The effect of spinal position on sciatic nerve excursion during seated neural mobilisation exercises: an in vivo study using ultrasound imaging

Longitudinal Movements and Stiffness of Lower Extremity Nerves Measured by Ultrasonography and Ultrasound Elastography in Symptomatic and Asymptomatic Populations: A Systematic Review With Meta-analysis

This study was aimed at analyzing the effectiveness of ultrasonography (US) and ultrasound elastography (UE) in evaluating longitudinal sliding and stiffness of nerves. In line with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement, we analyzed 1112 publications (range: 2010-2021) extracted from MEDLINE, Scopus and Web of Science focusing on specific outcomes, including shear wave velocity (m/s), shear modulus (kPa), strain ratio (SR) and excursion (mm). Thirty-three papers were included and evaluated for overall quality and risk of bias. From the analysis of data concerning 1435 participants, mean shear wave velocity (SWV) in the sciatic nerve was 6.70 ± 1.26 m/s in controls and 7.51 ± 1.73 m/s in participants presenting with leg pain; in the tibial nerve, mean SWV was 3.83 ± 0.33 m/s in controls and 3.42 ± 3.53 m/s in participants presenting with diabetic peripheral neuropathy (DPN). The mean shear modulus (SM) was 20.9 ± 9.33 kPa for sciatic nerve, whereas it was an average of 23.3 ± 7.20 kPa for the tibial nerve. Considering 146 subjects (78 experimental, 68 controls) no significant difference was observed in SWV when comparing participants with DPN with controls (standard mean difference [SMD]: 1.26, 95% confidence interval [CI]: 0.54, 1.97), whereas a significant difference was observed in the SM (SMD: 1.78, 95% CI: 1.32, 2.25); furthermore, we found significant differences between left and right extremity nerves (SMD:1.14. 95% CI: 0.45, 1.83) among 458 participants (270 with DPN and 188 controls). No descriptive statistics are available for excursion because of the variability in participants and limb positions, whereas SR is considered only a semiquantitative outcome and therefore not comparable among different studies. Despite the presence of some limitations in study designs and methodological biases, on the basis of our findings, we can conclude that US and UE are effective methods in assessing longitudinal sliding and stiffness of lower extremity nerves in both symptomatic and asymptomatic subjects.

Assessing Sciatic Nerve Excursion and Strain with Ultrasound Imaging during Forward Bending

Entrapment neuropathies affecting the sciatic nerve tract may adversely affect neural biomechanical features such as excursion and strain. There is a paucity of in vivo evidence examining the effects of forward bending upon sciatic nerve excursion and strain. The purpose of this study was to assess the reliability of ultrasound imaging in measuring sciatic nerve excursion and strain during forward bending movements. Secondary aims were to quantify sciatic nerve excursion and strain during forward bending movements and to assess the relationship between sciatic nerve excursion and movements of the hip and lumbar spine. The reliability of measuring sciatic nerve excursion was high to excellent whilst measurement of sciatic nerve strain was moderate. The amount of hip flexion, during forward bending, was a strong predictor of sciatic nerve excursion. These findings will support clinicians in the assessment and treatment of entrapment neuropathies, in addition to providing a foundation for future research.

Sciatic nerve excursion during neural mobilization with ankle movement using dynamic ultrasound imaging: a cross-sectional study

PURPOSE

Ankle movement is used as a sensitizing maneuver for sciatica during neurodynamic techniques. In vivo studies on the sciatic nerve biomechanics associated with ankle movement during different positions of neighboring joints are scarce. The aim of this study was to investigate sciatic nerve excursion during ankle dorsiflexion in different positions in a healthy population.

METHODS

This is a cross-sectional study. High-resolution dynamic ultrasound imaging was used to measure longitudinal excursion of the sciatic nerve in the posterior thigh of 27 healthy participants during ankle dorsiflexion in six positions of the neck, hip, and knee. Both the long and short distance of the nerve excursion were measured. Wilcoxon signed-rank tests were used for data analysis, and Eta squared (r) was used to quantify the effect size.

RESULTS

Ankle dorsiflexion resulted in distal sciatic nerve excursion that was significantly higher in positions in which the knee was extended (median 0.7-1.6 mm) than in positions in which the knee was flexed (median 0.5-1.4 mm) (P ≤ 0.049, r ≥ 0.379). There were no significant differences in nerve excursion between positions where the neck was neutral compared with positions where the neck was flexed (P ≥ 0.710, r ≤ 0.072) or between positions where the hip was neutral compared with positions where the hip was flexed (P ≥ 0.456, r ≤ 0.143).

CONCLUSION

The positions of adjacent joints, particularly the knee, had an impact on the excursion of the sciatic nerve in the thigh during ankle movement.

Inadequacies of the Lasègue test, and how the Slump and Bowstring tests are useful for the diagnosis of sciatica

Diagnosis of sciatica mainly relies on pain reproduction by stretching of the lumbar roots since neurological examination and medical history are usually not sufficient to guarantee diagnosis. The Lasègue test is the most popular method, which starts with the straight leg-raising test (SLR). However it is not perfect, and is not always well performed or interpreted. Passive ankle dorsiflexion at the end of the SLR (Bragard test) is more sensitive, but can also remain normal in some cases of sciatica. Other stretching tests can help to recognise lumbar root damage in patients with poorly defined pain in a lower extremity: firstly, the Christodoulides test, i.e. reproduction of L5 sciatic pain by a femoral stretch test; secondly, the Slump test, performed on a patient in a sitting position, by slowly extending their painful leg then passively bending their neck (or the opposite); and thirdly, the Bowstring test, which requires, at the end of the Lasègue test, once the knee has been slightly flexed, pressing on the course of the peroneal and/or tibial nerves in the popliteal fossea to try and reproduce the exact pain felt by the patient. The combination of all these tests takes less than 2minutes, and could improve both the sensitivity and specificity of the physical examination for the diagnosis of sciatica. This article is a review of the limitations of the Lasègue/SLR tests and of the efficacy of these other tests for stretching the lumbar roots.

Quantitative Ultrasound Imaging Pixel Analysis of the Intrinsic Plantar Muscle Tissue between Hemiparesis and Contralateral Feet in Post-Stroke Patients

Quantitative ultrasound imaging of the muscle tissue may be applied in the neurology field, due to B-mode grayscale pixels values could be used as potential biomarkers for disease progression and intervention effects in poststroke patients. Thus, the study aim was to compare and analyze the ultrasound imaging B-mode pixels differences between the intrinsic plantar muscles cross-sectional area (CSA) in hemiparetic and contralateral feet from poststroke patients by means of the Image J software. A case-control design and a convenience sampling method were used in order to recruit 22 feet from 11 poststroke patients. This total sample was divided into 11 hemiparetic feet and 11 contralateral feet. The Image J software was used in order to evaluate the interface distance, CSA as well as measure the pixels mean, standard deviation (SD) and count from all offline images in the flexor digitorum brevis, abductor hallucis (AbH), and flexor hallucis brevis muscles. Statistically significant differences (p = 0.003) were only shown for the pixels count in the AbH muscle. The rest of outcome measurements did not show any statistically significant difference (p > 0.05). Therefore, B-mode ultrasound imaging Image J software differences for the pixels count reduction were shown in the AbH muscle between hemiparetic and contralateral feet from poststroke patients. Further studies are necessary in order to apply our findings as potential biomarkers during the stroke disease course.

Femoral nerve excursion with knee and neck movements in supine, sitting and side-lying slump: An in vivo study using ultrasound imaging

BACKGROUND

Neurodynamic assessment and management are advocated for femoral nerve pathology. Contrary to neurodynamic techniques for other nerves, there is limited research that quantifies femoral nerve biomechanics.

OBJECTIVES

To quantify longitudinal and transverse excursion of the femoral nerve during knee and neck movements.

DESIGN

Single-group, experimental study, with within-participant comparisons.

METHODS

High-resolution ultrasound recordings of the femoral nerve were made in the proximal thigh/groin region in 30 asymptomatic participants. Scans were made during knee flexion in supine and a semi-seated position, and during neck flexion in side-lying slump (Slump _FEMORAL). Healthy participants were assessed to reveal normal nerve biomechanics, not influenced by pathology. Data were analysed with one-sample and paired t-tests. Reliability was assessed with intraclass correlation coefficients (ICC).

RESULTS

Longitudinal and transverse excursion measurements were reliable (ICC≥0.87). With knee flexion, longitudinal femoral nerve excursion was significant and larger in supine than in sitting (supine (mean (SD)): 3.6 (2.0) mm; p < 0.001; sitting: 1.1 (1.6) mm; p = 0.001; comparison: p = 0.001). There was also excursion in a medial direction (supine: 1.4 (0.3) mm; p < 0.001; sitting: 0.7 (0.6) mm; p < 0.001) and anterior direction (supine: 0.2 (0.2) mm; p < 0.001; sitting: 0.1 (0.2) mm; p = 0.06). Neck flexion in Slump _FEMORAL did not result in longitudinal (0.0 (0.3) mm; p = 0.55) or anteroposterior (0.0 (0.1) mm; p = 0.10) excursion, but resulted in medial excursion (1.1 (0.5) mm; p < 0.001).

CONCLUSION

Although the femoral nerve terminates proximal to the knee, femoral nerve excursion in the proximal thigh occurred with knee flexion; Neck flexion in Slump _FEMORAL resulted in medial excursion.

Ultrasound Elastographic Measurement of Sciatic Nerve Displacement and Shear Strain During Active and Passive Knee Extension

There is current need for objective measures of sciatic nerve mobility in patients with sciatic-type pain. The objective of the study was to assess the feasibility and reliability of ultrasound elastography to quantify sciatic nerve displacement and shear strain at the sciatic nerve-hamstring muscle interface during active and passive knee extension-flexion exercises performed while sitting in healthy people. Ultrasound elastography showed excellent intrarater within-session reliability for assessing sciatic nerve displacement and sciatic nerve-hamstring muscle interface shear strain during active knee extension-flexion exercises. These findings will inform similar future work conducted in patients with sciatic-type pain.

Ultrasound assessment of fascial connectivity in the lower limb during maximal cervical flexion: technical aspects and practical application of automatic tracking

Background

The fascia provides and transmits forces for connective tissues, thereby regulating human posture and movement. One way to assess the myofascial interaction is a fascia ultrasound recording. Ultrasound can follow fascial displacement either manually or automatically through two-dimensional (2D) method. One possible method is the iterated Lucas-Kanade Pyramid (LKP) algorithm, which is based on automatic pixel tracking during passive movements in 2D fascial displacement assessments. Until now, the accumulated error over time has not been considered, even though it could be crucial for detecting fascial displacement in low amplitude movements.

The aim of this study was to assess displacement of the medial gastrocnemius fascia during cervical spine flexion in a kyphotic posture with the knees extended and ankles at 90°.

Methods

The ultrasound transducer was placed on the extreme dominant belly of the medial gastrocnemius. Displacement was calculated from nine automatically selected tracking points. To determine cervical flexion, an established 2D marker protocol was implemented. Offline pressure sensors were used to synchronize the 2D kinematic data from cervical flexion and deep fascia displacement of the medial gastrocnemius.

Results

Fifteen participants performed the cervical flexion task. The basal tracking error was 0.0211 mm. In 66 % of the subjects, a proximal fascial tissue displacement of the fascia above the basal error (0.076 mm ± 0.006 mm) was measured. Fascia displacement onset during cervical spine flexion was detected over 70 % of the cycle; however, only when detected for more than 80 % of the cycle was displacement considered statistically significant as compared to the first 10 % of the cycle (ANOVA, p < 0.05).

Conclusion

By using an automated tracking method, the present analyses suggest statistically significant displacement of deep fascia. Further studies are needed to corroborate and fully understand the mechanisms associated with these results.