Role of non-invasive objective markers for the rehabilitative diagnosis of central sensitization in patients with fibromyalgia: A systematic review

Article type: Review Article

Authors: Smeets, Yasemin^a | Soer, Remko^{b; c} | Chatziantoniou, Evangelia^d | Preuper, Rita H.R. Schiphorst^e | Reneman, Michiel F.^f | Wolff, André P.^g | Timmerman, Hans^{h; *}

Affiliations: [a] University of Groningen, University Medical Center Groningen, Department of Anesthesiology, Pain Center, Groningen, The Netherlands | [b] University of Groningen, University Medical Center Groningen, Department of Anesthesiology, Pain Center, Groningen, The Netherlands | [c] mProve Hospitals, Zwolle, The Netherlands | [d] University of Groningen, University Medical Center Groningen, Department of Anesthesiology, Pain Center, Groningen, The Netherlands | [e] University of Groningen, University Medical Center Groningen, Department of Rehabilitation Medicine, Groningen, The Netherlands | [f] University of Groningen, University Medical Center Groningen, Department of Rehabilitation Medicine, Groningen, The Netherlands | [g] University of Groningen, University Medical Center Groningen, Department of Anesthesiology, Pain Center, Groningen, The Netherlands | [h] University of Groningen, University Medical Center Groningen, Department of Anesthesiology, Pain Center, Groningen, The Netherlands

Correspondence: [*] Corresponding author: Hans Timmerman, Department of Anesthesiology, University Medical Center Groningen (UMCG), Pain Center, Location Beatrixoord, HPC CD48, PO Box 30.002, 9750 RA Haren, The Netherlands. E-mail: [email protected].

Abstract: BACKGROUND: Central sensitization cannot be demonstrated directly in humans. Therefore, studies used different proxy markers (signs, symptoms and tools) to identify factors assumed to relate to central sensitization in humans, that is, Human Assumed Central Sensitization (HACS). The aims of this systematic review were to identify non-invasive objective markers of HACS and the instruments to assess these markers in patients with fibromyalgia (FM). METHODS: A systematic review was conducted with the following inclusion criteria: (1) adults, (2) diagnosed with FM, and (3) markers and instruments for HACS had to be non-invasive. Data were subsequently extracted, and studies were assessed for risk of bias using the quality assessment tools developed by the National Institute of Health. RESULTS: 78 studies (n= 5234 participants) were included and the findings were categorized in markers identified to assess peripheral and central manifestations of HACS. The identified markers for peripheral manifestations of HACS, with at least moderate evidence, were pain after-sensation decline rates, mechanical pain thresholds, pressure pain threshold, sound ‘pressure’ pain threshold, cutaneous silent period, slowly repeated evoked pain sensitization and nociceptive flexion reflex threshold. The identified markers for central manifestations of HACS were efficacy of conditioned pain modulation with pressure pain conditioning and brain perfusion analysis. Instruments to assess these markers are: pin-prick stimulators, cuff-algometry, repetitive pressure stimulation using a pressure algometer, sound, electrodes and neuroimaging techniques. CONCLUSIONS: This review provides an overview of non-invasive markers and instruments for the assessment of HACS in patients with FM. Implementing these findings into clinical settings may help to identify HACS in patients with FM.

Keywords: Fibromyalgia, central sensitization, nociplastic pain, non-invasive markers, pain threshold, electrophysiological techniques, human assumed central sensitization

DOI: 10.3233/BMR-220430

Journal: Journal of Back and Musculoskeletal Rehabilitation, vol. Pre-press, no. Pre-press, pp. 1-60, 2023