Assessment of the carpal tunnel and associated neural structures with superb microvascular imaging: a scoping review.

INTRODUCTION: Superb microvascular imaging (SMI) is an advanced ultrasound technique that portrays microcirculation. Its clinical applications have been studied in various diseases, including carpal tunnel syndrome (CTS) i.e. the most common entrapment neuropathy. This scoping review explores the role of SMI in diagnosing CTS or the assessment of relevant neural structures. METHODS: We conducted a comprehensive search of electronic databases (PubMed, Embase and Web of Science) up to 26 September 2023. Two independent authors conducted the literature search, quality assessment, and data extraction. RESULTS: This review includes seven studies comprising 385 wrists. SMI consistently revealed increased intraneural vascularity in the median nerves of patients with CTS compared to healthy individuals. While SMI demonstrated higher sensitivity than traditional Doppler methods for detecting CTS, its specificity was somewhat lower. Combining SMI with B-mode ultrasound appears to enhance the diagnostic accuracy for CTS. However, the relationship between SMI findings and CTS severity remains unclear. CONCLUSIONS: This review highlighted the ability of SMI to provide detailed vascular structures in both healthy wrists and those with CTS. Additional research is crucial to determine the typical SMI findings of the carpal tunnel and within that context, tailor more precise diagnostic/therapeutic applications for the CTS population.

Ultrasonography-assisted assessment of the influence of the volar prominence of the plate on the median nerve in distal radius fractures.

OBJECTIVE: The study aimed to explore the effect of differing volar locking plate (VLP) prominence on the median nerve (MN) in distal radius fracture (DRF) with ultrasound assistance to guide clinical treatment. METHODS: Forty-four patients who received VLP for DRF at our department were admitted and followed-up between January 2019 and May 2021. Different plate positions were graded using Soong classification; 13 were Grade 0, 18 were Grade 1, and 13 were Grade 2. The MN parameters at different wrist positions in patients with different Soong grades were measured with ultrasound assistance, including the median nerve cross-sectional area (MNCSA), diameter in the radial-ulnar direction (D1), and diameter in the dorsal-palmar direction (D2). The sensation in the affected finger and grip strength were collected at follow-up, scored using the Disabilities of the Arm, Shoulder, and Hand (DASH) scale to determine function, and statistically analysed. RESULTS: The MNCSA differed significantly across Soong grades. The MNCSA at the flexed, neutral, and extended wrist positions was smallest at Grade 0 and largest at Grade 2 (P < 0.05), and that at the neutral position was not significantly different between Grades 1 and 2 (P > 0.05). There was no significant interaction between the wrist positions and Soong grade (P > 0.05). The differences in D1 and D2 among different Soong grades were not statistically significant (P > 0.05). There were no statistical differences in grip strength, DASH, and sensation among different Soong grades (P > 0.05). CONCLUSIONS: Differing plate protrusions in DRF treatment did not cause clinical symptoms during follow-up; however, excessive plate protrusion (Soong Grade 2) increased the cross-sectional area of the MN. We recommend placing the plate as proximal as possible during VLP treatment of DRFs to avoid excessive bulges affecting the MN.

Repeatability, Reproducibility and Sources of Variability in the Assessment of Backscatter Coefficient and Texture Parameters from High-Frequency Ultrasound Acquisitions in Human Median Nerve.

Ultrasound (US) is an increasingly prevalent and effective diagnostic modality for neuromuscular imaging. Gray-scale B-mode imaging has been the dominant US approach to evaluating nerves qualitatively or making morphometric measurements of nerves, providing important insights into pathological changes for conditions such as carpal tunnel syndrome. Among more recent ultrasound strategies, high-frequency ultrasound (often defined as >15 MHz for clinical applications), quantitative ultrasound and image textural analysis offer promising enhancements for improved and more objective approaches to nerve imaging. In this study, we evaluated the repeatability and reproducibility of backscatter coefficient (BSC) and imaging texture features extracted by gray-level co-occurrence matrices (GLCMs) in homogeneous tissue-mimicking reference phantoms and in median nerves in the wrists of healthy participants. We also investigated several practical sources of variability in the assessment of quantitative parameters, including influences of operators, and participant-to-participant variability. Overall, BSC- and GLCM-based outcomes are highly repeatable and reproducible after operator training, based on measurement of descriptive statistics, repeatability coefficient (RC) and reproducibility coefficient recommended by Quantitative Imaging Biomarker Alliance (QIBA RDC). GLCM parameters appear more reproducible and repeatable than BSC-based parameters in healthy participants in vivo. However, such variability noted here must be compared with the value ranges and variability of the results in pathological nerves, including median nerves afflicted by trauma, overuse syndromes such as carpal tunnel syndrome and after surgical repair.

Assessment Of Carpal Tunnel Syndrome With Ultrasonography.

BACKGROUND: Carpal tunnel syndrome (CTS) is the most common nerve entrapment neuropathy caused by compression of median nerve at wrist as it passes through Osseo fibrous canal known as carpal tunnel. Epidemiological statistics shows one in every ten people develops the disease at any stage of life. CTS mostly affect females than males with mean age of 50. Clinical features are considered to be enough for establishing the diagnosis of carpal tunnel syndrome. However, nerve conduction studies give quantitative information regarding median nerve function therefore good at predicting outcome of intervention. Ultrasound being easily available, cost effective and real time is a promising modality for diagnosis and grading carpal tunnel syndrome. METHODS: This correlational study was conducted in collaboration of Neurology and Radiology Department of Pakistan Institute of Medical Sciences, Islamabad from January 2018 to January 2019. Total 50 patients with 85 wrists involved were included in the study. All patients with positive nerve conduction study were included. Patient with history of wrist trauma were not included. Detailed history and clinical features were recorded. All patients with positive result on nerve conduction studies underwent ultrasound examinations. Fifty control wrists were also included to establish the normal median nerve cross sectional area value in our study population. Results were recorded. Data was analyzed and appropriate statistical tests were applied by using SPSS v20. RESULTS: Mean cross sectional area of median nerve for controls was 6.34±1.23. Mean cross sectional area of median nerve for mild CTS was 8.05±1.72, moderate CTS was 11.15±2.32, severe was 17.49±4.93. Strong correlation was found between (r=0.76, p-value <0.0001) between increased cross-sectional area on Ultrasonography and severity of CTS on NCS. Other finding on Ultrasonography included flattening in 4 and fluid in 10 affected wrists. CONCLUSIONS: Increased cross-sectional area on Ultrasonography and severity of carpal tunnel syndrome on nerve conduction studies are very strongly correlated.

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.

Accurate automated diagnosis of carpal tunnel syndrome using radiomics features with ultrasound images: A comparison with radiologists' assessment.

PURPOSE: Ultrasonography is the most common imaging modality used to diagnose carpal tunnel syndrome (CTS). Recently artificial intelligence algorithms have been used to diagnose musculoskeletal diseases accurately without human errors using medical images. In this work, a computer-aided diagnosis (CAD) system is developed using radiomics features extracted from median nerves (MN) to diagnose CTS accurately. METHOD: This study is performed on 228 wrists from 65 patients and 57 controls, with an equal number of control and CTS wrists. Nerve conduction study (NCS) is considered as the gold standard in this study. Two radiologists used two guides to evaluate and categorize the pattern and echogenicity of MNs. Radiomics features are extracted from B-mode ultrasound images (Ultrasomics), and the robust features are fed into support vector machine classifier for automated classification. The diagnostic performances of two radiologists and the CAD system are evaluated using ROC analysis. RESULTS: The agreement of two radiologists was excellent for both guide 1 and 2. The honey-comb pattern clearly appeared in control wrists (based on guide 1). In addition, CTS wrists indicated significantly lower number of fascicles in MNs (based on guide 2). The area under ROC curve (AUC) of the radiologist 1 and 2 are 0.658 and 0.667 based on guide 1 and 0.736 and 0.721 based on guide 2, respectively. The CAD system indicated higher performance than two radiologists with AUC of 0.926. CONCLUSION: The proposed CAD system shows the benefit of using ultrasomics features and can assist radiologists to diagnose CTS accurately.

Ultrasound assessment of carpal tunnel in rheumatoid arthritis and idiopathic carpal tunnel syndrome.

OBJECTIVES: To comparatively assess the sonographic spectrum of carpal tunnel syndrome (CTS) in patients with rheumatoid arthritis (RA) and in patients with idiopathic CTS. METHODS: Fifty-seven RA patients and 25 idiopathic CTS patients were consecutively enrolled. The diagnosis of CTS in RA patients was made according to clinical history and examination. The following sonographic findings were assessed at carpal tunnel level: median nerve cross-sectional area (CSA) at the carpal tunnel proximal inlet, finger flexor tendons tenosynovitis, radio-carpal synovitis and intraneural power Doppler (PD) signal. RESULTS: CTS was diagnosed in 15/57 RA patients (26.3%). Twenty-three RA wrists with CTS, 84 RA wrists without CTS and 34 idiopathic CTS wrists were evaluated. The average CSA of the median nerve was higher in idiopathic CTS than in RA wrists with CTS (17.7 mm2 vs 10.6 mm2, p < 0.01). A higher rate of inflammation of synovial structures (flexor tendons sheath and/or radio-carpal joint) was found in RA wrists with CTS compared with those without CTS (p = 0.04) and idiopathic CTS (p = 0.02). Intraneural PD signal was more common in CTS (in both RA and idiopathic CTS) wrists compared with wrists without CTS (p < 0.01). CONCLUSION: The sonographic spectrum of CTS in RA patients is characterized by an inflammatory pattern, defined by the presence of finger flexor tendons tenosynovitis and/or radio-carpal joint synovitis. Conversely, a marked median nerve swelling is the dominant feature in idiopathic CTS. Intraneural PD signal is a frequent finding in both conditions. Key Points • Carpal tunnel syndrome (CTS) associated with rheumatoid arthritis (RA) and idiopathic CTS have distinct ultrasound patterns. • The most characteristic sonographic features of CTS in RA patients are those indicative of synovial tissue inflammation at carpal tunnel level. Conversely, marked median nerve swelling is the dominant finding in idiopathic CTS. • Intraneural power Doppler signal is a frequent finding in both conditions. • In patients with CTS, differently from electrophysiology, US can provide clues prompting a rheumatology referral in case of prominent inflammatory findings at carpal tunnel level.

Relationship between anthropometric variables and the cross-sectional area of the median nerve by ultrasound assessment in healthy subjects.

OBJECTIVE: Ultrasound study of the wrist in patients with suspected entrapment syndrome has severe limitations due to the variability of what is considered normal for the cross-sectional area of the median nerve and where to proceed to measure it. We aim to determine the extent to which different anthropometric variables influence the median nerve area in subjects without carpal tunnel syndrome. METHODS: We conducted an observational study based on a multivariate linear regression analysis using as a dependent variable the area of the median nerve cut at two specific points in the wrist of healthy subjects. The independent variables were sex, age, height, weight, body mass index, finger flexor strength, and carpal circumference. MAJOR RESULTS: The measurements of the median nerve cross-sectional area were normalized using a quadratic fixing procedure. Of all the variables included in the linear regression analysis, only carpal circumference and sex (0: female, 1: male) contributed significantly in the final model using the wrist crease as the measurement point (Constant B=-209.45, carpal circumference coefficient=21.07, sex coefficient 10.87). At four centimeters distal to the carpal fold, the model included the same variables (Constant B=-221.84, carpal circumference coefficient=24.01, and sex coefficient=11.41). CONCLUSION: Both the wrist circumference and the sex are variables that should be considered to determine cut-off points of normality in future validation studies about the cross-sectional area of the median nerve.

Influence of limb position on assessment of nerve mechanical properties by using shear wave ultrasound elastography.

INTRODUCTION: Evaluation of nerve mechanical properties has the potential to improve assessment of nerve impairment. Shear wave velocity, as measured by using shear wave (SW) ultrasound elastography, is a promising indicator of nerve mechanical properties such as stiffness. However, elucidation of external factors that influence SW velocity, particularly nerve tension, is required for accurate interpretations. METHODS: Median and ulnar nerve SW velocities were measured at proximal and distal locations with limb positions that indirectly altered nerve tension. RESULTS: Shear wave velocity was greater at proximal and distal locations for limb positions that induced greater tension in the median (mean increase proximal 89.3%, distal 64%) and ulnar (mean increase proximal 91.1%, distal 37.4%) nerves. DISCUSSION: Due to the influence of nerve tension when SW ultrasound elastography is used, careful consideration must be given to limb positioning.

Sonographic assessment of nerve blood flow in diabetic neuropathy.

AIMS: To undertake sonographic assessment of nerve blood flow in people with Type 2 diabetes and correlate the findings with neuropathy severity scores and electrophysiological measurements. METHODS: Median and tibial nerve ultrasound scans were undertaken in 75 people with diabetes and 30 aged-matched controls without diabetes, using a high-resolution linear probe at non-entrapment sites. Nerve blood flow was quantified using power Doppler techniques to obtain the vessel score and the maximum perfusion intensity. Neuropathy severity was assessed using a total neuropathy score. RESULTS: Diabetic nerves had higher rates of nerve blood flow detection (28%) compared to the control group (P < 0.0001). Significant correlations were found between nerve blood flow measurements and nerve size (P <0.001), reported sensory symptoms (P < 0.05) and neuropathy severity scores (P < 0.001). The cohort with diabetes had significantly larger median (8.5 ± 0.3 mm2 vs 7.2 ± 0.1 mm2 ; P < 0.05) and tibial nerves (18.0 ± 0.9 mm2 vs 12.8 ± 0.5 mm2 ; P < 0.05) compared with controls. CONCLUSION: Peripheral nerve hypervascularity is detectable by ultrasonography in moderate to severe diabetic neuropathy with prominent sensory dysfunction.

Value of Grayscale and Power Doppler High-Resolution Ultrasound in Assessment of Patients with Clinically Suspected Carpal Tunnel Syndrome.

OBJECTIVES: To determine the value of grayscale and power Doppler ultrasound (PDUS) in the evaluation of carpal tunnel syndrome (CTS) in clinically suspected patients. METHODS: Eighty-seven wrists of 61 patients with clinically suspected CTS and 57 wrists of 30 healthy control participants were included in our study. Median nerve (MN) cross-sectional area (CSA) measurements were performed at the tunnel inlet level (wCSA) and proximal pronator quadratus muscle level (fCSA). Two parameters were calculated: CSA absolute difference (ΔCSA), which was the difference between the two measurements; and CSA ratio (RCSA), calculated by dividing wCSA over fCSA. The MN at the wrist level was evaluated for hypervascularity with PDUS. RESULTS: The mean wCSA, R-CSA, and ΔCSA values were significantly higher in patients (17 mm2 , 2.45, and 9.9 mm2 , respectively) than in control participants (8 mm2 , 1.29, and 1.65 mm2 ; (P < .0001). At their corresponding cutoff values, the wCSA yielded higher sensitivity (95%) and lower specificity (88%) compared to the RCSA and ΔCSA (89% and 93% sensitivity and 93% and 89% specificity). Power Doppler US was the most specific US parameter (100%) but the least sensitive (76%). A multivariate logistic regression model including the wCSA, RCSA, and PDUS yielded 97% diagnostic accuracy at their optimal cutoffs, which increased to 99% after eliminating age and body mass index confounding effects. CONCLUSIONS: The combination of MN swelling measurements and PDUS increases the diagnostic accuracy of US in patients with clinically suspected CTS.

Ultrasound Measurement of the Cross-Sectional Area of the Median Nerve: The Effect of Teaching on Measurement Accuracy.

BACKGROUND: The purpose of this study was to determine the effect of concise instruction and guidance on the accuracy of measuring the cross-sectional area of the median nerve at the carpal tunnel inlet. METHODS: Seven orthopedic residents and 5 hand fellows obtained serial measurements of the median nerve at the carpal tunnel inlet using a 15-6 MHz ultrasound (US) probe. After a 5-minute teaching session, all participants repeated measurements. A single cadaveric specimen was used. Measurements were compared with the measurement of a fellowship-trained hand surgeon with extensive experience in US diagnosis of carpal tunnel syndrome. This was considered the reference standard. RESULTS: The rate of participants selecting the correct structure to measure on US was 36% before instruction and 97% after. Discarding the measurements of the incorrect structure, the average measurement was 4.8 mm2 before instruction and 5.2 mm2 after. The standard measurement was 6 mm2. The average deviation from the standard measurement -.2 mm2 before instruction and -0.8 mm2 after. The percent of measurements (of the correct structure) that fell within 1 mm2 of the standard measurement increased from 62% to 74%. Participant self-reported confidence in performing measurements elevated from 2.4/10 before instruction to 6.5/10 after. CONCLUSIONS: US of the median nerve cross-sectional area can be efficiently taught and results in measurements consistent with that of an experienced operator.

Compliance assessment and flip-angle measurement of the median nerve: sonographic tools for carpal tunnel syndrome assessment?

OBJECTIVES: To assess the diagnostic performance of median nerve (MN) flip-angle measurements, deformation during wrist flexion [transit deformation coefficient (TDC)], during compression [compression deformation coefficient (CDC)] and fascicular freedom to potentially identify fibrotic MN changes in patients with carpal tunnel syndrome (CTS). METHODS: This prospective study was performed with institutional review board approval; all participants provided oral and written informed consent. Wrists in 21 healthy participants and 29 patients with CTS were examined by ultrasound. MN movement during wrist flexion, MN deformation during transition over the flexor tendons (TDC) and during controlled compression (CDC) as well as fascicular freedom were assessed. Diagnostic properties of these parameters were calculated and compared to clinical findings and cross-section area measurements (ΔCSA). RESULTS: Low flip angles were associated with high ΔCSA at a receiver-operator characteristics area under the curve (AUC) of 0.62 (0.51-0.74). TDC [AUC, 0.83 (0.73-0.92), 76.3% (59.8-88.6%) sensitivity, 88.5% (76.6-95.7%) specificity], restricted fascicular movement [AUC, 0.86 (0.78-0.94), 89.5% (75.2-97.1%) sensitivity, 80.8% (67.5-90.4%) specificity] and compression-based CDC [AUC, 0.97 (0.94-1.00), 82.1% (66.5-92.5%) sensitivity, 94.2% (84.1-98.8%) specificity] demonstrated substantial diagnostic power (95% confidence intervals in parentheses). CONCLUSIONS: Fascicular mobility, TDC and CDC show substantial diagnostic power and may offer insights into the underlying pathophysiology of CTS. KEY POINTS: • Dynamic ultrasonography during wrist flexion and compression enables median nerve deformability assessment. • Overall, reduced median nerve deformability is highly indicative of CTS. • Median nerve compressibility shows higher diagnostic power than conventional cross-section area measurements.

Assessment of Peripheral Nerves With Shear Wave Elastography in Type 1 Diabetic Adolescents Without Diabetic Peripheral Neuropathy.

OBJECTIVES: To investigate the utility of shear wave elastography (SWE) in detecting morphologic abnormalities of the median nerve and posterior tibial nerve in transverse and longitudinal axes in adolescents with type 1 diabetes mellitus (DM) without diabetic peripheral neuropathy (DPN). METHODS: The median nerves and posterior tibial nerves of 25 adolescents with diagnosis and follow-up of type 1 DM without DPN and 32 healthy volunteers were evaluated with SWE by 2 observers on the transverse and longitudinal axes. The cross-sectional area and thickness of the nerves and disease duration were noted, and probable associations of these parameters with SWE features were analyzed. Interobserver and intraobserver correlations were also examined. The statistical significance level was set at P < .05. RESULTS: Both the median nerve and posterior tibial nerve were smaller, thinner, and stiffer in the patient group for both observers on both axes. The disease duration weakly correlated with median nerve SWE features (r = 0.245-0391). The thickness and cross-sectional area had no correlations with SWE features. CONCLUSIONS: The median nerve and posterior tibial nerve in adolescents with type 1 DM without DPN have morphologic abnormalities that can be displayed by SWE regardless of the imaging axis. Shear wave elastography may have a potential role in subclinical DPN, but the reliability of the findings is not as high as desirable.

The diagnostic accuracy of median nerve ultrasonography in elderly patients with carpal tunnel syndrome: sensitivity and specificity assessment.

BACKGROUND: Accurate diagnosis of carpal tunnel syndrome (CTS), the most common entrapment neuropathy, and its differentiation from other diseases are essential, especially in older individuals with advanced symptoms and modified electrophysiological abnormalities. The current study was conducted to evaluate the diagnostic accuracy of ultrasonography (US), regarding sensitivity and specificity in the diagnosis of CTS in elderly patients. METHODS: Individuals with upper limb complaints and reference subjects were recruited from the Rofaydeh Hospital, Tehran, Iran, from June 2013 to October 2014 - (15 months). We evaluate case and control subjects for health status, demographics, clinical characteristics of CTS, median nerve physiology by electrodiagnostic tests, and anatomy by US. Median nerve cross-sectional area (CSA) at precanal, tunnel inlet, midcanal, tunnel outlet, and antecubital levels was measured applying US examination. RESULTS: Of the 723 complaining patients, we assessed 380 patients with CTS symptoms. Electrodiagnostic studies (EDX) confirmed the CTS diagnosis in 203 of these clinically diseased patients. A total of 103 patients (of the 113 reference subjects) had normal EDX in the reference group. Comparisons of wrists between the afflicted and reference subjects demonstrated the CSA at precanal, tunnel inlet, midcanal, and tunnel outlet levels being significantly more abundant in the diseased hands than in the nondiseased hands. CSA at the tunnel inlet and the inlet-to-antecubital CSA ratio with a threshold of 8.5 mm2 and 0.65 gave the best diagnostic accuracy with a sensitivity and specificity of 96.9 and 93.6% for the inlet CSA and 99 and 28% for the CSA ratio, respectively. CONCLUSION: The US as a noninvasive diagnostic method may serve for the investigation of CTS in elderly patients with excellent sensitivity and specificity.

Sonographic assessment of carpal tunnel syndrome in diabetic patients with and without polyneuropathy.

The objective of this study is to determine whether the cross sectional area (CSA) measurement of the median nerve at the wrist differ between carpal tunnel syndrome (CTS) in diabetic patients with and without diabetic polyneuropathy (DPN).This study included 44 patients with type II diabete millitus (DM) with CTS, 32 patients with CTS and DPN, 46 patients with idiopathic CTS, and 42 healthy subjects. Ultrasonographic measurement of the CSA of the median nerve was made at the level of the wrist, together with nerve conduction studies.The median CSA at the wrist was significantly larger in all patient groups compared with healthy subjects. The median nerve CSA was significantly larger in diabetic patients with CTS than patients with idiopathic CTS. The median nerve CSA at wrist was significantly smaller in patients with CTS and DPN compared with diabetic patients with CTS only.The median nerve CSA at the wrist was larger in diabetic patients with CTS than patients with idiopathic CTS and CTS with DPN. Median nerve CSA can help to differentiate between diabetic patients with CTS with and without DPN.

Usefulness of ultrasound assessment of median nerve mobility in carpal tunnel syndrome.

BACKGROUND: Carpal tunnel syndrome (CTS) is the most common peripheral compression neuropathy of the upper extremity. Recently, dynamic ultrasound (US) imaging has shown differences in median nerve mobility between the affected and unaffected sides in CTS. PURPOSE: The present study was performed to compare the median nerve mobility between patients with CTS and healthy individuals, and to correlate median nerve mobility with the severity of CTS. MATERIAL AND METHODS: A total of 101 patients (128 wrists) with CTS and 43 healthy individuals (70 wrists) were evaluated. Electrodiagnostic studies were initially conducted to determine the neurophysiological grading scale (NGS). The cross-sectional area (CSA) of the median nerve and the grade of median nerve mobility were measured using US. RESULTS: The mean grade of median nerve mobility in the CTS group (1.9) was significantly lower than that in the control group (2.6; P < 0.001). There were significant negative correlations between the grade of median nerve mobility and distal motor latency of the median nerve (r = -0.218, P = 0.015), NGS (r = -0.207, P = 0.020) and CSA of the median nerve (r = -0.196, P = 0.028). CONCLUSION: The grade of median nerve mobility was negatively correlated with the severity of CTS. US assessment of median nerve mobility may be useful in diagnosing and determining the severity of CTS.

Carpal tunnel syndrome assessment with diffusion tensor imaging: Value of fractional anisotropy and apparent diffusion coefficient.

OBJECTIVES: To quantitatively assess carpal tunnel syndrome (CTS) with DTI by evaluating two approaches to determine cut-off values. METHODS: In forty patients with CTS diagnosis confirmed by nerve conduction studies (NCs) and 14 healthy subjects (mean age 58.54 and 57.8 years), cross-sectional area (CSA), apparent diffusion coefficient (ADC) and fractional anisotropy (FA) at single and multiple levels with intraobserver agreement were evaluated. RESULTS: Maximum and mean CSA and FA showed significant differences between healthy subjects and patients (12.85 mm2 vs. 28.18 mm2, p < 0.001, and 0.613 vs. 0.524, p=0.007, respectively) (10.12 mm2 vs. 19.9 mm2, p<0.001 and 0.617 vs. 0.54, p=0.003, respectively), but not maximum and mean ADC (p > 0.05). For cut-off values, mean and maximum CSA showed the same sensitivity and specificity (93.3 %). However, mean FA showed better sensitivity than maximum FA (82.6 % vs. 73.9 %), but lower specificity (66.7 % vs. 80 %), and significant correlation for maximum CSA, 97 % (p < 0.01), with good correlation for maximum ADC and FA, 84.5 % (p < 0.01) and 62 % (p=0.056), respectively. CONCLUSIONS: CSA and FA showed significant differences between healthy subjects and patients. Single measurement at maximum CSA is suitable for FA determination. Key Points • DTI showed that FA is stronger than ADC for CTS diagnosis. • Single- and multiple-level approaches were compared to determine FA and ADC. • Single-level evaluation at the thickest MN cross-sectional area is sufficient.

Ultrasound elastography assessment of the median nerve in leprosy patients.

INTRODUCTION: We sought to compare median nerve elasticity between leprosy patients (LPs) and healthy volunteers (HVs) using ultrasound elastography (UE). METHODS: Two radiologists independently measured the strain ratio of the median nerve/flexor digitorum superficialis muscle (MN/FDSM) of 18 LP and 18 HV using real-time freehand UE. Statistical analysis included intra-class correlation coefficients (ICC) and Mann-Whitney test. RESULTS: The MN/FDSM strain ratios of the LP and HV were 2.66 ± 1.30 and 3.52 ± 0.93, respectively (P < 0.05). We observed a significantly lower MN/FDSM strain ratio in LP with reactions (types 1 and 2 cutaneous reactions associated with or without neuritis) (2.30 ± 0.91) compared with LP without reactions (3.60 ± 1.70). We found no significant differences between HV and LP without reactions. The intra- and inter-observer ICCs were 0.50 (95% confidence interval [CI], 0.11-0.72) and 0.34 (95% CI, 0.28-0.52), respectively. CONCLUSIONS: MN/FDSM strain ratios were significantly lower in LP with reactions. UE may be useful for nerve elasticity evaluation in leprosy. Muscle Nerve 56: 393-398, 2017.

High-Resolution Axonal Bundle (Fascicle) Assessment and Triple-Echo Steady-State T2 Mapping of the Median Nerve at 7 T: Preliminary Experience.

OBJECTIVES: The aims of this preliminary study were to determine the number of axonal bundles (fascicles) in the median nerve, using a high-resolution, proton density (PD)-turbo spin echo (TSE) fat suppression sequence, and to determine normative T2 values, measured by triple-echo steady state, of the median nerve in healthy volunteers and in patients with idiopathic carpal tunnel syndrome (CTS), at 7 T. MATERIALS AND METHODS: This prospective study was approved by the local ethics committee and conducted between March 2014 and January 2015. All study participants gave written informed consent. Six healthy volunteers (30 ± 12 years) and 5 patients with CTS (44 ± 16 years) were included. Measurements were performed on both wrists in all volunteers and on the affected wrist in patients (3 right, 2 left). Based on 5-point scales, 2 readers assessed image quality (1, very poor; 5, very good) and the presence of artifacts that might have a possible influence on fascicle determination (1, severe artifacts; 5, no artifacts) and counted the number of fascicles independently on the PD-TSE sequences. Furthermore, T2 values by region of interest analysis were assessed. Student t tests, a hierarchic linear model, and intraclass correlation coefficients (ICCs) were used for statistical analysis. RESULTS: Proton density-TSE image quality and artifacts revealed a median of 5 in healthy volunteers and 4 in patients with CTS for both readers. Fascicle count of the median nerve ranged from 13 to 23 in all subjects, with an ICC of 0.87 (95% confidence interval [CI], 0.67-0.95). T2 values were significantly higher (P = 0.023) in patients (24.27 ± 0.97 milliseconds [95% CI, 22.19-26.38]) compared with healthy volunteers (21.01 ± 0.65 milliseconds [95% CI, 19.61-22.41]). The ICC for all T2 values was 0.97 (95% CI, 0.96-0.98). CONCLUSIONS: This study shows the possibility of fascicle determination of the median nerve in healthy volunteers and patients with CTS (although probably less accurately) with high-resolution 7 T magnetic resonance imaging, as well as significantly higher T2 values in patients with CTS, which seems to be associated with pathophysiological nerve changes.