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

Current and future utility of ultrasound imaging in upper extremity musculoskeletal rehabilitation: A scoping review

STUDY DESIGN

This study was a scoping review.

BACKGROUND

Continued advances in musculoskeletal sonography technology and access have increased the feasibility of point-of-care use to support day-to-day clinical care and decision-making. Sonography can help improve therapeutic outcomes in upper extremity (UE) rehabilitation by enabling clinicians to visualize underlying structures during treatment.

PURPOSE OF THE STUDY

This study aimed to (1) evaluate the growth, range, extent, and composition of sonography literature supporting UE rehabilitation; (2) identify trends, gaps, and opportunities with regard to anatomic areas and diagnoses examined and ultrasound techniques used; and (3) evaluate potential research and practice utility.

METHODS

Searches were completed in PubMed, CINAHL, SPORTDiscus, PsycINFO, and BIOSIS. We included data-driven articles using ultrasound imaging for upper extremity structures in rehabilitation-related conditions. Articles directly applicable to UE rehabilitation were labeled direct articles, while those requiring translation were labeled indirect articles. Articles were further categorized by ultrasound imaging purpose. Article content between the two groups was descriptively compared, and direct articles underwent an evaluation of evidence levels and narrative synthesis to explore potential clinical utility.

RESULTS

Average publication rates for the final included articles (n = 337) steadily increased. Indirect articles (n = 288) used sonography to explore condition etiology, assess measurement properties, inform medical procedure choice, and grade condition severity. Direct articles (n = 49) used sonography to assess outcomes, inform clinical reasoning, and aid intervention delivery. Acute UE conditions and emerging sonography technology were rarely examined, while tendon, muscle, and soft tissue conditions and grayscale imaging were common. Rheumatic and peripheral nerve conditions and Doppler imaging were more prevalent in indirect than direct articles. Among reported sonography service providers, there was a high proportion of nonradiologist clinicians.

CONCLUSION

Sonography literature for UE rehabilitation demonstrates potential utility in evaluating outcomes, informing clinical reasoning, and assisting intervention delivery. A large peripheral knowledge base provides opportunities for clinical applications; however, further research is needed to determine clinical efficacy and impact for specific applications.

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.

Carpal tunnel mechanics and its relevance to carpal tunnel syndrome

The carpal tunnel is an elaborate biomechanical structure whose pathomechanics plays an essential role in the development of carpal tunnel syndrome. The purpose of this article is to review the movement related biomechanics of the carpal tunnel together with its anatomical and morphological features, and to describe the pathomechanics and pathophysiology associated with carpal tunnel syndrome. Topics of discussion include biomechanics of the median nerve, flexor tendons, subsynovial tissue, transverse carpal ligament, carpal tunnel pressure, and morphological properties, as well as mechanisms for biomechanical improvement and physiological restoration. It is our hope that the biomechanical knowledge of the carpal tunnel will improve the understanding and management of carpal tunnel syndrome.

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.

Cross-sectional changes of the distal carpal tunnel with simulated carpal bone rotation

This study simulated the cross-sectional changes in the distal carpal tunnel resulting from inward rotations of the hamate and trapezium. Rotations which decreased the carpal arch width, increased the carpal arch area. For example, simultaneous rotation of 5 degrees around the hamate and trapezium centroids decreased the carpal arch width by 1.69 ± 0.17 mm and increased the carpal arch area by 6.83 ± 0.68 mm2. Although the bone arch area decreased, decompression of the median nerve would likely occur due to the adjacent location of the nerve near the transverse carpal ligament.

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.

Carpal Arch Changes in Response to Thenar Muscle Loading

This study investigated the biomechanical effects of thenar muscles (abductor pollicis brevis (APB), superficial head of flexor pollicis brevis (sFPB), opponens pollicis (OPP)) on the transverse carpal ligament formed carpal arch under force application by individual or combined muscles (APB, sFPB, OPP, APB-sFPB, sFPB-OPP, APB-OPP, and APB-sFPB-OPP). In ten cadaveric hands, thenar muscles were loaded under 15% of their respective maximal force capacity, and ultrasound images of the cross section of the distal carpal tunnel were collected for morphometric analyses of the carpal arch. The carpal arch height and area were significantly dependent on the loading condition (p < 0.01), muscle combination (p < 0.05), and their interaction (p < 0.01). The changes to arch height and area were significantly dependent on the muscle combinations (p = 0.001 and p < 0.001, respectively). The arch height and area increased under the loading combinations of APB, OPP, APB-sFPB, APB-OPP, or APB-sFPB-OPP (p < 0.05), but not under the combinations of sFPB (p = 0.893) or sFPB-OPP (p = 0.338). The carpal arch change under the APB-sFPB-OPP or APB-OPP loading was greater than that under the loading of APB-sFPB (p < 0.001). This study demonstrated that thenar muscle forces exert biomechanical effects on the transverse carpal ligament to increase carpal arch height and area, and these increases were different for individual muscles and their combinations.

Ligament and Bone Arch Partition of the Carpal Tunnel by Three-Dimensional Ultrasonography

The carpal tunnel is geometrically irregular due to the complex composition of many carpal bones intercalated by numerous intercarpal ligaments. The purpose of the study was to investigate the relative contributions of the ligament and bone arches to carpal tunnel space at the proximal, middle, and distal tunnel regions. A catheter ultrasound probe acquired fan-like images inside cadaveric carpal tunnels for three-dimensional reconstruction of the tunnel. The total tunnel volume was 5367.6 ± 940.1 mm3 with contributions of 12.0%, 6.9%, and 4.1% by proximal, middle, and distal ligament arches, respectively, and 27.0%, 25.3%, and 24.7% by proximal, middle, and distal bone arches, respectively. The bone arch occupied more tunnel space than the ligament arch at all regions (p < 0.05). The ligament arch was largest at the proximal region of the tunnel and significantly decreased toward the distal region (p < 0.05). However, the bone arch significantly decreased only from the proximal to middle region (p < 0.05) but not from the middle to distal region (p = 0.311). Consequently, it was observed that the ligament arch was the key contributor to the unequal carpal tunnel space across regions. Partitional and regional tunnel morphometric information may provide a better understanding of tunnel abnormality associated with various wrist pathological conditions. The developed framework of ultrasonography and data processing can be applied to other areas of interest in the musculoskeletal system.