Trigger Points

Myofascial pain syndrome (MPS) is described as the sensory, motor, and autonomic symptoms caused by myofascial trigger points (TrPs). Knowing the potential causes of TrPs is important to prevent their development and recurrence, but also to inactivate and eliminate existing TrPs. There is general agreement that muscle overuse or direct trauma to the muscle can lead to the development of TrPs. Muscle overload is hypothesized to be the result of sustained or repetitive low-level muscle contractions, eccentric muscle contractions, and maximal or submaximal concentric muscle contractions. TrPs may develop during occupational, recreational, or sports activities when muscle use exceeds muscle capacity and normal recovery is disturbed.

BackgroundA myofascial trigger point is defined as a hyperirritable spot in skeletal muscle that is associated with a hypersensitive palpable nodule in a taut band. It has been suggested that myofascial trigger points take part in chronic pain conditions including primary headache disorders. The aim of this narrative review is to present an overview of the current imaging modalities used for the detection of myofascial trigger points and to review studies of myofascial trigger points in migraine and tension-type headache.FindingsDifferent modalities have been used to assess myofascial trigger points including ultrasound, microdialysis, electromyography, infrared thermography, and magnetic resonance imaging. Ultrasound is the most promising of these modalities and may be used to identify MTrPs if specific methods are used, but there is no precise description of a gold standard using these techniques, and they have yet to be evaluated in headache patients. Active myofascial trigger points are prevalent in migraine patients. Manual palpation can trigger migraine attacks. All intervention studies aiming at trigger points are positive, but this needs to be further verified in placebo-controlled environments. These findings may imply a causal bottom-up association, but studies of migraine patients with comorbid fibromyalgia syndrome suggest otherwise. Whether myofascial trigger points contribute to an increased migraine burden in terms of frequency and intensity is unclear. Active myofascial trigger points are prevalent in tension-type headache coherent with the hypothesis that peripheral mechanisms are involved in the pathophysiology of this headache disorder. Active myofascial trigger points in pericranial muscles in tension-type headache patients are correlated with generalized lower pain pressure thresholds indicating they may contribute to a central sensitization. However, the number of active myofascial trigger points is higher in adults compared with adolescents regardless of no significant association with headache parameters. This suggests myofascial trigger points are accumulated over time as a consequence of TTH rather than contributing to the pathophysiology.ConclusionsMyofascial trigger points are prevalent in both migraine and tension-type headache, but the role they play in the pathophysiology of each disorder and to which degree is unclarified. In the future, ultrasound elastography may be an acceptable diagnostic test.

BackgroundNeck and shoulder disorders may be linked to the presence of myofascial trigger points (MTrPs). These disorders can significantly impact a person's activities of daily living and ability to work. MTrPs can be involved with pain sensitization, contributing to acute or chronic neck and shoulder musculoskeletal disorders. The aim of this review was to synthesise evidence on the prevalence of active and latent MTrPs in subjects with neck and shoulder disorders.MethodsWe conducted an electronic search in five databases. Five independent reviewers selected observational studies assessing the prevalence of MTrPs (active or latent) in participants with neck or shoulder disorders. Two reviewers assessed risk of bias using a modified Downs and Black checklist. Subject characteristics and prevalence of active and latent MTrPs in relevant muscles was extracted from included studies.ResultsSeven articles studying different conditions met the inclusion criteria. The prevalence of MTrPs was compared and analysed. All studies had low methodologic quality due to small sample sizes, lack of control groups and blinding. Findings revealed that active and latent MTrPs were prevalent throughout all disorders, however, latent MTrPs did not consistently have a higher prevalence compared to healthy controls.ConclusionsWe found limited evidence supporting the high prevalence of active and latent MTrPs in patients with neck or shoulder disorders. Point prevalence estimates of MTrPs were based on a small number of studies with very low sample sizes and with design limitations that increased risk of bias within included studies. Future studies, with low risk of bias and large sample sizes may impact on current evidence.

To evaluate the therapeutic efficacy of myofascial trigger point acupuncture combined with gabapentinoids compared with gabapentinoid therapy alone in patients with postherpetic neuralgia, and to identify clinical factors influencing treatment response. A total of 494 patients with postherpetic neuralgia were randomly assigned to receive either gabapentinoids alone (control group, n = 247) or combined myofascial trigger point acupuncture and gabapentinoids (experimental group, n = 247). Pain intensity was assessed using the Numerical Rating Scale (NRS) at baseline, week 3, and week 6, and changes from baseline (ΔNRS) were calculated to reflect short-term pain improvement. Regression analyses were performed to identify prognostic factors associated with the magnitude of pain reduction rather than to estimate causal treatment effects. Both groups improved significantly, but the experimental group showed greater pain reduction at week 3 and week 6 (P < .001). Multivariate analysis revealed that older age and higher body mass index were independently associated with poorer treatment response at both time points, while pain location was associated with variability in pain reduction at week 6 (patients with thoracic [chest/back] pain showed the greatest improvement). Myofascial trigger point acupuncture combined with gabapentinoids may provide additional short-term pain relief compared with pharmacological therapy alone, with thoracic pain showing the most favorable response; however, baseline imbalance and the absence of sham control limit causal inference. Age and body mass index were associated with poorer efficacy, highlighting the need for individualized strategies. Longer-term randomized trials, including an acupuncture-only arm and multidimensional pain assessments, are warranted to confirm and extend these findings.