Women with Chronic Pelvic Pain Demonstrate Increased Lumbopelvic Muscle Stiffness Compared to Asymptomatic Controls.

Background: Although lumbopelvic muscle stiffness is commonly clinically assessed in women with chronic pelvic pain (CPP), it has not been objectively quantified in this population, and its association with other pain-related impairments has not yet been established. Objective: To compare superficial lumbopelvic muscle stiffness in women with and without CPP. In addition, pressure pain threshold (PPT) was compared between groups and the associations between muscle stiffness and PPT were assessed in women with CPP. Study Design: Case-control. Methods: Muscle stiffness and PPT of 11 lumbopelvic muscles were assessed in 149 women with CPP and 48 asymptomatic women. Subjective outcome measures, including pelvic floor function, health history, and psychosocial outcomes, were collected before muscle stiffness and PPT measurements. Analysis of covariance was used to compare muscle stiffness differences between groups, and independent t-tests were used to compare PPT between groups. Associations between measurements of PPT and muscle stiffness were calculated using correlation analysis. Results: Five of the 11 muscles measured were significantly stiffer in women with CPP than those without CPP (p < 0.05). PPT was significantly decreased in all muscles measured in women with CPP; however, there was not a significant association between muscle stiffness and PPT in women with CPP. Conclusion: The study identified the abdominal lumbopelvic muscles that have increased stiffness in women with CPP compared to asymptomatic women. In addition, muscle stiffness and PPT are two distinct impairments within this population. The results suggest that women with CPP have peripheral muscle impairments, which may be addressed without intravaginal or intrarectal intervention. Clinical Trial Registration: NCT04851730.

Effect of dry needling on lumbar muscle stiffness in patients with low back pain: A double blind, randomized controlled trial using shear wave elastography.

BACKGROUND: Dry needling treatment focuses on restoring normal muscle function in patients with musculoskeletal pain; however, little research has investigated this assertion. Shear wave elastography (SWE) allows quantification of individual muscle function by estimating both resting and contracted muscle stiffness. OBJECTIVE: To compare the effects of dry needling to sham dry needling on lumbar muscle stiffness in individuals with low back pain (LBP) using SWE. METHODS: Sixty participants with LBP were randomly allocated to receive one session of dry needling or sham dry needling treatment to the lumbar multifidus and erector spinae muscles on the most painful side and spinal level. Stiffness (shear modulus) of the lumbar multifidus and erector spinae muscles was assessed using SWE at rest and during submaximal contraction before treatment, immediately after treatment, and 1 week later. Treatment effects were estimated using linear mixed models. RESULTS: After 1 week, resting erector spinae muscle stiffness was lower in individuals who received dry needling than those that received sham dry needling. All other between-groups differences in muscle stiffness were similar, but non-significant. CONCLUSION: Dry needling appears to reduce resting erector spinae muscle following treatment of patients with LBP. Therefore, providers should consider the use of dry needling when patients exhibit aberrant stiffness of the lumbar muscles.

Lumbar muscle stiffness is different in individuals with low back pain than asymptomatic controls and is associated with pain and disability, but not common physical examination findings.

BACKGROUND: Lumbar muscle dysfunction is commonly implicated in low back pain (LBP). Shear-wave elastography (SWE) uses ultrasound technology to quantify absolute soft tissue stiffness (shear modulus), thereby allowing for estimation of individual muscle contraction and function. OBJECTIVES: To compare resting and contracted stiffness of lumbar spine musculature in individuals with and without LBP using SWE. A secondary aim was to explore for relationships between common self-report and physical examination measures and resting and contracted muscle stiffness in individuals with LBP. DESIGN: Cross-sectional. METHODS: Shear modulus of the lumbar musculature was measured in 60 participants with LBP and 60 asymptomatic controls (120 total) using SWE. The lumbar erector spinae were imaged at rest only, while the lumbar multifidus was imaged at rest and during contraction. Before imaging, participants with LBP underwent a standardized clinical examination including a brief history, self-report questionnaires, and a physical examination. Lumbar muscle shear modulus was compared between participants with LBP and asymptomatic controls using ANCOVA. Potential associations between shear modulus and selected self-report and physical examination measures were assessed using correlation analysis. RESULTS: Stiffness of the erector spinae and lumbar multifidus at rest (but not during contraction) was greater in participants with LBP than in asymptomatic controls (p < 0.05). Many of the self-report measures, but none of the physical examination findings were associated with muscle stiffness. CONCLUSION: Resting lumbar muscle stiffness is greater in individuals with LBP than asymptomatic controls and is associated with self-reported pain and disability, but not physical exam findings.

Characterization of tissue stiffness of the infraspinatus, erector spinae, and gastrocnemius muscle using ultrasound shear wave elastography and superficial mechanical deformation.

The aim of this study was to compare measurement methods of tissue stiffness using ultrasound shear wave elastography (SWE) and superficial mechanical deformation (MyotonPRO) in the infraspinatus, erector spinae, and gastrocnemius muscles. Thirty healthy volunteers were assessed during rest, 40% and 80% maximum voluntary isometric contraction (MVIC). Correlation of the two methods in the three muscle regions was significant (r = 0.23-0.71, p < .05), and strongest in the gastrocnemius. MyotonPRO reliability was excellent (ICC > 0.93), and demonstrated ability to discriminate between the three levels of muscle contraction. SWE demonstrated good reliability in the resting condition (ICC > 0.88), but lower during the 2 MVIC conditions. The utility of SWE during isometric contraction may be limited due to the inability to discriminate between 40% and 80% MVIC.