The effect of vibration therapy on neck myofascial trigger points: A randomized controlled pilot study
Introduction
Myofascial pain syndrome is defined as a cluster of signs and symptoms associated with active and latent myofascial trigger points (MTrPs). An MTrP is a hyperirritable focus within a taut band of skeletal muscle that is painful on compression and which, when stimulated, can evoke a characteristic pattern of referred pain and related autonomic phenomena (Simons et al., 1999).
MTrPs are a common source of regional pain in patients presenting with musculoskeletal pain. Indeed, the prevalence of MTrPs has been found to be up to 85% of the general population (Fleckenstein et al., 2010). Sleeping posture is related to musculoskeletal disorders of the shoulder or neck (Gordon et al., 2010). Moreover, it is known that sleep disturbances are frequent among patients with neck pain (Artner et al., 2013; Lobbezoo et al., 2004). Specifically, poor cervical posture during sleep, which is believed to increase biomechanical stresses on the structure of the cervical spine, can produce cervical pain and stiffness, headache, and scapular or arm pain, resulting in low-quality sleep (Gordon et al., 2010). From a clinical point of view, MTrPs may be either active or latent. Active and latent MTrPs have similar physical manifestations, except that latent MTrPs do not elicit spontaneous symptoms and the local and referred pain reproduced by stimulating latent MTrPs is not familiar to the patient (Simons, 2004). Active, but not latent, MTrPs have been recognized as a common cause of local musculoskeletal pain and dysfunction (Simons, 2004), but recent research has emphasized the importance of latent MTrPs both in diagnosis and treatment (Celik and Mutlu, 2013). In addition, elimination of latent MTrPs is accompanied by normalization of impaired motor activation patterns (Lucas et al., 2004).
Several treatment strategies have been suggested to treat MTrPs, ranging from conservative techniques such as massage (Vernon and Schneider, 2009), pressure release (Sarrafzadeh et al., 2012), ischemic compression (Cagnie et al., 2013; Cagnie et al., 2015), and spray and stretch (Hong et al., 1993), to invasive interventions such as dry needling (Cagnie et al., 2015; Hong et al., 1993; Kietrys et al., 2013; Pecos-Martín et al., 2015) or injections (Kim et al., 2015). Within massage techniques, Swedish massage is probably the most commonly used among physical therapists. Massage has been claimed to promote relaxation and decrease tissue adhesion, increase intramuscular circulation (Franklin et al., 2014; Weerapong et al., 2005) and decrease neuromuscular excitability (Weerapong et al., 2005). In addition, massage has been found to reduce myalgia symptoms by approximately 25% to 50% (Frey Law et al., 2008) and have preventive effects (Khamwong et al., 2011). In fact, vibration massage applied for five minutes followed by kneading manoeuvres was the treatment proposed by Lindemann et al. (Lindemann et al., 1970) in the 1970s to reduce myogelosis, an expression synonymous with MTrPs. Despite the extensive application of massage therapies, clinical trials investigating their efficacy in subjects with MTrPs are scarce (Kraft et al., 2013).
In the last two decades, the use of mechanical vibration for rehabilitation purposes has attracted the interest of researchers (Issurin, 2005; Veqar and Imtiyaz, 2014). Vibration therapy (VT) is used to stimulate edema absorption, improve blood flow, alleviate wound healing and for its anti-inflammatory and antifibrous effects (Armstrong et al., 2010; Jahr et al., 2008). In addition, the effects of VT on pain relief have also been widely demonstrated. In particular, this technique has been shown to be beneficial for patients with fibromyalgia (Kraft et al., 2013), acute and chronic musculoskeletal pain (Lundeberg et al., 1984), delayed onset muscle soreness (DOMS) (Imtiyaz et al., 2014; Veqar and Imtiyaz, 2014), and myotendinous injuries that involve MTrPs (Peer et al., 2009). Although previous studies have examined the use of massage techniques on patients with MTrPs (Chan et al., 2015; Gam et al., 1998), to our knowledge there are no studies which have evaluated the effectiveness of VT on MTrPs.
Self-management strategies are considered essential to the management of persistent musculoskeletal disorders such as neck pain (Hutting et al., 2019). Effective self-management is based on skills to encourage patients to actively participate in, and take responsibility for, common or persistent conditions (Jonkman et al., 2016). These strategies may contribute to the long-term management of these conditions (Hutting et al., 2017), improve adherence (Bal et al., 2016) and promote a healthy lifestyle in the patients.
The aim of this pilot study was therefore to investigate the efficacy of low-frequency self- administered VT for neck pain, disability and pressure pain thresholds (PPT) in patients with non-specific neck pain and MTrPs. We hypothesized that patients receiving VT would report lower levels of perceived neck pain and disability and present higher PPTs after receiving VT when compared with a no-treatment control group (CG).
Section snippets
Participants
Subjects between 18 and 45 years old with a history of chronic non-specific neck pain were invited to participate in this study. Recruitment was performed by advertisement by the University of Valencia (Spain), from September 2014 to December 2019. Besides having a history of neck pain lasting three months or more over the previous year, subjects were required to have a Neck Disability Index (NDI) score of ≥5/50 (Vernon and Mior, 1991) and have active or latent MTrPs in the upper trapezius or
Results
Thirty-eight subjects were screened for possible eligibility criteria, and 22 subjects successfully completed the study protocol (VG n = 11, CG n = 11). Fig. 3 shows a flow diagram representing the subject process of recruitment and dropouts. The baseline characteristics of the final sample are summarized in Table 1. No adverse effects were reported by the participants from the vibration group (VG).
Discussion
To our knowledge, this is the first randomized controlled study investigating the effect of VT on pressure pain sensitivity at cervical MTrPs and self-reported neck pain and disability in people with chronic non-specific neck pain. In this study, patients treated with self-applied mechanical VT showed a significant reduction in neck pain and disability and an increase in PPT at cervical MTrPs, compared to a CG, which did not receive a comparable treatment, while not receiving any intervention.
Conclusions
This pilot study shows that 10 sessions of self-administered VT using 35–50 Hz frequency ranges improved pressure pain sensitivity over trapezius and levator scapulae MTrPs and self-reported neck pain and disability in patients with chronic non-specific neck pain. Further large population studies are needed to determine the true efficacy of VT. Thus, self-applied VT may be an effective intervention for releasing non-specific neck pain and this tool could be used as part of a comprehensive
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Declaration of Competing Interest
None.
Acknowledgments
We would like to thank all the participants as well as the European Sleep Care Institute for making this study possible.
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