Predominant patterns of median nerve displacement and deformation during individual finger motion in early carpal tunnel syndrome

Median nerve versus flexor tendons: visualization of median nerve level changes in the proximal carpal tunnel during wrist movement with dynamic high-resolution ultrasound

Aim

The purpose of this prospective ultrasound study was to document dorso-palmar (vertical) displacement of the median nerve in relation to the superficial flexor tendons at the level of the carpal tunnel. Furthermore, the gliding patterns of the median nerve were characterized. The presence of vertical gliding was intended to serve as an additional bio-kinematic parameter of median nerve movement, and will be referred to as a 'level change'.

Material and methods

In this study, a total of 32 healthy young individuals underwent dynamic high-resolution ultrasound examinations of both wrists. The neutral position, and maximum flexion and extension of the wrist had to be reached in active and passive movement. The gliding patterns were determined in relation to the superficial flexor tendons. When no vertical nerve gliding was observed, it was characterized as 'no level change'.

Results

The presence of a level change prevailed in the healthy young cohort and was observed in 84% (27/32) of individuals during wrist flexion. The following gliding pattern was distinctively the most common: gliding of the entire nerve in between the flexor tendons in active but not in passive movement of the right and left wrists (13/27; 48%). The extent of vertical displacement was found to be associated with the gliding pattern (Kruskal-Wallis test).

Conclusions

Movement in the carpal tunnel allows the median nerve to adapt to biomechanical stress. Dynamic ultrasound can demonstrate median nerve level changes in response to wrist movements. Furthermore, a typical gliding pattern was characterized. The presence of level change and gliding patterns were proposed as additional movement parameters during wrist flexion in healthy individuals.

Impaired median nerve mobility in patients with carpal tunnel syndrome: a systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis investigated the mobility of the median nerve (MN) in carpal tunnel syndrome (CTS) patients compared to healthy people.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline was followed and the electronic databases including PubMed, Scopus, EMBASE, and Cochrane Library were searched up to April 2022. All published observational studies comparing the excursion of MN between participants with and without CTS were included. The quality of research was assessed by the Newcastle-Ottawa Scale tool. The primary outcome was the excursion of the MN under dynamic examination, representing nerve mobility quantified by the standardized mean difference (SMD) for random effect meta-analysis.

RESULTS

Fourteen studies were included in the qualitative review, and twelve entered the meta-analysis involving a total of 375 CTS patients and 296 healthy controls. The forest plot revealed that the mobility of the MN significantly decreased in the CTS group compared to the non-CTS control (SMD = -1.47, 95% CI: -1.91, -1.03, p < 0.001, heterogeneity 82%). In subgroup analysis, both transverse and longitudinal methods for nerve excursion showed less nerve mobility in CTS than in non-CTS.

CONCLUSIONS

This meta-analysis showed that the patients with CTS exhibited less mobility of the MN than those without CTS, suggesting MN mobility as a potential CTS marker.

KEY POINTS

• The patients with CTS revealed less mobility of the median nerve than those without CTS. • The mobility of the median nerve could be regarded as a potential CTS marker.

The effects of wrist position and radioulnar wrist compression on median nerve longitudinal mobility

BACKGROUND

Carpal tunnel syndrome is an entrapment neuropathy at the wrist characterized by compromised median nerve mobility. The purpose of this study was to investigate the effect of wrist position on median nerve longitudinal mobility in healthy subjects and the effect of radioulnar wrist compression on the median nerve mobility under non-neutral wrist positions.

METHODS

Dynamic B mode ultrasound images captured longitudinal median nerve motion in the carpal tunnel in 10 healthy subjects at wrist neutral position, 30-degree flexion, and 30-degree extension. In each position, RWC of 0, 5, 10, and 15 N were applied. One-way repeated measure analysis of variance (ANOVA), Post-hoc Tukey's tests, and the Friedman Test were used to show the significant differences of median nerve longitudinal mobility at different wrist positions and force conditions.

FINDINGS

Median nerve longitudinal mobility was found to be significantly influenced by wrist position (P < 0.05). The mobility under wrist neutral position was 3.02 mm/s, 38% higher than under wrist flexion (2.18 ± 0.60 mm/s), and 32% higher than under wrist extension (2.29 ± 0.43 mm/s). The impaired median nerve mobility was significantly restored under 10 N radioulnar wrist compression (P < 0.05), by 34.4% under wrist flexion (3.03 ± 0.85 mm/s), and 38.9% under wrist extension (3.07 ± 0.79 mm/s).

INTERPRETATION

Non-neutral wrist positions compromise median nerve longitudinal mobility, but moderate radioulnar compressive forces are beneficial in the recovery of median nerve longitudinal mobility, and may help to prevent symptoms associated with carpal tunnel syndrome.

Sonographic Diagnosis of Carpal Tunnel Syndrome

Diagnostic ultrasound in the diagnosis of carpal tunnel syndrome is firmly established. Preoperative evaluation is based on quantitative parameters such as measurement of the pathologically enlarged cross-sectional area of the nerve. The value of postoperative ultrasound lies in the visualization of the anatomy and the conclusions that can be drawn from it. It focuses on the semiquantitative sonographic parameters of nerve compression. Nerve lesions and persistent strictures can be visualized and clearly localized. In recurrent disease, the primary focus is to dynamically exclude postoperative scarring, which results in a reduction of nerve gliding.

An ultrasound study of the mobility of the median nerve during composite finger movement in the healthy young wrist

INTRODUCTION/AIMS

There is a lack of consensus regarding median nerve movement in the carpal tunnel during composite finger flexion in healthy individuals. In this study we examined the amount and direction of median nerve movement and differentiate nerve mobility between dominant and nondominant sides in a large, healthy, young adult cohort.

METHODS

Sonographic videos of the median nerve during composite finger motion from extension to full flexion were analyzed in 197 participants without median nerve pathology. Displacement of the nerve's centroid was calculated based on a change in the relative location of the nerve. Longitudinal nerve sliding was categorized as none, independently from the tendons, or with the tendons.

RESULTS

In short axis, median nerves moved within 1 mm vertically and 3 mm horizontally; no direction was predominant. About half of the nerves (52.5%) slid independently while 26.9% slid with the tendons; 21.3% did not slide at all. On the nondominant side, median nerves that slid with the tendons had a larger absolute vertical displacement than nerves that slid independently or did not slide at all (P < .01). Nerves on the dominant side moved in a radial direction more frequently than on the nondominant side (P = .02).

DISCUSSION

Transverse nerve movement during composite finger flexion in healthy individuals varies widely with no clear pattern in the direction of transverse movement or amount of longitudinal sliding. These data provide a foundation for future research to better understand the biomechanical contribution of nerve movement to median nerve pathologies.

Carpal tunnel syndrome treatment and the subsequent alterations in tendon and connective tissue dynamics

BACKGROUND

Carpal tunnel syndrome patients demonstrate diminished motion of the median nerve and fibrotic changes in the subsynovial connective tissue within the carpal tunnel. Currently, there are few prognostic factors to help predict the outcome of commonly performed treatments including surgical carpal tunnel release and corticosteroid injections. This study aimed to non-invasively assess the changes in the dynamic response of the subsynovial tissue relative to tendon motion after the intervention and to correlate this with disease severity.

METHODS

A total of 145 patients with carpal tunnel syndrome were recruited into this study. Clinical and demographic data, electrophysiological severity and dynamic ultrasound images were collected before and after treatment, either by injection or surgery. The relative motion of the subsynovial tissue with the underlying middle finger flexor digitorum superficialis tendon was measured using a speckle tracking algorithm and was expressed as a shear index (SI). Baseline and follow-up data, the association between change in SI and severity, and the role of treatment modality were analyzed and statistically compared.

FINDINGS

Overall, there was a significant increase (more relative motion) after treatment in the mean shear index from 79.9% (±15.4% SD) to 82.9% (±14.8% SD) (p = 0.03). Secondary analyses showed that this change was mostly present in those with mild disease severity undergoing surgery (p = 0.01).

INTERPRETATION

This study shows that the relative subsynovial tissue movement increases in patients after intervention. The present study lays a foundation for future studies to non-invasively assess the role of carpal tunnel dynamics in response to treatment.

Relative Motion of the Connective Tissue in Carpal Tunnel Syndrome: The Relation with Disease Severity and Clinical Outcome

Excursion of the median nerve and the surrounding subsynovial connective tissue (SSCT) is diminished in patients with carpal tunnel syndrome (CTS). This study sought to determine if SSCT excursion could be utilized to predict surgical outcome. Idiopathic CTS patients were reviewed with ultrasound and electrodiagnostic tests at baseline. A speckle tracking algorithm was used to determine SSCT relative to tendon motion (shear index). Analysis of variance tests were used to compare SSCT motion with disease severity at baseline. Adjusted linear regressions were used to test the association with patient-reported outcome. A total of 90 CTS patients were analyzed and found to have an average shear index of 79% (95% confidence interval: 76.3%-81.6%). SSCT motion was lower in CTS patients with increasing electrophysiological severity (p = 0.0475). There was no significant association of pre-operative SSCT motion with symptomatic improvement (p = 0.268). Overall, SSCT motion is decreased in CTS patients, but exhibits limited correlation with clinical severity.

Location-dependent change of median nerve mobility in the carpal tunnel of patients with carpal tunnel syndrome

INTRODUCTION

The purpose of this study was to investigate in vivo median nerve longitudinal mobility in different segments of the carpal tunnel associated with active finger motion in carpal tunnel syndrome (CTS) patients in a comparison with healthy controls.

METHODS

Eleven healthy volunteers and 11 CTS patients participated in this study. Dynamic ultrasound images captured location-dependent longitudinal median nerve mobility within the carpal tunnel during finger flexion at the metacarpophalangeal joints using a speckle cross-correlation algorithm.

RESULTS

Median nerve longitudinal mobility in the carpal tunnel was significantly smaller in CTS patients (0.0037 ± 0.0011 mm/degree) compared with controls (0.0082 ± 0.0026 mm/degree) (P < .05), especially in the proximal (0.0064 vs 0.0132 mm/degree on average) and middle (0.0033 vs 0.0074 mm/degree on average) carpal tunnel sections.

DISCUSSION

Median nerve mobility can potentially serve as a biomechanical marker when diagnosing CTS, or when assessing the effectiveness of surgical and conservative treatments.

Morphological Changes of the Median Nerve Within the Carpal Tunnel During Various Finger and Wrist Positions: An Analysis of Intensive and Nonintensive Electronic Device Users

PURPOSE

To investigate the effects of static hand postures during various finger and wrist positions on morphological changes of the median nerve within the carpal tunnel in intensive and nonintensive electronic device users.

METHODS

Forty-eight university students, equally divided into intensive and nonintensive users (≥5 h/d and <5 h/d of electronic device usage, respectively), were randomly selected after questionnaire responses and evaluated clinically and by ultrasonography.

RESULTS

Intensive users reported more wrist/hand pain with a high severity score than nonintensive users. They also had larger median nerve cross-sectional areas, flattening ratios, and perimeters than nonintensive users, and showed less median nerve deformation under various finger and wrist positions. Compared with the neutral wrist position with all fingers extended for both intensive and nonintensive users, the cross-sectional areas decreased under finger flexion and grip, as well as wrist extension-flexion and radial-ulnar deviation. Overall, the average median nerve size of the dominant hand was much larger than that of the nondominant hand, especially for intensive users.

CONCLUSIONS

Wrist deviation from neutral can lead to more pronounced deformation of the median nerve than finger flexion for both intensive and nonintensive users. To minimize compression on the median nerve, it is important to keep the wrist as near to the neutral position as possible during computer-related work and avoid keeping the thumb and fingers in a static flexed position when using mobile devices, especially for single-hand use.

CLINICAL RELEVANCE

On the basis of this observational study, intensive users had enlarged and flattened median nerves as well as decreased nerve deformation during hand motions compared with nonintensive users. As overuse of electronic devices may adversely affect the median nerve, caution may be warranted.

Changes of median nerve conduction, cross-sectional area and mobility by radioulnar wrist compression intervention in patients with carpal tunnel syndrome

BACKGROUND

Owing to the compressive nature of the neuropathy, patients with carpal tunnel syndrome (CTS) have prolonged distal motor latency (DML), sensory nerve latency (SNL), median nerve swelling and restricted median nerve mobility. The purpose of this study was to noninvasively augment carpal tunnel space using radioulnar wrist compression (RWC) and evaluate its effects on median nerve pathological properties in patients with CTS. It was hypothesized that the RWC intervention would reduce the median nerve DML, SNL and cross-sectional area (CSA) and enhance longitudinal median nerve mobility in patients. with CTS.

METHODS

Eleven patients diagnosed with CTS participated in this study. A portable RWC intervention splint was developed to apply 10 N of compressive force across the wrist. Three daily sessions of RWC were performed over 4 weeks of intervention (15 min per session, 45 min per day, 7 days per week). Each 15-min session consisted of three 5-min blocks of RWC, with a 1-min rest in between consecutive blocks. Patients were evaluated at Week 0 (baseline), Week 2 (mid-intervention) and Week 4 (end of intervention). DML and SNL of the median nerve were evaluated using established nerve conduction study techniques. Median nerve CSA at the distal wrist crease was obtained by ultrasound imaging. Median nerve motion associated with finger flexion/extension was captured by dynamic ultrasound imaging and quantified using a speckle cross-correlation algorithm. Finger flexion/extension was recorded using an electrogoniometer. The slope of the regressed linear equation of median nerve displacement as a function of finger flexion angle was used to quantify nerve mobility.

RESULTS

Patients with CTS showed significantly decreased DML (p = 0.048) and median nerve CSA (p < 0.001) and increased nerve mobility (p < 0.001) at mid-intervention compared to baseline. However, DML, CSA and mobility of the median nerve did not differ significantly between Weeks 2 and 4 (p = 0.574, 1.00 and 0.139, respectively). Median nerve SNL was not significantly affected throughout the 4-week intervention (p = 0.330 for Week 0 vs. 2; p = 1.00 for Week 2 vs. 4).

CONCLUSION

This study revealed that RWC intervention with 10-N force applied to the wrist in the radioulnar direction could restore impaired neurophysiological and biomechanical functions of the median nerve. The beneficial effects of RWC intervention for the median nerve were in evidence after a relatively short period of two weeks. These functional improvements could be explained by intermittent decompression of the median nerve via RWC-induced augmentation of the carpal arch.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

Biomechanically manipulating the carpal tunnel by RWC decompresses the median nerve and has the potential to become an alternative treatment for CTS.

Enhancement in median nerve mobility during radioulnar wrist compression in carpal tunnel syndrome patients

BACKGROUND

Carpal tunnel syndrome is a compression neuropathy at the wrist associated with compromised median nerve mobility. The purpose of this study was to investigate the effects of radioulnar wrist compression on median nerve longitudinal mobility within the carpal tunnel in carpal tunnel syndrome patients as well as healthy subjects.

METHODS

Dynamic ultrasound images captured longitudinal median nerve motion in the carpal tunnel during radioulnar wrist compression force application in 11 healthy subjects and 11 carpal tunnel syndrome patients.

FINDINGS

We found that median nerve mobility was not significantly affected by radioulnar wrist compression in healthy subjects (P = 0.34), but improved by 10 N radioulnar wrist compression in carpal tunnel syndrome patients (P < 0.05). Analysis of segmental median nerve mobility in carpal tunnel syndrome patients showed significantly improved mobility in the proximal tunnel section under 10 N radioulnar wrist compression force condition compared to the no compression condition (P < 0.05).

INTERPRETATION

Moderate radioulnar wrist compression force application helps restore impaired median nerve mobility and may be effective in improve nerve function and symptoms associated with carpal tunnel syndrome.

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.

Is there a relationship between impaired median nerve excursion and carpal tunnel syndrome? A systematic review

STUDY DESIGN

Systematic review.

INTRODUCTION

It is accepted that the etiology of carpal tunnel syndrome (CTS) is multifactorial. One of the most commonly accepted etiologic factors for CTS is compromise of the kinematic behavior and excursion of the median nerve.

PURPOSE OF THE STUDY

The objective of this systematic review was to establish if there is a relationship between impaired median nerve excursion and CTS.

METHODS

A systematic review, following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, was conducted. Studies were sought where in vivo median nerve excursion was compared between people with CTS to an appropriate control group. Quality appraisal for each study was conducted using the Newcastle-Ottawa Scale by 2 independent evaluators.

RESULTS

Ten case-control studies using ultrasound imaging to quantify median nerve excursion were included. All studies were rated as of "moderate" methodologic quality having scored 6 or 7 (of 9 stars) for the Newcastle-Ottawa Scale. Seven of the 10 studies concluded that median nerve excursion was reduced in a CTS population when compared with controls.

CONCLUSION

The literature suggests that median nerve excursion is reduced in people with CTS when compared with healthy controls.

LEVEL OF EVIDENCE

3a.

Carpal arch and median nerve changes during radioulnar wrist compression in carpal tunnel syndrome patients

The purpose of this study was to investigate the morphological changes of the carpal arch and median nerve during the application of radiounlarly directed compressive force across the wrist in patients with carpal tunnel syndrome. Radioulnar compressive forces of 10 N and 20 N were applied at the distal level of the carpal tunnel in 10 female patients diagnosed with carpal tunnel syndrome. Immediately prior to force application and after 3 min of application, ultrasound images of the distal carpal tunnel were obtained. It was found that applying force across the wrist decreased the carpal arch width (p < 0.001) and resulted in increased carpal arch height (p < 0.01), increased carpal arch curvature (p < 0.001), and increased radial distribution of the carpal arch area (p < 0.05). It was also shown that wrist compression reduced the flattening of the median nerve, as indicated by changes in the nerve's circularity and flattening ratio (p < 0.001). This study demonstrated that the carpal arch can be non-invasively augmented by applying compressive force across the wrist, and that this strategy may decompress the median nerve providing symptom relief to patients with carpal tunnel syndrome. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1234-1240, 2016.

Assessing the Reliability of Ultrasound Imaging to Examine Radial Nerve Excursion

Ultrasound imaging allows cost effective in vivo analysis for quantifying peripheral nerve excursion. This study used ultrasound imaging to quantify longitudinal radial nerve excursion during various active and passive wrist movements in healthy participants. Frame-by-frame cross-correlation software allowed calculation of nerve excursion from video sequences. The reliability of ultrasound measurement of longitudinal radial nerve excursion was moderate to high (intraclass correlation coefficient range = 0.63-0.86, standard error of measurement 0.19-0.48). Radial nerve excursion ranged from 0.41 to 4.03 mm induced by wrist flexion and 0.28 to 2.91 mm induced by wrist ulnar deviation. No significant difference was seen in radial nerve excursion during either wrist movement (p > 0.05). Wrist movements performed in forearm supination produced larger overall nerve excursion (1.41 ± 0.32 mm) compared with those performed in forearm pronation (1.06 ± 0.31 mm) (p < 0.01). Real-time ultrasound is a reliable, cost-effective, in vivo method for analysis of radial nerve excursion.