Clinical efficacy of symmetric constant-current biphasic pulses for deep brain stimulation

Deep brain stimulation (DBS) is an effective therapy for movement disorder patients whose symptoms have become refractory to drug therapies alone. Conventionally, DBS devices employ asymmetric biphasic pulses consisting of a brief, high amplitude phase followed by a long, low amplitude balancing phase. Traditionally, voltage-controlled pulses have also been used; however recently there has been a shift towards constant-current stimulation to account for electrode impedance fluctuations. This study aims to determine whether symmetric constant-current biphasic pulses, in which both phases are of equal duration and amplitude, are a clinically viable alternative to conventional DBS waveforms. Symmetric pulses are successfully used in other neurostimulation applications, such as cochlear implants.