Cerebral mechanisms of experimental hyperalgesia in fibromyalgia

Abstract

The present study examined the hyperresponsiveness of the central nervous system in patients with fibromyalgia syndrome (FMS) related to mechanical hyperalgesia. The goals were to differentiate between increased pain ratings and hyperalgesia related either to peripheral or to central sensitization and to correlate with cerebral activation pattern. Seventeen patients and 17 healthy controls were examined, placing an experimental incision in the right volar forearm and causing tonic pain. Experimental pain, primary and secondary hyperalgesia were assessed during the time course of the experimental pain, and the changes in hyperalgesia were correlated to brain activation (functional magnetic resonance imaging). Patients with FMS experienced the experimental pain during the time course as more painful than healthy controls (F(score) = 3.93, p(score) = 0.008). While they did not present a different course of primary hyperalgesia (F(score) = 1.01, p(score) = 0.40), they did show greater secondary hyperalgesia (F(score) = 5.45, p(score) = 0.004). In patients with FMS, the cerebral pattern corresponding to secondary hyperalgesia was altered. The activity in the dorsolateral prefrontal cortex was inversely correlated with secondary hyperalgesia in healthy controls (R = -0.34 p = 0.005); in patients, this correlation was disrupted (R = 0.19 p = 0.12). These findings point to an alteration of pain transmission at the central level in FMS (e.g., loss of inhibition) and might be related to changes in cerebral-midbrain-spinal mechanisms of pain inhibition.

Stress-Induced Allodynia – Evidence of Increased Pain Sensitivity in Healthy Humans and Patients with Chronic Pain after Experimentally Induced Psychosocial Stress

“…In line with the existing literature, patients with FMS displayed hypersensitivity to heat, cold, mechanical and pressure stimuli at the baseline testing [49]–[51] supporting the hypothesis of an alteration of the central pain processing mechanisms [52]–[54]. Even though our exploratory study design and the limited number of participants preclude a direct comparison of the two groups, the FMS-specific result of a stress-related allodynia/hyperalgesia in response to pressure stimuli might give new insights into the underlying etiological factors in FMS because there might be differences in nociceptive processing originating in cutaneous as compared to deep muscular structures [55].…”

Fibromyalgia: A Critical and Comprehensive Review

“…Patients with FMS showed a negative correlation between pre-incision activations in the supplemental motor area, mid cingulate cortex and right precentral gyrus and the subsequent pain intensity at incision, whereas the correlations were positive in healthy controls and patients with RA [289]. The area of secondary hyperalgesia, but not of primary hyperalgesia, after an incision was significantly greater in patients with FMS compared to healthy controls [290]. In healthy controls, activation in the DLPFC, and the bilateral sensorimotor cortex showed modest but statistically highly significant negative correlations with the extent of secondary hyperalgesia.…”

Sex‐based differences in brain alterations across chronic pain conditions

“…In addition, patients with dysmenorrhea demonstrate greater menstrual-related increases in primary somatosensory cortex gray matter volume compared to female healthy controls (Tu et al 2013). Furthermore, additional primary sensorimotor cortical alterations including connectivity, intrinsic activity, reactivity, and perfusion have been noted in female-specific chronic pain studies (Arkink et al 2012; Burgmer et al 2012; Ellingson et al 2012; Guedj et al 2008; Guedj et al 2007; Gupta et al 2015; Kamping et al 2013; Kilpatrick et al 2014; Kim et al 2013; Lee et al 2013; Liu et al 2015a; Liu et al 2015b; Pujol et al 2014; Rahm et al 2015; Tu et al 2009). …”