Parameters of Spinal Cord Stimulation and Their Role in Electrical Charge Delivery: A Review

Objective: All spinal cord stimulation (SCS) parameters (amplitude, pulse width, frequency) influence the interaction of stimulation with the nervous system and impact the delivery of charge. Regardless of the stimulation pattern, there are certain crucial elements related to dose, and a basic fundamental knowledge of the parameters used to administer the therapy is fundamentally important. Methods: This paper reviews basic concepts of energy delivery in neurostimulation (amplitude, pulse width, and frequency) and introduces the concept of the duty cycle and charge per sec as another way to characterize stimulation patterns. Results: Results from recent clinical publications indicate that an important aspect of the therapy may be the total charge delivery over a period of time. Viewed in this way, rate of charge delivery may be analogous to dosage of medication, and SCS parameters that use different duty cycles may exert distinct therapeutic effects by allowing different amounts of energy to be delivered to neural tissue with less sensory percept or even none at all. Conclusions: The basic parameters of amplitude, pulse width, and frequency have important implications for the delivery of charge in SCS. Modern programming strategies require an understanding of charge delivery for conventional SCS therapy as well as new therapies such as 10 kHz and burst SCS.