High-Density in Spinal Cord stimulation: Virtual Expert Registry (DISCOVER): Study Protocol for a Prospective Observational Trial.

Background: Spinal cord stimulation (SCS) is a proven and effective treatment for neuropathic pain conditions such as failed back surgery syndrome (FBSS). The hypothesis that different settings for SCS parameters activate unique, pain-relieving mechanisms has boosted the development of various SCS paradigms. High density spinal cord stimulation (HD-SCS) is one of those promising, novel stimulation forms characterized by subthreshold stimulation, delivering more pulses per second and a higher pulse density to the spinal cord than conventional SCS.

Objectives: The aim of DISCOVER is to gather evidence about the effectiveness, feasibility, and (possible) side effects of HD stimulation.

Methods: The prospective, non-interventional, multi-center, clinical study, DISCOVER, is currently restricted to Belgium where 19 neuromodulation centers were selected. Patient recruitment started in October 2016 and is expected to end in October 2017. Subjects included are (1) patients with insufficient pain relief from conventional SCS or (2) neurostimulation-naïve patients suited for SCS. Patients will be assessed 1 month, 3 months, and 12 months after conversion to HD-SCS settings. Each patient's visit will include: a numerical rating scale (NRS), Oswestry disability index (ODI), Pittsburgh sleep quality index (PSQI), EQ-5D, a pain map, registration of SCS settings, and a list of used pain medication.

Conclusions: Although promising results have been reported, adequate registration of its effectiveness and (possible) side-effects remains an unmet need. Main results are expected in 2019.