Role of fasciae around the median nerve in pathogenesis of carpal tunnel syndrome: microscopic and ultrasound study

Immersive virtual reality in the rehabilitation of athlete nerve entrapments

INTRODUCTION

The implementation of Virtual Reality technology is approaching a breakthrough within the medical, and rehabilitation fields. The level of immersion in the virtual environment is profound and the potential applications are vast.

METHODS

This article reviews the capabilities of Virtual Reality in conjunction with the rehabilitation of nerve entrapments in sport athletes and examines the interactions between our body and brain within the virtual realm. In clinical practice it could be used as a complement to face-to-face therapy to asynchronous use by the patient in any location as a telerehabilitation system.

CONCLUSION

The use of Virtual Reality is a novel, potential, and promising tool in the treatment of nerve entrapments, even possible in the form of telerehabilitation. The response of body and brain in a virtual setting is good, the evolutions in technology can only improve this and this need to be substantiated by further scientific research.

The Median Nerve Displays Adaptive Characteristics When Exposed to Repeated Pinch Grip Efforts of Varying Rates of Force Development: An Ultrasonic Investigation

OBJECTIVES

Repeated gripping with high grip forces and high rates of grip force development are risk factors for carpal tunnel syndrome. As the nerve's adaptive ability is crucial to prevent disease progression, we investigated how these risk factors influence median nerve deformation and displacement over the time course of a repeated pinch grip task.

METHODS

Seventeen healthy participants performed a repeated grip task against a load cell while their carpal tunnel was scanned with ultrasound. The grip task involved pulp-pinching three consecutive times from 0 to 40% maximal voluntary exertion (MVE), performed at three different rates of force development (RFD): 40% MVE/1 second; 2 seconds; and 5 seconds. Ultrasound images were analyzed at 10% MVE intervals. Nerve circularity, width, height, and cross-sectional area were measured to assess deformation. Median nerve displacement was assessed by its change in position relative to the flexor digitorum superficialis tendon of the third digit (FD) in both radioulnar and palmodorsal axes.

RESULTS

Linear mixed modeling indicated that median nerve deformation increased, becoming more circular, with each repeated pulp-pinch (P < .01) and with grip force magnitude (P < .01). However, a faster RFD decreased nerve deformation (P < .01). Furthermore, the nerve displaced ulnarly during pulp-pinching, with greater displacement during the fastest (ie, 40% MVE/1 second) RFD (P < .01).

CONCLUSIONS

The median nerve deformed and displaced in response to pulp-pinching; however, faster rates of force development hindered this adaptive response. This likely reflects the viscoelastic properties of the healthy nerve and subsynovial connective tissue, highlighting the importance of tissue compliance in preventing nerve compression.

The causal relationship between thyroid dysfunction and carpal tunnel syndrome: A Mendelian randomization study

Mendelian randomization was used to investigate the causal relationship between thyroid dysfunction (including hypothyroidism and hyperthyroidism) and carpal tunnel syndrome. Genetic loci independently associated with hypothyroidism and hyperthyroidism were selected as instrumental variables from pooled data from genome-wide association studies. Inverse variance weighting (IVW) was used to analyze the causal effect, supplemented by weighted median and MR-Egger. Heterogeneity test, pleiotropy testing and leave-one-out analysis were used to analyze the sensitivity test to explore the robustness of the results. Both hypothyroidism and hyperthyroidism increase the risk of carpal tunnel syndrome (hypothyroidism: IVW, OR = 1.04, 95% CI = 1.01-1.08, P = .017; hyperthyroidism: IVW, OR = 1.08, 95% CI = 1.05-1.12, P = 9.218E-06, no pleiotropy was found in both tests. Patients with thyroid dysfunction have an increased risk of carpal tunnel syndrome.

Smoking may be a risk factor for carpal tunnel syndrome: Insights from Mendelian randomization analysis

INTRODUCTION

It is currently uncertain whether smoking is a risk factor for carpal tunnel syndrome (CTS). This study aims to elucidate association between smoking and CTS using Mendelian randomization (MR) analysis.

METHODS

This study was a secondary analysis of publicly available GWAS data, using four smoking phenotypes (smoking initiation, smoking status, lifetime smoking, and never smoking) as exposures, and two CTS datasets (discovery and validation sets) as outcomes for MR analysis. The discovery set (n=480201) was used to explore the causal relationship between smoking and CTS, while the validation set (n=385304) was used to confirm the results. The effects of smoking on CTS were assessed using inverse variance weighted (IVW), MR-Egger, and weighted median methods. Cochran's Q test was used to detect heterogeneity, and MREgger to test for pleiotropy. Finally, a meta-analysis was performed on the IVW results from both the discovery and validation sets.

RESULTS

IVW results showed that in both the discovery and validation sets, smoking initiation, smoking status, and lifetime smoking are risk factors for CTS. The summary results from the meta-analysis are as follows: smoking initiation (OR=1.17; 95% CI: 1.08-1.27, p<0.001), smoking status (OR=1.87; 95% CI: 1.56-2.24, p<0.001), and lifetime smoking (OR=2.46; 95% CI: 2.03-3.00, p<0.001). Conversely, never smoking is a protective factor against CTS, with the summary result of the meta-analysis being: OR=0.55; 95% CI: 0.42-0.71, p<0.001.

CONCLUSIONS

Based on genetic evidence, smoking may be a risk factor for CTS. Further clinical trials are needed to confirm this causal relationship.

The effect of manual lymphatic drainage on intraneural edema of the median nerve in patients with carpal tunnel syndrome: A randomized controlled trial

BACKGROUND

Intraneural edema is an important factor in the pathophysiology of carpal tunnel syndrome (CTS). Manual Lymphatic Drainage (MLD) is a manual treatment widely used to treat edema in a variety of conditions.

PURPOSE

This study aimed to evaluate the effect of MLD on intraneural edema of the median nerve in CTS patients, as well as its impact on symptom severity and hand function.

STUDY DESIGN

Randomized controlled study.

METHODS

Twenty-seven patients (aged 48.9 ± 9.9) with mild-to-moderate bilateral CTS were recruited for the study. One hand of each subject was allocated to the experimental group and the other hand in the control group randomly. The experimental group underwent MLD, myofascial release (MFR) therapy and conventional physiotherapy (CP). The control group received sham MLD, MFR and CP. Interventions were performed 2 days a week for 6 weeks. The distal motor latency (DML), motor nerve (MNCV), and sensory nerve (SNCV) conduction velocity of the median nerve were evaluated using electrodiagnostic techniques. As secondary evaluations, grip strength, pressure pain threshold, pain intensity, symptom severity, and hand functions were assessed. The cross-sectional area (CSA) of the median nerve was measured by ultrasound. All assessments were performed at baseline and 6 weeks after intervention.

RESULTS

According to the analysis of a two-way repeated measures of ANOVA, the experimental group showed greater improvement in CSA (p < 0.001; η2 = 0.510), DML (p < 0.001; η2 = 0.549), sensory (p < 0.001; η2 = 0.408), and motor conduction velocity (p < 0.001; η2 = 0.419) of the median nerve than the control group. There was no significant difference between the groups in the secondary evaluation results (p > 0.05).

CONCLUSION

MLD may contribute to symptom relief in CTS by reducing intraneural edema in the median nerve.

The Impact of Lymphatic Drainage and Nerve Mobilization Techniques on Nerve Morphology in Mild-to-Moderate Carpal Tunnel Syndrome: A Randomized Controlled Trial

OBJECTIVE

To investigate whether nerve mobilization related to nerve mobility or the removal of edema using lymphatic drainage affects the cross-sectional area of the nerve, hand function, and symptom severity in carpal tunnel syndrome.

DESIGN

The study is a prospective randomized controlled trial. Data were analyzed between groups using ANOVA, Chi-squared test, and Kruskal-Wallis test.

SETTING

Treatment lasted 4 weeks. Splint group wore the splint daily. Splint+manual lymphatic drainage received lymphatic drainage 5 days a week. Splint+nerve mobilization performed neuromobilization exercises as home exercises 5 days a week. Evaluations were conducted before and after 4 weeks of treatment.

PARTICIPANTS

The study included 80 patients with mild-to-moderate carpal tunnel syndrome.

INTERVENTIONS

The patients were randomly divided into three groups: splint (n = 27), splint+manual lymphatic drainage (n = 27), or the splint+nerve mobilization (n = 26).

MAIN OUTCOME MEASURES

The main outcome measures were ultrasound assessments and the Boston Carpal Tunnel Questionnaire (Symptom Severity Scale and Boston Functional Status Scale).

RESULTS

Compared to the other groups, the nerve cross-sectional area decreased at both the carpal tunnel (p = 0.003) and mid-forearm (p = 0.014) levels in the drainage group. Nerve mobilization did not result in a significant change in the nerve cross-sectional area. All groups showed significant improvements in both symptom severity and functional status scores (p < 0.001).

CONCLUSION

The reduction of edema through lymphatic drainage contributes to a decrease in the cross-sectional area of the median nerve. Additionally, all three methods appear to positively impact the functional capacity of the hand and alleviate symptoms.

The median nerve´s system of connective tissue distal to the pronator teres to the carpal tunnel

BACKGROUND

Connective tissue serves a role beyond mere spatial filling. Furthermore, there is increasing evidence that connective tissue plays an important role in the pathogenesis of conditions such as carpal tunnel syndrome (CTS). According to our hypothesis, the median nerve (MN) is surrounded by a system of connective tissue distal to the pronator teres and extending up to, and including, the carpal tunnel.

METHODS

To visualize the connective tissue surrounding the median nerve, we dissected the forearms of 15 body donors from pronator teres to the carpal tunnel, created plastination slices stained with Periodic Acid-Schiff (PAS), and injected ink into the seen spaces. We verified our findings with a segmentational analysis of radiological data of 10 healthy individuals.

RESULTS

We macroscopically describe the median nerve´s system of connective tissue (MC) distal to the pronator teres and up to and including the carpal tunnel. This system creates, connects, and separates spaces. At least from the pronator teres to the carpal tunnel it also creates subspaces from proximal to distal. For the MC, we established a mean cross-sectional area of 153.1 mm2 (SD=37.15) in the carpal tunnel. The median nerve consistently resides at the center of this MC, which further connects to flexor muscles of the forearm, and to the radius bone. In the carpal tunnel, the MC creates subspaces inside. There, it also acts as the outermost internal layer enveloping flexor tendons, and the MN.

DISCUSSION

The term MC does not negate but orders the existence of other "connectives", like subsynovial connective tissue, endo-, epi- or perineuria, epimysia, periostea, or peritendinea, to a hierarchy related to the median nerve. Diseases of the MN are common. Knowing the anatomy of the MC and how it relates to MN function may help clinicians recognize and understand conditions like CTS.

Time-varying changes in median nerve deformation and position in response to quantified pinch and grip forces

The ability of the median nerve (MN) to adapt in response to altered carpal tunnel conditions is important to mitigate compressive stress on the nerve. We assessed changes in MN deformation and position throughout the entire time course of hand force exertions. Fourteen right-handed participants ramped up force from 0% to 50% of maximal voluntary force (MVF) before ramping force back down in three different hand force exertion tasks (pulp pinch, chuck pinch, power grip). Pinch and grip forces were measured with a digital dynamometer, which were time synchronized with transverse carpal tunnel images obtained via ultrasound. Ultrasound images were extracted in 10% increments between 0% and 50% MVF while ramping force up (loading phase) and down (unloading phase). MN deformation and position relative to the flexor digitorum superficialis tendon of the long finger were assessed in concert. During loading, the nerve became more circular while displacing dorsally and ulnarly. These changes primarily occurred at the beginning of the hand force exertions while ramping force up from 0% to 20%, with very little change between 20% and 50% MVF. Interestingly, deformation and position changes during loading were not completely reversed during unloading while ramping force down. These findings indicate an initial reorganization of carpal tunnel structures. Mirrored changes in nerve deformation and position may also reflect strain-related characteristics of adjoining subsynovial connective tissue. Regardless, time-varying changes in nerve deformation and position appear to be an important accommodative mechanism in the healthy carpal tunnel in response to gripping and pinching tasks.

Diffusion tensor imaging combined with the dual-echo steady-state (DESS) protocol for the evaluation of the median nerve in the carpal tunnel: A preliminary study

Background

Carpal tunnel syndrome (CTS) is diagnosed based on neurological, electrophysiology, and radiological findings. Due to the technical development of magnetic resonance imaging (MRI), the median nerve is evaluated with several MRI protocols. However, diffusion tensor imaging (DTI) combined with a dual-echo steady-state (DESS) protocol is not frequently used to evaluate the median nerve of CTS. This study aimed to evaluate the median nerve in the carpal tunnel using DTI combined with a DESS protocol.

Methods

Five healthy volunteers and seven patients with CTS were enrolled. The patients underwent MRI for CTS pre- and post-operatively. The median nerve was evaluated using a 3-T MRI scanner. The parameters of the DESS protocol were as follows: Repetition time (TR)/echo time (TE) = 10.83/3.32 ms, slice thickness = 0.45 mm, field of view (FoV) = 350 × 253 × 350 mm, and 3D voxel size = 0.5 × 0.5 ×0.4 mm. The parameters of the DTI sequence were as follows: TR/TE = 4000/86 ms, slice thickness = 3 mm, FoV = 160 × 993 × 90 mm, 3D voxel size = 1.2 × 1.2 ×3.0 mm, and b value = 0.1000 s/mm2. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of the median nerve were statistically analyzed. Statistical significance was set at P< 0.05.

Results

The FA value of healthy volunteers was 0.576 ± 0.058, while those of the patients were 0.357 ± 0.094 and 0.395 ± 0.062 pre-and post-operatively, respectively. Statistically significant differences were identified between the FA values of healthy volunteers and pre-operative/post-operative patients. The ADC values of healthy volunteers and pre-operative patients were 0.931 ± 0.096 and 1.26 ± 0.282 (10-3 mm2/s), respectively (P< 0.05).

Conclusion

This MRI protocol may be useful for evaluating the median nerve in the carpal tunnel.

The effectiveness of nerve mechanical interface treatment for entrapment neuropathies in the limbs: A systematic review with metanalysis

BACKGROUND

Neurodynamic approach employs neural mobilization and mechanical nerve interface techniques. While published studies investigated the efficacy of neural mobilization, it is currently unknown whether manual treatment of the nerve mechanical interface is effective in the treatment of people with entrapment neuropathies.

OBJECTIVES

Assess the effectiveness of mechanical interface treatment, including joint and soft tissue techniques, on pain and function in people with peripheral entrapment neuropathies.

DESIGN

Intervention systematic review with metanalysis.

METHODS

the databases MEDLINE, CINAHL, AMED, APA PsycINFO, SPORTDiscus, PubMed and ScienceDirect were searched from their inception to October 2022. Randomized controlled trials investigating mechanical interface treatment in isolation in patients with peripheral entrapment neuropathies were included. Two independent reviewers performed study selection, data extraction and risk of bias assessment using the Cochrane RoB 2.0 tool. Certainty of evidence for each outcome was judged using the GRADE framework.

RESULTS

11 studies were included in the review, all investigating carpal tunnel syndrome (CTS). Due to high heterogeneity of interventions and comparators, only five studies were pooled in a random-effects meta-analysis. There was evidence of mechanical interface techniques being more effective in reducing pain than sham (MD -2.47 [-3.94;-0.99]) and similarly effective as neural mobilization (MD -0.22 [-0.76; 0.33]) in CTS, albeit with low to very low certainty in the results.

CONCLUSION

mechanical interface techniques are effective for improving pain and function in people with CTS. However, the marked heterogeneity of included interventions and comparators prevents clinical recommendation of specific treatments.

Comparison of in-situ release and submuscular anterior transposition of ulnar nerve for refractory cubital tunnel syndrome, previously treated with subfascial anterior transfer-A retrospective study of 24 cases

BACKGROUND

Although cubital tunnel syndrome is the second most common type of compressive neuropathy in the upper extremities, the indication and optimal surgical method for recurrent or refractory cubital tunnel syndrome remains controversial. This study evaluates the functional outcomes of revision surgery for cubital tunnel syndrome.

MATERIAL & METHODS

This study was a retrospective observational multicenter single-institution study including 660 patients who underwent surgery for cubital tunnel syndrome from 2010 to 2019. Among the 660 patients, 42(6.4%) received revision surgery due to remaining or recurrent symptoms confirmed with electromyography(EMG). After excluding those with concurrent elbow fracture, dislocation, osteoarthritis and wound infection, a total of 24 patients were included in the study. The patients were evaluated of disease severity, revision surgical method, time interval to recurrence, underlying diseases and postoperative functional outcomes.

RESULTS

All patients received ulnar nerve subfascial anterior transposition for the initial cubital tunnel syndrome surgery. Among the 24 patients (3.7%) who received revision surgery, nine received in situ neurolysis, 12 received submuscular transposition, and three received subcutaneous transfer. 21 patients (88%) reported improved mean VAS score of 4.3, while three patients complained of remaining symptoms that did not improve even after revision surgery. The patients with remaining symptoms all had underlying diabetes mellitus and were treated with subcutaneous transfer. The difference of surgical outcomes between the in situ neurolysis group and the nerve transfer groups were non-significant (p = 0.23). The most common cause of recurrent or persistent symptoms was adhesion and fibrosis at sling area. The mean follow up period before revision surgery was 26.3 months and postoperative follow up period after revision surgery was 8.5 months.

CONCLUSION

The outcomes of this study imply that in-situ neurolysis may be as effective as anterior submuscular transfer of ulnar nerve for refractory cubital tunnel syndrome after anterior subfascial transfer.

Ultrasound measurement of subsynovial connective tissue thickness in the carpal tunnel: An intrarater/interrater reliability and agreement study

OBJECTIVES

Non-inflammatory thickening of the subsynovial connective tissue (SSCT) in the carpal tunnel is commonly found in subjects with carpal tunnel syndrome (CTS), and quantification may shed light on CTS pathogenesis. To date, information on the reliability of ultrasound quantification of SSCT is scarce. Therefore, we investigated intrarater and interrater reliability/agreement for ultrasound quantification of SSCT thickness in subjects with and without CTS, and predictors for tissue thickness.

MATERIAL AND METHODS

Two investigators quantified SSCT thickness and thickness ratio on ultrasound in 16 healthy subjects (age, 24-65 years; 16 left/14 right wrists) and 17 subjects with CTS (age, 37-83 years; 14 left/14 right wrists). Intra- and inter-rater reliability/agreement were assessed on intraclass correlation coefficients, standard error of measurement and minimal detectable change. A mixed-effects model was used to evaluate potential predictors for SSCT thickness.

RESULTS

Intra- and inter-rater reliability analysis showed good to excellent intraclass correlation coefficients in both groups, ranging from 0.772 to 0.965. The maximum percentage standard error of measurement was 8%. The maximum minimal detectable change was 14% within raters, and 20% between raters. Both intra- and inter-rater reliability values for thickness ratio were poor. Presence of CTS (ß = 0.180; p = 0.015) correlated positively with SSCT thickness.

CONCLUSIONS

Ultrasound is a reliable method for quantification of SSCT thickness, but not for thickness ratio. Presence of CTS correlates positively with SSCT thickness.

Deep Learning-Based Approaches for Enhanced Diagnosis and Comprehensive Understanding of Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is a prevalent medical condition resulting from compression of the median nerve in the hand, often caused by overuse or age-related factors. In this study, a total of 160 patients participated, including 80 individuals with CTS presenting varying levels of severity across different age groups. Numerous studies have explored the use of machine learning (ML) and deep learning (DL) techniques for CTS diagnosis. However, further research is required to fully leverage the potential of artificial intelligence (AI) technology in CTS diagnosis, addressing the challenges and limitations highlighted in the existing literature. In our work, we propose a novel approach for CTS diagnosis, prediction, and monitoring disease progression. The proposed framework consists of three main layers. Firstly, we employ three distinct DL models for CTS diagnosis. Through our experiments, the proposed approach demonstrates superior performance across multiple evaluation metrics, with an accuracy of 0.969%, precision of 0.982%, and recall of 0.963%. The second layer focuses on predicting the cross-sectional area (CSA) at 1, 3, and 6 months using ML models, aiming to forecast disease progression during therapy. The best-performing model achieves an accuracy of 0.9522, an R2 score of 0.667, a mean absolute error (MAE) of 0.0132, and a median squared error (MdSE) of 0.0639. The highest predictive performance is observed after 6 months. The third layer concentrates on assessing significant changes in the patients' health status through statistical tests, including significance tests, the Kruskal-Wallis test, and a two-way ANOVA test. These tests aim to determine the effect of injections on CTS treatment. The results reveal a highly significant reduction in symptoms, as evidenced by scores from the Symptom Severity Scale and Functional Status Scale, as well as a decrease in CSA after 1, 3, and 6 months following the injection. SHAP is then utilized to provide an understandable explanation of the final prediction. Overall, our study presents a comprehensive approach for CTS diagnosis, prediction, and monitoring, showcasing promising results in terms of accuracy, precision, and recall for CTS diagnosis, as well as effective prediction of disease progression and evaluation of treatment effectiveness through statistical analysis.

The effectiveness of biophysical agents in the treatment of carpal tunnel syndrome- an umbrella review

BACKGROUND

Our objective was to summarize, synthesize, and integrate the evidence evaluating the effectiveness of biophysical agents compared to other conservative treatments, for the management of carpal tunnel syndrome (CTS).

METHODS

This was an overview of systematic reviews (SRs). We searched several online databases and obtained SRs relating to managing CTS using biophysical agents. Two independent researchers screened and appraised the quality of the SRs using the A MeaSurement Tool to Assess systematic Reviews-2 appraisal tool. We extracted information related to study characteristics as well as the effectiveness of biophysical agents for CTS, the effect sizes, and between-group significances. We categorized the information based on the type of biophysical agent. We also performed a citation mapping and calculated the corrected covered area index.

RESULTS

We found 17 SRs addressing 12 different biophysical agents. The quality of the SRs was mainly critically low (n = 16) or low (n = 1). The evidence was inconclusive for the effectiveness of Low-level Laser therapy and favorable for the short-term efficacy of non-thermal ultrasound in improving symptom severity, function, pain, global rating of improvement, satisfaction with treatment, and other electrophysiological measures compared to manual therapy or placebo. Evidence was inconclusive for Extracorporeal Shockwave therapy, and favorable for the short-term effectiveness of Shortwave and Microwave Diathermy on pain and hand function. The corrected covered area index was lower than 35% indicating a low overlap of the SRs.

CONCLUSIONS

The findings were based on low-quality primary studies, with an unclear or high risk of bias, small sample sizes, and short follow-ups. Therefore, no recommendations can be made for the long-term effectiveness of any biophysical agents. High-quality evidence is needed to support evidence-based recommendations on the use of biophysical agents in the management of CTS.

PROSPERO REGISTRATION NUMBER

CRD42022319002, registered on 17/04/2022.

Persistent Pain as an Early Indicator for Operative Carpal Tunnel Revision after Primary Release: A Retrospective Analysis of Recurrent and Persistent Carpal Tunnel Syndrome

BACKGROUND

Prolonged symptoms of carpal tunnel syndrome (CTS) after primary carpal tunnel release (CTR) can reduce the quality of life and lead to multiple referrals across specialties. The following study aimed to identify differences in symptoms, signs, and intraoperative findings between recurrent and persistent CTS cases to avoid undesired outcomes after primary CTR.

METHODS

A retrospective analysis was conducted on revision CTRs performed between 2005 and 2015 using literature-based definitions for recurrent (a relapse of symptoms occurs following a symptom-free period of ≥3 months) and persistent (symptoms persisting longer than three months after surgical release) CTS. The parameters assessed were symptoms, clinical signs, and intraoperative findings.

RESULTS

Out of 53 cases, 85% (n = 45) were external referrals, whereby our own revision rate was 0.67% (n = 8/1199). Paresthesia and numbness were frequent in both groups; however, abnormal postoperative pain was reported more often in persistent cases (86%; n = 30/35) in comparison to recurrent cases (50%; n = 9/18; p = 0.009). Scarring around the median nerve was observed in almost all recurrent cases (94%; n = 17/18) and in 40% (n = 14/35) of persistent cases (p < 0.001). Incomplete division of the palmar ligament was the primary cause for revision in the persistent cohort (49%; n = 17/35).

CONCLUSIONS

For patients experiencing symptoms for more than three months after CTR, primarily presenting as pain, it is advisable to consider referring the patient to a certified hand clinic for additional evaluation.

Potential Relationships between the Median Nerve Cross-Sectional Area and Physical Characteristics in Unilateral Symptomatic Carpal Tunnel Syndrome Patients

Background: The present study investigated the relationships between the median nerve cross-sectional area (CSA) and physical characteristics in patients with unilateral symptomatic carpal tunnel syndrome (CTS). Methods: Height, weight, body mass index (BMI), disease duration, results of electrodiagnostic testing (EDX), and median nerve CSA at the level of the wrist crease were recorded in 81 patients with CTS who presented with symptoms on only one side. Correlation coefficients between median nerve CSA and physical characteristics, disease duration, and results of EDX were analyzed. Results: Median nerve CSA at the wrist crease (mm2) was significantly larger on the symptomatic side (14.1 ± 3.8) than on the asymptomatic side (11.5 ± 2.9). Median nerve CSA correlated with body weight (correlation coefficient = 0.39) and BMI (correlation coefficient = 0.44) on the asymptomatic side, but not on the symptomatic side. These correlations were slightly stronger in females (correlation coefficient = 0.46) than in males (correlation coefficient = 0.40). No correlations between median nerve CSA and disease duration and the results of EDX were observed in both sides. Conclusions: In patients with unilateral symptomatic CTS, median nerve CSA correlated with BMI only on the asymptomatic side. The present results suggest that the relationship between median nerve CSA and BMI in CTS is significant until symptom onset but may be masked by edema and pseudoneuroma after its onset. A higher BMI is associated with a larger CSA of the median nerve, which may be a risk factor for the development of CTS.

From Muscle to the Myofascial Unit: Current Evidence and Future Perspectives

The "motor unit" or the "muscle" has long been considered the quantal element in the control of movement. However, in recent years new research has proved the strong interaction between muscle fibers and intramuscular connective tissue, and between muscles and fasciae, suggesting that the muscles can no longer be considered the only elements that organize movement. In addition, innervation and vascularization of muscle is strongly connected with intramuscular connective tissue. This awareness induced Luigi Stecco, in 2002, to create a new term, the "myofascial unit", to describe the bilateral dependent relationship, both anatomical and functional, that occurs between fascia, muscle and accessory elements. The aim of this narrative review is to understand the scientific support for this new term, and whether it is actually correct to consider the myofascial unit the physiological basic element for peripheral motor control.

Carpal arch space increased by volar force applied to the skin surface above the carpal tunnel

BACKGROUND

Carpal arch space augmentation can help decompress the median nerve. The augmentation can be achieved by mechanical manipulations utilizing the biomechanics of the tunnel structure. The purpose of this study was to expand the carpal arch in vitro by applying volar forces on the surface of the wrist.

METHODS

The mechanism was implemented in eight cadaver hands by attaching a volar force transmitter to the palmar surface of the wrist and pulling the transmitter volarly at six force levels (0, 3, 6, 9, 12, and 15 N). Ultrasound images of the cross section at the distal carpal tunnel were collected for morphological analysis.

FINDINGS

The carpal arch height, width, and area were significantly altered by the volarly applied force (P < 0.001). The arch height and area were increased but the arch width was decreased by the force. Pearson's correlation coefficient showed that there was a positive correlation between the arch height and force magnitude; and between the arch area and force magnitude. A negative correlation existed between the arch width and force magnitude (P < 0.001). The magnitude of change of the arch height, width, and area was increased as the force magnitude increased.

INTERPRETATION

This study demonstrated that applying external forces on the wrist skin to increase the carpal arch space was feasible. The magnitude of the force influenced its effect on altering the carpal arch. Study limitations include small sample size and inclusion of male specimens. Future in vivo work is needed for clinical translation feasibility.

Infrared thermographic changes after decompression surgery in patients with carpal tunnel syndrome

BACKGROUND

Digital infrared thermal imaging (DITI), which detects infrared rays emitted from body surface to create a body heat map, has been utilized at various musculocutaneous conditions. Notably, DITI can demonstrate autonomic vasomotor activity in the nerve-innervated area, and thus may be of use in carpal tunnel syndrome (CTS). In this study, we compared DITI findings before and after carpal tunnel release (CTR) surgery in patients with unilateral CTS to investigate the corresponding neurophysiological changes.

METHODS

In this retrospective cohort study, DITI parameters such as the temperature differences between the median and ulnar nerve territories and median nerve-innervated digital anisometry were measured. Subjective symptom duration, pain scale, and ultrasonographic findings were also compared before and after CTR. Patients were evaluated before and 6 weeks after CTR, respectively.

RESULTS

A total of 27 patients aged 59.0 ± 11.2 years were finally included. After CTR, median nerve-innervated thermal anisometry was improved (2.55 ± 0.96 °C to 1.64 ± 1.34 °C; p = 0.003). The temperature differences between the median and ulnar nerve territories were not significantly changed. Subjective pain, the Simovic Weinberg Clinical Scale, and palmar bowing of the flexor retinaculum were also significantly improved (p <  0.001 for all comparisons).

CONCLUSIONS

Our results demonstrated that DITI findings could reflect an improvement in autonomic function after CTR. Therefore, DITI can be an objective method to assess pre- and post-operative neurophysiologic changes in CTS.

Dynamic ultrasound for evaluating the adequacy of median nerve decompression following minimally invasive carpal tunnel release: technical innovation and case study

Background

Minimally invasive carpal tunnel release has recently emerged as the primary surgical approach for recalcitrant carpal tunnel syndrome. A major concern related to surgical failure with this technique is the incomplete release of the flexor retinaculum.

Case presentation

We developed a technique using dynamic ultrasound for evaluating the adequacy of median nerve decompression following minimally invasive carpal tunnel release. This novel imaging method was applied to two patients who showed significant symptom relief after the intervention. This case study also provides details of the dynamic ultrasound protocol and highlights the advantages of this technique.

Conclusion

Dynamic ultrasound imaging can be used to confirm the completeness of carpal tunnel decompression. A large-scale prospective trial should be conducted to validate whether additional dynamic ultrasound examination can improve the outcome of minimally invasive carpal tunnel release.

Fibrosis-Associated Signaling Molecules Are Differentially Expressed in Palmar Connective Tissues of Patients with Carpal Tunnel Syndrome and Dupuytren's Disease

Carpal tunnel syndrome (CTS) and Dupuytren's disease (DD) are fibrotic conditions that affect the connective tissue of the hand and limit its functionality. The exact molecular mechanism underlying the fibrosis is unknown, and only some profibrotic factors have been investigated. In this cross-sectional study, we analyzed the expression of FGF signaling pathway molecules associated with fibrotic changes in the palmar fascia and the flexor retinaculum of 15 CTS patients and both clinically affected and unaffected palmar fascia of 15 DD patients, using immunofluorescence techniques. The expression of FGFR1, FGFR2, and CTGF in the blood vessel walls and surrounding connective tissue cells differed significantly between the analyzed groups, with changes in expression present even in clinically unremarkable tissues from DD patients. We also found altered expression of the analyzed factors, as well as TGF-β1 and syndecan-1 in DD-associated sweat glands, possibly implicating their role in the pathophysiology of the disease. The increased expression of profibrotic factors in the clinically unaffected palmar fascia of DD patients may indicate that more extensive excision is needed during surgical treatment, while the profibrotic factors could be potential targets for developing pharmacological therapeutic strategies against DD-associated fibrosis.

Ultrasonographical Evaluation of the Median Nerve Mobility in Carpal Tunnel Syndrome: A Systematic Review and Meta-Analysis

Diagnostic ultrasound is widely used for evaluating carpal tunnel syndrome (CTS), an entrapment neuropathy of the median nerve (MN). Decreased mobility of the MN inside the carpal tunnel has been reported in CTS, and various methods have been used to evaluate MN mobility; however, there is still no conclusive understanding of its connection with CTS. The purpose of this study is to conduct a systematic review and meta-analysis of the current published literature on ultrasonographic evaluations of transverse and longitudinal MN displacement and to identify the relationship between MN mobility and CTS. This study was conducted in accordance with the 2020 PRISMA statement and the Cochrane Collaboration Handbook. Comparative studies that investigated differences in MN displacement between CTS patients and healthy controls were retrieved by searching the Cochrane Library, Embase and PubMed. A total of 15 case–control studies were included. Nine of 12 studies evaluating transverse MN displacement and 4 of 5 studies evaluating longitudinal MN gliding showed that the MN was less mobile in CTS patients than in healthy subjects. Despite the large heterogeneity among the 15 included studies, this systematic review and meta-analysis provide evidence that the mobility of the MN is significantly reduced in both transverse and longitudinal planes in CTS patients compared to healthy controls. Five of the 15 included studies reported that a decrease in transverse or longitudinal MN displacement in CTS was correlated with clinical symptoms or with severity as measured by a nerve conduction study (NCS).

A prospective cohort study: platelet-rich plasma combined with carpal tunnel release treating carpal tunnel syndrome

Background

PRP injection was proved to promote the health condition of individuals with mild to moderate Carpal Tunnel Syndrome (CTS). However, carpal tunnel release (CTR) was still a necessary treatment for individuals with moderate and severe CTS.

Methods

To explore whether adjuvant PRP treatment would improve the prognosis while using CTR, we included 82 patients in this study. Preoperative and postoperative visual analog scale (VAS), Boston carpal tunnel syndrome questionnaire-symptom severity scale (BCTQ-SSS), Boston carpal tunnel syndrome questionnaire-functional status scale (BCTQ-FSS), and grip strength were used to examine the patient's symptoms and function.

Results

CTR combined with PRP treatment improved the VAS (1.9 ± 0.5 versus 1.4 ± 0.4, P < .05), BCTQ-SSS (1.8 ± 0.4versus 1.5 ± 0.3, P < .05) and BCTQ-FSS (1.8 ± 0.5 versus 1.4 ± 0.6, P < .05) in patients with moderate symptoms within one month after surgery. At the same time, it does not show any advantages in treating individuals with severe carpal tunnel syndrome.

Conclusions

PRP does not affect long-term prognosis while increasing the surgery cost. To conclude, PRP as an adjuvant treatment of CTR has limited effect. Considering the additional financial burden on patients, CTR combined with PRP should be cautious in CTS treatment.

Anatomy of the Palmar Region of the Carpus of the Dog

The palmar region of the canine carpus is anatomically complex, and the information found in the literature about its anatomy is inconsistent. The aims of this prospective, descriptive, anatomic study were (1) the clarification and (2) the description of the precise anatomic composition of the palmar region of the canine carpus, with special reference to the canalis carpi. For this study, 92 cadaveric specimens were obtained from 46 dogs that had died for reasons unrelated to this study. Of these, 43 medium-to-large-breed dogs were randomly selected for the dissection of transverse slices of the carpus. Samples of the flexor retinaculum and flexor carpi radialis tendon and surrounding tissues were taken for complementary histology. For additional histology of the palmar structures in their anatomical position, three small breed dogs were randomly selected for obtaining transverse slices. The anatomic characteristics of the components of the palmar region of the canine carpus were qualitatively described, with special attention to the following structures: flexor retinaculum, flexor carpi radialis muscle, arteria and vena mediana, nervus medianus, interflexorius muscle, flexor digitorum profundus muscle, canalis carpi, and arteria and nervus ulnaris. The findings from this study provide reference information about the anatomy of the palmar region of the canine carpus.

EURO-MUSCULUS/USPRM Dynamic Ultrasound Protocols for Wrist and Hand

ABSTRACT

In this dynamic protocol, ultrasound evaluation of the wrist and hand is described using various maneuvers for relevant conditions. Scanning videos are coupled with real-time patient examination videos. The authors believe that this practical guide - prepared by the international consensus of several experts - will help musculoskeletal physicians perform a better and uniform/standard examination approach.

Clinical Value Analysis of High-Frequency Ultrasound Combined with Carpal Dorsiflexion Electrophysiological Detection in the Diagnosis of Early Carpal Tunnel Syndrome

Objective

To investigate the clinical value of ultrasound combined with electrophysiological examination in the diagnosis of early carpal tunnel syndrome, we aimed to provide a new EMG (electromyography) method for detecting early carpal tunnel syndrome by exploring the wrist back stretch position and electrophysiological examination.

Methods

For the 82-lateral wrist (case group) of 62 patients with clinical symptoms or confirmed carpal tunnel syndrome and 40 normal healthy patients, neuroelectrophysiological measurements were performed using a Keypoint6.0 EMG evoked potentiometer, measuring each group twice: conventional position (before compression) and dorsal wrist extension position. The measures for each measurement included DSL, DML, and CAMP. Measure sensory conduction first and then measure motor conduction. The measurements were analyzed in a comprehensive comparative analysis. Combined ultrasound examination, the positive rate of combined ultrasound examination and electrophysiological examination was compared, respectively.

Results

In the carpal tunnel syndrome (CTS) group, the anterior and posterior median nerve DSL was (4.27 ± 0.73) ms and (4.82 ± 0.65) ms, and SNAP was (13.32 ± 13.68) UV and (12.19 ± 11.04) UV; the median nerve (wrist-bunions) DML was (5.29 ± 1.26) ms and (5.54 ± 1.29) ms, and CMAP was (6.44 ± 2.40) mV and (6.21 ± 2.46) mV. Mid-median DSL and DM in the CTS group L were significantly longer than before compression; median nerve SNAP and CMAP were significantly reduced compared with before compression.

Conclusion

Electrophysiological testing at the dorsal carpal extension position has high diagnostic value in the diagnosis of mild carpal tunnel syndrome. It helps to improve the diagnostic rate of early carpal tunnel syndrome, while providing a more accurate and effective EMG detection of early carpal tunnel syndrome, and combination examination of neuroelectrophysiology and ultrasound can improve the diagnosis rate of compression peripheral nerve diseases and clarify the site, nature, and scope of compression lesions, which is worthy of clinical application.

Compartments of the antebrachial fascia of the forearm: clinically relevant ultrasound, anatomical and histological findings

PURPOSE

Acute compartment syndrome is defined as a limb-threatening condition caused by bleeding or oedema in a closed muscle compartment surrounded by fascia or bone. It is most commonly encountered in the forearm, which has three compartments: posterior, anterior and lateral. These are surrounded and closed in by the antebrachial fascia, formed by dense connective tissue that facilities their study on ultrasound and is key to fasciotomy treatment. The purpose of this study was to broaden existing ultrasound, anatomical and histological knowledge of the fascia of the forearm to facilitate their identification on ultrasound, with possible clinical and therapeutic applications.

METHODS

The study was performed in 50 cryopreserved upper limbs from adult cadavers from the dissection room of the Faculty of Medicine and Health Sciences. They were examined on ultrasound and subsequent anatomical dissection and microscopy to study the fascia and its relationship with different muscles of the forearm compartments.

RESULTS

Distinct anatomical relationships were observed on ultrasound and dissection between the fascia and the extensor carpi ulnaris, extensor digiti minimi, and anconeus muscle in the posterior compartment, and the flexor carpi radialis and flexor carpi ulnaris in the anterior compartment. They were isolated by the antebrachial fascia and had distinct relationships with the neurovascular structures.

CONCLUSION

These results demonstrate that high-definition ultrasound enables us to locate the antebrachial fascia and particular muscles with a distinct relationship with neurovascular structures. This helps better identify these structures, facilitating diagnosis of any pathology in the area, with potential therapeutic and clinical applications.

Topography and evidence of a separate "fascia plate" for the femoral nerve inside the iliopsoas - A dorsal approach

The femoral nerve stretch test is an essential part of clinical neurological examinations. This test is performed alongside Magnetic Resonance Imaging (MRI) to determine if there is any evidence of nerve root irritation, usually as a consequence of disc prolapse. The test occasionally gives false positive results. Why such false positives can occur, is subject to continued research, however, no obvious reason has yet emerged. We hypothesize that connectives of the femoral nerve may explain such a phenomenon. To see these connectives, we approached the femoral nerve from dorsal in 12 cases. With the use of ink injection into the subparaneural compartment of the femoral nerve and dissections, a thin transparent structure can clearly be seen that is separate from the epineurium, perineurium, and a paraneural sheath. A continuation of the paraneural sheath produces a fascia plate approximately 1.5 cm in width and with a thickness of around 3 mm, which not only circumnavigates the nerve but projects into the surrounding tissues. Our qualitative observations show that not only does this femoral nerve fascia plate exists, but it also contains nerves and vessels. Furthermore, we show that the femoral nerve is connected to the myofascial complex of the iliopsoas, and in a separate fascia plate from the iliopsoas fascia. This plate is a hitherto neglected connective which extends as far as the spinal dura mater. Evidence from our plastinates and histological sections suggests that when tension is applied to the femoral nerve during the femoral nerve stretch test, tension is also applied to the femoral nerve fascia plate. The femoral nerve fascia plate could be a specific factor that contributes to pain resulting in a false positive femoral nerve stretch test.

Myofascial Injection Using Fascial Layer-Specific Hydromanipulation Technique (FLuSH) and the Delineation of Multifactorial Myofascial Pain

Background and objectives: The aims of this study were to delineate the contribution of specific fascial layers of the myofascial unit to myofascial pain and introduce the use of ultrasound-guided fascial layer-specific hydromanipulation (FLuSH) as a novel technique in the treatment of myofascial pain. Materials and Methods: The clinical data of 20 consecutive adult patients who underwent myofascial injections using FLuSH technique for the treatment of myofascial pain were reviewed. The FLuSH technique involved measuring the pain pressure threshold using an analog algometer initially and after each ultrasound guided injection of normal saline into the specific layers of the myofascial unit (superficial fascia, deep fascia, or muscle) in myofascial points corresponding with Centers of Coordination/Fusion (Fascial Manipulation^®). The outcome measured was the change in pain pressure threshold after injection of each specific fascial layer. Results: Deep fascia was involved in 73%, superficial fascia in 55%, and muscle in 43% of points. A non-response to treatment of all three layers occurred in 10% of all injected points. The most common combinations of fascial layer involvement were deep fascia alone in 23%, deep fascia and superficial fascia in 22%, and deep fascia and muscle in 18% of injected points. Each individual had on average of 3.0 ± 1.2 different combinations of fascial layers contributing to myofascial pain. Conclusions: The data support the hypothesis that multiple fascial layers are responsible for myofascial pain. In particular, for a given patient, pain may develop from discrete combinations of fascial layers unique to each myofascial point. Non-response to treatment of the myofascial unit may represent a centralized pain process. Adequate treatment of myofascial pain may require treatment of each point as a distinct pathologic entity rather than uniformly in a given patient or across patients.

Quantitative Evaluation of the Echo Intensity of Paraneural Area and Myofascial Structure around Median Nerve in Carpal Tunnel Syndrome

The aim of this study was to investigate whether the echo intensity (EI) of the paraneural area (PA), the median nerve (MN) at the carpal tunnel, the EI of the myofascial structure (MS) around MN, the ‘PA and MN’ at the mid-forearm, and the MN transversal displacement at both sites differs between persons with carpal tunnel syndrome (CTS) and control subjects. Methods: In total, 16 CTS patients and 16 controls, age- and gender-matched, were recruited. Cross-sectional ultrasound images of MN were obtained to evaluate the EI of the PA, the MN at carpal tunnel, the EI of MS, and the ‘PA and MN’ at the mid-forearm in a natural position, then images were taken after a whole-hand grasp movement, to evaluate MN transversal displacement. Inter-rater and intra-rater reliability in control, and differences in the EI and MN displacement between CTS and control, were analyzed. In addition, the correlations between ultrasound parameters and MN displacement were evaluated. Results: The quantitative EI of PA, MN, EI of MS, ‘PA and MN’ had high inter-rater and intra-rater reliability in the control. The EI of PA, MS and ‘PA and MN’ were significantly higher in CTS subjects (p < 0.01), whilst there was no significant difference in the EI of MN at the carpal tunnel. MN displacement was significantly decreased both at the carpal tunnel and the mid-forearm in CTS subjects (p < 0.01). In addition, there were negative correlations among the EI of PA (rs = −0.484, p = 0.004), EI of MS (rs = −0.479, p = 0.002), EI of ‘PA and MN’ (rs = −0.605, p < 0.001) and MN transversal displacement. Conclusions: The higher EI of PA and MS around MN in CTS may indicate greater fibrosis along the course of MN, reducing fascial adaptability, influencing the synergy and coordination of the MS, and increasing the shear stress between MS and MN, and it may further increase the abnormal pressure on the MN not only at the carpal tunnel, but also at the mid-forearm. These results may partly explain the role of PA and MS in CTS pathogenesis.