Effects of Tonic Spinal Cord Stimulation on External Mechanical and Thermal Stimuli Perception Using Quantitative Sensory Testing

Abstract

Objectives: Tonic spinal cord stimulation (SCS) is currently used to treat neuropathic pain. With this type of stimulation, an implantable pulse generator generates electrical paresthesias in the affected area through 1 or more epidural leads. The goal of this study was to evaluate the impact of tonic SCS on the sensory perception of chronic pain patients using quantitative sensory testing (QST). Materials and Methods: Forty-eight patients (mean age: 57 y) with chronic leg pain due to failed back surgery syndrome or complex regional pain syndrome treated with SCS were recruited from 3 research centers. Test procedures included 2 sessions (stimulation On or Off), with measures of detection thresholds for heat, touch, vibration, and of pain thresholds for cold, heat, pressure, the assessment of dynamic mechanical allodynia, and temporal pain summation. Three different areas were examined: the most painful area of the most painful limb covered with SCS-induced paresthesias (target area), the contralateral limb, and the ipsilateral upper limb. Wilcoxon signed-rank tests were used to compare the mean difference between On and Off for each QST parameter at each area tested. P-values <0.05 were considered significant. Results: Regarding the mean difference between On and Off, patients felt less touch sensation at the ipsilateral area (−0.4±0.9 g, P=0.0125) and were less sensitive at the contralateral area for temporal pain summation (−4.9±18.1 on Visual Analog Scale 0 to 100, P=0.0056) with SCS. Discussion: It is not clear that the slight changes observed were clinically significant and induced any changes in patients’ daily life. Globally, our results suggest that SCS does not have a significant effect on sensory perception.

Classification of Qualitative Fieldnotes Collected During Quantitative Sensory Testing: A Step Towards the Development of a New Mixed Methods Approach in Pain Research

“…Qualitative fieldnotes were collected among 48 patients with chronic neuropathic pain during an independent multicenter QST study. 21 Recruitment for the QST study occurred between January 2016 and November 2017 at three research centers: CHU de Québec – Université Laval, Canada; University of Toledo Medical Center, USA; and Centre hospitalier de l’Université de Montréal, Canada. Inclusion criteria were the following: older than 18 years old; French or English speaker; diagnosed with complex regional pain syndrome and failed back surgery syndrome (meeting the International Association for the Study of Pain’s criteria 22 , 23 ); implanted with a spinal cord stimulator device for at least 6 months; having the same programming parameters or medication for at least 30 days before testing; using tonic stimulation mode only; feeling the paresthesia induced by tonic spinal cord stimulation (SCS) in one or both legs.…”

“…Accordingly, our first objective was to organize and classify qualitative fieldnotes of sensory abnormalities collected during a previous QST study. 21 A second objective was to generate a qualitative interview guide, based on these qualitative results, that could be included in the traditional QST procedure as a step towards the development of a mixed methods approach.…”

Dorsal Root Ganglion Stimulation Normalizes Measures of Pain Processing in Patients with Chronic Low‐Back Pain: A Prospective Pilot Study using Quantitative Sensory Testing

“…A recent systematic review investigated QST changes with SCS and concluded that conventional tonic SCS does not seem to have an influence on most QST parameters 45 . The inconsistent QST results that Bordeleau et al found were suggested to potentially be related to a broad range of pain disorders included, heterogeneity in the QST methods used, and heterogeneity in the study designs.…”

Quantitative Sensory Testing of Spinal Cord and Dorsal Root Ganglion Stimulation in Chronic Pain Patients

“…Early SCS studies by Lindblom and Meyerson, and Eisenberg et al have reported significant effects of stimulation on VDT in chronic pain patients (69, 70). However, more recent studies have reported minor effects or no effects on VDT with SCS (28, 51, 71). We anticipated that SCS and DRGS treatment would significantly modulate (increase) VDT via stimulation‐induced excitation of low‐threshold, large‐diameter Aβ fibers in the dorsal columns of the spinal cord, and in the dorsal root ganglia, at spinal levels innervating the pain region(s) or corresponding dermatome of the body, respectively.…”

“…Because our sample size was small ( n = 16), and our dataset was not normally distributed, we used the Wilcoxon signed‐rank test, a non‐parametrical test for statistical comparisons, to assess for treatment effects of SCS and DRGS. Previously published SCS studies have used the Wilcoxon signed‐rank test for comparing paired samples of non‐normally distributed data in relatively small and large populations of chronic pain patients (29,51). We calculated the effect size (or “ r ” value) for the Wilcoxon's test using previously established formula for this test (52,53).…”