Spinal cord stimulator (SCS) has been used to manage chronic pain for more than 50 years(1). The basic concept of SCS is to generate an electrical field that stimulates the spinal cord structures. This stimulation reduces painful inputs to spinal cord and brain(2). The SCS consists of an electrode lead put on the epidural space, a pulse generator put inside the subcutaneous pocket, and a programmer which adjusts stimulation. SCS is programmed by controlling amplitude, pulse width, pulse rate, and lead type to produce desired concordant paresthesia which is between perception threshold and discomfort threshold.
Although the SCS treatment may be still regarded as the last resort for managing intractable chronic pain, the enormous development of technology has helped the SCS more popular for an increasing number of patients. In 1967, the first SCS system could not be reprogrammed, once implanted; however, since the 1970’s, the lithium-powered pulse generator has been introduced and allowed the SCS to be totally implantable with a fine stimulation control(2). In 1980’s, SCS system has been developed to be reprogrammed with an external transmitter by adjusting the stimulation parameters. But patients with SCS systems commonly reported inconsistent neurostimulation, which disrupts therapy(3). One remarkable development to make SCS more patient friendly was the position adaptive SCS system(4).
The posture has been found to affect stimulation parameters(5) and can occasionally induce inconsistent paresthesia(6). Once the paresthesia gets out of optimal range, stimulation can be adjusted manually by patient programmer or the patient need to change their body position to adjust paresthesia intensity. The need for multiple adjustment may affect negatively to the effectiveness of the SCS treatment, patient’s satisfaction and quality of life. Therefore, a system which automatically adapts stimulation according to patients’ position can be a solution that meet the need to provide consistent paresthesia. The position adaptive SCS system modulates electrical current with triaxial accelerometers so that adequate neurostimulation can be delivered automatically depending on the patients’ posture change.
We could find three prospective study which compare automatic position adaptive system with conventiona manual system. In a study by North et al. in 2003, the automatic adaptive system group presented improved clinical efficacy and the possibility of reducing treatment costs by increasing battery life(7). In a study conducted by Schade et al. in 2011, automatic adaptive system showed higher overall patient satisfaction rating(8). In 2012, Schultz and colleagues report that the use of automatic adaptive system reduces the number of programming button presses by an average of 41% and gives functional improvements of patients(9).