Ultrasound Strain Elastography in Assessment of Muscle Stiffness in Acute Levodopa Challenge Test: A Feasibility Study

Stretchable ultrasonic arrays for the three-dimensional mapping of the modulus of deep tissue

Serial assessment of the biomechanical properties of tissues can be used to aid the early detection and management of pathophysiological conditions, to track the evolution of lesions and to evaluate the progress of rehabilitation. However, current methods are invasive, can be used only for short-term measurements, or have insufficient penetration depth or spatial resolution. Here we describe a stretchable ultrasonic array for performing serial non-invasive elastographic measurements of tissues up to 4 cm beneath the skin at a spatial resolution of 0.5 mm. The array conforms to human skin and acoustically couples with it, allowing for accurate elastographic imaging, which we validated via magnetic resonance elastography. We used the device to map three-dimensional distributions of the Young's modulus of tissues ex vivo, to detect microstructural damage in the muscles of volunteers before the onset of soreness and to monitor the dynamic recovery process of muscle injuries during physiotherapies. The technology may facilitate the diagnosis and treatment of diseases affecting tissue biomechanics.

Objective Methods of Muscle Tone Diagnosis and Their Application-A Critical Review

"Muscle tone" is a clinically important and widely used term and palpation is a crucial skill for its diagnosis. However, the term is defined rather vaguely, and palpation is not measurable objectively. Therefore, several methods have been developed to measure muscle tone objectively, in terms of biomechanical properties of the muscle. This article aims to summarize these approaches. Through database searches, we identified those studies related to objective muscle tone measurement in vivo, in situ. Based on them, we described existing methods and devices and compared their reliability. Furthermore, we presented an extensive list of the use of these methods in different fields of research. Although it is believed by some authors that palpation cannot be replaced by a mechanical device, several methods have already proved their utility in muscle biomechanical property diagnosis. There appear to be two issues preventing wider usage of these objective methods in clinical practice. Firstly, a high variability of their reliability, and secondly, a lack of valid mathematical models that would provide the observed mechanical characteristics with a clear physical significance and allow the results to be compared with each other.

Skeletal Muscle Assessment Using Quantitative Ultrasound: A Narrative Review

Ultrasound (US) is an important imaging tool for skeletal muscle analysis. The advantages of US include point-of-care access, real-time imaging, cost-effectiveness, and absence of ionizing radiation. However, US can be highly dependent on the operator and/or US system, and a portion of the potentially useful information carried by raw sonographic data is discarded in image formation for routine qualitative US. Quantitative ultrasound (QUS) methods provide analysis of the raw or post-processed data, revealing additional information about normal tissue structure and disease status. There are four QUS categories that can be used on muscle and are important to review. First, quantitative data derived from B-mode images can help determine the macrostructural anatomy and microstructural morphology of muscle tissues. Second, US elastography can provide information about muscle elasticity or stiffness through strain elastography or shear wave elastography (SWE). Strain elastography measures the induced tissue strain caused either by internal or external compression by tracking tissue displacement with detectable speckle in B-mode images of the examined tissue. SWE measures the speed of induced shear waves traveling through the tissue to estimate the tissue elasticity. These shear waves may be produced using external mechanical vibrations or internal "push pulse" ultrasound stimuli. Third, raw radiofrequency signal analyses provide estimates of fundamental tissue parameters, such as the speed of sound, attenuation coefficient, and backscatter coefficient, which correspond to information about muscle tissue microstructure and composition. Lastly, envelope statistical analyses apply various probability distributions to estimate the number density of scatterers and quantify coherent to incoherent signals, thus providing information about microstructural properties of muscle tissue. This review will examine these QUS techniques, published results on QUS evaluation of skeletal muscles, and the strengths and limitations of QUS in skeletal muscle analysis.

Levodopa challenge test: indications, protocol, and guide

A drug challenge test in Parkinson's disease, such as the levodopa challenge test (LCT), is an easy and generally safe procedure, which has been used by clinicians for various indications. The results of the test have significant implications in the management of patients, from preoperative evaluation for deep brain stimulation to providing the basis for medication adjustments to address motor or non-motor fluctuations and dyskinesias. This paper reviews the different indications and protocols commonly used in an acute LCT. Potential complications of the procedure and an overview of levodopa responsiveness and unresponsiveness are also discussed.

Quantitative Measurement of Rigidity in Parkinson´s Disease: A Systematic Review

Rigidity is one of the cardinal symptoms of Parkinson´s disease (PD). Present in up 89% of cases, it is typically assessed with clinical scales. However, these instruments show limitations due to their subjectivity and poor intra- and inter-rater reliability. To compile all of the objective quantitative methods used to assess rigidity in PD and to study their validity and reliability, a systematic review was conducted using the Web of Science, PubMed, and Scopus databases. Studies from January 1975 to June 2019 were included, all of which were written in English. The Strengthening the Reporting of observational studies in Epidemiology Statement (STROBE) checklist for observational studies was used to assess the methodological rigor of the included studies. Thirty-six studies were included. Rigidity was quantitatively assessed in three ways, using servomotors, inertial sensors, and biomechanical and neurophysiological study of muscles. All methods showed good validity and reliability, good correlation with clinical scales, and were useful for detecting rigidity and studying its evolution. People with PD exhibit higher values in terms of objective muscle stiffness than healthy controls. Rigidity depends on the angular velocity and articular amplitude of the mobilization applied. There are objective, valid, and reliable methods that can be used to quantitatively assess rigidity in people with PD.

Quantitative Ultrasound Imaging to Assess Skeletal Muscles in Adults with Multiple Sclerosis: A Feasibility Study

OBJECTIVES

The aim of this study was to assess the feasibility of quantitative ultrasound imaging (QUI) in assessing the biceps brachii muscle and gastrocnemius muscle in adults with multiple sclerosis (MS).

METHODS

From May to October 2018, we prospectively performed B-mode ultrasound imaging and ultrasound strain elastography of the biceps brachii muscle and gastrocnemius muscle in 24 patients with MS and 10 age-matched healthy volunteers. ImageJ (https://imagej.nih.gov/ij) was used to assess the muscle pixel intensity in grayscale images. Using 2-dimensional speckle-tracking software, we estimated the muscle axial peak strain (maximum deformation) produced by manual compression with an ultrasound transducer and the muscle longitudinal peak strain (maximum displacement) produced by passive elbow and ankle movements. Muscle QUI parameters used in the study included the mean pixel intensity, axial peak strain ratio (SR = muscle strain/subcutaneous tissue strain), and longitudinal peak SR. Statistical analyses included 1-way analysis of variance and a post hoc test to examine the differences in QUI parameters among 3 groups (1, affected muscle in patients with MS; 2, unaffected muscle in patients with MS; and 3, healthy muscle in controls) and, in all paired groups, an unpaired t test to compare the muscle SR in patients with MS with a Modified Ashworth Scale (MAS) score of 1 or higher to those with an MAS score of 0.

RESULTS

The mean age of the 24 patients with MS was 43 years, and all patients and volunteers were female. We observed a significant difference in QUI parameters among the affected muscle in MS, unaffected muscle in MS, and healthy muscle in all paired groups and in patients with MS between an MAS score of 1 or higher and an MAS score of 0 (all P < .05). Interobserver and intraobserver variability in performing QUI was good (intraclass correlation coefficients >0.75).

CONCLUSIONS

Our results suggest that QUI is feasible to assess muscle echogenicity and mechanical behaviors in adult MS.

Effects of physical therapy agents on pain, disability, quality of life, and lumbar paravertebral muscle stiffness via elastography in patients with chronic low back pain

Objectives

This study aims to evaluate early effects of combined hot pack (HP) and transcutaneous electrical nerve stimulation (TENS) treatment and therapeutic ultrasound (US) on pain, quality of life, disability, and the multifidus muscle stiffness.

Patients and methods

Between December 2016 and March 2017, a total of 69 patients (36 females, 33 males; mean age 48.9±10.9; range, 27 to 73 years) were included in this randomized-controlled study. The patients were divided into three groups as HT + TENS (Group H+T, n=23), HP + TENS + US (Group H+T+U, n=23), and controls (control group, n=23). All patients filled out the Numeric Rating Scale (NRS), Oswestry Disability Index (ODI), and Short Form-36 (SF-36) questionnaire at baseline and at the end of treatment. The left multifidus muscle strain ratio at fourth lumbar spinal level was obtained from the upper, middle, and lower parts of the muscle along the longitudinal axis on the first and last days of treatment.

Results

There was a significant improvement in the NRS, ODI, and SF-36 physical function, physical role function, pain, and general health perceptions in the H+T and H+T+U groups, compared to the control group (p<0.05). However, there was no significant difference between the H+T and H+T+U groups. The H+T+U group showed an improvement in the SF-36 social role function and emotional role function. There was no significant difference in the multifidus muscle strain ratios among the groups.

Conclusion

Our study results suggest that H+T treatment has a beneficial effect on pain, disability, and certain subscales of the quality of life. However, US seems not to have an additional benefit.