TABLE 2.
Studies characteristics
| Study | Foci (#): CP versus CTRL | Stimulation type | Localization: in/out chronic pain body regions | Matching: perceived pain (P) or stimulus intensity (S) | Perceived pain (P) scores or stimulus intensity (S) | Between‐group differences for perceived pain (P) or stimulus intensity (S) | Employed scale for diagnosis | |
|---|---|---|---|---|---|---|---|---|
| Fibromyalgia | ↑ | ↓ | ||||||
| Gracely et al. (2002) | 13 | 1 | Mechanical press | Out‐L thumb | S | 0.45–4.5 kg/mm2 (S) | CP > CTRL (P) | Am. Coll. Rheum. |
| Pujol et al. (2009) a | 5 | 0 | Mechanical press | Out‐R thumb | P | 70/100 (P) | CP < CTRL (S) | Am. Coll. Rheum. |
| Jensen et al. (2009) | 0 | 2 | Mechanical press | Out‐thumb | P | 50/100 (P) | CP < CTRL (S) | Not reported |
| Burgmer et al. (2012) | 1 | 2 | Mechanical press | Out‐R forearm | S | Incision (S) | CP > CTRL (P) | Am. Coll. Rheum. |
| Kim et al. (2013) | 8 | 0 | Mechanical press | Out‐L thumb | P | 14/21 (P) | CP < CTRL (S) | Not reported |
| Schreiber et al. (2017) | 6 | 0 | Mechanical press | Out‐L calf | P | 40/100 (P) | CP < CTRL (S) | Am. Coll. Rheum. |
| Low‐back pain | ||||||||
| Derbyshire et al. (2002) a | 1 | 3 | Thermal | Out‐R hand | P | 40–60/100 (P) | CP = CTRL (S) | Not reported |
| Baliki et al. (2010) | 0 | 2 | Thermal | In‐back | S | 47°–51°C (S) | CP = CTRL (P) | Not reported |
| Rodriguez‐Raecke et al. (2014) | 1 | 0 | Thermal | Out‐L forearm | S | 48°C (S) | CP = CTRL (P) | Quebec task force |
| Irritable bowel syndrome | ||||||||
| Verne et al. (2003) a | 8 | 2 | Mechanical dist | In‐rectum | S | 55 mmHg (S) | CP > CTRL (P) | Rome III |
| Elsenbruch et al. (2010) a | 2 | 0 | Mechanical dist | In‐rectum | P | 5/6 (P) | CP = CTRL (S) | Rome III |
| Bouhassira et al. (2010) a | 5 | 0 | Mechanical dist | In‐rectum | P | 5/6 (P) | CP < CTRL (S) | Rome III |
| Guleria et al. (2017) a | 4 | 2 | Mechanical dist | In‐rectum | P | Mod‐sev(P) | CP < CTRL (S) | Rome III |
| Neuropathic pain | ||||||||
| Albuquerque et al. (2006) | 6 | 3 | Thermal | In‐R trigeminus | S | 47°‐49° C (S) | CTRL = CTRL | Not reported |
| Vartiainen et al. (2009) a | 3 | 7 | Thermal | Out‐bil. Hand | P | 6–7/10 (P) | CP < CTRL (S) | Not reported |
| Neuropathic pain and fibromyalgia | ||||||||
| Hampson et al. (2013) a | 1 | 0 | Mechanical press | Out‐L thumb | P | 13.5/21 (P) | CP < CTRL (S) | Not reported |
| Total foci | 64 | 22 | ||||||
Studies contributing to the cluster identified in the analysis of Dataset#2 employing the coordinate density analysis (ABC). Foci(#): CP versus CTRL: number of foci of abnormal activity (↑ = increased activity, ↓ = decreased activity) observed in the comparison between chronic pain patients and control participants. Stimulation type: type of painful stimulation applied for inducing pain; Stimulation site (in/out chronic pain body regions): part of the body subjected to painful stimulation and whether this body part was located in or out the regions where chronic pain was experienced; Matching perceived pain (P) or stimulus intensity (S): chronic pain patients and control participants were matched for the perceived pain (P) or for the intensity of painful stimulation (S); Pain scores or Stimulus intensity: scores on VAS or Likert scale for perceived pain (when groups were matched for perceived pain) or intensity of the stimulation (when groups were matched for the intensity of painful stimulation); Between‐group difference for pain (P) or stimulation (S): direction of the behavioral differences in the perceived pain (when groups were matched for the intensity of painful stimulation) or in the intensity of the applied painful stimulation (when groups were matched for perceived pain). Bibliography in Supporting Information.
Abbreviations: Am. Coll. Rheum., American College of Rheumatology; CP, chronic pain patients; CTRL, control individuals; dist, distension; L, left; mod‐sev = from moderate to severe; press, pressure; R, right.