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Background: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy worldwide, but there are few reports investigating its prevalence using subjects diagnosed by both clinical symptoms and nerve conduction studies (NCSs) in a population-based cohort. This study aimed to determine the epidemiology of CTS diagnosed by sensory disturbance findings and NCSs using a randomly sampled resident population. Methods: Subjects aged between 50 and 89 years were randomly sampled from the basic resident registry of a rural Japanese town. Subjects indicating a history of CTS surgery in a written questionnaire were classified as having past CTS. Subjects with both sensory disturbance of the median nerve area and delays in NCSs were diagnosed as having present CTS. Subjects with past or present CTS were judged as affected with CTS. We calculated the prevalence of CTS and investigated for possible risk factors. Results: Seventeen subjects (14 female and 3 male) were affected with CTS among 379 enrolled subjects. Adjusting these results to Japanese population values, the weighted prevalence of CTS was 4.7% (female: 7.2%, male: 1.8%) in the Japanese population aged 50 to 89 years. Statistically significant positive correlations were found between CTS and female, higher BMI, rheumatoid arthritis, and trigger digit. In females affected with CTS, third metacarpal length was significantly shorter than in those without CTS. Conclusions: This epidemiological study clarified the prevalence of CTS among Japanese seniors as 4.7%. Female, higher BMI, rheumatoid arthritis, trigger digit, and shorter third metacarpal length in females were risk factors for CTS.

Background: During the surgery for a distal radius fracture, we encountered a large anomalous muscle lying across the distal radius. The muscle was identified as a flexor carpi radialis brevis muscle (FCRB), based on its location, function, and innervation. This experience led us to clarify its prevalence in living subjects and alert surgeons of its presence., Methods: We reviewed wrist MRI scans of 515 hands of 379 patients with carpal tunnel syndrome (CTS). The prevalence of the FCRB was calculated. The cross sectional area (CSA) of the FCRB was compared with that of the hypothenar muscles. Signal intensity and fat infiltration of the FCRB were assessed using semiquantitative methods. The anterior compartment ratio (CSA of the anterior compartment of the forearm was divided by CSA of the forearm. CSA of the FCRB was excluded for measurement) was compared between patients with and without FCRB., Results: We found seven hands of six patients (1.6%) with a FCRB. All of these tendons were inserted into the second metacarpal base. CSA of FCRB was smaller than that of the hypothenar muscles. Semiquantitative assessment revealed normal signal intensities of the FCRB compared with those of other muscles. The anterior compartment ratio was smaller in patients with FCRB than without FCRB. None of the FCRB in our series demonstrated any sign of tendinitis on MRI. Furthermore, the postoperative clinical course for those patients was uneventful., Conclusions: Prevalence of FCRB in patients with CTS was 1.6%. FCRB should function as a wrist flexor. Its strength varied according to the individuals but was not greater than that of the hypothenar muscles. It is still unclear if the FCRB could cause the development of CTS. However, it was found that the FCRB could be a mass which occupies and narrows the anterior compartment., (Copyright © 2017 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: The clinical characteristics of wild-type transthyretin amyloid deposition among patients with carpal tunnel syndrome (CTS) have not been well investigated., Methods: One-hundred and seven patients with idiopathic CTS who underwent carpal tunnel release were enrolled. They underwent physical examination of the hand, nerve-conduction study, and magnetic resonance imaging (MRI) study of the wrist, and completed a patient-oriented questionnaire. The tests, except for MRI, were repeated 1, 3, and 6 months postoperatively. Synovial tissue was obtained during surgery and analyzed by Congo red and immunohistochemical staining. Ordinal logistic regression analysis was used to evaluate the significance of different clinical and subjective findings between patients with and without amyloid deposition. Postoperative improvements were also compared., Results: Wild-type transthyretin amyloid deposition was observed for 38 patients. Greater symptom severity and 2-point discrimination scores, and larger cross-sectional areas of the carpal tunnel, were significantly correlated with a larger amount of preoperative amyloid deposition. However, the presence and amount of preoperative amyloid deposition did not affect postoperative improvements in physical findings and nerve-conduction studies., Conclusions: Although transthyretin amyloid deposition can worsen CTS symptoms, postoperative improvements were similar for patients with and without this deposition.

The purpose of this study is to investigate the structural changes of the carpal tunnel, median nerve, and flexor tendons in magnetic resonance imaging (MRI) before and after endoscopic carpal tunnel release (ECTR). We studied 36 hands undergoing ECTR. In MRI, the cross-sectional area of the carpal tunnel and the median nerve at the hamate and the pisiform levels were measured. The distance from the volar side of carpal bone to the median nerve or tendons and the volar displacement were measured. In post-operative MRI, the transverse carpal ligament could not be well delineated and the carpal tunnel was significantly enlarged both at the hamate and pisiform levels. The median nerve was enlarged at the hamate level. The median nerve and flexor tendons significantly moved to the volar side. The volar displacement of the median nerve and flexor digitorum superficialis in the long and ring fingers was greater than the other tendons.

Carpal tunnel syndrome is the most common type of entrapment neuropathy. However, the cause of carpal tunnel syndrome remains unclear in most cases. Senile systemic amyloidosis, induced by wild-type transthyretin deposition, is a prevalent aging-related disorder and often accompanied by carpal tunnel syndrome. In this study, we measured the frequency of unrecognized wild-type transthyretin deposition in patients with idiopathic carpal tunnel syndrome. One hundred twenty-three patients with carpal tunnel syndrome, including 100 idiopathic patients, treated by carpal tunnel release surgery were analyzed. Tenosynovial tissues obtained at surgery were analyzed by Congo red and immunohistochemical staining. If staining for transthyretin was positive, the entire transthyretin gene was analyzed by direct DNA sequencing. We also analyzed tenosynovial tissues from 32 autopsy cases as controls. Thirty-four patients (34.0%) with idiopathic carpal tunnel syndrome showed amyloid deposition in the tenosynovial tissue, and all amyloid showed specific immunolabeling with antitransthyretin antibody. Direct DNA sequencing of the entire transthyretin gene did not reveal any mutations, indicating that all amyloid deposits were derived form wild-type transthyretin. Statistical analysis using logistic regression showed that the prevalence of transthyretin deposition in the idiopathic carpal tunnel syndrome group was significantly higher than that in controls (odds ratio, 15.8; 95% confidence interval, 3.3-5.7), and age and male sex were independent risk factors for transthyretin amyloid deposition. Our results demonstrate that wild-type transthyretin deposition is a common cause of carpal tunnel syndrome in elderly men. It is likely that many patients develop carpal tunnel syndrome as an initial symptom of senile systemic amyloidosis.

Background: It is well known that carpal tunnel syndrome (CTS) can occur in a wide range of time periods after distal radius fracture (DRF). Few studies have evaluated in detail the relationship between fracture and electrophysiological finding characteristics and time to onset of CTS after DRF. To clarify the characteristics of CTS after DRF, we classified a large number of clinical cases based on the period from the injury to onset of CTS. These cases were analyzed retrospectively., Methods: We reviewed 105 wrists with CTS following DRF. Patients' ages ranged from 13 to 89 years. These 105 wrists were divided into three groups according to the period of post-fracture onset of CTS. Twenty-eight wrists were classified into the acute onset group (when the symptoms of CTS occurred within 1 week after fracture). Forty-seven wrists were classified into the subacute onset group (when symptoms of CTS occurred from 1 to 12 weeks after fracture). The remaining 30 wrists were classified into the delayed onset group (when symptoms of CTS occurred more than 12 weeks after fracture). Deformity of the distal radius on X-ray films was evaluated and distal motor latency (DML) of the median nerve was recorded to compare values among these three groups., Results: In the acute onset group, 68% had an AO C-type fracture and 46% were caused by a high-energy injury. The percentage of this fracture pattern and mechanism was significantly higher in the acute onset group than in the other groups (P < 0.05; Kruskal-Wallis test). In the subacute onset and delayed onset groups, 79% and 63% had an A-type fracture and more than 90% were caused by a low-energy injury. In the delayed onset group, the incidence of prolonged DML in the contralateral wrists was 71%, which was significantly higher than in the other two onset groups (P < 0.05; Kruskal- Wallis test)., Conclusions: There were three onset patterns of CTS after DRF, and each CTS onset pattern had different etiologic mechanisms and different clinical features of CTS. In the acute onset group, a high-energy fracture pattern was associated with CTS. In the subacute and the delayed onset groups, lowenergy injury in elderly women was associated with CTS. Both deformity of the fracture and preexisting median nerve dysfunction were suggested as predisposing factor for CTS.

The current concepts of carpal tunnel syndrome (CTS) with respect to its pathophysiology, treatment, and evaluation are discussed. With regard to the pathophysiology of idiopathic CTS, biomechanical studies to determine the kinematics of the flexor tendon, and the median nerve inside the carpal tunnel may provide valuable insights. Different degrees of excursion between the flexor tendons and the median nerve could cause strain and microdamage to the synovial tissue; this has been microscopically observed. A biomechanical approach for elucidating the events that trigger the development of CTS seems interesting; however, there are limitations to its applications. Endoscopic carpal tunnel release (ECTR) is a useful technique for achieving median nerve decompression. However, it is not considered superior to conventional open carpal tunnel release in terms of fast recovery of hand function. Unless the effect of inserting a cannula into the diseased carpal tunnel on the median nerve function is quantitatively elucidated, ECTR will not be regarded as a standard procedure for relieving the median nerve from chronic compression. The treatment of CTS should be evaluated on the basis of patient-oriented questionnaires as well as conventional instruments because these questionnaires have been validated and found to be highly responsive to the treatment. It should be noted that nerve conduction studies exclusively evaluate the function of the median nerve, whereas patient-oriented questionnaires take into account not only the symptoms of CTS but other accompanying pathologies as well, such as flexor tenosynovitis. In Japan, the number of CTS patients is expected to rise; this may be attributed to a general increase in the life-span of the Japanese and increase in the number of diabetic patients. Thus, more efforts should be directed toward elucidating the pathophysiology of so-called idiopathic CTS, so that new treatment strategies can be established for CTS of different pathologies.

Background: We evaluated the correlation between Japanese versions of patient-oriented questionnaires and electrophysiological examinations in patients with carpal tunnel syndrome (CTS)., Methods: A series of 45 patients who were diagnosed with carpal tunnel syndrome and subsequently underwent carpal tunnel release surgery were analyzed. There were 8 men and 37 women with an average age of 64.8 years. They completed the Japanese Society for Surgery of the Hand version of the Carpal Tunnel Syndrome Instrument (CTSI-JSSH), which consisted of a Symptom Severity Score (CTSI-JSSH-SS), Functional Score (CTSI-JSSH-FS), and Japanese Society for Surgery of the Hand version-Quick Disability of Arm, Shoulder, and Hand questionnaire (QuickDASH-JSSH) both preoperatively and 3 months postoperatively. Nerve conduction studies (NCSs) were also performed and included motor distal latency (MDL) and sensory nerve conduction velocity (SCV) measurements. The responsiveness of each instrument was evaluated by calculating the standardized response mean (SRM) and effect size (ES). Correlation coefficients between preoperative and postoperative questionnaire scores and NCS parameters were calculated., Results: Responsiveness (SRM/ES) was as follows: CTSI-JSSH-SS (-1.06/-1.14), CTSI-JSSH-FS (-0.75/-0.74), Quick-DASH-JSSH (-0.65/-0.62), MDL (-1.45/-1.11), and the neurophysiological stage of the disease (-0.90/-1.42). No significant correlation was observed between the preoperative and postoperative patient-oriented questionnaires and nerve conduction studies (P > 0.05)., Conclusions: Although NCSs and the Japanese version of patient-oriented questionnaires are highly responsive to treatment, they are not parallel. Multifaceted assessment of CTS treatment is possible by performing both outcome measurements.

Purpose: To reduce the rate of median nerve injury occurring during Chow's original 2-portal technique, we developed a modified procedure. The surgical technique was introduced, and the results were evaluated with regard to the clinical findings, nerve conduction studies, and Disabilities of the Arm, Shoulder, and Hand (DASH) score., Methods: We analyzed 119 hands of 119 patients with idiopathic carpal tunnel syndrome who underwent our procedure, wherein a cannula assembly was inserted after a partial division of both distal and proximal parts of the transverse carpal ligament through the entry and exit portals. Postoperative examinations, including evaluation of numbness, grip strength, pinch strength, tenderness over and around the wounds, and nerve conduction studies, were performed at 1 month (n = 119), 3 months (n = 119), 6 months (n = 102), and 12 months (n = 39). The DASH score was also evaluated preoperatively and at 3, 6, or 12 months postoperatively. The rate of structural damage to the median nerve, the tendon, and the artery was calculated., Results: The patients resumed their daily activities or work by 13 days postoperatively. Tenderness around the wounds was detected in 66% of patients by 3 months postoperatively. Numbness disappeared or decreased in 99% of patients by 6 months postoperatively. The DASH score was available for 82 patients, and it improved from 28.2 to 18.3 points postoperatively. Nerve conduction studies indicated a significant decrease in motor distal latency postoperatively. Temporal worsening of median nerve function was observed in 2 patients; however, no structural damage to the nerve, tendon, or artery was observed., Conclusions: We found no injury to the tendon or artery and no laceration to the nerve in all 119 patients. However, temporal worsening of median nerve function was observed in 2 patients., Level of Evidence: Level IV, therapeutic case series.

Background: The Carpal Tunnel Syndrome Instrument (CTSI) is a disease-specific, self-administered questionnaire that consists of a symptom severity scale (SS) and a functional status scale (FS). The CTSI was cross-culturally adapted and developed by the Impairment Evaluation Committee, Japanese Society for Surgery of the Hand (JSSH). The purpose of this study was to test the reliability, validity, and responsiveness of the Japanese version of the CTSI (CTSI-JSSH)., Methods: A consecutive series of 87 patients with carpal tunnel syndrome completed the CTSI-JSSH, the JSSH version of the Disability of the Arm, Shoulder, and Hand questionnaire (DASH-JSSH), and the 36-Item Short-Form Health Survey (SF-36). Seventy-two of the patients were reassessed for test-retest reliability 1 or 2 weeks later. Reliability was investigated by the reproducibility and the internal consistency. To analyze the validity, a factor analysis (principal axis factoring) of the CTSI-JSSH and the correlation coefficients between the CTSI-JSSH and DASH-JSSH were obtained. The responsiveness was examined by calculating the standardized response mean (SRM; mean change/SD) and effect size (mean change/SD of baseline value) after carpal tunnel release in 42 patients., Results: Cronbach's alpha coefficients for the CTSI-JSSH-SS and the CTSI-JSSH-FS were 0.84 and 0.90, respectively, and the intraclass correlation coefficients were 0.82 and 0.83, respectively. The unidimensionality of the CTSI-JSSH-SS was barely confirmed; the unidimensionality of the CTSI-JSSH-FS was confirmed. The correlation coefficients between the CTSI-JSSH-FS and the CTSI-JSSH-SS or DASH-JSSH were 0.58 and 0.80, respectively. The correlation coefficient between the CTSI-JSSH-SS and DASH-JSSH was 0.54. The correlation coefficients between the subscales of SF-36 and the CTSI-JSSH-SS or the CTSI-JSSH-FS ranged from -0.23 to -0.66 and from -0.19 to -0.63, respectively. The SRMs/effect sizes of the CTSI-JSSH-SS and the CTSI-JSSH-FS were -0.85/-0.99 and -0.70/-0.61, which indicated that they were more than moderately sensitive., Conclusions: The CTSI-JSSH has sufficient reliability, validity, and responsiveness to assess the health status in carpal tunnel syndrome.

Background: The Quick Disability of the Arm, Shoulder, and Hand (QuickDASH) questionnaire is a region-specific, self-administered questionnaire, which consists of a disability/symptom (QuickDASH-DS) scale, and the same two optional modules, the work (DASH-W) and the sport/music (DASH-SM) modules, as the DASH. After the Japanese version of DASH (DASH-JSSH) was cross-culturally adapted and developed, we made the Japanese version of QuickDASH (QuickDASH-JSSH) by extracting 11 out of 30 items of the DASH-JSSH regarding disability/symptoms. The purpose of this study was to test the reliability, validity, and responsiveness of QuickDASH-JSSH., Methods: A series of 72 patients with upper extremity disorders completed the QuickDASH-JSSH, the 36-Item Short-Form Health Survey (SF-36), and the Visual Analog Scale (VAS) for pain. Thirty-eight of the patients were reassessed for test-retest reliability 1 or 2 weeks later. Reliability was investigated by the reproducibility and internal consistency. To analyze the validity, a principal component analysis and the correlation coefficients between the QuickDASH-JSSH and the SF-36 were obtained. The responsiveness was examined by calculating the standardized response mean (SRM; mean change/SD) and effect size (mean change/SD of baseline value) after carpal tunnel release of the 17 patients with carpal tunnel syndrome., Results: Cronbach's alpha coefficient in the QuickDASH-DS was 0.88. The intraclass correlation coefficient (ICC) for the same was 0.82. The unidimensionality of the QuickDASH-DS was confirmed. The correlation coefficients between the QuickDASH-DS and the DASH-DS, DASH-W, or the DASH-SM were 0.92, 0.81, or 0.76, respectively. The correlation coefficients between the QuickDASH-DS score and the subscales of the SF-36 ranged from -0.29 to -0.73. The correlation coefficient between the QuickDASH-DS score and the VAS for pain was 0.52. The SRM/effect size of QuickDASH-DS was -0.54/-0.37, which indicated moderate sensitivity., Conclusion: The Japanese version of QuickDASH has equivalent evaluation capacities to the original QuickDASH.

Although the coexistence of carpal tunnel syndrome and trigger digit in the same hand is well documented, the interactive relationship between them is unclear. This study was conducted to examine the factors that may impact on the development of trigger digit in the hand with idiopathic carpal tunnel syndrome. One hundred and eighty-one patients were enrolled. Their gender, age, dominant side, severity of carpal tunnel syndrome, history or presence of trigger digit, and treatment type were recorded. The patients were evaluated for the presence of trigger digit at 1, 3, 6 and 12 months after surgery or the initial evaluation. Two hundred and sixty-five hands in 152 patients were included in the final assessment. Logistic regression analysis revealed that surgery was a significant risk factor for the onset of trigger digit and may accelerate development of trigger digit when carpal tunnel syndrome was mild to moderate, but not when it was severe. In severe disease, other unknown factors, such as hypertrophy of the flexor tenosynovium, may mask the effect of surgery.

Objective: To evaluate the adverse effects of Chow's two-portal endoscopic carpal tunnel release (ECTR) performed by an experienced surgeon on median nerve function in patients with idiopathic carpal tunnel syndrome, as compared to open carpal tunnel release (OCTR)., Methods: Eighty-seven hands subjected to ECTR and 65 hands subjected to OCTR were reviewed. Both groups of patients were similar with regard to age, gender, and severity of the disease. Both groups were compared for the number of hands showing worsening of motor distal latency, sensory conduction velocity, and sensory disturbance after surgery., Results: Thirteen hands of 12 patients showed worsening of median nerve function after ECTR, while only one hand showed worsening after OCTR. This difference was statistically significant (p=0.0041)., Conclusions: Median nerve damage, although transient or not serious, may occur even if the procedure is done correctly.

Background: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy worldwide, but there are few reports investigating its prevalence using subjects diagnosed by both clinical symptoms and nerve conduction studies (NCSs) in a population-based cohort. This study aimed to determine the epidemiology of CTS diagnosed by sensory disturbance findings and NCSs using a randomly sampled resident population. Methods: Subjects aged between 50 and 89 years were randomly sampled from the basic resident registry of a rural Japanese town. Subjects indicating a history of CTS surgery in a written questionnaire were classified as having past CTS. Subjects with both sensory disturbance of the median nerve area and delays in NCSs were diagnosed as having present CTS. Subjects with past or present CTS were judged as affected with CTS. We calculated the prevalence of CTS and investigated for possible risk factors. Results: Seventeen subjects (14 female and 3 male) were affected with CTS among 379 enrolled subjects. Adjusting these results to Japanese population values, the weighted prevalence of CTS was 4.7% (female: 7.2%, male: 1.8%) in the Japanese population aged 50 to 89 years. Statistically significant positive correlations were found between CTS and female, higher BMI, rheumatoid arthritis, and trigger digit. In females affected with CTS, third metacarpal length was significantly shorter than in those without CTS. Conclusions: This epidemiological study clarified the prevalence of CTS among Japanese seniors as 4.7%. Female, higher BMI, rheumatoid arthritis, trigger digit, and shorter third metacarpal length in females were risk factors for CTS. [ABSTRACT FROM AUTHOR]

Closed flexor tendon ruptures in the little finger can be caused by fracture or nonunion of the hook of the hamate, but no case of the disorder secondary to the sclerosis and thinning of the hamate hook has been reported. We report two rare cases with this complication due to rough surface of the hamate hook. Carpal tunnel view radiographs and computed tomography showed the sclerosis and thinning of the hook. [ABSTRACT FROM AUTHOR]

Purpose: To reduce the rate of median nerve injury occurring during Chow’s original 2-portal technique, we developed a modified procedure. The surgical technique was introduced, and the results were evaluated with regard to the clinical findings, nerve conduction studies, and Disabilities of the Arm, Shoulder, and Hand (DASH) score. Methods: We analyzed 119 hands of 119 patients with idiopathic carpal tunnel syndrome who underwent our procedure, wherein a cannula assembly was inserted after a partial division of both distal and proximal parts of the transverse carpal ligament through the entry and exit portals. Postoperative examinations, including evaluation of numbness, grip strength, pinch strength, tenderness over and around the wounds, and nerve conduction studies, were performed at 1 month (n = 119), 3 months (n = 119), 6 months (n = 102), and 12 months (n = 39). The DASH score was also evaluated preoperatively and at 3, 6, or 12 months postoperatively. The rate of structural damage to the median nerve, the tendon, and the artery was calculated. Results: The patients resumed their daily activities or work by 13 days postoperatively. Tenderness around the wounds was detected in 66% of patients by 3 months postoperatively. Numbness disappeared or decreased in 99% of patients by 6 months postoperatively. The DASH score was available for 82 patients, and it improved from 28.2 to 18.3 points postoperatively. Nerve conduction studies indicated a significant decrease in motor distal latency postoperatively. Temporal worsening of median nerve function was observed in 2 patients; however, no structural damage to the nerve, tendon, or artery was observed. Conclusions: We found no injury to the tendon or artery and no laceration to the nerve in all 119 patients. However, temporal worsening of median nerve function was observed in 2 patients. Level of Evidence: Level IV, therapeutic case series. [Copyright &y& Elsevier]

Forty hands of 36 patients who had undergone endoscopic carpal tunnel release (ECTR), utilising Chow's two-portal technique after being diagnosed with idiopathic carpal tunnel syndrome, were subjected to longitudinal median nerve conduction studies. The distal motor latency (DML) was examined pre-operatively on all the hands, which were re-examined at the post-operative 1st, 3rd, 6th and 12th months. Rapid improvement of DML was observed post-operatively in the first three months. These improvements patterns are not much different from those after open carpal tunnel release (OCTR) reported in the literatures. We consider that the data reported herein can be used as standards of DML course after ECTR. [ABSTRACT FROM AUTHOR]