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

Successful evaluation of a new image-based parameter for the diagnosis of carpal tunnel syndrome: ultrasound assessment of longitudinal median nerve gliding in patients, healthy volunteers, and cadavers

BACKGROUND

Reduced longitudinal median nerve gliding is a new promising diagnostic feature in carpal tunnel syndrome (CTS). However, the complexity of existing ultrasound analysis protocols undermines the application in routine clinical practice.

AIM

To provide a simple method for assessing longitudinal gliding with ultrasound, without the need for post-hoc image analysis.

DESIGN

1) Retrospective cohort study, validation by external blinded reviewers; 2) proof of concept in body donors.

SETTING

1) Outpatient clinic; 2) anatomy department.

POPULATION

The population included 48 patients with idiopathic CTS diagnosed by electrodiagnostic testing and ultrasound, as well as 15 healthy controls. Twelve, non-frozen, non-embalmed body donors were enrolled.

METHODS

Longitudinal gliding of the median nerve in the carpal tunnel was visualized in all patients with idiopathic CTS and healthy controls. All ultrasound videos were pseudonymized, equipped with a scale, and randomized. Videos were analyzed by four independent radiologists, all blinded to clinical characteristics. The endpoint was gliding rated as millimeters. Validity of the technique was tested by using speckle tracking software, and in body donors, directly measuring nerve excursion in situ, simultaneously to ultrasound.

RESULTS

Gliding differed significantly between controls and patients with CTS, decreasing with incremental CTS severity. A cut-off value of 3.5 mm to identify patients with CTS, yielded 93.8% sensitivity and 93.3% specificity. Intraclass correlation coefficient among senior author and raters was 0.798 (95% CI 0.513 to 0.900, P<0.001), indicating good reliability. Speckle tracking and especially direct validation in body donors correlated well with ultrasound findings.

CONCLUSIONS

First, longitudinal median nerve gliding can reliably be assessed using this simple technique without the need for complicated procedures. Second, a decrease in gliding was found with progressive severity of CTS. Reproducibility for measured distances is good among raters.

CLINICAL REHABILITATION IMPACT

An easy to apply sonography parameter would bolster the diagnostic ability of specialists in physical medicine and rehabilitation in daily routine.

Localization of the Median Nerve and Flexor Pollicis Longus at the Carpal Tunnel Inlet in Patients With and Without Carpal Tunnel Syndrome Using Ultrasound

BACKGROUND

Current illustrations of the carpal tunnel vary greatly. The relative positions of the components such as the median nerve and flexor pollicis longus (FPL) tendon seem often arbitrarily chosen. The purpose of this study was to determine the locations of the median nerve and FPL in the carpal tunnel using ultrasound (US) and to determine whether the position of the median nerve changes in carpal tunnel syndrome (CTS).

METHOD

Patients with and without CTS underwent US examination of the wrist. A 4 × 10 grid was fitted to each saved cross-sectional image. The center points of the median nerve and FPL were identified, and their horizontal and vertical coordinates were recorded.

RESULTS

The median nerve was identified in 115 wrists (average x = 0.70, y = 0.82), and FPL was identified in 90 wrists (average x = 0.86, y = 0.59). A scatter plot was created by stacking all US images to demonstrate the average positions of the median nerve and FPL. There were 97 wrists without CTS (No CTS) and 17 wrists with CTS. There was a significant difference in the vertical position of the median nerve between No CTS and CTS wrists (P = .0006).

CONCLUSIONS

The locations of the median nerve and FPL within the carpal tunnel were determined using US of 115 wrists, and a heat map was created to illustrate these locations. The median nerve was found to be more superficial in the setting of CTS.

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.

Convolutional Neural Network Approaches in Median Nerve Morphological Assessment from Ultrasound Images

Ultrasound imaging has been used to investigate compression of the median nerve in carpal tunnel syndrome patients. Ultrasound imaging and the extraction of median nerve parameters from ultrasound images are crucial and are usually performed manually by experts. The manual annotation of ultrasound images relies on experience, and intra- and interrater reliability may vary among studies. In this study, two types of convolutional neural networks (CNNs), U-Net and SegNet, were used to extract the median nerve morphology. To the best of our knowledge, the application of these methods to ultrasound imaging of the median nerve has not yet been investigated. Spearman's correlation and Bland-Altman analyses were performed to investigate the correlation and agreement between manual annotation and CNN estimation, namely, the cross-sectional area, circumference, and diameter of the median nerve. The results showed that the intersection over union (IoU) of U-Net (0.717) was greater than that of SegNet (0.625). A few images in SegNet had an IoU below 0.6, decreasing the average IoU. In both models, the IoU decreased when the median nerve was elongated longitudinally with a blurred outline. The Bland-Altman analysis revealed that, in general, both the U-Net- and SegNet-estimated measurements showed 95% limits of agreement with manual annotation. These results show that these CNN models are promising tools for median nerve ultrasound imaging analysis.

Non-Surgical Carpal Arch Space Augmentation for Median Nerve Decompression

The carpal tunnel is a tightly bounded space, making the median nerve prone to compression and eventually leading to carpal tunnel syndrome. Carpal tunnel release surgery transects the transverse carpal ligament to expand the tunnel arch space, decompress the median nerve, and relieve the associated symptoms. However, the surgical procedure unavoidably disrupts essential anatomical, biomechanical and physiological functions of the wrist, potentially causing reduced grip strength, pillar pain, carpal bone instability, scar tissue formation, and perineural fibrosis. It is desirable to decompress the median nerve without surgically transecting the transverse carpal ligament. This paper is to review several approaches we have developed for nonsurgical carpal arch space augmentation (CASA), namely, radio ulnar wrist compression, muscle-ligament interaction, palmar pulling, and collagenolysis of the transverse carpal ligament. Briefly summarized is the research work on the CASA topic about theoretical considerations, in vitro and in situ experiment, computational modeling, and human subject studies with asymptomatic and carpal tunnel syndrome hands.

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.

A preliminary study of radioulnar wrist compression in improving patient-reported outcomes of carpal tunnel syndrome

Previous studies have shown radioulnar wrist compression augments carpal arch space. This study investigated the effects of radioulnar wrist compression on patient-reported outcomes associated with carpal tunnel syndrome. Subjects underwent thrice-daily (15 min each time 45 min daily) wrist compression over 4 weeks with an additional four weeks of follow-up without treatment. Primary outcomes included Boston Carpal Tunnel Questionnaire symptom and functional severity scales (SSS and FSS) and symptoms of numbness/tingling based on Visual Analog Scales. Our results showed that radioulnar wrist compression improved SSS by 0.55 points after 2 weeks (p < 0.001) and 0.51 points at 4 weeks (p < 0.006) compared to the baseline scale. At the four-week follow-up, SSS remined improved at 0.47 points (p < 0.05). Symptoms of numbness/tingling improved at two and 4 weeks, as well as the follow-up (p < 0.05). Hand motor impairment such as weakness had a lower frequency across carpal tunnel syndrome sufferers and does not significantly improve (p > 0.05). Radioulnar wrist compression might be an effective alternative treatment in improving sensory related symptoms in patients with mild to moderate carpal tunnel syndrome.

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.