![]() When patients go back to their more active daily life, inevitably they experience episodes of overstimulation as the leads come closer to the spinal cord at different intervals. Paresthesia is a common occurrence with conventional SCS systems because they are programed based on patients’ sitting and inactive position in the office. ![]() Because overstimulation has plagued SCS for decades, strategies like “paresthesia-free” stimulation or subperception programming have been used to minimize painful stimulation resulting from changes in position or activity. Positions like lying supine and activities like coughing or sneezing increase stimulation to the point of discomfort (i.e., overstimulation). For example, most patients want to minimize paresthesias, which are affected by their position or activity. The next impulse is sent and the process repeats.Ī self-adjusting SCS system can internally preserve optimal programming parameters while adapting to the patient’s experiences or activities.If the ECAP is not “just right,” the pulse generator will adjust the intensity of the very next impulse to correct for any overstimulation or understimulation.The pulse generator records and analyzes the ECAP and evaluates whether it is too high, too low, or “just right.”.Using contacts proximal and distal to the one that delivered the impulse, it creates the ECAP as it propagates in either direction, away from the point of stimulus. ![]() A percutaneously placed cylindrical lead in the epidural space delivers an electrical impulse to the dorsal column of the spinal cord-the same as any other platform.The bottom figure represents the static nature of conventional SCS systems such that regardless of over- or understimulation, the device will remain unchanged and continue to send the same level of stimulation, unless it is manually reprogrammed. The top figure represents the flux in stimulation of the cord (represented by ECAPs) based on positional changes. In essence, the device will send the same electrical impulse, time after time, regardless of whether the patient is being overstimulated or understimulated (Figure 2).įigure 1: Evoked compound action potential (ECAP)įigure 2: Conventional, fixed-output, open-loop spinal cord stimulation (SCS) Despite SCS’s innovations in the past decade, it is still unable to read and interpret ECAPs to identify whether the stimuli are too strong or weak for an individual’s electrophysiology in given position at a given moment. The waveform reflects the movements of sodium and potassium across the cell membrane and the propagation of multiple action potentials away from the point of stimulus. The spinal cord has a measurable electrical rhythm known as an evoked compound action potential (, Figure 1). Pain, on the other hand, is not life threatening, so for SCS not to have the capability was never questioned. The very idea of using CP without the ability to monitor ECG that could only guess when to send an electrical impulse not only seems illogical but dangerous, because an unstable rhythm can be life threatening it was a vital feature. ![]() For decades, CP platforms have read and interpreted the heart’s real-time electrical signals (electrocardiogram ), which dictate how and when the device will send an electrical impulse. However, although CP technology advanced over time, SCS remained largely stagnant until recent years. Since it was first used in the 1960s, spinal cord stimulation (SCS) has consistently been compared to cardiac pacemakers (CP) because both therapies use artificially generated electricity to modulate human tissue that relies on electricity propagate signals.
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