Prospective Evaluation of Patient Usage of Above and Below Threshold Waveforms With Traditional Spinal Cord Stimulation Devices

Objectives: Spinal cord stimulation (SCS) is an efficacious therapy used to treat chronic pain. The type of SCS programming is important in improving patients' quality of life and overall satisfaction. In this study, 19 patients who underwent SCS with traditional devices were given between 4 and 6 programs including programs with stimulation below sensory threshold and above sensory threshold. Usage patterns and preferences were assessed.

Methods: SCS patients were given 4-6 programs, some above sensory threshold and some below threshold immediately postoperatively after permanent implantation. Usage patterns of different programs were documented, including percent of time that the settings were used and preference for above threshold vs. below threshold settings during sleeping, walking, sitting, and vigorous activity. Improvements at three months in Oswestry disability index (ODI), numeric rating scale (NRS), Beck depression inventory (BDI), McGill pain questionnaire (MPQ), pain catastrophizing scale (PCS), insomnia severity index (ISI), and Epworth sleepiness scale (ESS) were evaluated.

Results: Patients were all trialed on above sensory threshold programs. Six weeks after implantation, most patients preferred above threshold stimulation (74%) vs. below threshold waveforms (21%). Patient diagnosis, type/location of lead or recharging burden played no role in patient preference. Above threshold patients had significantly better improvement in BDI scores than did below threshold patients (p < 0.05) at three-month follow-up but also had worse ESS scores (p < 0.05). Above threshold stimulation was preferred for walking and sitting (p < 0.05).

Conclusions: Results indicate that when given the option between waveforms inducing paresthesias and those that do not, SCS patients tend to prefer waveforms that induce paresthesias. Among users of above threshold waveforms, there was preference for these settings during walking and sitting. There was a trend for below threshold preference in vigorous activity and sleeping.