Lengthened Cutaneous Silent Period in Fibromyalgia Suggesting Central Sensitization as a Pathogenesis

Abstract

The pathogenesis of fibromyalgia (FM) has not been clearly elucidated, but central sensitization, which plays an important role in the development of neuropathic pain, is considered to be the main mechanism. The cutaneous silent period (CSP), which is a spinal reflex mediated by A-delta cutaneous afferents, is useful for the evaluation of sensorimotor integration at the spinal and supraspinal levels. To understand the pathophysiology of FM, we compared CSP patterns between patients with FM and normal healthy subjects. Twenty-four patients with FM diagnosed in accordance with the 1990 American College of Rheumatology classification system and 24 age- and sex-matched healthy volunteers were recruited. The CSP was measured from the abductor pollicis brevis muscle. Demographic data, number of tender points, and visual analog scale and FM impact questionnaire scores were collected. The measured CSP and clinical parameters of the patient and control groups were compared. In addition, possible correlations between the CSP parameters and the other clinical characteristics were analyzed. Mean CSP latencies did not differ between patients (55.50 ± 10.97 ms) and healthy controls (60.23 ± 11.87 ms; p = 0.158), although the mean CSP duration was significantly longer in patients (73.75 ± 15.67 ms) than in controls (63.50 ± 14.05 ms; p = 0.021). CSP variables did not correlate with any clinical variables. The significantly longer CSP duration in FM patients suggests central dysregulation at the spinal and supraspinal levels, rather than peripheral small fiber dysfunction.

Fibromyalgia: Genetics and epigenetics insights may provide the basis for the development of diagnostic biomarkers

“…However, the pathogenesis of FM is not fully understood, especially because compared to neuropathic conditions in FM, the source of sensory inputs is unknown; 7 some hypothesis on peripheral and central pathophysiological mechanisms have been proposed. Evidence support a central sensitization and a central dysregulation at a spinal and supra-spinal levels in FM patients compared to controls: FM patients showed an exaggerated pain response after sensory stimulation and an extended cutaneous silent period; 8,9 in healthy subjects, the application of an intense painful stimulus produces generalized whole-body analgesia, defined as conditioned pain modulation , while it is consistently reduced or even absent in FM subjects; 10,11 these observations lead to hypothesize a decreased serotonergic and noradrenergic activities. 12,13 The related neurotransmitters are involved in one of the principal descending monoaminergic pain control pathways 14 and thus play a fundamental role in the mechanism underlying acute and chronic pain.…”

The Importance of Electromyographic Findings in Determining the Etiology of Mastalgia

“…Although many studies have evaluated the relationship between fibromyalgia and the nociceptive flexion reflex, we did not find any study evaluating the relationship of nociceptive flexion reflex with mastalgia (30,31). Furthermore, only a few studies have evaluated the relationship between fibromyalgia and CSP, and we found no study investigating the relationship between mastalgia and CSP (25)(26)(27). Thus, our unique study was aimed at assessing EMG results in the PM muscle in the non-mastalgia and mastalgia sides of the breasts to determine whether unilateral mastalgia without organic breast disease is due to a muscle pathology.…”

“…The CSP is a prospective electrophysiological method for the diagnosis of small fiber dysfunction. However, only a few studies have shown a relationship between CSP and fibromyalgia with chronic pain, and there are a limited number of studies evaluating the relationship between mastalgia and CSP (25)(26)(27).…”

Patterns of Orthostatic Blood Pressure Changes in Patients with Orthostatic Hypotension

“…The QSART was performed according to the standard method with the Q-Sweat device (WR Medical Electronics, Maplewood, MN, USA). 7 12 13 The stimulus involved applying 10% acetylcholine via iontophoresis at 2 mA for 5 minutes, which was followed by an additional 5 minutes of recording. Responses were recorded quantitatively from four sites: proximal forearm (25% of the distance from the ulnar epicondyle to the pisiform bone), distal forearm (75% of the distance from the ulnar epicondyle to the pisiform bone), proximal leg (5 cm distal to the fibular head), and distal leg (5 cm proximal to the medial malleolus).…”