(2011). Treatment of central sensitization in patients with ‘unexplained’ chronic pain: what options do we have? Expert Opinion on Pharmacotherapy: Vol. 12, No. 7, pp. 1087-1098. doi: 10.1517/14656566.2011.547475

A systematic review was performed to evaluate the existing evidence related to the prevalence, incidence, localization, and pathophysiology of myofascial trigger points (MTrPs) in patients with spinal (back and neck) pain. A systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed in 2 electronic databases (PubMed and Web of Science) using predefined keywords regarding MTrPs and spinal pain. A "PICOS" questionnaire was used to set up the search strategies and inclusion criteria. Full-text reports concerning MTrPs in patients with back or neck pain, which described their prevalence, incidence, location, or underlying physiopathology were included and screened for methodological quality by 3 independent researchers. Each study was assessed for risk of bias using a checklist derived from the Web site of the Dutch Cochrane Centre. Fourteen articles were retrieved for quality assessment and data extraction. Studies reporting the incidence of MTrPs in patients with spinal pain were lacking. Within spinal pain, patients with neck pain were found to have the highest prevalence rates of MTrPs. The trapezius descendens, levator scapulae, and suboccipitales muscles were the most prevalent locations for active MTrPs in patients with neck pain. Latent MTrPs were present in asymptomatic people, but no significant differences were found in the prevalence rate of latent MTrPs between patients with spinal (neck) pain and healthy controls. The only study investigating prevalence of MTrPs in different localizations of the same muscle reported no significant differences in prevalence between active and latent MTrPs within the trapezius descendens muscle. Studies examining pathophysiological mechanisms underlying MTrPs demonstrated an acidic environment, high concentration of algogenic/inflammatory substances, stiffer muscle tissue, retrograde diastolic blood flows, spontaneous muscle activity at rest, and loss of muscle contractibility in muscles with MTrPs. Altered central processing was also found to play a role in the development of MTrPs. Myofascial trigger points are a prevalent clinical entity, especially in patients with neck pain. Evidence was not found to support or deny the role of MTrPs in other spinal pain. Compelling evidence supports local mechanisms underlying MTrPs. Future research should unravel the relevance of central mechanisms and investigate the incidence of MTrPs in patients with spinal pain.

The objective of this cross-sectional study was to analyze the relationship between symptoms of central sensitization (CS) and important cognitive behavioral and psychosocial factors in a sample of patients with chronic nonspecific low back pain. Participants with chronic nonspecific low back pain for at least 3 months were included in the study. They completed several questionnaires and a functional test. Pearson's correlation was used to analyze associations between symptoms of CS and pain behavior, functioning, pain, pain catastrophizing, kinesiophobia, and illness perceptions. Additionally, a between-group analysis was performed to compare patients with and without clinically relevant symptoms of CS. Data from 38 participants were analyzed. Significant associations were found between symptoms of CS and all other outcomes, especially current pain (r = 0.510, P = .001), mean pain during the past 7 days (r = 0.505, P = .001), and pain catastrophizing (r = 0.518, P = .001). Patients with clinically relevant symptoms of CS scored significantly worse on all outcomes compared with persons without relevant symptoms of CS, except on functioning (P = .128). Symptoms of CS were significantly associated with psychosocial and cognitive behavioral factors. Patients exhibiting a clinically relevant degree of symptoms of CS scored significantly worse on most outcomes, compared with the subgroup of the sample with fewer symptoms of CS.