Ultrasound-guided hydrodissection decreases gliding resistance of the median nerve within the carpal tunnel.

INTRODUCTION: The aim of this study was to assess alterations in median nerve (MN) biomechanics within the carpal tunnel resulting from ultrasound-guided hydrodissection in a cadaveric model. METHODS: Twelve fresh frozen human cadaver hands were used. MN gliding resistance was measured at baseline and posthydrodissection, by pulling the nerve proximally and then returning it to the origin. Six specimens were treated with hydrodissection, and 6 were used as controls. RESULTS: In the hydrodissection group there was a significant reduction in mean peak gliding resistance of 92.9 ± 34.8 mN between baseline and immediately posthydrodissection (21.4% ± 10.5%; P = 0.001). No significant reduction between baseline and the second cycle occurred in the control group: 9.6 ± 29.8 mN (0.4% ± 5.3%; P = 0.467). DISCUSSION: Hydrodissection can decrease the gliding resistance of the MN within the carpal tunnel, at least in wrists unaffected by carpal tunnel syndrome. A clinical trial of hydrodissection seems justified. Muscle Nerve 57: 25-32, 2018.

Influence of Injection Volume on Rate of Subsequent Intervention in Carpal Tunnel Syndrome Over 1-Year Follow-Up.

PURPOSE: The optimal volume and dose of corticosteroid injections for treatment of carpal tunnel syndrome (CTS) have not yet been established. It is unknown whether the volume of injectate influences the outcome of carpal tunnel injection. The purpose of this study was to assess whether there is an association between the volume of injectate and subsequent intervention in the treatment of CTS. METHODS: This study evaluated residents of Olmsted County, MN, who were treated with a corticosteroid injection for CTS between 2001 and 2010. Failure of treatment was the primary outcome, defined as a subsequent intervention: either a second injection or carpal tunnel release within 1 year of initial injection. General estimating equations logistic regression was used to assess the association between injectate volume and rate of treatment failure, adjusting for age, sex, effective dose of steroid, type of steroid injected, electrodiagnostic severity, and the presence of comorbidities such as rheumatoid arthritis, diabetes mellitus, peripheral neuropathy, and radiculopathy. RESULTS: There were 856 affected hands in 651 patients. A total of 56% (n = 484) of treated hands received subsequent treatment within 1 year. Multivariable analysis showed that a larger injectate volume was significantly associated with reduced rate of treatment failure within 1 year. Rheumatoid arthritis and ultrasound-guided procedures were also associated with a reduced rate of treatment failure, whereas severe electrodiagnostic results were associated with an increased rate of failure. CONCLUSIONS: This study showed that a larger volume of corticosteroid injection is associated with reduced odds of subsequent intervention after a single corticosteroid injection in CTS. Further research is needed to determine the optimal volume for steroid injections in the treatment of CTS. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.

Relative Motion of the Connective Tissue in Carpal Tunnel Syndrome: The Relation with Disease Severity and Clinical Outcome.

Excursion of the median nerve and the surrounding subsynovial connective tissue (SSCT) is diminished in patients with carpal tunnel syndrome (CTS). This study sought to determine if SSCT excursion could be utilized to predict surgical outcome. Idiopathic CTS patients were reviewed with ultrasound and electrodiagnostic tests at baseline. A speckle tracking algorithm was used to determine SSCT relative to tendon motion (shear index). Analysis of variance tests were used to compare SSCT motion with disease severity at baseline. Adjusted linear regressions were used to test the association with patient-reported outcome. A total of 90 CTS patients were analyzed and found to have an average shear index of 79% (95% confidence interval: 76.3%-81.6%). SSCT motion was lower in CTS patients with increasing electrophysiological severity (p = 0.0475). There was no significant association of pre-operative SSCT motion with symptomatic improvement (p = 0.268). Overall, SSCT motion is decreased in CTS patients, but exhibits limited correlation with clinical severity.

Speckle Tracking of Tendon Displacement in the Carpal Tunnel: Improved Quantification Using Singular Value Decomposition.

Ultrasound is a real-time image modality enabling the analysis of tendon dynamics for the diagnosis of carpal tunnel syndrome. Automatic tendon displacement quantification algorithms based on speckle tracking generally suffer from underestimation due to stationary background present in the tendon region. We propose an improved quantification method using singular value decomposition (SVD) filtering to suppress the clutter. The accuracy of our improved speckle tracking (IST) method was validated against a ground truth and compared to the accuracy of our original block matching (OBM) algorithm and commercial tissue tracking (CTT) software. The methods were evaluated in experiments involving six human cadaver arms. The ground-truth displacements were generated by tracking metal markers inserted in the tendons. The relative displacement errors with respect to the ground truth for IST were 12 ± 16.9%, which was significantly lower than for OBM (19.7 ± 20.8%) and for CTT (25.8 ± 18.4%). These findings show that SVD filtering improves the tendon tracking by reducing underestimation due to clutter.

Reliability of ultrasound speckle tracking with singular value decomposition for quantifying displacement in the carpal tunnel.

Inhibited movement patterns of carpal tunnel structures have been found in carpal tunnel syndrome (CTS) patients. Motion analysis on ultrasound images allows us to non-invasively study the (relative) movement of carpal tunnel structures and recently a speckle tracking method using singular value decomposition (SVD) has been proposed to optimize this tracking. This study aims to assess the reliability of longitudinal speckle tracking with SVD in both healthy volunteers and patients with CTS. Images from sixteen healthy volunteers and twenty-two CTS patients were used. Ultrasound clips of the third superficial flexor tendon and surrounding subsynovial connective tissue (SSCT) were acquired during finger flexion-extension. A custom made tracking algorithm was used for the analysis. Intra-class correlation coefficients (ICCs) were calculated using a single measure, two-way random model with absolute agreement and Bland-Altman plots were added for graphical representation. ICC values varied between 0.73 and 0.95 in the control group and 0.66-0.98 in the CTS patients, with the majority of the results classified as good to excellent. Tendon tracking showed higher reliability values compared to the SSCT, but values between the control and CTS groups were comparable. Speckle tracking with SVD can reliably be used to analyze longitudinal movement of anatomical structures with different sizes and compositions within the context of the carpal tunnel in both a healthy as well as a pathological state. Based on these results, this technique also holds relevant potential for areas where ultrasound based dynamic imaging requires quantification of motion.

Median Nerve Transverse Mobility and Outcome after Carpal Tunnel Release.

Nerve movement is decreased in patients with carpal tunnel syndrome and can be assessed with ultrasound. In addition to morphologic features, this study describes a novel approach in which nerve movement and the association with short-term patient-reported outcome are assessed. Ultrasound images at the carpal tunnel inlet were acquired during finger and wrist flexion. Linear regression models were used with the Boston Carpal Tunnel Questionnaire as main outcome. Eighty-five patients were included; 93% completed the 3-mo follow-up. Pre-surgical mean nerve area was 14.5 ± 4.2 mm2 and decreased to 13.3 ± 3.8 mm2 (p < 0.001). Displacement in dorsal direction with wrist flexion increased from 1.9 ± 1.3 to 2.4 ± 1.3 mm (p < 0.01). A pre-surgical larger nerve area was associated with more functional improvement (ß = -0.024, p = 0.02), but baseline mobility was not. Change in excursion with finger flexion was associated with symptomatic improvement, but with a small effect (ß = -0.05, p = 0.01). This indicates that there is limited prognostic potential for dynamic transverse ultrasound in carpal tunnel syndrome.

Hand Surgeons Performing More Open Carpal Tunnel Releases Do Not Show Better Patient Outcomes.

BACKGROUND: Although previous studies have shown that more experienced surgeons have better patient outcomes following a variety of procedures, in hand surgery and carpal tunnel release in particular, this relation remains unproven. The authors assessed whether there is an association between surgeon volume and patient outcomes following open carpal tunnel release. METHODS: Patients who underwent carpal tunnel release between 2011 and 2015 at outpatient hand surgery clinics in The Netherlands were included. Surgeon annual volume was defined as the average number of carpal tunnel releases performed per year per participating surgeon over the study period. Primary outcome measures were the Symptom Severity Scale and Functional Status Scale of the Boston Carpal Tunnel Questionnaire 6 months postoperatively. Multilevel random intercept linear regression analyses were performed to assess whether there was an association between surgeon annual volume and outcome measures, with adjustment for patient characteristics, concomitant procedures, and intake score on the Boston Carpal Tunnel Questionnaire. RESULTS: A total of 1345 patients were included, operated on by 17 surgeons. Median annual surgeon volume was 75 (interquartile range, 50 to 149). Only 0.5 to 0.6 percent of the total variance in patient outcome on the Boston Carpal Tunnel Questionnaire could be explained by random differences between surgeons. The authors did not find an association between annual surgeon volume and outcome measures 6 months postoperatively (Symptom Severity Scale: ß = 0.000; 95 percent CI, -0.001 to 0.001; and Functional Status Scale: ß = 0.000; 95 percent CI, -0.001 to 0.001). CONCLUSION: In the authors' sample of highly specialized hand surgeons operating in high-volume centers, they found no differences in outcome between high- and low-volume surgeons.

Effectiveness of Ultrasound-Guided Compared to Blind Steroid Injections in the Treatment of Carpal Tunnel Syndrome.

OBJECTIVE: To compare the effectiveness of ultrasound-guided injections to blind injections in the treatment of carpal tunnel syndrome (CTS) in a large community-based cohort. METHODS: This study evaluated residents of Olmsted County, Minnesota, treated with a corticosteroid injection for CTS between 2001 and 2010. The proportion of patients receiving retreatment and the duration of retreatment-free survival between blind and ultrasound-guided injections were compared. Propensity score matching was used to control for confounding by indication. RESULTS: In the matched data set consisting of 234 (of 600) hands treated with a blind injection and 87 (of 89) ultrasound-guided injection cases, ultrasound guidance was associated with a reduced hazard of retreatment (hazard ratio 0.59 [95% confidence interval (95% CI) 0.37-0.93]). In addition, ultrasound guidance was associated with 55% reduced odds of retreatment within 1 year compared to blind injections (adjusted odds ratio 0.45 [95% CI 0.24-0.83]). CONCLUSION: This study indicates that ultrasound-guided injections are more effective in comparison to blind injections in the treatment of CTS.

Corticosteroid Injections for Carpal Tunnel Syndrome: Long-Term Follow-Up in a Population-Based Cohort.

BACKGROUND: Corticosteroid injection is a recommended treatment option for carpal tunnel syndrome, before considering surgery. Nevertheless, injections remain controversial because there is strong evidence of only short-term benefits. This study aimed to determine the reintervention rate and to identify prognostic indicators for subsequent treatment after corticosteroid injection for carpal tunnel syndrome. METHODS: This study evaluated residents of Olmsted County treated with a corticosteroid injection for carpal tunnel syndrome between 2001 and 2010. Treatment failure was the primary outcome of interest. Two definitions for failure were examined: (1) the patient receiving subsequent procedural intervention and (2) the patient undergoing carpal tunnel release. Survival was estimated using Kaplan-Meier methods, and association of covariates with increased failure was modeled using Cox proportional hazards regression. RESULTS: The study included 774 affected hands in 595 patients. The median follow-up period was 7.4 years. Reintervention was performed in 68 percent of cases, of which 63 percent resulted in eventual surgery. Injectate volume was significant for the outcome of any retreatment [hazard ratio, 0.879 (95 percent CI, 0.804 to 0.96)] and surgery [hazard ratio, 0.906 (95 percent CI, 0.827 to 0.99)]. Rheumatoid arthritis was also significant in both models, with a hazard ratio of 0.627 (95 percent CI, 0.404 to 0.97) for any retreatment and 0.493 (95 percent CI, 0.292 to 0.83) for surgery. CONCLUSIONS: In this cohort, 32 percent of patients did not receive subsequent treatment after a single injection, which indicates that there is a therapeutic role for corticosteroid injections in treating carpal tunnel syndrome. Further research is necessary to identify those patients who will benefit from an injection, to provide more individually tailored treatment. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

3D Volumetric Measurement of Neurofibromatosis Type 2-Associated Meningiomas: Association Between Tumor Location and Growth Rate.

OBJECTIVE: Treatment of meningiomas in neurofibromatosis type II (NF2) patients is challenging because the natural history of these tumors is unclear. More insight in tumor growth and factors predicting growth may contribute to a better clinical management. In this study, growth characteristics of supratentorial NF-related meningiomas were examined and the association between tumor growth rate and location was evaluated. METHODS: In all NF2 patients followed up at the VU University Medical Center, who underwent a minimum of 3 consecutive scans, tumor volumes were assessed by using 3D volumetric measurement (Brainlab, Feldkirchen, Germany). Growth patterns were visually analyzed. To assess the association between tumor growth rate and tumor location, the meningiomas were divided in 3 groups on the basis of their location: skull base, convexity, and "other." Univariable and multivariable logistic regression models were built. RESULTS: Twenty-one patients (13 females) with a mean (standard deviation) follow-up period of 5.55 (2.48) years and a total of 210 meningiomas were included in the analyses. Tumors followed different growth patterns and did not increase in size simultaneously within 1 patient. Skull base meningiomas had a significantly higher absolute growth rate compared with convexity (ß = 0.91, 95% confidence interval [CI] 0.08-1.73) and "other" (ß = 1.07, 95% CI 0.27-1.86) and a significantly higher relative growth rate on both linear and geometric growth rate compared with "other" (ß = 90.73, 95% CI 5.50-175.95 and ß = 18.63, 95% CI 2.94-34.31, respectively) on multivariable logistic regression. CONCLUSION: Within a single patient, NF2-related meningiomas follow different growth patterns. Skull base meningiomas grow faster compared with other locations. Yearly magnetic resonance imaging scans and timely treatment of skull base meningiomas should be considered.

Altered blood rheology in obstructive sleep apnea as a mediator of cardiovascular risk.

BACKGROUND: Cardiovascular complications are common in patients with obstructive sleep apnea (OSA). Blood rheology is a major determent of coagulation and an established risk factor for cardiovascular events. Since nocturnal hypoxemia could influence parameters of blood rheology, we hypothesized that OSA alters blood rheology independent of other cardiovascular risk factors. METHODS: One hundred and ten consecutive patients admitted to the sleep laboratory were included. The association of plasma fibrinogen and viscosity (as parameters of blood rheology) with OSA was evaluated. RESULTS: One hundred and ten patients aged 61.4+/-10.1 years (body mass index 28.4+/-4.1 kg/m2) were included. OSA was confirmed in 63 patients (57.2%) with an apnea-hypopnea index (AHI) of 28.7+/-14.9 events/hour. Patients with OSA showed higher levels of plasma viscosity (1.36+/-0.09 vs. 1.31+/-0.08 mPas, p=0.005). Nevertheless, hypertensive apneics have even higher levels of plasma viscosity than nonapneics (1.38+/-0.091 vs. 1.32+/-0.028 mPas, p=0.018). Similar results were found in patients with coronary artery disease, where OSA was associated with elevated plasma viscosity (1.36+/-0.076 vs. 1.31+/-0.081 mPas, p=0.007). Plasma fibrinogen was correlated with nocturnal minimal oxygen saturation (r=-0275, p=0.0036) and AHI (r=0.297, p=0.001). OSA was associated with higher plasma fibrinogen (353+/-83 vs. 317+/-62 mg/dl, p=0.015). These differences persist with control for cardiovascular risk factors. CONCLUSIONS: Patients with OSA have elevated morning fibrinogen levels and a higher plasma viscosity, which correlate positively with indices of sleep apnea severity. These changes in blood rheology are independent of cardiovascular risk factors, and therefore, might be specific mechanisms of OSA. This supports the pathophysiological concept that sleep apnea is a cardiovascular risk factor.