Musculoskeletal pain represents a significant burden on individuals and the healthcare system in Spain, where 20% of adults experience pain, and 7% suffer from it daily. Myofascial pain syndrome (MPS), one of the most frequent causes of musculoskeletal pain, affects over 85% of the general population at some point. MPS is characterized by local or referred pain and the presence of myofascial trigger points (MTrPs). Despite advancements in diagnostic technologies, the evaluation of MTrPs still largely relies on manual palpation due to the absence of conclusive findings for their objective identification. Ultrasound presents a promising alternative as a widely available, cost-effective, and non-invasive diagnostic tool for MTrPs. While prior studies on ultrasound for MTrP detection have shown variable sensitivity and specificity (ranging from 33% to 100%), no consensus has been reached on a standardized ultrasound methodology for reliable clinical use. The ability to accurately identify MTrPs through ultrasound could shift the current paradigm, facilitating earlier diagnosis and preventing the chronicity of musculoskeletal pain, thus improving patient care and reducing healthcare costs. This study aims to evaluate ultrasound as a potential gold standard for MTrP diagnosis and characterization. By exploring optimal ultrasound modes (B-mode, Doppler), we aim to standardize a highly reliable inter-examiner diagnostic protocol that can be easily applied in clinical practice using accessible technology, such as portable wireless ultrasound devices. Specific objectives include: 1) developing ultrasound exploration protocols for MTrP detection; 2) evaluating vibration parameters for enhanced MTrP visualization; 3) characterizing MTrPs through ultrasound by analyzing size, shape, location, and echotextural features; and 4) validating proposed protocols by correlating them with manual palpation and clinical measures. This research will contribute significantly to understanding MTrPs, providing innovative diagnostic tools and protocols that will improve the precision and effectiveness of musculoskeletal pain assessment. The findings may also have important clinical implications for MTrP-related conditions, enhancing patient care and quality of life.
This exploratory study aims primarily to characterize myofascial trigger points (MTrPs) and identify the optimal ultrasound protocol for their real-time visualization. Participants will be subjected to vibratory stimuli applied to the MTrP location. As a secondary objective, the study will explore variations in ultrasound imaging of muscles without MTrPs, comparing measurements taken within the same muscle between different subjects. The goal is to establish a reference point for defining the normal range of various muscle echotexture values in ultrasound images of healthy individuals. This analysis will include metrics such as mean echogenicity, coefficient of variation of echogenicity, co-occurrence, and run-length matrices, among others. To achieve this, the study will recruit subjects without musculoskeletal disorders (with or without latent MTrPs) and those with myofascial/musculoskeletal pain (with at least one active MTrP). Ultrasound images of the gastrocnemius medialis muscle, which has been selected because of the prevalence of MTrPs and its accessibility for palpation and ultrasound, will be analyzed. To identify MTrPs in the selected muscle, both in participants with and without pain, at least two of the following diagnostic criteria must be met: 1) a palpable taut band within the muscle; 2) the presence of a hypersensitive spot within the taut band; and 3) referred pain when the MTrP is compressed. Although we are aware of the risk of false negatives, for participants with pain, to differentiate an active MTrP from a latent one, an active MTrP must reproduce the patient's symptoms, as both active and latent MTrPs commonly exhibit a taut band and hypersensitive spot. The analysis of the data extracted from this study aims to discern any distinguishing features that could contribute to developing a model capable of accurately identifying MTrPs. This will involve using machine learning techniques or statistical modeling. Additionally, the study will incorporate an analysis of the diagnostic reliability and validation of MTrP exploration protocol in superficial muscles, leveraging the recruited sample. This analysis aims to validate the MTrP exploration protocol by evaluating diagnostic reliability between ultrasound and manual palpation. Manual palpation is currently the most widely accepted criterion for MTrP diagnosis. An expert physiotherapist specialized in myofascial pain will use manual palpation to diagnose MTrPs in gastrocnemius medialis muscle. Using a dermographic pen, the exact area of the MTrP, as well as a control area outside the MTrP and tight band within the same muscle, will be marked. If no MTrP is detected, a random area within the muscle of interest will be marked instead. In both cases, a cross will be drawn to ensure precision in ultrasound probe placement for both longitudinal and transverse sections. This dual evaluation approach, combining manual palpation and ultrasound, aims to provide a comprehensive and reliable assessment of MTrPs in superficial muscles. The results will further clarify the effectiveness and accuracy of the MTrP exploration protocol, offering essential insights for clinicians and researchers involved in myofascial pain diagnosis and treatment.
Study Type
OBSERVATIONAL
Enrollment
60
Both groups of participants-those with myofascial and/or musculoskeletal pain and those without musculoskeletal alterations-will undergo a standardized intervention focused on the application of vibratory stimuli, alongside real-time ultrasound imaging. Vibratory stimuli will be applied directly to the region of interest, specifically over the identified MTrP in participants with active myofascial pain. In participants without musculoskeletal alterations, the stimuli will be applied either over a latent MTrP or in a randomly selected area of the gastrocnemius medialis muscle, ensuring a consistent methodology across both groups. Simultaneously, real-time ultrasound imaging will be performed to capture detailed images of the muscle tissue during the application of vibratory stimuli. Imaging will be conducted in two planes (longitudinally and transversely).
Centro de Salud Romareda-Seminario
Zaragoza, Aragon, Spain
Faculty of Health Sciences of the University of Zaragoza
Zaragoza, Aragon, Spain
Echovariation
Echovariation is the primary variable of interest in this study. It refers to the variability of pixel intensities within an ultrasound image and is calculated as the ratio of the standard deviation to the mean echogenicity (brightness) of the image. This metric allows for an assessment of the texture and homogeneity of the tissue, providing insight into potential abnormalities such as the presence of myofascial trigger points (MTrPs). Echovariation is a key indicator of muscle tissue´s structural integrity and is critical in differentiating between healthy and pathological regions. The evaluation of echovariation will be conducted on ultrasound images captured from gastrocnemius medialis muscle in both longitudinal and transverse planes.
Time frame: At a single 1 day time point
Muscle thickness
Muscle thickness refers to the greatest distance between the superior and inferior edges of a muscle, measured in millimeters. This variable provides a morphometric analysis of muscle size and is particularly useful for identifying any changes in muscle structure related to the presence of MTrPs. Ultrasound images will be used to measure the muscle thickness at predefined anatomical landmarks in the gastrocnemius medialis muscle.
Time frame: At a single 1 day time point
Mean echogenicity
Mean echogenicity refers to the average brightness level of the pixels in the ultrasound image. It is a measure of tissue density and is influenced by the structural composition of the muscle. In this study, mean echogenicity will be quantified to assess the relative brightness of muscle tissue in participants, with a focus on identifying any deviations that may indicate the presence of MTrPs or other pathologies.
Time frame: At a single 1 day time point
Myofascial trigger point area
The area of myofascial trigger points (MTrPs) will be calculated from ultrasound images by delineating the boundary of each identified trigger point. This provides an additional dimension to the morphometric analysis and offers insight into the size and spatial distribution of the MTrPs within the muscle tissue. The area will be measured in square millimeters and compared across participants with and without active MTrPs.
Time frame: At a single 1 day time point
Grey Level Run-Length Matrices (GLRLM)
GLRLM calculates statistics based on the length of consecutive pixels that have the same grey level in an ultrasound image. This method identifies the homogeneity of pixel intensities over specific regions of the image, contributing to the understanding of the internal architecture of the muscle. The GLRLM analysis will focus on determining the presence of consistent grey-level patterns that may be indicative of structural alterations in the muscle tissue related to MTrPs.
Time frame: At a single 1 day time point
Pressure Pain Threshold (PPT)
Pressure pain threshold (PPT) will be measured using a handheld pressure algometer, which quantifies the amount of pressure applied to a specific point on the body until the participant perceives pain. The measurement will be conducted with participants lying in a supine or prone position, depending on the muscle group being assessed. Three consecutive trials will be performed at 30-second intervals, and the mean value will be used for analysis, reported in kg/cm². Prior to measurement, participants will be familiarized with the algometer to ensure they can accurately identify when the sensation of pressure transitions into pain. The reliability of PPT measurements has been shown to be excellent when performed in triplicate within the same session.
Time frame: At a single 1 day time point
Grey Level Co-occurrence Matrices (GLCM)
GLCM is a texture analysis method used to quantify the spatial relationship between pairs of pixels within an ultrasound image. It measures the frequency and correlation of grey-level values at specific distances and angles within the image. This analysis will be performed on regions of interest in both healthy and pathological muscle tissue to asses tissue texture complexity and heterogeneity.
Time frame: At a single 1 day time point
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