Background: Painful diabetic neuropathy (PDN) is a progressive chronic pain condition that significantly affects the quality of life of patients with long-standing diabetes mellitus. Sensory deficits may result in falls, foot ulceration, and lower limb amputations. Recently, spinal cord stimulation (SCS) was studied for treatment of painful diabetic neuropathy. In addition to pain relief, we were surprised to discover that sensory improvements were also demonstrated. No mechanistic explanation has yet been offered to explain these findings.
Objectives: Sensory improvements were observed in patients during the Senza-PDN clinical trial. Our objective was to offer a hypothesis to explain these results.
Study design: The randomized, prospective, multicenter, open-label Senza-PDN clinical trial was aimed at documenting the value of 10 kHz SCS in addition to conventional medical management alone. We formulated an hypothesis to explain the neurologic improvement observed while using SCS in these study patients.
Setting: This work was conducted in a private clinical practice.
Results: SCS resulted in an overall decrease in pain for the enrolled PDN patients. An unexpected improvement in neurologic outcomes was also noticed at up to 12 months, which had never been reported before. We hypothesized that stochastic resonance mechanism could explain these sensory improvements. We believe that waveforms delivered to the spinal cord may have had the unexpected effect of creating noise-enhanced signal processing.
Limitations: Further research will have to be performed to confirm the plausibility of the stochastic resonance hypothesis formulated.
Conclusions: SCS might have unexpected benefits in patients with PDN beyond pain reduction. The Senza-PDN trial is the first to describe improved sensation in association with SCS. While the mechanism of action are still unknown, we hypothesize that noise-enhanced signal processing via stochastic resonance may explain these results. Stochastic resonance, or the benefit of additional randomness, should be further studied in the context of spinal cord stimulation. Further, SCS programming that optimizes for stochastic resonance should also be investigated for restoration of sensory and possibly even motor function.
Keywords: Senza; high frequency spinal cord stimulation; neuropathy; spinal cord stimulation; stochastic resonance; Painful diabetic neuropathy.