High-frequency ultrasound in carpal tunnel syndrome: assessment of patient eligibility for surgical treatment

Diagnostic and Interventional US of the Wrist and Hand: Quadrant-based Approach

Diagnostic and interventional US of the wrist and hand can be challenging due to the small size and superficial location of structures and various disorders that need to be considered. A quadrant-based approach (volar, ulnar, dorsal, and radial) provides a rational method for performing a focused examination and joint positioning during both diagnostic imaging and intervention. Volar wrist disorders primarily involve the median nerve and the digital flexor system comprised of the flexor tendons and pulleys. The ulnar nerve and extensor carpi ulnaris tendon are chiefly responsible for ulnar-sided wrist pain. The differential diagnosis for dorsal-sided symptoms typically involves the extensor tendon compartments and includes distal intersection syndrome, extensor pollicis longus tear, and digital extensor apparatus injury. The soft-tissue ganglion is the most common abnormality in the dorsal wrist, typically associated with wrist ligaments or joint capsule. Radial-sided pain may be secondary to de Quervain tenosynovitis and must be differentiated from the more proximal intersection syndrome. US is an important tool for assessing the ulnar collateral ligament of the first metacarpophalangeal joint of the thumb and differentiating between displaced and nondisplaced tears, thereby influencing management. Despite the complexity of the anatomy and potential pathologic features within the wrist, a focused quadrant-based examination can permit the sonologist to focus on the structures of relevance. In conjunction with a systematic approach, this can aid in precise and efficient diagnostic scanning and intervention of the wrist and hand. ©RSNA, 2023 Supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Effect of Wrist Dorsiflexion/Palmar Flexion on Median Nerve Deviation and Cross-Sectional Area in Patients with Carpal Tunnel Syndrome

Objective

To evaluate the effect of wrist dorsiflexion/palmar flexion on median nerve excursion and cross-sectional area in patients with carpal tunnel syndrome.

Methods

From November 2019 to December 2021, 85 patients (110 affected wrists) who presented to our department and were diagnosed with carpal tunnel syndrome were collected and classified by severity as mild to moderate. Twenty-five healthy controls were selected during the same period, with a total of 50 healthy wrists. All patients and healthy volunteers underwent high-frequency ultrasonography to measure the vertical deviation between the median nerve and the transverse carpal ligament during wrist dorsiflexion/palmar flexion and the changes in the cross-sectional area of the median nerve in the pisiform plane. All patients with carpal tunnel syndrome underwent neurophysiological testing to measure median nerve sensory conduction velocity, sensory latency time, and sensorimotor point fluctuation amplitude.

Results

The mean age of the patients was 50 ± 8 years, the proportion of males was 18%, and the disease course was 2.3 ± 1.2 years. In terms of severity grading, 38 patients (34.5%) had mild carpal tunnel syndrome, 30 patients (27.3%) had moderate carpal tunnel syndrome, and 42 patients (38.2%) had severe carpal tunnel syndrome. Compared with the control group, the distance between the proximal median nerve and the transverse carpal ligament, the distance between the distal median nerve and the transverse carpal ligament, and the cross-sectional area were decreased in the carpal tunnel syndrome group compared with those during wrist dorsiflexion, and the differences were statistically significant (P < 0.05). Compared with the control group, there were significant differences in the vertical distance and cross-sectional area between the median nerve and the transverse carpal ligament at the proximal and distal ends in the mild, moderate, and severe groups (P < 0.05). The proximal vertical distance of the median nerve was positively correlated with sensory latency (P < 0.05) and negatively correlated with sensory conduction velocity (P < 0.05). The vertical distance of the distal end of the median nerve was also significantly positively correlated with sensory latency (P < 0.05) and significantly negatively correlated with sensory conduction velocity (P < 0.05).

Conclusion

Wrist dorsiflexion/palmar flexion can affect median nerve deviation and cross-sectional area in patients with carpal tunnel syndrome. High-frequency ultrasound is helpful to detect such an effect and can also help determine the severity of carpal tunnel syndrome, which is worthy of clinical promotion.

Assessment of L-carnitine effectiveness on carpal tunnel syndrome

Background: Carpal tunnel syndrome (CTS) is the most prevalent entrapment neuropathy. Due to the results of recent studies about the protective effects of L-carnitine on nerves, this study was conducted to evaluate the effects L-carnitine on CTS improvement in terms of patient's function, electrodiagnostic study (EDX), and median nerve sonography. Methods: In this double-blind, randomized, controlled trial, patients with CTS were selected based on the inclusion and exclusion criteria, and then, divided into two groups of placebo and L-carnitine at a dose of 500 mg twice daily for 6 weeks. They were assessed at baseline, and 4 and 6 weeks later using Boston Carpal Tunnel Questionnaire (BCTQ)‎, median nerve conduction study (EDX), and sonography. Results: There was no statistically significant difference between the intervention and control groups in terms of BCTQ‎ scores, electrodiagnostic findings, and sonographic indexes. Although based on the results of the repeated measures test of the intervention and control groups separately, there was a statistically significant difference in some electrodiagnostic criteria and BCTQ‎ scores. These indexes improved after the intervention. Conclusion: The effectiveness of L-carnitine on mild to moderate CTS improvement cannot be approve based on the findings of this study and more studies and systematic reviews are required in this regard.

Systematic Review of the Use of Power Doppler Ultrasound in the Imaging of Peripheral Nerve Compression Neuropathy

BACKGROUND

Power Doppler ultrasonography has been used as an adjunct in the diagnosis of peripheral nerve compression neuropathy. To better characterize its sensitivity and specificity, the authors performed a systematic review of its use in carpal and cubital tunnel syndrome diagnosis.

METHODS

The authors systematically reviewed published literature on the use of power Doppler ultrasound to diagnose peripheral compression neuropathy using Ovid MEDLINE, Embase.com, Scopus, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Health Technology Assessment Database, NHS Economic Evaluation Database, World Health Organization International Clinical Trial Repository Platform, and Clinicaltrials.gov. No filters for language, date, or publication type were used.

RESULTS

After reviewing 1538 identified studies, 27 publications were included involving 1751 participants with compression neuropathy (2048 median and 172 ulnar). All but three studies examined patients with carpal tunnel syndrome. Heterogeneity between study design and methodology was a noted limitation. Sensitivity and specificity of power Doppler ultrasound in the diagnosis of carpal tunnel syndrome ranged from 2.2 to 93.4 percent, and 89 to 100 percent, respectively, whereas sensitivity for cubital tunnel syndrome was 15.3 to 78.9 percent. There was variability in power Doppler signal detection based on location, with higher sensitivities at the carpal tunnel inlet and in areas of increased nerve swelling.

CONCLUSIONS

Power Doppler ultrasound is unreliable as a screening test but appears to increase diagnostic accuracy of ultrasonography in compression neuropathies. It is most beneficial in moderate to severe disease and may be valuable in detecting early cases and in disease surveillance.

Combination of high-frequency ultrasound and virtual touch tissue imaging and quantification improve the diagnostic efficiency for mild carpal tunnel syndrome

Background

Carpal tunnel syndrome (CTS) is the most common entrapment symptom in the peripheral nerves. High-frequency ultrasound (HFUS) is widely used in the diagnosis of CTS. Virtual Touch Tissue Imaging and Quantification (VTIQ), which provides more information about the hardness of organization, is used to diagnose CTS. However, the data of diagnostic value of them in various degrees of CTS are limited. Whether the combination of HFUS and VTIQ can improve the diagnostic efficiency also remains unknown. The study aimed to explore the diagnostic value of HFUS and VTIQ in various degrees of CTS and whether combination of HFUS and VTIQ could improve the diagnostic efficiency of CTS.

Methods

A collection and analysis of 133 CTS patients and 35 volunteers from January 2016 to January 2019 were performed. We compared the clinical characteristics, cross-sectional area (CSA) value and shear wave velocity SWV_mean value of CTS group with volunteer group.

Results

The CSA value and SWV_mean value of CTS cohort were significantly higher than volunteer group (10.79 ± 2.88 vs. 8.06 ± 1.39, p < 0.001, 4.36 ± 0.95 vs. 3.38 ± 1.09, p < 0.001, respectively). The area under the curve (AUC) of receiver operating characteristic (ROC) curve of CSA value and SWV_mean value were 0.794 and 0.757, respectively. Hierarchical analysis of CSA value and SWV_mean value showed that the AUC in the moderate and severe CTS group were higher than in mild CTS group. Furthermore, the CSA value combined with SWV_mean value used to diagnose mild CTS was 0.758, which was higher than that of single CSA value or single SWV_mean value.

Conclusions

Both HFUS and VTIQ technology were feasible to evaluate CTS. HFUS was suitable for use in diagnosis of moderate and severe CTS. For mild CTS, combination of HFUS and VTIQ was relevant to improve the diagnostic efficiency of CTS.

Cross-sectional area of the median nerve at the wrist: Comparison of sonographic, MRI, and cadaveric measurements

BACKGROUND

This study compares median nerve cross-sectional area (CSA) measurements at the wrist obtained with ultrasound (US) and magnetic resonance imaging (MRI) using cadaveric measurements as the gold standard.

METHODS

Median nerve CSA was measured using US and MRI in 9 cadaveric wrists obtained from 5 subjects at 5 locations: distal forearm, proximal to tunnel inlet, at tunnel inlet, at tunnel outlet, and distal to tunnel outlet and then on identical cadaveric transverse sections obtained with a bandsaw. All US, MRI, and cadaveric measurements were repeated to determine reliability. Median nerves of 10 patients with clinical carpal tunnel syndrome (CTS) were measured with US and MRI using an identical method US.

RESULTS

Median nerve CSA MRI measurements correlated better (Pearson correlation: 0.80-0.95, P < .05) with cadaveric measurements than with US measurements (Pearson correlation: 0.61-0.79, P < .05). Median nerve CSA US measurements (8.6-12.5 mm² , P < .05) were smaller at all levels than MRI (11.3-14.7 mm² ) or cadaveric (11.0-14.9 mm² ) measurements while MRI and cadaver measurements were similar at all levels. Median nerve CSA MRI measurements in CTS patients were larger than US measurements at all levels.

CONCLUSION

Median nerve CSA measurements by MRI are larger than US measurements and correlated better with cadaveric measurements. Median nerve CSA criteria used for diagnosing CTS on US are not likely to be applicable to MRI.

Ultrasonography Predictive Factors of Response to Local Steroid Injection in Patients with Carpal Tunnel Syndrome

Background:

The aim of this study is to determine the predictive value of ultrasonography for results of local steroid injection in patients with carpal tunnel syndrome (CTS).

Materials and Methods:

This prospective cohort study was conducted during a 1-year period in outpatient clinics of rehabilitation and physical medicine including 35 patients with moderate and severe CTS who receive ultrasonography-guided local steroid injection. The Boston self-assessment questionnaire and electrodiagnosis parameters were recorded at baseline, 1 month, and 3 months after therapy. We also recorded the baseline ultrasonography parameters to determine the predictors of outcome.

Results:

The sensory severity score and functional status scale along with electrodiagnosis parameters decreased significantly at 1 month (P < 0.001) and remained unchanged after 3 months. Volar bulging was negatively associated with sensory nerve action potential latency (r = −0.392; P = 0.020). Cross-sectional area (CSA) of maximal swelling (MS; r = 0.409; P = 0.015), CSA at 2-cm of MS (r = 0.563; P < 0.001), and CSA at 12-cm of MS (r = 0.521; P = 0.001) correlated positively with compound muscle action potential (CMAP) amplitude while maximal swelling/12-cm MS ratio (r = −0.439; P = 0.008) and maximal swelling/2-cm MS ratio (r = −0.342; P = 0.045) correlated negatively. CSA at 12-cm of MS also correlated positively with CMAP amplitude nerve conduction velocity (r = 0.436; P = 0.010).

Conclusion:

Volar bulging, CSA of maximal swelling, CSA of MS at 2-cm, and CSA of MS at 12-cm are among the ultrasonographic predictors of response to local steroid injection in patients with CTS.

Diagnostic Value of Virtual Touch Tissue Imaging Quantification for Evaluating Median Nerve Stiffness in Carpal Tunnel Syndrome

OBJECTIVES

To measure the shear wave velocity (SWV) of the median nerve by Virtual Touch tissue imaging quantification (VTIQ; Siemens AG, Erlangen, Germany) through the beginning of the carpal tunnel and to determine whether VTIQ could be used to diagnose carpal tunnel syndrome.

METHODS

This study recruited 49 consecutive patients (72 wrists) with a definitive diagnosis of carpal tunnel syndrome and 23 healthy volunteers (46 wrists). We measured the median nerve diameter and cross-sectional area by 2-dimensional sonography and the SWV by VTIQ. The interobserver variability was analyzed, and diagnostic values were evaluated by drawing a receiver operating characteristic curve.

RESULTS

The median nerve SWV was significantly higher in the carpal tunnel syndrome group (3.857 m/s) than the control group (2.542 m/s; P < .05). A 3.0-m/s SWV cutoff value revealed sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 83.3%, 91.3%, 93.8%, 77.8%, and 86.4%, respectively. The interobserver agreement was excellent for the SWV measurements.

CONCLUSIONS

The median nerve SWV at the carpal tunnel inlet is significantly higher in patients with carpal tunnel syndrome, for whom VTIQ appears to be a highly reproducible diagnostic technique.

Wrist ultrasound examination - scanning technique and ultrasound anatomy. Part 2: Ventral wrist

Ultrasound imaging of the musculoskeletal system is an important element of the diagnostic and therapeutic protocol. Clinical decisions, including those regarding surgical procedures, are often based solely on ultrasound imaging. However, detailed knowledge on the anatomy and a correct scanning technique are crucial for an accurate diagnosis. Modern ultrasonographic equipment allows obtaining detailed anatomical images of muscle tendons, ligaments, nerves and vessels of the carpal area. Ventral wrist ultrasound is one of the most common diagnostic procedures in patients with suspected carpal tunnel syndrome. Ventral wrist evaluation is also often performed in patients with wrist pain of unclear etiology, rheumatic diseases, wrist injuries or symptoms of ulnar neuropathy. The aim of this paper is to present ultrasound images with corresponding anatomical schemes. The technique of ultrasound examination of the ventral wrist along with practical guidance to help obtain highly diagnostic images is also discussed. The present paper is the second part of an article devoted to ultrasound anatomy and wrist ultrasound technique – the part discussing the dorsal side of the wrist was published in the Journal of Ultrasonography, Vol. 15, No 61. The following anatomical structures should be visualized during an ultrasound examination of the ventral wrist, both in the carpal tunnel as well as proximally and distally to it: four flexor digitorum superficialis tendons, four flexor digitorum profundus tendons, flexor pollicis longus, flexor carpi radialis tendon, median nerve and flexor retinaculum; in the carpal tunnel as well as proximally and distally to it: the ulnar nerve, ulnar artery and veins; the tendon of the flexor carpi ulnaris muscle; carpal joints.