Recent Advances in Ultrasound Diagnosis of Carpal Tunnel Syndrome.
ABSTRACT: With the widespread use of high-resolution ultrasonography, ultrasonic examination has been shown to be useful as a diagnostic method for carpal tunnel syndrome. The main advantages of ultrasonography are that it is simple, quick, non-invasive, and economical. Another advantage is that tissue dynamics can be observed with real-time imaging. In recent reports, it has been shown that ultrasonic examination can provide similar diagnostic accuracy as nerve conduction study in the diagnosis of carpal tunnel syndrome. It has been expected that ultrasound demand in daily medical care will continue to increase. Ultrasonography in carpal tunnel syndrome shows an enlarged median nerve in proximal carpal tunnel, thickening of the flexor retinaculum, and edema around flexor tendons in cross-sectional images. In addition, with the introduction of new technologies such as ultrasonic elastography and speckle tracking, it has become possible to quantify dynamics and material property changes of nerves, tendons, and their surrounding structures. In this review, we describe recent advancements of carpal tunnel syndrome diagnosis based on ultrasound dynamic images, and discuss its pathology.
Project description:The carpal tunnel is an osteofibrous canal situated in the volar wrist. The boundaries are the carpal bones and the flexor retinaculum. In addition to the medial nerve, the carpal tunnel contains nine tendons: the flexor pollicis longus, the four flexor digitorum superficialis and the four flexor digitorum profundus. Ultrasound (US) study of the carpal tunnel generally involves short-axis imaging of the tendons, and in the presence of disease, long-axis imaging and dynamic maneuvers are added. There are numerous reports of anatomical variants of the wrist involving vessels, nerves, tendons and muscles, and they can all be studied by US. Some are particularly relevant from a clinical point of view and will therefore be accurately described. The anatomy is complex, and the US operator should therefore be thoroughly familiar with the normal anatomy as well as the anatomical variants that may have a role in the pathogenesis of carpal tunnel syndrome or influence treatment.
Project description:Ultrasound (US) is used with a minimally invasive cutting device to perform carpal tunnel release with a 3 mm wrist incision. US localizes tendons, arteries, and median nerve for safe introduction of the device into the wrist. The device is inserted in a blunt configuration under the flexor retinaculum, and a cutting wire is deployed that advances a 0.9-mm needle in the palm. The surgeon releases the flexor retinaculum from the inside out through the two skin punctures. Flexor retinaculum release is confirmed with US.
Project description:Carpal tunnel syndrome is a frequently encountered peripheral nerve disorder caused by mechanical insult to the median nerve, which may in part be a result of impingement by the adjacent digital flexor tendons. Realistic finite element (FE) analysis to determine contact stresses between the flexor tendons and median nerve depends upon the use of physiologically accurate material properties. To assess the transverse compressive properties of the digital flexor tendons and median nerve, these tissues from ten cadaveric forearm specimens were compressed transversely while under axial load. The experimental compression data were used in conjunction with an FE-based optimization routine to determine apparent hyperelastic coefficients (? and ?) for a first-order Ogden material property definition. The mean coefficient pairs were ?=35.3 kPa, ?=8.5 for the superficial tendons, ?=39.4 kPa, ?=9.2 for the deep tendons, ?=24.9 kPa, ?=10.9 for the flexor pollicis longus (FPL) tendon, and ?=12.9 kPa, ?=6.5 for the median nerve. These mean Ogden coefficients indicate that the FPL tendon was more compliant at low strains than either the deep or superficial flexor tendons, and that there was no significant difference between superficial and deep flexor tendon compressive behavior. The median nerve was significantly more compliant than any of the flexor tendons. The material properties determined in this study can be used to better understand the functional mechanics of the carpal tunnel soft tissues and possible mechanisms of median nerve compressive insult, which may lead to the onset of carpal tunnel syndrome.
Project description:Peripheral nerves are mobile structures, stretching and translating in response to changes in the position of adjuvant anatomic structures. The objective of this study was to develop a novel method to characterize the relative motion and deformation of the median nerve on cross-sectional ultrasound images of the carpal tunnel during active finger motion.Fifteen volunteers without a history of carpal tunnel syndrome or wrist trauma were recruited. An ultrasound scanner and a linear array transducer were used to evaluate the motion of the median nerve and the flexor tendons within the carpal tunnel during motion from full extension to full flexion by the four fingers (fist motion) and by the long finger alone. The displacement of the median nerve relative to the long-finger flexor digitorum superficialis tendon as well as the perimeter, cross-sectional area, circularity, and aspect ratio of a minimum enclosing rectangle of the median nerve were measured. The data were compared between single-digit motion and fist motion and between extension and flexion positions.The distance between the long-finger flexor digitorum superficialis tendon and the median nerve with isolated long-finger flexion was decreased in the ulnar-radial direction and increased in the palmar-dorsal direction as compared with the distance with four-finger flexion (p < 0.01). Compared with the values with fist motion, the aspect ratio was decreased and the circularity was increased with long-finger motion (p < 0.01).This report presents a method with which to assess displacement and deformation of the median nerve on a cross-sectional ultrasound image during different finger motions. This method may be useful to assess pathological changes within the carpal tunnel, and we plan to perform a similar study of patients with carpal tunnel syndrome on the basis of these preliminary data.
Project description:BACKGROUND:Carpal tunnel syndrome is a common neuropathy disorder for which surgical treatment consists of release and reconstruction of the flexor retinaculum. Reports of postoperative clinical outcomes after carpal tunnel release with or without flexor retinaculum reconstruction in several studies are controversial. This meta-analysis aimed to compare the efficacy and safety of carpal tunnel release with or without flexor retinaculum reconstruction. METHODS:The PubMed, EMBASE, Web of Science, Ovid, Cochrane Library and Clinical Tri Org databases were searched for randomized controlled trials that compared carpal release with and without transverse carpal ligament reconstruction for carpal tunnel syndrome. Outcomes included postoperative Boston Carpal Tunnel Questionnaire Symptom Severity Scale (SSS), Functional Status Scale (FSS), grip strength and complications. The follow-up time was categorized into short-term (0-3mon) and long-term(>3mon). RESULTS:A total of 7 studies with 613 patients met the inclusion criteria and were analyzed in detail. Statistical analysis showed no significant difference between two groups on postoperative long-term grip strength (MD 5.85, 95% CI -1.05 to 12.76) long-term SSS (MD -0.31, 95% CI -0.75 to 0.13) and occurrence of complications (RR 1.14, 95% CI 0.84 to 1.54), whereas statistically significant difference was found between groups regarding short-term grip strength (MD 1.51, 95% CI 0.86 to 2.17) and long-term FSS (MD -0.34, 95% CI -0.47 to -0.21). CONCLUSION:Carpal tunnel release with flexor retinaculum reconstruction for carpal tunnel syndrome may result in improved long-term functional status while there's no advantage regarding grip strength, symptom severity and safety over individual carpal tunnel release in short- and long-term outcomes.
Project description:<h4>Background</h4>Carpal tunnel syndrome (CTS) is by far the most common entrapment neuropathy (Adams et al. Am J Ind Med 25:527-536, 1994; Cheadle et al. Am J Public Health 84:190-196, 1994; Stevens et al. Neurology 38:134-138, 1988). A combination of described symptoms, clinical findings and electrophysiological testing is used to confirm the diagnosis. Several studies have suggested that in patients with a clinical diagnosis of CTS, the accuracy of nerve sonography is similar to that for electromyography (Chen et al. BMC Med Imaging 11:22, 2011; Guan et al. Neurol Res 33:970-953, 2011; Kele et al. Neurology 61:389-391, 2003; Tai et al. Ultrasound Med Biol 38:1121-1128, 2012). In special cases though, the nerve sonography can reveal the cause of the median entrapment neuropathy (Fumière et al. JBR-BTR 85:1-3, 2002; Kele et al. J Neurosurg 97:471-473, 2002; Kele et al. Neurology 61:389-391, 2003; Zamora et al. J Clin Ultrasound 39:44-47, 2011).<h4>Methods</h4>A 43-year-old farmer was admitted to our department with 1 year of intermittent pain in the left hand and numbness of the thumb, index and middle finger. The pain and the numbness could be reproduced by extension of the wrist and fingers. The electrophysiological testing revealed signs of an entrapment median neuropathy in carpal tunnel.<h4>Results</h4>The high-resolution sonography (18 MHz) revealed signs of entrapment neuropathy with increased cross-sectional area, disturbed echostructure of the nerve and pathological wrist-to-forearm ratio, confirming the results from a similar study (Kele et al. Neurology 61:389-391, 2003). In addition, an elongated muscle belly of the flexor digitorum superficialis in the carpal tunnel could be identified. During the extension of the wrist and fingers, a greater protrusion of the muscle belly could be demonstrated causing compression of the median nerve.<h4>Conclusions</h4>We present a video case report of the sonographic findings of a patient diagnosed with carpal tunnel syndrome due to an elongated muscle belly of the flexor digitorum superficialis in the carpal tunnel. Our case highlights the importance of nerve sonography in the differential diagnosis of the cause of a carpal tunnel syndrome. With the aid of ultrasonography, it is possible to obtain very important information concerning different aspects of this case. First, in showing the presence of the elongated muscle belly of the flexor digitorum superficialis, the cause of the symptoms could be explained. Second, it was possible through the ultrasound study to explain the atypical clinical appearance in this case, demonstrating the compression neuropathy only after extension of the wrist and fingers. There have been no previous reports in which authors described an elongated muscle belly as cause of a CTS. Third, and perhaps most important, ultrasonography had a direct influence on our selection of therapeutical strategy and approach. As a result, we recommended in this patient a surgical therapy to completely solve the problem, but the patient declined this option and preferred a conservative therapy with a hand orthosis to prevent wrist extension. In conclusion we recommend ultrasonography as a very useful method in the diagnostic evaluation of carpal tunnel syndrome. We have clearly demonstrated that ultrasonography can be used to discover the cause of median nerve compression, especially in cases with an atypical clinical presentation.
Project description:The tenosynovium in the human carpal tunnel is connected to the flexor tendons and the median nerve by the subsynovial connective tissue (SSCT). The most common histological finding in carpal tunnel syndrome (CTS), a compression neuropathy of the median nerve, is noninflammatory fibrosis of the SSCT. The relationship, if any, between the fibrosis and nerve pathology is unknown, although some have speculated that a change in the SSCT volume or stiffness might be the source of the compression. Yet, while animal models have been used to study the physiology of nerve compression, so far none have been used to study the relationship of the SSCT pathology to the neurophysiological abnormalities. The purpose of this study was to identify animal models that might be appropriate to study the interaction of SSCT and nerve function in the development of CTS. The front paws of a rat, rabbit, dog, and baboon were dissected. The carpal tunnel anatomy and SSCT of these animals were also examined by light and scanning microscopy and compared to the relevant human anatomy and ultrastructure. The carpal tunnel anatomy and contents of the baboon and rabbit are similar to humans. The canine carpal tunnel lacks the superficial flexor tendons and the rat carpal tunnel is very small. The human, baboon, and rabbit specimens had very similar organization of the SSCT, and content of the carpal canal. We conclude that, while both the baboon and rabbit would be good animal models to study the relationship of the SSCT to CTS, the rabbit is likely to be more practical, in terms of cost and animal care concerns.
Project description:Dynamics of structures within the carpal tunnel may alter in carpal tunnel syndrome (CTS) due to fibrotic changes and increased carpal tunnel pressure. Ultrasound can visualize these potential changes, making ultrasound potentially an accurate diagnostic tool. To study this, we imaged the carpal tunnel of 113 patients and 42 controls. CTS severity was classified according to validated clinical and nerve conduction study (NCS) classifications. Transversal and longitudinal displacement and shape (changes) were calculated for the median nerve, tendons and surrounding tissue. To predict diagnostic value binary logistic regression modeling was applied. Reduced longitudinal nerve displacement (p??0.019), increased nerve cross-sectional area (p??0.006) and perimeter (p??0.007), and a trend of relatively changed tendon displacements were seen in patients. Changes were more convincing when CTS was classified as more severe. Binary logistic modeling to diagnose CTS using ultrasound showed a sensitivity of 70-71% and specificity of 80-84%. In conclusion, CTS patients have altered dynamics of structures within the carpal tunnel.
Project description:Tenosynovitis refers to an inflammatory condition involving the synovial sheath of a tendon. Stenosing tenosynovitis is a peculiar entity caused by multiple factors, including local anatomy, mechanical factors, and hormonal factors. The main forms include de Quervain tendinopathy; trigger finger (stenosing tenosynovitis involving the flexor digitorum tendons); stenosing tenosynovitis of the extensor carpi ulnaris, extensor carpi radialis, or extensor comunis tendons; stenosing tenosynovitis of the flexor hallucis tendon; and stenosing tenosynovitis of the peroneal tendons. The cardinal finding on ultrasonography is the presence of a thickened retinaculum or pulley that constricts the osseofibrous tunnel through which the tendon runs.
Project description:INTRODUCTION: This study compares anatomical findings at wrist level in patients with known carpal tunnel syndrome (CTS) and controls by ultrasonography (US). MATERIAL AND METHODS: Wrist-US investigations of 28 consecutive patients with 38 diagnosed, idiopathic CTS were compared to 49 healthy volunteers without history of CTS. Internal wrists dimensions, the presence of flexor muscle bellies in the carpal tunnel, and cross-sectional area of the median nerve were analyzed. The findings were correlated to gender, age, and BMI. RESULTS: US demonstrated a square internal carpal tunnel configuration in CTS patients compared to controls (P < 0.001). Patients with CTS showed a trend towards the presence of flexor muscles bellies in the carpal tunnel (odds ratio 1.77, 95% CI 0.337-8.33). CTS was present in women with higher BMI (P = 0.015). CONCLUSION: US allowed detection of specific anatomical features at wrist level in CTS patients. This observation may enable--following confirmation in larger prospective studies--risk evaluation for CTS development.