Correlation between the severity of carpal tunnel syndrome and color Doppler sonography findings

Evaluation of ultrasound as diagnostic tool in patients with clinical features suggestive of carpal tunnel syndrome in comparison to nerve conduction studies: Study protocol for a diagnostic testing study

BACKGROUND

Carpal Tunnel Syndrome (CTS) is the most common compressive neuropathy, accounting for 90% of all neuropathies. Its prevalence ranges from 3.8%-7.8% in the population. The gold standard for its diagnosis is the neurophysiological study (85% sensitivity and 95% specificity), with the disadvantage of being invasive, complex and expensive, which means an increase in cost and time for the diagnosis of the disease. The main objective of this diagnostic test evaluation study is to investigate the value of ultrasound in the diagnosis of CTS, and among the secondary objectives, to establish the ultrasound parameters that are predictors of CTS in comparison with neurophysiological studies, attempting to standardize a protocol and reference values that determine the presence or absence of CTS.

METHODS

Prospective, cross-sectional study. The reference test with which we compared the ultrasound is the neurophysiological test (NPT). Patients will come consecutively from the Neurophysiology Department of the Virgen Macarena Hospital, with clinical suspicion of CTS and fulfilling the inclusion/exclusion criteria. To calculate the sample size (EPIDAT program) we proposed a sensitivity of 78% and specificity of 87% with a confidence level of 95%, requiring 438 patients (264 NPT positive, 174 NPT negative). We followed an ultrasound study protocol that included the ultrasound variables: cross-sectional area at the entrance and exit of the tunnel, range of nerve thinning, wrist-forearm index, flexor retinaculum bulging, power Doppler uptake and the existence of adjacent wrists or masses. We propose a timeline for the study to be performed between 2020 and 2023. Finally, we propose a cost-effectiveness analysis.

DISCUSSION

Ultrasound not only allows to objectify the alterations of the median nerve but also the underlying pathological mechanisms in CTS. A multitude of ultrasound parameters have been described that should be regarded in syndrome's study, among which we included the cross-sectional area, the range of nerve thinning, the wrist-forearm index, flexor retinaculum bulging, power Doppler uptake and assessment of anatomical alterations. The use of ultrasound as a diagnostic tool in CTS has many advantages for both doctors and the patients, as it is a non-invasive, convenient, and fast tool increasingly accessible to professionals.

TRIAL REGISTRATION

Trials registry number: NCT05556278.

Correlation between Electrodiagnostic Study and Imaging Features in Patients with Suspected Carpal Tunnel Syndrome

Electrodiagnostic studies (EDXs) are the confirmative diagnostic tool for carpal tunnel syndrome (CTS). Previous studies have evaluated the relationship between EDXs and ultrasonography (US) but not with X-rays. Recently, many studies on the diagnostic value of X-rays in various diseases have been reported, but data on CTS are lacking. We evaluated the relationship between electrodiagnostic parameters and roentgenographic and ultrasonographic features in CTS and investigated the usefulness of X-rays and US for CTS. This retrospective study included 97 wrists of 62 patients. All patients with suspected CTS underwent EDXs, wrist US, and wrist X-rays. The CTS patients were classified into mild, moderate, and severe groups. The roentgenographic features included the ulnar variance (UV) and the anteroposterior diameter of the wrist (APDW), and the ultrasonographic features included the flattening ratio (FR) and the thickest anteroposterior diameter of the median nerve (TAPDM). Most EDX parameters showed significant correlations with roentgenographic and US features. The electrodiagnostic severity was also correlated with all imaging features. Therefore, both wrist X-rays and wrist US can be useful for the diagnosis of CTS as supplements to EDXs.

Diagnostic Value of Ultrasound for Detecting Carpal Tunnel Syndrome in Patients With Rheumatoid Arthritis: A Three-Arm Cross-Sectional Study

Objective:

This study was conducted to assess the diagnostic value of sonography in detecting carpal tunnel syndrome (CTS) in patients with rheumatoid arthritis (RA) and to compare the results with a normal control group.

Materials and Methods:

In this three-arm cross-sectional study, the sonographically measured median nerve cross-sectional area (MNCSA) was compared in three groups: RA patients with CTS, RA patients without CTS, and normal subjects (no RA, no CTS). A nerve conduction study (NCS) was performed for all enrolled participants, across the three study arms.

Results:

In this study, 38 RA patients (17 in CTS group and 21 in no CTS group) and 19 healthy subjects were recruited. The MNCSAs were 11.86 (±1.87) mm2 in RA patients with CTS, 10.16 (±1.71) mm2 in RA patients without CTS, and 9.42 (±1.46) mm² in healthy control patients. The accuracy of sonography in detecting CTS was 0.79 (95% confidence interval, 0.67–0.91), with a sensitivity and specificity of 88% and 57%, respectively. The MNCSA in CTS group was significantly higher than the control group ( P = .02).

Conclusion:

In this cohort, the sonographic measurement of MNCSA was an accurate and sensitive method for the diagnosis of CTS, especially in its early stages. In addition, in this cohort, RA without CTS did not increase the MNCSA.

Sonographic Diagnosis of Carpal Tunnel Syndrome

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

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.

Machine learning-based approach for disease severity classification of carpal tunnel syndrome

Identifying the severity of carpal tunnel syndrome (CTS) is essential to providing appropriate therapeutic interventions. We developed and validated machine-learning (ML) models for classifying CTS severity. Here, 1037 CTS hands with 11 variables each were retrospectively analyzed. CTS was confirmed using electrodiagnosis, and its severity was classified into three grades: mild, moderate, and severe. The dataset was randomly split into a training (70%) and test (30%) set. A total of 507 mild, 276 moderate, and 254 severe CTS hands were included. Extreme gradient boosting (XGB) showed the highest external validation accuracy in the multi-class classification at 76.6% (95% confidence interval [CI] 71.2–81.5). XGB also had an optimal model training accuracy of 76.1%. Random forest (RF) and k-nearest neighbors had the second-highest external validation accuracy of 75.6% (95% CI 70.0–80.5). For the RF and XGB models, the numeric rating scale of pain was the most important variable, and body mass index was the second most important. The one-versus-rest classification yielded improved external validation accuracies for each severity grade compared with the multi-class classification (mild, 83.6%; moderate, 78.8%; severe, 90.9%). The CTS severity classification based on the ML model was validated and is readily applicable to aiding clinical evaluations.

Median Nerve's Microcirculation in Carpal Tunnel Syndrome: Superb Microvascular Imaging

BACKGROUND

The objectivity of physical and electrodiagnostic tests is limited in detecting carpal tunnel syndrome and its recurrence. Predicting the median nerve blood supply using superb microvascular imaging will allow exact diagnosis and a good follow-up system. The aims of this study include using superb microvascular imaging to correlate with electromyographic diagnosis, and to determine the impact of surgery on improvement in superb microvascular imaging.

METHODS

Between July of 2019 and January of 2020, 32 wrists of 21 patients were evaluated prospectively. After preoperative electrodiagnostic studies and vascular index measurement with superb microvascular imaging, open carpal tunnel release was performed by a single surgeon, and 3 months later standardized superb microvascular imaging was performed. Preoperative vascular indexes were compared with the mild, moderate, and severe electrodiagnostic study results. Preoperative and postoperative vascular index results were compared.

RESULTS

The average of the preoperative and postoperative imaging groups was 2.77 and 1.48, respectively, and there was a statistically significant difference between the two groups (p < 0.05). Although no significant difference was found between preoperative and postoperative vascular index values in patients presenting with mild carpal tunnel syndrome (p > 0.05), there was a significant decrease in vascular index values in patients presenting with moderate and severe carpal tunnel syndrome after surgical decompression.

CONCLUSIONS

Superb microvascular imaging is emerging as a groundbreaking, new, and reliable technique. Evaluation of the median nerve blood supply is a reliable method that would be helpful for early diagnosis, planning treatment, determining the severity of carpal tunnel syndrome, and postoperative follow-up.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, IV.

Ultrasonography Findings of the Carpal Tunnel after Endoscopic Carpal Tunnel Release for Carpal Tunnel Syndrome

Objective

To investigate changes in the median nerve, retinaculum, and carpal tunnel on ultrasound after successful endoscopic carpal tunnel release (ECTR).

Materials and Methods

This prospective study involved 37 wrists in 35 patients (5 male, 30 female; mean age ± standard deviation [SD], 56.9 ± 6.7 years) with primary carpal tunnel syndrome (CTS). An in-house developed scoring system (0–3) was used to gauge the clinical improvement after ECTR. Ultrasound was performed before ECTR, and at 1, 3, and 12 months post-ECTR. Changes in the median nerve, flexor retinaculum, and carpal tunnel morphology on ultrasound after ECTR were analyzed. Ultrasound parameters for different clinical improvement groups were compared.

Results

All patients improved clinically after ECTR. The average clinical improvement score ± SD at 12 months post-ECTR was 2.2 ± 0.7. The median nerve cross-sectional area proximal and distal to the tunnel decreased at all time intervals post-ECTR but remained swollen compared to normal values. Serial changes in the median nerve caliber and retinacular bowing after ECTR were more pronounced at the tunnel outlet than at the tunnel inlet. The flexor retinaculum had reformed in 25 (68%) of 37 wrists after 12 months.

Conclusion

Postoperative changes in median nerve and retinaculum parameters were most pronounced at the tunnel outlet. Even in patients with clinical improvement after ECTR, nearly all ultrasound parameters remain abnormal at one year post-ECTR. These ultrasound parameters should not necessarily be relied upon to diagnose persistent CTS after ECTR.

Effect of Force, Posture, and Repetitive Wrist Motion on Intraneural Blood Flow in the Median Nerve

OBJECTIVES

Pinching, deviated wrist postures, and repetitive motion are risk factors for carpal tunnel syndrome. Hypervascularization of the median nerve and increased intraneural blood flow proximal to the carpal tunnel result in finger force and deviated wrist postures. The purpose of this study was to determine the effects of pinching with and without force, wrist posture, and repetitive wrist motion on intraneural blood flow in the median nerve.

METHODS

Eleven healthy and 11 carpal tunnel syndrome-symptomatic individuals completed 3 sections of this study: 15 pinch posture force trials, 3 repetitive wrist motion trials, and 3 static wrist posture trials. Intraneural blood flow (centimeters per second) was measured with pulsed wave Doppler ultrasound during each trial. Transverse B-mode images obtained from static trials were used to calculate the median nerve cross-sectional area and circumference.

RESULTS

An analysis of variance statistical analysis revealed significant main effects of pinch posture force (F_4,80 = 21.397; P < .001) and wrist posture (F_2,40 = 14.545; P < .001). Intraneural blood flow velocities were significantly greater when 6 N of force was applied by the thumb, finger, or pinch compared to no applied force in the same postures. Intraneural blood flow velocities were higher at 30° wrist flexion (mean ± SD, 2.24 ± 0.42 cm/s) than neutral (2.06 ± 0.45 cm/s) and 30° wrist extension (1.97 ± 0.46 cm/s). No changes were found in response to repetitive wrist motion.

CONCLUSIONS

Flexed wrists as well as applied finger and thumb forces increase median nerve blood flow at the entry to the carpal tunnel, which may negatively affect the median nerve.

Advanced Musculoskeletal Ultrasound Techniques: What Are the Applications?

OBJECTIVE. The purpose of this article is to cover technical advances in musculo-skeletal ultrasound from the viewpoint of the radiologist. CONCLUSION. Among the advances in musculoskeletal ultrasound that we highlight the use of ultrahigh-frequency transducers to visualize ever-finer anatomic detail, the expanding practical clinical applications for microvascular imaging, and the use of elastography to predict function and, possibly, healing potential.

Clinico-radiological review of peripheral entrapment neuropathies - Part 1 upper limb

PURPOSE

This article aims to review the pertinent anatomy, etiopathogenesis, current clinical and radiological concepts and principles of management in case of upper limb entrapment neuropathies.

METHODS

The review is based on critical analysis of the existing literature as well as our experience in dealing with entrapment neuropathies.

RESULTS

Entrapment neuropathies of the upper limb peripheral nerves are common conditions that are often misdiagnosed because of their varying clinical presentations and lack of standardized diagnostic methods. Clinical assessment and electrodiagnostic studies have been the mainstay; however, imaging techniques have provided newer insights into the pathophysiology of these entities, leading to a paradigm shift in their diagnosis and management. The current best practice protocols for entrapment syndromes are constantly evolving with increasing emphasis on the role high-resolution ultrasound and magnetic resonance imaging. Many imaging criteria are described and we have tried to present the most validated measurements for diagnosing entrapment neuropathies.

CONCLUSION

It is imperative for a clinical radiologist to be familiar with the etiopathogenesis and clinical features of these conditions, in addition to being thorough with the anatomy and the latest imaging strategies.

Ultrasound-guided insulin injection for carpal tunnel syndrome in type 2 diabetes mellitus patients

OBJECTIVE

To compare effectiveness of ultrasound-guided local insulin injection, local steroid injection, and local steroid followed by insulin injections in treating mild to moderate carpal tunnel syndrome (CTS) in type 2 diabetes mellitus (DM).

METHOD

Study included 60 patients with electrophysiologic evidence of mild to moderate CTS. They were randomly divided into three groups: group I received insulin injection locally into the affected carpal tunnel at first visit and a similar dose after 2 weeks; group II received single injection of 40 mg methylprednisolone acetate injection; and group III received steroid injection then followed by insulin injection twice after 2 and 4 weeks. All injections were performed with ultrasonographic guidance. All patients were assessed by modified Boston Carpal Tunnel Questionnaire (FD score), CTS severity score (SS score), and neurophysiological and ultrasonographic assessments at baseline and 10 weeks after treatment.

RESULTS

A significant improvement in mean FD score, SS score, DML (distal motor latency), SNCV (sensory nerve conduction velocity), PSL (peak sensory latency), Samp (sensory amplitude), and CSA (cross-sectional area of median nerve) observed in all groups (with exception of mean DML and Samp in the second group and mean Samp in the third group). Group III showed significant improvement in CSA especially when compared to group II by post hoc analysis (P = 0.005).

CONCLUSIONS

Local insulin injection is as effective as steroid in treating mild to moderate CTS in type 2 DM and is a safer alternative. Adding insulin injections after steroid shows more sonographic improvement than steroid alone. Key Points • Local insulin injection is as effective as steroid in treating mild to moderate CTS in type 2 diabetic patients. • Measuring CSA of median nerve at CT inlet by US is a better tool for monitoring median nerve changes after treatment. • Adding insulin injections after steroid has more sonographic improvement than steroid alone.

Comparison of Magnetic Resonance Imaging and Ultrasonography in Diagnosing and Grading Carpal Tunnel Syndrome: A Prospective Study

OBJECTIVE

To use anatomic measurements on magnetic resonance imaging (MRI) and ultrasonography (USG) in diagnosing and grading carpal tunnel syndrome (CTS) using nerve conduction studies (NCS) as the gold standard.

MATERIAL AND METHODS

In this prospective study, 26 patients with CTS (45 wrists; 22 female and 4 male patients; mean ± SD age of 49.42 + 14.47 years) and 19 age and sex matched healthy volunteers (32 wrists; 15 female and 4 male volunteers, mean ± SD age of 42.52 + 10.85 years) underwent MRI and USG. Cross-sectional area (CA) of median nerve was measured using free hand ROI at four levels: hamate hook (H0), pisiform bone (PI0), 1 cm proximal (PI1) and 2 cm proximal to PI0 (PI2). Relative median nerve signal intensity (MNSI) was calculated as ratio of median nerve signal intensity with hypothenar muscle signal intensity. Flexor retinacular bowing was calculated at hamate hook level. Echogenicity and Power Doppler vascularity of median nerve were assessed on USG. Independent t-test, chi square test and receiver operating characteristic curve analysis were used as appropriate.

RESULTS

On USG, CA measured at PI0 (95% confidence interval of 0.872-0.987) and retinacular bowing (0.816-0.912), while, on MRI, CA at PI1 (0.874-0.997) were most useful in diagnosing CTS based on the ROC and Zombie plot analysis. Area under curves for CA measurements on USG and MRI were not significantly different. CA at PI1 on MRI (0.752-0.965) was significantly different between minimal to moderate CTS and severe to extreme CTS groups (on NCS).

CONCLUSION

CA of median nerve is the most useful parameter to diagnose and grade CTS and USG and MRI are comparable for measurements. Increased retinacular bowing on USG and hypoechogenicity of median nerve increase the diagnostic confidence while MRI helps in picking up important associated conditions.

Sonographic Findings Associated With Carpal Tunnel Syndrome

PURPOSE

The purpose of this study was to identify associations between the clinical manifestations of carpal tunnel syndrome (CTS) and the sonographic measurements of the median nerve in the carpal tunnel. We hypothesized that sonographic changes in the median nerve from proximal to distal along the carpal tunnel would be associated with symptom severity scores.

METHODS

We report on 38 patients with clinical signs and symptoms of CTS in a prospective investigation. Subjects underwent sonographic evaluation with measurement of median nerve cross-sectional area (CSA) at 3 locations: the level of the pronator quadratus, pisiform, and hamate. In addition, we measured dimensions of the carpal tunnel at the levels of the pisiform (inlet) and hamate (outlet). Finally, we recorded maximal thickness of the transverse carpal ligament (TCL). Patients underwent routine clinical evaluation and 31 patients had electrodiagnostic examination. Patients completed the Levine Katz Questionnaire (LKQ) to characterize severity of clinical symptoms. Each clinician was blinded to symptom severity scores. Pearson correlation coefficients were calculated to measure the relationship between LKQ score and sonographic measures.

RESULTS

Median nerve CSA decreased over the course of the carpal tunnel from proximal to distal in 30 of 38 wrists. A greater absolute change in CSA of the median nerve over the course of the carpal tunnel between the pisiform and the hamate as well as between the pronator quadratus and the hamate correlated with increased severity of clinical symptoms. Increased thickening of the TCL also correlated with greater symptom severity scores.

CONCLUSIONS

Changes in CSA of the median nerve as well as thickening of the TCL correlate with CTS severity.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

Superb Microvascular Imaging of the Median Nerve in Carpal Tunnel Syndrome: An Electrodiagnostic and Ultrasonographic Study

OBJECTIVE

To evaluate intraneural blood flow of the median nerve using superb microvascular imaging (SMI) and power Doppler ultrasonography (PDUS), and to examine their correlation with electroneuromyography in patients with carpal tunnel syndrome (CTS).

METHODS

A cross-sectional survey was used, and the study was conducted in the research unit of a training and research hospital. Patients diagnosed with CTS according to electroneuromyography studies were included in the study. Ultrasound measurements were taken using an Aplio-500 (Toshiba Medical System Corporation, Tokyo, Japan) device and a linear multifrequency 14-MHz probe. The cross-sectional area of the median nerve at the carpal tunnel level was measured by the direct tracing method using electronic calipers. The power Doppler ultrasonography and superb microvascular imaging scores were recorded by grading the vascularity between 0 and 3.

RESULTS

Evaluation was made of a total of 113 hands of 80 patients (18 men, 62 women) with a mean age of 34.67 ± 12.82 years. The mean duration of symptoms was 12.34 ± 6.66 months. When the patients were grouped as mild, moderate, and severe CTS, there was a statistically significant difference between the SMI and PDUS grades (P < .05). As the severity of CTS increased, an increase in SMI and PDUS scores was observed. There was a strong correlation between SMI scores and motor distal latency (r = .71/P = .026), amplitude of sensory action potential (r = -.77/P = .029), and sensory neurotransmission rate (r = .77/P = .029).

CONCLUSION

SMI seems to be more sensitive than PDUS for evaluating the vascularity of the median nerve in patients with CTS, and SMI grading is correlated with the ENMG results.

Blood Flow Changes in Subsynovial Connective Tissue on Contrast-Enhanced Ultrasonography in Patients With Carpal Tunnel Syndrome Before and After Surgical Decompression

OBJECTIVES

Although qualitative alteration of the subsynovial connective tissue in the carpal tunnel is considered to be one of the most important factors in the pathophysiologic mechanisms of carpal tunnel syndrome (CTS), little information is available about the microcirculation in the subsynovial connective tissue in patients with CTS. The aims of this study were to use contrast-enhanced ultrasonography (US) to evaluate blood flow in the subsynovial connective tissue proximal to the carpal tunnel in patients with CTS before and after carpal tunnel release.

METHODS

The study included 15 volunteers and 12 patients with CTS. The blood flow in the subsynovial connective tissue and the median nerve was evaluated preoperatively and at 1, 2, and 3 months postoperatively using contrast-enhanced US.

RESULTS

The blood flow in the subsynovial connective tissue was higher in the patients with CTS than in the volunteers. In the patients with CTS, there was a significant correlation between the blood flow in the subsynovial connective tissue and the median nerve (P = .01). The blood flow in both the subsynovial connective tissue and the median nerve increased markedly after carpal tunnel release.

CONCLUSIONS

Our results suggest that increased blood flow in the subsynovial connective tissue may play a role in the alteration of the microcirculation within the median nerve related to the pathophysiologic mechanisms of CTS. The increase in the blood flow in the subsynovial connective tissue during the early postoperative period may contribute to the changes in intraneural circulation, and these changes may lead to neural recovery.

Inter-Rater and Intra-Rater Reliability of Sonographic Median Nerve and Wrist Measurements

Background:

Electrophysiologic studies have been considered the “gold standard” in diagnosing carpal tunnel syndrome (CTS); however, reports of false-negative results, as well as discomfort for the patient during the procedure has paved the use of ultrasound, being a painless and cost-efficient tool, as an alternative means for its diagnosis. Various ultrasound parameters assessing the median nerve and wrist dimensions have been described, but description of landmarks to assess these in a reliable manner has been lacking.

Methodology:

A systematic search of different databases yielded data regarding ultrasound parameters for CTS diagnosis, the landmarks used, and presence of reliability testing. Based on this, three sonologists discussed the external and sonographic landmarks that will be used in measuring the median nerve measurements, bowing of the flexor retinaculum and the carpal tunnel dimensions. A pilot test with two consecutive healthy participants using the discussed ultrasound parameters was carried out, and results were subjected to inter- and intra-rater reliability testing. Modifications were accordingly made on the acquisition of ultrasound image using external landmarks. The reliability testing proper was done with ten consecutive healthy participants.

Results:

Based on the systematic review and the pilot study, external landmarks were used to locate the median nerve in the forearm, carpal tunnel inlet and outlet. For the forearm measurement, it was taken 10 cm proximal from the distal palmar crease. The distal palmar crease was the external landmark used for the carpal tunnel inlet, while for the carpal tunnel outlet; it was measured 1 cm distal to the distal palmar crease. Instead of using the inner edge of the hook of hamate and trapezium, the apices of these bones were used as the landmarks in measuring the carpal tunnel outlet dimensions. There was excellent intra-rater reliability (mid-forearm, carpal tunnel inlet and outlet) except for the following: cross-sectional area (CSA) of the median nerve at the carpal tunnel inlet and outlet; and bowing of the flexor retinaculum. All the parameters had an excellent inter-rater reliability measured at the three levels (intraclass correlation [ICC]: Of 0.77–0.99) except for CSA of the median nerve at the levels of the forearm (fair-to-good with ICC of 0.71) and the carpal tunnel inlet (fair-to-good reliability of ICC: 0.43).

Conclusion:

There was an improved inter- and intra-rater reliability when external landmarks were used instead of sonographic landmarks.

Ultrasound assessment of the sural nerve in patients with neuropathic pain after ankle surgery

INTRODUCTION

The sural nerve may be damaged after ankle injury. The aim of our study was to determine the diagnostic utility of high-resolution sonography in patients with ankle fractures treated by open reduction and internal fixation in whom there was a clinical suspicion of sural neuropathy.

METHODS

We examined the ultrasound (US) characteristics of patients with and without postsurgical sural neuropathic pain and healthy volunteers. Cross-sectional area (CSA), echogenicity, and vascularization of the sural nerves were recorded.

RESULTS

Fourteen participants and all sural nerves were identified. CSA (P < 0.001) and vascularization (P = 0.002) were increased in symptomatic patients when compared with asymptomatic patients and healthy volunteers. There were no significant differences in nerve echogenicity (P = 0.983).

DISCUSSION

US may be a valuable tool for evaluating clinically suspected sural nerve damage after ankle stabilization surgery. Sural nerve abnormalities are seen in patients with postsurgical neuropathic pain. Muscle Nerve 57: 407-413, 2018.

Value of superb microvascular imaging ultrasonography in the diagnosis of carpal tunnel syndrome: Compared with color Doppler and power Doppler

The aim of this study was to compare the value of superb microvascular imaging (SMI) in carpal tunnel syndrome (CTS) with that of color Doppler ultrasonography (CDUS) and power Doppler ultrasonography (PDUS).Fifty patients with symptomatic CTS and 25 healthy volunteers were enrolled. The cross-sectional area (CSA), CDUS score, PDUS score, and SMI score of the median nerve (MN) at the carpal tunnel were recorded. The value of different ultrasonography (US) diagnostic strategies was calculated.The blood flow display ratio in the MN of the healthy volunteers had no statistical difference between CDUS, PDUS, and SMI (20%, 32%, and 48%, respectively, P >.05). The blood flow display ratio for SMI in patients was significantly higher than that of CDUS and PDUS (90%, 52%, and 60%, respectively, P <.005). The accuracy of SMI score ≥2 (79%) was much higher than that of CDUS and PDUS (61% and 63%, respectively, P <.05). Comprehensive consideration of SMI and CSA, CSA≥10.5 mm, and/or SMI score ≥2 has the highest accuracy (83%), significantly higher than that of CSA combination with CDUS or PDUS (68% and 69%, respectively, P <.05).SMI is more sensitive to display the blood flow in the MN with CTS than CDUS and PDUS. It might significantly improve the diagnosis value for CTS.

Diagnostic accuracy of quantitative neuromuscular ultrasound for the diagnosis of intensive care unit-acquired weakness: a cross-sectional observational study

Background

Neuromuscular ultrasound is a noninvasive investigation, which can be easily performed at the bedside on the ICU. A reduction in muscle thickness and increase in echo intensity over time have been described in ICU patients, but the relation to ICU-acquired weakness (ICU-AW) is unknown. We hypothesized that quantitative assessment of muscle and nerve parameters with ultrasound can differentiate between patients with and without ICU-AW. The aim of this cross-sectional study was to investigate the diagnostic accuracy of neuromuscular ultrasound for diagnosing ICU-AW.

Methods

Newly admitted ICU patients, mechanically ventilated for at least 48 h, were included. As soon as patients were awake and attentive, an ultrasound was made of four muscles and two nerves (index test) and ICU-AW was evaluated using muscle strength testing (reference standard; ICU-AW defined as mean Medical Research Council score <4). Diagnostic accuracy of muscle thickness, echo intensity and homogeneity (echo intensity standard deviation) as well as nerve cross-sectional area, thickness and vascularization were evaluated with the area under the curve of the receiver operating characteristic curve (ROC–AUC). We also evaluated diagnostic accuracy of z-scores of muscle thickness, echo intensity and echo intensity standard deviation.

Results

Seventy-one patients were evaluated of whom 41 had ICU-AW. Ultrasound was done at a median of 7 days after admission in patients without ICU-AW and 9 days in patients with ICU-AW. Diagnostic accuracy of all muscle and nerve parameters was low. ROC–AUC ranged from 51.3 to 68.0% for muscle parameters and from 51.0 to 66.7% for nerve parameters.

Conclusion

Neuromuscular ultrasound does not discriminate between patients with and without ICU-AW at the time the patient awakens and is therefore not able to reliably diagnose ICU-AW in ICU patients relatively early in the disease course.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-017-0263-8) contains supplementary material, which is available to authorized users.

Diagnosing carpal tunnel syndrome with Doppler ultrasonography: a comparison of ultrasonographic measurements and electrophysiological severity

INTRODUCTION

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy. Diagnosis is based on clinical history, physical examination, and electrophysiological studies. Imaging techniques are performed for difficult-to-diagnose cases because they provide information about the morphology of the median nerve. More recently, it has been shown that Doppler ultrasonography can detect increased intraneural blood flow in CTS. The aim of our study is to evaluate the relationship between the severity of CTS, hypervascularization, and cross-sectional area (CSA) to determine the diagnostic value of Doppler ultrasonography.

PATIENTS AND METHODS

The study group comprised 125 wrists of 75 patients who had been diagnosed with CTS, both clinically and electrophysiologically. The control group comprised 100 wrists of 50 healthy volunteers. Wrists were classified into five stages of CTS severity based on electrophysiologic studies. A radiologist examined the wrists blindly with grayscale images and Doppler ultrasonography to assess CSA and hypervascularization.

RESULTS

A total of 121 wrists were included. There were 28 wrists with minimal CTS severity stage, 36 with mild, 36 with moderate, and 21 with severe. The sensitivity and specificity of CSA and hypervascularization in detecting CTS was 90.9, 94.0, 93.4, and 90.0%, respectively. There was a significant correlation between CTS severity and hypervascularization (p < 0.005) for all stages.

CONCLUSION

Our study shows that Doppler ultrasonography results strongly correlate with CTS severity. Hence, this is a useful method for diagnosing CTS and estimating its severity.

Review of Ultrasonography in the Diagnosis of Carpal Tunnel Syndrome and a Proposed Scanning Protocol

Carpal tunnel syndrome is the most common peripheral compressive neuropathy. Ultrasonography (US) is an emerging technology that can be used in the diagnosis of carpal tunnel syndrome. Although the cross-sectional area is the most studied and validated measurement for carpal tunnel syndrome, there is no standardized neuromuscular US scanning protocol. We review the most studied neuromuscular US characteristics and protocols in the evaluation of carpal tunnel syndrome and propose a standardized protocol for evaluating carpal tunnel syndrome with neuromuscular US based on current literature.

Doppler sonography for ulnar neuropathy at the elbow

INTRODUCTION

The aim of this study was to determine the value of Doppler sonography for evaluation of ulnar neuropathy at the elbow (UNE).

METHODS

A total of 102 patients with a clinical suspicion of UNE and 50 healthy controls were examined by Doppler and gray-scale sonography.

RESULTS

Intraneural vascularization was found in 31 (46.3%) of 67 patients with confirmed UNE and in 3 (6.0%) of 50 healthy controls. Combining gray-scale sonography measurement of nerve size and the presence of intraneural vascularization increased sensitivity by 3%, but decreased the specificity. Patients with intraneural vascularization had more severe disease than those without intraneural vascularization (P < 0.05). The variables obtained by Doppler sonography were associated with the severity of UNE (P < 0.05).

CONCLUSIONS

Doppler sonography is not helpful for diagnosing UNE but can be used to assess the severity of UNE. Muscle Nerve 54: 258-263, 2016.

Reliability Assessment of Various Sonographic Techniques for Evaluating Carpal Tunnel Syndrome

Objectives-The aim of this study was to determine the intra- and inter-rater reliability of sonographic measurements of the median nerve cross-sectional area in individuals with carpal tunnel syndrome and healthy control participants.Methods-The median nerve cross-sectional area was evaluated by sonography in 18 participants with carpal tunnel syndrome (18 upper extremities) and 9 control participants (18 upper extremities) at 2 visits 1 week apart. Two examiners, both blinded to the presence or absence of carpal tunnel syndrome, captured independent sonograms of the median nerve at the levels of the carpal tunnel inlet, pronator quadratus, and mid-forearm. The cross-sectional area was later measured by each examiner independently. Each also traced images that were captured by the other examiner.Results-Both the intra- and inter-rater reliability rates were highest for images taken at the carpal tunnel inlet (radiologist, r = 0.86; sonographer, r = 0.87; inter-rater, r = 0.95; all P < .0001), whereas they was lowest for the pronator quadratus (r = 0.49, 0.29, and 0.72, respectively; all P < .0001). At the mid-forearm, the intra-rater reliability was lower for both the radiologist and sonographer, whereas the inter-rater reliability was relatively high (r = 0.54, 0.55, and 0.81; all P < .0001). Tracing of captured images by different examiners showed high concordance for the median cross-sectional area at the carpal tunnel inlet (r = 0.96-0.98; P < .0001).Conclusions-The highest intra- and inter-rater reliability was found at the carpal tunnel inlet. The results also demonstrate that tracing of the median nerve cross-sectional area from captured images by different examiners does not contribute significantly to measurement variability.

Does the ratio of the carpal tunnel inlet and outlet cross-sectional areas in the median nerve reflect carpal tunnel syndrome severity?

Although ultrasound measurements have been used in previous studies on carpal tunnel syndrome to visualize injury to the median nerve, whether such ultrasound data can indicate the severity of carpal tunnel syndrome remains controversial. The cross-sectional areas of the median nerve at the tunnel inlet and outlet can show swelling and compression of the nerve at the carpal. We hypothesized that the ratio of the cross-sectional areas of the median nerve at the carpal tunnel inlet to outlet accurately reflects the severity of carpal tunnel syndrome. To test this, high-resolution ultrasound with a linear array transducer at 5-17 MHz was used to assess 77 patients with carpal tunnel syndrome. The results showed that the cut-off point for the inlet-to-outlet ratio was 1.14. Significant differences in the inlet-to-outlet ratio were found among patients with mild, moderate, and severe carpal tunnel syndrome. The cut-off point in the ratio of cross-sectional areas of the median nerve was 1.29 between mild and more severe (moderate and severe) carpal tunnel syndrome patients with 64.7% sensitivity and 72.7% specificity. The cut-off point in the ratio of cross-sectional areas of the median nerve was 1.52 between the moderate and severe carpal tunnel syndrome patients with 80.0% sensitivity and 64.7% specificity. These results suggest that the inlet-to-outlet ratio reflected the severity of carpal tunnel syndrome.

Diagnostic criteria of carpal tunnel syndrome using high-resolution ultrasonography: correlation with nerve conduction studies

The aim of this work was to evaluate the diagnostic performance of grey-scale, color Doppler, and dynamic ultrasound (US) for diagnosing carpal tunnel syndrome (CTS) using the medical diagnostic test called nerve conduction study (NCS) as the reference standard, and to correlate the increase in median nerve (MN) cross-sectional area (CSA) with severity of CTS. Fifty-one patients (95 wrists) with clinical symptoms of idiopathic CTS were recruited. The CSA and flattening ratio of the MN were measured at the distal radio-ulnar joint, pisiform, and hamate levels; bowing of the flexor retinaculum was determined at the hamate level. The hypervascularity of the MN was evaluated. The transverse sliding of the MN was observed dynamically and recorded as being either normal or restricted/absent. Another 15 healthy volunteers (30 wrists) were recruited as controls. Interoperator reliability was established for all criteria. CTS was confirmed in 75 wrists (75/95: 79%; 14 minimal, 21 mild, 23 moderate, 17 severe). CSA at the pisiform level was found to be the most reliable and accurate grey-scale criterion to diagnose CTS (optimum threshold: 9.8 mm(2)). There was a good correlation between the severity of NCS and CSA (r = 0.78, p < 0.001). The sensitivity and specificity of color-Doppler and dynamic US in detecting CTS was 69, 95, 58, and 86%, respectively. Combination of these subjective criteria with CSA increases the sensitivity to 98.3%. US measurement of CSA provides additional information about the severity of MN involvement. Color-Doppler and dynamic US are useful supporting criteria that may expand the utility of US as a screening tool for CTS.

Doppler sonography for the diagnosis of carpal tunnel syndrome: a critical review

INTRODUCTION

Doppler sonography may detect increased intraneural blood flow of the median nerve in carpal tunnel syndrome (CTS). The purpose of this review is to critically evaluate the literature about the diagnostic value of increased intraneural flow detected by sonography in CTS Methods: Systematic review of studies published between 1985 and 2013.

RESULTS

The 7 studies we found had considerable differences in study design and had methodological shortcomings. Doppler sonography had a median sensitivity of 72% (range, 41-95%) and a median specificity of 88% (range, 71-100%). Most studies could not compare the diagnostic value of sonography to that of electrophysiological studies, because the latter were often used as a reference test.

CONCLUSIONS

Increased intraneural flow detected by Doppler sonography may be a promising diagnostic test for CTS, but further studies are needed before it can be implemented in clinical practice.

High-resolution ultrasonographic evaluation of "hourglass-like fascicular constriction" in peripheral nerves: a preliminary report

An hourglass-like constriction is a focal fascicular lesion observed in one or a few places in one or a few fascicles of a peripheral nerve trunk, and usually affects the anterior interosseous (AIN) or posterior interosseous (PIN) nerve. Constrictions have previously been discovered only by surgical exploration, and have been unable to be recognized on pre-operative imaging. We encountered some cases in which the lesion was able to be diagnosed pre-operatively by high-resolution ultrasonography; these findings were then confirmed intra-operatively. Five consecutive cases were included in this study. In three cases with constrictions revealed on pre-operative ultrasound, the findings were confirmed intra-operatively. In the remaining two cases in which no constrictions were detected pre-operatively, no constriction was revealed intra-operatively. High-resolution ultrasonography may play a significant role in the diagnosis of hourglass-like constrictions, and may thus lead to significant changes in treatment strategies for AIN and PIN palsy.

A handy review of carpal tunnel syndrome: From anatomy to diagnosis and treatment

Carpal tunnel syndrome (CTS) is the most commonly diagnosed disabling condition of the upper extremities. It is the most commonly known and prevalent type of peripheral entrapment neuropathy that accounts for about 90% of all entrapment neuropathies. This review aims to provide an outline of CTS by considering anatomy, pathophysiology, clinical manifestation, diagnostic modalities and management of this common condition, with an emphasis on the diagnostic imaging evaluation.

Reliability of peripheral intraneural microhemodynamics evaluation by using contrast-enhanced ultrasonography

PURPOSE

The purpose of the study was to validate the reliability of quantitative intraneural enhancement patterns by using contrast-enhanced ultrasonography (CEUS).

METHODS

Nine asymptomatic wrists underwent a total of three CEUS examinations each conducted at 1-month intervals. The CEUS enhancement pattern of median nerves was quantitatively evaluated. The area under the time-intensity curve was calculated by placing the regions of interest at the proximal, center, and distal regions of the median nerve. An intra-class correlation coefficient for intra-observer, inter-observer, and inter-examination reproducibility was calculated.

RESULTS

The intra- and inter-observer reproducibility was almost perfect. Inter-examination reproducibility of the proximal, center, and distal regions was 0.891, 0.614, and 0.535, respectively. In this study, we found that the reproducibility of the distal and center regions of the median nerve in the carpal tunnel was lower than that of the proximal region.

CONCLUSION

High intra-observer, inter-observer, and inter-examination reproducibility of CEUS was obtained in the evaluation of the intraneural enhancement pattern when the region of interest was placed in the proximal region of the median nerve.

Ultrasonography of peripheral nerves

Over the last decade, neuromuscular ultrasonography has emerged as a useful tool for the diagnosis of peripheral nerve disorders. This article reviews sonographic findings of normal nerves, including key quantitative ultrasound measurements that are helpful in the evaluation of focal and possibly generalized peripheral neuropathies. It also discusses several recent articles outlining the evidence base for the use of this technology, as well as new findings in compressive, traumatic, and generalized neuropathies. Ultrasonography is well suited for use in electrodiagnostic laboratories, where physicians, experienced in both the clinical evaluation of patients and the application of hands-on technology, can integrate findings from the patient's history, physical examination, electrophysiological studies, and imaging for diagnosis and management.

Increased nerve vascularization detected by color Doppler sonography in patients with ulnar neuropathy at the elbow indicates axonal damage

INTRODUCTION

The aim of this study was to establish the prevalence of increased intraneural vascularization detected by ultrasonography (IVUS) in patients with ulnar neuropathy at the elbow (UNE) and to determine its relationship to clinical, ultrasonographic, and electrodiagnostic findings.

METHODS

High-resolution ultrasonography and color Doppler imaging were performed in 137 patients with confirmed UNE, 24 patient controls, and 70 healthy controls (HCs).

RESULTS

IVUS was found in 21 (15%) of 137 patients with UNE, in 1 (4%) of 24 patient controls, and in 0 of 70 HCs (P = 0.001). Patients with IVUS were more likely to have severe weakness (P = 0.01), severe atrophy of ulnar-innervated muscles (P = 0.008), axonal damage (P = 0.001), and more pronounced nerve enlargement (P = 0.03) than those without IVUS.

CONCLUSIONS

IVUS in the ulnar nerve can be detected in patients with UNE and is associated with nerve enlargement and clinical and electrodiagnostic severity. In addition, IVUS is associated with axonal damage.