Reference Electrode Position in Cochlear Implants

This study aims to evaluate the increase in power of cochlear implants (CI) as the reference electrode (RE) position changes. Patients in whom it is necessary to use the full power of the device to achieve the desired stimulation levels, this strategy will ensure that stimulation capability is maximized.

The variability in RE placement in the temporal bone has a measurable effect on the electrical current, impedance, and power consumption, and if the electrode position has a functional effect on the stimulation intensity. The following three approaches were used: 1) classical circuit analysis, 2) 2-dimensional numerical simulations, and 3) real temporal bone measurements using a purpose-made CI.

The three approaches demonstrate a significant decrease in the current intensity and electrical resistance for distances that are closer to the intra-cochlear electrode. The results also demonstrate that to maintain a constant current, shorter distances require 33% less power.

Reference electrode position during surgery can make significant differences in CI power consumption and threshold intensity, which allows a more powerful stimulation in complicated patients (i.e., those with otosclerosis). This study presents an attractive perspective to surgeons, as it shows a way to decrease consumption that might result in a longer battery life or more power to be devoted to coding strategy performance.