Numerical analysis of spinal cord stimulation with triple leads with guarded cathode

Abstract

Spinal cord stimulation (SCS) is a alternative treatment method for drug free treatment for chronic pain. Electrodes are placed to Spinal column's epidural tissue to blocked transfer of pain to brain and to stimulate dorsally column of pain. Today there are two two designs of electrode which are used in Spinal cord stimulation (SCS): a percutaneous (PERC) design, consisting of annular electrodes distributed along a flexible cylindrical shaft, which is inserted with a hypodermic needle; and a laminectomy/paddle design (LAM) implanted during a surgical laminectomy, consisting of a grid of rectangular electrodes on a flexible planar substrate. Also, only controlled percutaneous cathode electrode is used for stimulation a certain area in spinal cord. In this study, numerical studies of direct current application are done using percutaneous lead with 3-electrode model. Spinal canal is modeled in four layers which are epidural fat, CSF, white matter and gray matter tissues as 3D with using Finite Element Method (FEM). The lead with 3-electrode is placed in epidural fat. Anode and cathode electrodes are stimulated so as to flow current respectively 0.25mA and -2mA. At the contact surface of electrodes and epidural fat, obtained maximum current density is 128.161 mA/cm2 and this value is in the safety limits. The maximum electrical voltage occurred in the spinal canal is 2.133 V and this value is in the interval of perception value for patients.