Intra- and inter-session reliability of electrical detection and pain thresholds of cutaneous and muscle primary afferents in the lower back of healthy individuals

Daniel Streuli; Luana Nyirö; Jan Rosner; Andreas Schilder; Miklos Csato; Petra Schweinhardt

doi:10.1007/s00424-023-02851-7

Intra- and inter-session reliability of electrical detection and pain thresholds of cutaneous and muscle primary afferents in the lower back of healthy individuals

Pflugers Arch. 2023 Oct;475(10):1211-1223. doi: 10.1007/s00424-023-02851-7. Epub 2023 Aug 25.

Authors

Daniel Streuli¹, Luana Nyirö², Jan Rosner^{3

4}, Andreas Schilder⁵, Miklos Csato^{1

6}, Petra Schweinhardt¹

Affiliations

¹ Department of Chiropractic Medicine, Integrative Spinal Research, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
² Department of Chiropractic Medicine, Integrative Spinal Research, Balgrist University Hospital, University of Zurich, Zurich, Switzerland. luana.nyiroe@balgrist.ch.
³ Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.
⁴ Department of Neurology, University Hospital Bern, Inselspital, University of Bern, Bern, Switzerland.
⁵ Department of Orthopaedics and Trauma Surgery, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
⁶ Department of Radiology, Balgrist University Hospital, University of Zurich, Zurich, Switzerland.

Abstract

To advance evidence-based practice and targeted treatments of low back pain (LBP), a better pathophysiological understanding and reliable outcome measures are required. The processing of nociceptive information from deeper somatic structures (e.g., muscle, fascia) might play an essential role in the pathophysiology of LBP. In this study, we measured the intra- and inter-session reliability of electrical detection and pain thresholds of cutaneous and muscle primary afferents of the lower back. Twenty healthy participants attended two study visits separated by 27.7 ± 1.7 days. To determine the location-specific electrical detection threshold (EDT) and pain threshold (EPT), needle electrodes were inserted in the epidermal layer over, and in the lumbar erector spinae muscle. Additionally, established quantitative sensory testing (QST) parameters were assessed. Reliability was determined by differences between measurements, intraclass correlation coefficients (ICC_2,1), Bland-Altman plots, and standard error of measurement (SEM). Correspondence between QST parameters and electrical thresholds was assessed using Pearson's correlation. Except for cutaneous EPT, no significant (p ≤ 0.05) intra- and inter-session differences were observed. Excellent intra-session reliability was shown for cutaneous and intramuscular electrical stimulations and all QST parameters (ICC: 0.76-0.93). Inter-session reliabilities were good (ICC: 0.74-0.75) except for electrical stimulations (ICC: 0.08-0.36). Limits of agreement and SEM were higher for inter-session than intra-session. A medium to strong relationship was found between electrical and mechanical/pressure pain thresholds. In conclusion, cutaneous and intramuscular electrical stimulation will potentially close an important diagnostic gap regarding the selective examination of deep tissue afferents and provide location-specific information for the excitability of non-nociceptive and nociceptive afferents.

Keywords: Deep tissue afferents; Electrical stimulation; Experimental pain models; Low back pain; Muscle pain; Quantitative sensory testing.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Electric Stimulation
Humans
Low Back Pain* / diagnosis
Muscles
Pain Threshold*
Reproducibility of Results