Ultrasound elastography as a potential method to evaluate entrapment neuropathies in elite athletes: a mini-review

In Vivo Effects of Joint Movement on Nerve Mechanical Properties Assessed with Shear-Wave Elastography: A Systematic Review and Meta-Analysis

Peripheral nerves are subjected to mechanical tension during limb movements and body postures. Nerve response to tensile stress can be assessed in vivo with shear-wave elastography (SWE). Greater tensile loads can lead to greater stiffness, which can be quantified using SWE. Therefore, this study aimed to conduct a systematic review and meta-analysis to perform an overview of the effect of joint movements on nerve mechanical properties in healthy nerves. The initial search (July 2023) yielded 501 records from six databases (PubMed, Embase, Scopus, Web of Science, Cochrane, and Science Direct). A total of 16 studies were included and assessed with a modified version of the Downs and Black checklist. Our results suggest an overall tendency for stiffness increase according to a pattern of neural tensioning. The main findings from the meta-analysis showed a significant increase in nerve stiffness for the median nerve with wrist extension (SMD [95%CI]: 3.16 [1.20, 5.12]), the ulnar nerve with elbow flexion (SMD [95%CI]: 2.91 [1.88, 3.95]), the sciatic nerve with ankle dorsiflexion (SMD [95%CI]: 1.13 [0.79, 1.47]), and the tibial nerve with both hip flexion (SMD [95%CI]: 2.14 [1.76, 2.51]) and ankle dorsiflexion (SMD [95%CI]: 1.52 [1.02, 2.02]). The effect of joint movement on nerve stiffness also depends on the nerve segment, the amount of movement of the joint mobilized, and the position of other joints comprised in the entirety of the nerve length. However, due to the limited number of studies, many aspects of nerve behavior together with the effect of using different ultrasound equipment or transducers for nerve stiffness evaluation still need to be fully investigated.

Shear wave elastography of the common fibular nerve at the fibular head

ABSTRACT

The aim of this work is to study the sonoelastographic features of the common fibular nerve in healthy adult subjects.This is an observational cross-sectional study. Shear wave elastography was used to evaluate the common fibular nerve. Crosssectional area and stiffness were measured in kilopascal (kPa) and meters/second (m/s).The study included 82 common fibular nerves in 41 healthy adult subjects. The mean cross-sectional area of the common fibular nerve at the fibular head was 8.7 mm2. Positive correlation was noted between stiffness measurements between short and long axes by both methods. The mean stiffness of the common fibular nerve in the short axis was 22.5 kPa, and in the long axis (LA) was 35.4 kPa. Positive correlation was noted between height and stiffness measured by both methods in both axes by kPa. In m/s, the mean stiffness of the common fibular in the short axis was 2.6 m/s, and while in the LA was 3.4 m/s. Height showed positive correlation with both axes for stiff measurements in m\s. Weight showed positive correlation with stiffness measurements by m/s in the LA.The results obtained in our study could be a reference point for evaluating stiffness of the common fibular nerve in research involving different pathologies.

Diagnosis of Carpal Tunnel Syndrome using Shear Wave Elastography and High-frequency Ultrasound Imaging

OBJECTIVES

The performance of ultrasound features from shear wave elastography (SWE) and high-frequency ultrasound imaging was evaluated independently and in combination to diagnose carpal tunnel syndrome (CTS).

MATERIALS AND METHODS

Twenty-five subjects were imaged in a sitting position with an arm extended and palm facing up. SWE of the medial nerve (MN) was acquired at the wrist level (site 1) and proximal to the pronator quadratus muscle (site 2). Cross-sectional area (CSA) and vascularity of the MN were assessed at the wrist using a 24 MHz probe. Color and power Doppler imaging (CDI and PDI), monochrome and color-coded Superb Microvascular Imaging (SMI) were performed for vascularity assessments. The diagnosis and severity of CTS was determined by clinical and electrodiagnostic tests. Diagnostic performance of the ultrasound features was assessed by t-tests, ANOVAs, and ROC analysis.

RESULTS

The study included 20 control hands and 27 hands with CTS. All ultrasound features except for the stiffness ratio were significantly different between the CTS and control wrists (p<0.04). The stiffness of MN at site 1 showed a higher accuracy than at site 2. The combination of CSA and MN stiffness from site 2 showed an overall accuracy of 95% with a specificity and sensitivity of 100% and 93%, respectively. The CSA, MN stiffness from site 2, and CDI combination improved the accuracy to 96% with specificity and sensitivity of 100% and 93%, respectively. However, no ultrasound features (independently or in combination) differentiated all stages of CTS severity.

CONCLUSIONS

SWE with high-frequency ultrasound imaging showed potential for the diagnosis of CTS.

Imaging of traumatic peripheral nerve injuries

Nerves are commonly injured in case of blunt or penetrating trauma to the extremities. Patients with nerve injuries have profound consequences and thus a timely decision for operative management is a very important. Conventionally, management decisions have been based on clinical findings, patient course and electrophysiological studies. However, imaging modalities have an enormous role not only in localizing and grading of the nerve injuries but also in the follow-up of the nerve recovery. High-resolution ultrasound (HUS) is the modality of choice for evaluation of peripheral nerves. Magnetic resonance neurography (MRN) plays a complementary role, enabling better assessment of muscle changes and deeper nerves. Corresponding to the injured layer of the cross-section of the nerve, imaging manifestations differ in different grades of injury. Since imaging cannot detect ultrastructural changes at the microscopic level, thus there may be overlap in the imaging findings. Herewith, we discuss the imaging findings in different grades of nerve injury and propose a simple 3-tier grading for imaging (HUS and MRN) assessment of peripheral nerve injuries.

Shear wave elastography of the radial nerve in healthy subjects

Objective

This study was performed to examine the sonoelastographic features of the radial nerve in healthy subjects.

Methods

In this observational cross-sectional study, shear wave elastography was used to evaluate the radial nerve. The cross-sectional area and stiffness were measured.

Results

The study included 37 nerves in 20 healthy adult subjects. The mean cross-sectional area of the radial nerve at the arm was 6.1 mm². The mean stiffness of the radial nerve in the short axis was 30.3 kPa, and that in the long axis was 34.9 kPa. The elasticity measurements were significantly different between the long axis and short axis.

Conclusion

The elastic modulus of the radial nerve was studied in healthy subjects and can serve as a reference for future assessment of different radial nerve pathologies.

Effect of Perineural Injection with Different Dextrose Volumes on Median Nerve Size, Elasticity and Mobility in Hands with Carpal Tunnel Syndrome

This study aimed to investigate the effect of different injectate volumes on ultrasonographic parameters and the correlation to clinical outcomes under perineural dextrose injection (PDI). In this post hoc analysis of the randomized, double-blinded, three-arm trial, ultrasound-guided PDI with either 1 mL, 2 mL, and 4 mL 5% dextrose water was administered, respectively, in 14, 14, and 17 patients. Ultrasound outcomes included mobility, shear-wave elastography (SWE), and cross-sectional area (CSA) of the median nerve; clinical outcomes were Visual Analog Scale (VAS) and Boston Carpal Tunnel Questionnaire (BCTQ) score. Outcomes were measured before injection, and after injection at the 1st, 4th, 12th, and 24th week. For ultrasound outcomes, CSA decreased significantly from baseline data at all follow-up time-points in the 2 mL group (p = 0.005) and the 4 mL group (p = 0.015). The mean change of mobility from baseline showed a greater improvement on the 4 mL group than the other groups at the 1st week post-injection. For clinical outcomes, negative correlation between the VAS and mobility at the 1st (p = 0.046) and 4th week (p = 0.031) post-injection in the 4 mL group were observed. In conclusion, PDI with higher volume yielded better nerve mobility and decreased CSA of median nerve, but no changes of nerve elasticity.

Shear wave elastography of the tibial nerve in healthy subjects

The purpose of this study is to investigate sonoelastographic features of the tibial nerve.The study included 72 tibial nerves in 36 healthy subjects. High resolution ultrasound and Shear wave elastography were used to evaluate the tibial nerve. Cross sectional area and stiffness were measured.The mean cross sectional area of the tibial nerve was 13.4 mm2. The mean shear elastic modulus of the tibial nerve in the short axis was 23.3 kPa. The mean shear elastic modulus of the tibial nerve in long axis was 26.1 kPa. The tibial nerve elastic modulus also showed no correlation with cross sectional area neither in the long axis nor short axis. Age, height, weight, and body mass index showed no correlation with tibial nerve elastic modulus in short or long axes.The elastic modulus of the tibial nerve has been determined in healthy subjects and can serve as a reference for future assessment of polyneuropathy.

Shear wave elastography of the ulnar nerve at the forearm

The study included 38 ulnar nerves in 20 healthy subjects. High-resolution ultrasound and Shear wave elastography were used to evaluate the ulnar nerve at the mid forearm. The mean cross-sectional area of the ulnar nerve was 7.1 mm2. The mean shear elastic modulus of the nerve in the short axis was 27.4 kPa. The mean shear elastic modulus of the nerve in long axis was 24.7 kPa. No statistical relation could be noted between elasticity measurements in long and short axes. The ulnar nerve elastic modulus also showed no correlation with CSA neither in the long axis nor short axis. Age, height, weight, and body mass index showed no correlation with the ulnar elastic modulus in short or long axes. The elastic modulus of the ulnar nerve has been determined in healthy subjects and can serve as a reference for future assessment of compressive neuropathies of the ulnar nerve.

Shear wave elastography of the saphenous nerve

The purpose of this study is to study sonoelastographic features of the saphenous nerve.The study included 72 saphenous nerves in 36 healthy subjects. High resolution ultrasound and Shearwave elastography were used to evaluate the saphenous nerve. Cross sectional area (CSA) and stiffness were measured.The mean CSA of the saphenous nerve was 5.7 mm. The mean shear elastic modulus of the saphenous nerve in the short axis was 29.5 kPa. The mean shear elastic modulus of the saphenous nerve in long axis was 29.9 kPa. The saphenous nerve elastic modulus also showed no correlation with CSA in neither the long axis nor short axis. Positive correlation between elasticity measurements in the long and short axes. Age, height, weight, and BMI showed no correlation with saphenous nerve elastic modulus in short or long axes.The elastic modulus of the saphenous nerve has been determined in healthy subjects and can serve as a reference for future assessment of the saphenous nerve before different procedures.