Christine H Meyer-Frießem1,2, Theresa Wiegand2, Lynn Eitner2, Christoph Maier2, Tina Mainka2,3, Jan Vollert2,4, Elena K Enax-Krumova5. 1. Department of Anaesthesiology, Intensive Care Medicine, Palliative Care Medicine and Pain Management, Medical Faculty of Ruhr-University, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil GmbH Bochum. 2. Department of Pain Medicine. 3. Department of Neurology, Charité University Medicine Berlin, Berlin, Germany. 4. Pain Research, Department of Surgery and Cancer, Imperial College, London, UK. 5. Department of Neurology, Ruhr-University Bochum, BG-Kliniken Bergmannsheil, Bochum, Germany.
Abstract
OBJECTIVES: Spinal cord and peripheral nerve stimulation (SCS/PNS) may alleviate chronic pain; however, the underlying mechanisms remain controversial. The aim of this observational study was to assess sensory changes in the ON-conditions and OFF-conditions to obtain insights into the mechanism of analgesic effects of SCS/PNS. MATERIALS AND METHODS: We contacted 85 patients and selected 28 patients with sufficient pain relief by SCS (n=15) or PNS (n=13) to assess their ongoing pain intensity (Numerical Rating Scale, 0 to 10), pain thresholds using Quantitative Sensory Testing (DFNS-protocol), and conditioned pain modulation (CPM) in a nonrandomized manner 2 to 4 hours after SCS/PNS deactivation (OFF-condition) and during stimulation (ON-condition). For each patient, the number of abnormally decreased pain thresholds, the presence of dynamic mechanical allodynia, and/or increased pain sensitivity was additionally totaled OR summed. RESULTS: In the ON-condition, pain intensity decreased (Numerical Rating Scale SCS: 6.5±2.1 vs. 3.7±2.3, P<0.01; PNS: 6.2±1.4 vs. 4±1.9, P<0.01), but this did not correlate with any single sensory parameter. However, for SCS, the total number of parameters indicating hyperalgesia was significantly reduced in the ON-condition (45 vs. 23, P=0.001). A smaller CPM effect in the OFF-condition correlated with a greater CPM improvement during stimulation (SCS: r=-0.741, P=0.002; PNS: r=-0.773, P=0.003), independently from the spontaneous pain intensity. DISCUSSION: The analgesic effect of SCS/PNS did not correlate with changes of single sensory parameters, but SCS/PNS reduced the number of abnormal hyperalgesic findings disregarding the kind of applied stimuli, suggesting a general antihyperalgesic effect. In addition, stimulation improved the endogenous pain inhibition. Both findings indicate that SCS/PNS may modulate central circuits.
OBJECTIVES: Spinal cord and peripheral nerve stimulation (SCS/PNS) may alleviate chronic pain; however, the underlying mechanisms remain controversial. The aim of this observational study was to assess sensory changes in the ON-conditions and OFF-conditions to obtain insights into the mechanism of analgesic effects of SCS/PNS. MATERIALS AND METHODS: We contacted 85 patients and selected 28 patients with sufficient pain relief by SCS (n=15) or PNS (n=13) to assess their ongoing pain intensity (Numerical Rating Scale, 0 to 10), pain thresholds using Quantitative Sensory Testing (DFNS-protocol), and conditioned pain modulation (CPM) in a nonrandomized manner 2 to 4 hours after SCS/PNS deactivation (OFF-condition) and during stimulation (ON-condition). For each patient, the number of abnormally decreased pain thresholds, the presence of dynamic mechanical allodynia, and/or increased pain sensitivity was additionally totaled OR summed. RESULTS: In the ON-condition, pain intensity decreased (Numerical Rating Scale SCS: 6.5±2.1 vs. 3.7±2.3, P<0.01; PNS: 6.2±1.4 vs. 4±1.9, P<0.01), but this did not correlate with any single sensory parameter. However, for SCS, the total number of parameters indicating hyperalgesia was significantly reduced in the ON-condition (45 vs. 23, P=0.001). A smaller CPM effect in the OFF-condition correlated with a greater CPM improvement during stimulation (SCS: r=-0.741, P=0.002; PNS: r=-0.773, P=0.003), independently from the spontaneous pain intensity. DISCUSSION: The analgesic effect of SCS/PNS did not correlate with changes of single sensory parameters, but SCS/PNS reduced the number of abnormal hyperalgesic findings disregarding the kind of applied stimuli, suggesting a general antihyperalgesic effect. In addition, stimulation improved the endogenous pain inhibition. Both findings indicate that SCS/PNS may modulate central circuits.
Authors: Natalie H Strand; Ryan D'Souza; Christopher Wie; Stephen Covington; Moustafa Maita; John Freeman; Jillian Maloney Journal: Curr Pain Headache Rep Date: 2021-05-11
Authors: Natalie Strand; Ryan S D'Souza; Jonathan M Hagedorn; Scott Pritzlaff; Dawood Sayed; Nomen Azeem; Alaa Abd-Elsayed; Alexander Escobar; Mark A Huntoon; Christopher M Lam; Timothy R Deer Journal: J Pain Res Date: 2022-08-23 Impact factor: 2.832