University of Twente Student Theses

The feasibility of measuring nociceptive detection thresholds and electrical brain responses during spinal cord stimulation while electrical stimuli are applied to the foot dorsa : An explorative study in patients with persistent spinal pain syndrome type 2

Nelissen, M.L. (2023) The feasibility of measuring nociceptive detection thresholds and electrical brain responses during spinal cord stimulation while electrical stimuli are applied to the foot dorsa : An explorative study in patients with persistent spinal pain syndrome type 2.

PDF
4MB

Abstract:	Introduction: Chronic pain is a significant, global issue, and neuroplastic alterations underlying chronic pain are difficult to identify due to a lack of methods adequately measuring neurophysiological processes. This potentially hinders the development and limits the effect of treatment methods such as spinal cord stimulation (SCS). Recently, a method was developed to observe nociceptive processing mechanisms using nociceptive detection thresholds (NDTs) and evoked potentials (EPs) after intra-epidermal electrical stimulation (IES). This method has been studied in several patient populations including patients with persistent spinal pain syndrome type 2 (PSPS-T2), with promising results showing differences between healthy individuals and chronic pain patients. Preliminary results in PSPS-T2 patients treated by SCS indicated that applying stimuli to the foot dorsa could be the next step in the development of the NDT-EP method and the exploration of effects of SCS, as the feet are usually affected by PSPS-T2. However, it is unclear whether nociceptive processes can also be measured during SCS when stimuli are applied to an area that is affected by SCS. Research aim: to investigate feasibility of the NDT-EP method and stimulus application to the foot dorsa during SCS in PSPS-T2 patients, and further explore effects of SCS on NDTs and EPs. Methods: Twenty-three PSPS-T2 patients (11 male, 54.9 ± 8.6 years old) who were effectively treated by SCS (≥50% pain reduction) were included and randomised over two trial arms. Twelve patients (5 male, 55.9 ± 8.8 years old) underwent ‘SCS-OFF vs SCS-ON’ protocol, in which two NDT-EP measurements were performed with SCS turned off (SCS-OFF), followed by two NDT-EP measurements with SCS turned on (SCS-ON). Eleven patients (6 male, 53.7 ± 8.7 years old) underwent ‘SCS-ON1 vs SCS-ON2’ protocol, in which four measurements were performed during SCS-ON. During each measurement, 3 stimulus types were applied to the foot dorsum of either the affected or unaffected side: single pulse (SP), double pulse with a 10 ms inter-pulse interval (IPI) (DP10), and double pulse with a 40 ms IPI (DP40). Individual NDTs and slopes of the psychophysical curves were determined using a generalised linear model (GLM), and P2 and N1 amplitudes were analysed from a central (Cz-M1,M2) and a contralateral (T7-F4) EEG derivation, respectively. Results: 87 measurements were performed, of which 56 were deemed acceptable based on GLM fit, 67 based on signal-to-noise ratio (SNR) of P2, and 70 based on SNR of N1. EPs were identified in nearly all measurements used in respective EP analyses. After selection of adequate task performance (detection rate > 30%, false positive rate < 5%), 52 measurements were selected for NDT analysis, 52 for P2 analysis, and 53 for N1 analysis. NDTs and P2 amplitudes during SCS-OFF seemed higher on the unaffected side than the affected side, and were more similar during SCS-ON. N1 amplitudes were similar during SCS-OFF and SCS-ON, and seemed to present higher amplitudes on the affected side. When compared to healthy controls (HCs), SCS-ON seemingly showed slightly higher NDTs and N1 amplitudes. Generally, thresholds and slopes for SP stimuli seemed respectively higher and less steep than those of double pulse stimulus types. Conclusion: The NDT-EP method with stimulus application to the foot dorsa seems practically feasible, but technical feasibility is slightly questionable, due to great variability in detection rates and signal-to-noise ratios, occasionally high false positive rates, and the number of incorrectly fitted GLMs. Findings regarding NDTs on the affected and unaffected sides contradict those of previous work. It is recommended to investigate why task performance of SP stimuli is generally lower than both double pulse stimuli.
Item Type:	Essay (Master)
Faculty:	TNW: Science and Technology
Subject:	44 medicine, 50 technical science in general
Programme:	Technical Medicine MSc (60033)
Link to this item:	https://purl.utwente.nl/essays/94535
Export this item as:	BibTeX EndNote HTML Citation Reference Manager

Show download statistics for this publication

Repository Staff Only: item control page