The frequency of carpal tunnel syndrome in computer users at a medical facility

Effects of computer use on upper limb musculoskeletal disorders and function in academicians

Objectives. This study aimed to investigate the effects of academician's demographic characteristics and computer usage habits on upper limb musculoskeletal disorders (MSDs) and function. Methods. A cross-sectional observational study was conducted with 100 academicians. Data were collected using questionnaires, which included the patient-rated wrist evaluation questionnaire - Turkish version (PRWE-T), the Cornell musculoskeletal discomfort questionnaire - Turkish version (CMDQ-T), the upper extremity functional index - Turkish version (UEFI-T), demographic characteristics and average daily computer usage time. Results. A low-level significant correlation was found between the age of the individuals and the CMDQ-T forearm (p = 0.044; r = 0.202) and CMDQ-T wrist (p = 0.001; r = 0.337) scores. Women had higher CMDQ-T neck scores and lower UEFI-T scores than men (p < 0.05). Academicians who used computers for 6 h a day or more had higher PRWE-T and CMDQ-T neck, shoulder, upper arm and forearm scores, and had a lower UEFI-T score (p < 0.05). Conclusion. Neck, shoulder, upper arm and forearm symptoms were higher and upper extremity function was impaired in academicians who used computers for 6 h a day or more. Besides, gender and age were associated with upper limb MSDs and function, but occupation duration did not affect those outcomes in academicians.

Carpal tunnel syndrome and its associated factors among computer user bankers in South Gondar Zone, Northwest Ethiopia, 2021: a cross sectional study

INTRODUCTION

The use of information devices like computers is skyrocketed in recent years, leading injuries. Carpal Tunnel Syndrome is a leading cause of upper extremity MSDs specially to banking workers. Hence, this paper was intended to highlight its magnitude associated factors in the study area.

METHODS AND MATERIALS

Institutional based cross-sectional study was conducted from September 13, 2021 to October 09, 2021. A total of 422 private and government owned computer user bankers were participated. Simple random sampling technique was used to select the study participants. Data were collected using Durkan's compression test, flexion and compression test, Phalen's test, and Tinel's test. Multivariable logistic regression model was used to investigate the relationship between predictors and Carpal Tunnel Syndrome. P-value less than 0.05 was considered to declare as a significant and Adjusted Odds Ration for strength association between risk factors and Carpal Tunnel Syndrome.

RESULT

Among 422 participants, the annual prevalence of CTS was 11.7%. Being smoker [AOR: 4.2; 95% CI: 1.76-10.26], having > 5-year work experience [AOR: 7.98; 95% CI: 3.7-17.33], movement repetition [AOR: 3.9; 95% CI: 1.66-9.4] and lack of ergonomics training [AOR: 5.2; 95% CI: 2.8-9.5] were independently associated risk factors to Carpal Tunnel Syndrome.

CONCLUSION

Carpal Tunnel Syndrome was high (11.7%) among bankers in this study area. Carpal Tunnel Syndrome was predicted by smoking, length of employment, movement repetition, and not received ergonomics training. Therefore, fore the banking industry, it would be better to maintain strict follow-up and provision of ergonomics training.

Diabetic polyneuropathy and carpal tunnel syndrome together affect hand strength, tactile sensation and dexterity in diabetes patients

AIMS/INTRODUCTION

Carpal tunnel syndrome (CTS) and diabetic polyneuropathy (DPN) can occur together, and this concomitance is thought to be higher in diabetes patients. We aimed to examine and compare hand function in type 2 diabetes mellitus patients without CTS and DPN (CTS-DPN-), patients with CTS without DPN (CTS+DPN-), patients with DPN without CTS (CTS-DPN+), and patients with CTS and DPN (CTS+DPN+).

MATERIALS AND METHODS

A total of 161 type 2 diabetes mellitus patients underwent physical examination and electrodiagnostic tests. Grip and pinch strengths, tactile sensory thresholds were measured for each participant. Purdue pegboard test was used in evaluating the hand dexterity of the participants.

RESULTS

Of the 161 type 2 diabetes mellitus participants, 36 (22.4%) had both CTS and DPN. CTS participants had lower grip (26.6 ± 10.6 vs 35.2 ± 14.3, P < 0.001) and pinch (6.3 ± 2.6 vs 7.5 ± 2.9, P = 0.026) strengths compared with non-CTS participants, whereas DPN participants had elevated tactile sensory thresholds of both the second (2.8 [2.8-3.6] vs 2.4 [2.4-2.8], P < 0.001) and the fifth (2.8 [2.8-3.6] vs 2.4 [2.4-2.8], P < 0.001) fingers compared with non-DPN participants. The CTS+DPN+ group had lower Purdue pegboard test scores than other groups. Grip (r = 0.482, 0.530, 0.467, 0.498, all P < 0.001) and pinch (r = 0.246, P = 0.003; r = 0.265, P = 0.001; r = 0.264, P = 0.001; r = 0.235, P = 0.005) strengths were positively correlated with Purdue pegboard test scores, whereas tactile sensory thresholds were negatively correlated with Purdue pegboard test scores (r = -0.447 to -0.359, all P < 0.001).

CONCLUSION

Type 2 diabetes mellitus patients with both DPN and CTS had lower grip and pinch strengths and decreased tactile sensation, both of which were correlated with poorer hand dexterity.

Evaluation of occupational and non-occupational risk factors associated with carpal tunnel syndrome in dentists

BACKGROUND

Musculoskeletal disorders are very prevalent among dentists. Of these disorders, carpal tunnel syndrome (CTS) is notable.

OBJECTIVE

The aim of this study was to investigate the relationship between the occupational and non-occupational risk factors and CTS among dentists.

METHODS

It is a cross-sectional study. We evaluated 106 dentists from dental schools in Tehran. We collected data by a general questionnaire, a hand diagram, and physical examination. A nerve conduction velocity (NCV) test was used to confirm the diagnosis of CTS. The analysis was performed using an independent T-test and logistic regressions on SPSS software.

RESULTS

The prevalence of CTS among dentists was 17.9%. Significant risk factors of CTS included: vibration exposure greater than two hours per day (OR: 2.5), a wrist diameter ratio of greater than 0.7 (OR: 10.14), and female sex (OR: 13.38).

CONCLUSIONS

Exposure to the hand-arm vibration should be considered as an occupational risk factor for CTS in dentists. Female dentists should take more preventive measures.

Computer Use and Carpal Tunnel Syndrome: A Case-control Study

Context:

Carpal tunnel syndrome (CTS) is one of the musculoskeletal disorders that is often described as an occupational hazard, including occupations involving computer use. However, clear consensus is lacking as far as the association between the use of computer and risk of possible CTS is concerned.

Aim:

To assess the association between CTS and computer use.

Settings and Design:

A case-control study.

Materials and Methods:

A sample size of 411 (137 cases and 274 controls) was calculated using Epi Info (version 6). Thus, 137 confirmed cases of CTS and 274 controls (matched for age and sex) were studied using a structured questionnaire.

Statistical Analysis Used:

Odds ratio (OR) with 95% confidence interval was calculated between the two groups to analyze the association. For control of confounding factors, logistic regression analysis was done.

Results:

Current use of computer was found to be significantly higher in controls rather than cases (OR = 0.47, CI = 0.27–0.84, P = 0.009). Similarly, past use of computer was also found to be higher in controls. However, the difference was not statistically significant (OR = 0.38, CI = 0.11–1.35, P = 0.20). On applying logistic regression, variables found to be significantly associated with CTS were education (OR = 0.79, CI = 0.66–0.94, P = 0.01), obesity (OR = 3.11, 95%CI = 1.92–5.04, P = 0.00), and short stature (OR = 1.06, 95%CI = 1.02–1.1, P = 0.00). Although current use of computer (OR = 0.33, CI = 0.16–0.67, P = 0.00) was significantly associated with CTS in multivariate model, OR of value less than one does not indicate positive association between this variable and CTS.

Conclusion:

The study did not demonstrate any positive association between computer use and CTS.

Longitudinal Study of the Effects of an Adjustable Ergonomic Keyboard on Upper Body Musculoskeletal Symptoms

A longitudinal study assessed the differential impact of standard and adjustable ergonomic keyboards on musculoskeletal symptoms among 71 computer users over a six month period. A total of 73 subjects participated: 34 subjects used a standard, flat keyboard and 37 used an adjustable, ergonomic keyboard. Subjects completed weekly surveys of perceived keyboard comfort, and body discomfort, along with other items. The ergonomic keyboard was rated favorably and for users there were significantly improvements neck, shoulder and arm comfort.

Sonographic Findings of Median Nerve and Prevalence of Carpal Tunnel Syndrome in Computer Mouse Users

The purpose of this study was to evaluate the median nerve sonographically and estimate the prevalence of carpal tunnel syndrome (CTS) in computer mouse users. Forty-nine right wrists of 49 employees who had used a computer mouse were included in the study. Thirty-three right wrists of 33 non-mouse user employees were studied as a control group. Both the mouse user and non-mouse user employees underwent sonography and electromyography (EMG). Axial sonograms of the median nerve were obtained proximally, in the middle and distally in the carpal tunnel. At each level, flattening ratio and the cross-sectional area of the median nerve were calculated. We found no significant difference in any parameters between mouse users and control group ( p>0.05). However, when we compared mouse users according to the presence of pain, there was a significant increase in the cross-sectional area of the median nerve proximally in the mouse users having pain ( p<0.05). Of all mouse users, eight (16.3%) were diagnosed as sensory CTS, four (8.2%) as motor CTS by EMG. We also found that four (50%) CTS patients had a proximal cross-sectional area of median nerve exceeding 10 mm2 and five (62.5%) had a distal flattening ratio over three. Prolonged use of a mouse may pose an occupational risk for employees. Sonography can serve as an initial step in symptomatic patients for diagnosis of CTS.

The Clinical Practice Guideline on Carpal Tunnel Syndrome and Workers' Compensation

The American Academy of Orthopedic Surgeons has released an updated Clinical Practice Guideline (CPG) on the evaluation and treatment of carpal tunnel syndrome (CTS). In 2007, the initial CPG on CTS evaluated diagnosis and in 2008 and 2011, the CPG on CTS assessed treatment. The most recent CPG assesses both diagnosis and treatment in a generally non-controversial way. We assess the potential impact of this CPG on the care of workers compensation patients.

Computer use and carpal tunnel syndrome: A meta-analysis

BACKGROUND

Studies have reported contradictory results on the role of keyboard or mouse use in carpal tunnel syndrome (CTS). This meta-analysis aimed to assess whether computer use causes CTS.

METHODS

Literature searches were conducted in several databases until May 2014. Twelve studies qualified for a random-effects meta-analysis. Heterogeneity and publication bias were assessed.

RESULTS

In a meta-analysis of six studies (N=4964) that compared computer workers with the general population or other occupational populations, computer/typewriter use (pooled odds ratio (OR)=0.72, 95% confidence interval (CI) 0.58-0.90), computer/typewriter use ≥1 vs. <1h/day (OR=0.63, 95% CI 0.38-1.04) and computer/typewriter use ≥4 vs. <4h/day (OR=0.68, 95% CI 0.54-0.87) were inversely associated with CTS. Conversely, in a meta-analysis of six studies (N=5202) conducted among office workers, CTS was positively associated with computer/typewriter use (pooled OR=1.34, 95% CI 1.08-1.65), mouse use (OR=1.93, 95% CI 1.43-2.61), frequent computer use (OR=1.89, 95% CI 1.15-3.09), frequent mouse use (OR=1.84, 95% CI 1.18-2.87) and with years of computer work (OR=1.92, 95% CI 1.17-3.17 for long vs. short). There was no evidence of publication bias for both types of studies.

CONCLUSIONS

Studies that compared computer workers with the general population or several occupational groups did not control their estimates for occupational risk factors. Thus, office workers with no or little computer use are a more appropriate comparison group than the general population or several occupational groups. This meta-analysis suggests that excessive computer use, particularly mouse usage might be a minor occupational risk factor for CTS. Further prospective studies among office workers with objectively assessed keyboard and mouse use, and CTS symptoms or signs confirmed by a nerve conduction study are needed.

Personal and workplace factors and median nerve function in a pooled study of 2396 US workers

OBJECTIVE

Evaluate associations between personal and workplace factors and median nerve conduction latency at the wrist.

METHODS

Baseline data on workplace psychosocial and physical exposures were pooled from four prospective studies of production and service workers (N = 2396). During the follow-up period, electrophysiologic measures of median nerve function were collected at regular intervals.

RESULTS

Significant adjusted associations were observed between age, body mass index, sex, peak hand force, duration of forceful hand exertions, Threshold Limit Value for Hand Activity Limit, forceful repetition rate, wrist extension, and decision latitude on median nerve latencies.

CONCLUSIONS

Occupational and nonoccupational factors have adverse effects on median nerve function. Measuring median nerve function eliminates possible reporting bias that may affect symptom-based carpal tunnel syndrome case definitions. These results suggest that previously observed associations between carpal tunnel syndrome and occupational factors are not the result of such reporting bias.

Is carpal tunnel syndrome related to computer exposure at work? A review and meta-analysis

OBJECTIVE

A meta-analysis on epidemiological studies was undertaken to assess association between carpal tunnel syndrome (CTS) and computer work.

METHODS

Four databases (PubMed, Embase, Web of Science, and Base de Donnees de Sante Publique) were searched with cross-references from published reviews. We included recent studies, original epidemiological studies for which the association was assessed with blind reviewing with control group. Relevant associations were extracted, and a metarisk was calculated using the generic variance approach (meta-odds ratio [meta-OR]).

RESULTS

Six studies met the criteria for inclusion. Results are contradictory because of heterogeneous work exposure. The meta-OR for computer use was 1.67 (95% confidence interval [CI], 0.79 to 3.55). The meta-OR for keyboarding was 1.11 (95% CI, 0.62 to 1.98) and for mouse 1.94 (95% CI, 0.90 to 4.21).

CONCLUSION

It was not possible to show an association between computer use and CTS, although some particular work circumstances may be associated with CTS.

Prevalence of clinical findings of carpal tunnel syndrome in Isfahanian dentists

BACKGROUND

Carpal tunnel Syndrome (CTS) is the most common compression neuropathy. Jobs with frequent and repetitive hand movements are one of the risk factors for this syndrome. The aim of this study was to determine the prevalence of CTS in Isfahanian dentists.

MATERIALS AND METHODS

In this cross-sectional descriptive study, 240 dentists were evaluated for CTS. Diagnosis was made according to both questionnaire and clinical tests of Phalen and Tinel. Age, sex, years of experience, working hours per week and the type of procedure were considered as dependent variables. All data were analyzed by Chi-square and T-test using SPSS software 11.5 (α=0.05).

RESULTS

Among the dentists who were studied, 173 (72%) were male and 67 (28%) were female. 16.2% of males and 17.9% of females had symptoms of CTS and there wasn't any significant difference between them (P>0.05%). the prevalence increased with advancing age. In a way that it reached to 22.2% in ages more than 55 in contrast to 6% among individuals between 25-34 years old. With increasing of experience to 15 years the risk of CTS increased but an unexpected reduction was observed with more than 15 years of experience.

CONCLUSION

This study showed the prevalence of CTS was 16.7% among dentists and was more common in older dentists. CTS prevalence was increased with age. The dentist population with more working hours per week and more experience years were more susceptible for this syndrome. Using suitable gloves, wrist splints and short periods of resting during vigorous continuous working can decrease the symptoms of this disease.

Questionnaire tools for the diagnosis of carpal tunnel syndrome from the patient history

INTRODUCTION

There remains no "gold standard" for the diagnosis of carpal tunnel syndrome (CTS). Clinical diagnosis is often held to be paramount but depends on the skills of the individual practitioner. We describe two mathematical approaches to the analysis of a history obtained by questionnaire.

METHODS

We used two earlier instruments, a conventional logistic regression analysis, and an artificial neural network to analyze data from 5860 patients referred for diagnosis of hand symptoms. We evaluated their ability to predict whether nerve conduction studies would show evidence of CTS using receiver operating characteristic curves.

RESULTS

Both new instruments outperformed the existing tools, achieving sensitivity of 88% and specificity of 50% in predicting abnormal median nerve conduction. When combined, 96% sensitivity and 50% specificity were achieved.

CONCLUSION

The combined instrument can be used as a preliminary screening tool for CTS, for self-diagnosis, and as a supplement to diagnosis in primary care.

Effects of computer keyboarding on ultrasonographic measures of the median nerve

BACKGROUND

Keyboarding is a highly repetitive daily task and has been linked to musculoskeletal disorders of the upper extremity. However, the effect of keyboarding on median nerve injuries is not well understood. The purpose of this study was to use ultrasonographic measurements to determine whether continuous keyboarding can cause acute changes in the median nerve.

METHODS

Ultrasound images of the median nerve from 21 volunteers were captured at the levels of the pisiform and distal radius prior to and following a prolonged keyboarding task (i.e., 1 hr of continuous keyboarding). Images were analyzed by a blinded investigator to quantify the median nerve characteristics. Changes in the median nerve ultrasonographic measures as a result of continuous keyboarding task were evaluated.

RESULTS

Cross-sectional areas at the pisiform level were significantly larger in both dominant (P = 0.004) and non-dominant (P = 0.001) hands following the keyboarding task. Swelling ratio was significantly greater in the dominant hand (P = 0.020) after 60 min of keyboarding when compared to the baseline measures. Flattening ratios were not significantly different in either hand as a result of keyboarding.

CONCLUSION

We were able to detect an acute increase in the area of the median nerve following 1 hr of keyboarding with a computer keyboard. This suggests that keyboarding has an impact on the median nerve. Further studies are required to understand this relationship, which would provide insight into the pathophysiology of median neuropathies such as carpal tunnel syndrome.

Carpal tunnel syndrome: the role of occupational factors

Carpal tunnel syndrome (CTS) is a fairly common condition in working-aged people, sometimes caused by physical occupational activities, such as repeated and forceful movements of the hand and wrist or use of hand-held, powered, vibratory tools. Symptoms may be prevented or alleviated by primary control measures at work, and some cases of disease are compensable. Following a general description of the disorder, its epidemiology and some of the difficulties surrounding diagnosis, this review focusses on the role of occupational factors in causation of CTS and factors that can mitigate risk. Areas of uncertainty, debate and research interest are emphasised where relevant.

Prospective evaluation of the clinical prediction of electrodiagnostic results in carpal tunnel syndrome

OBJECTIVE

To develop a unique clinical prediction point-score system for the diagnosis of carpal tunnel syndrome (CTS) and to prospectively evaluate this clinical rule to determine its ability to predict electrodiagnostic results.

DESIGN

Retrospective case control to develop the clinical point-score system and then prospective diagnostic study with blind comparison to electrodiagnostic results.

SETTING

Community-based electrodiagnostic laboratory.

PATIENTS

A total of 348 subjects referred to the electrodiagnostic laboratory with a clinical suspicion of CTS to develop the clinical point-score system and then a different population of 278 subjects referred to the electrodiagnostic laboratory over a 1-year period with a clinical suspicion of CTS to prospectively evaluate the ability of the clinical rule to predict electrodiagnostic results.

MAIN OUTCOME MEASURES

Clinical point-score system results were compared with the electrodiagnostic results for CTS, which served as the primary outcome measure.

RESULTS

A "weighted" point-score system was developed from 9 clinical variables including: gender, duration of symptoms, presence of wrist pain (negative predictor), presence of neck pain (negative predictor), nocturnal symptoms, presence of thenar atrophy, abductor pollicis brevis weakness, median sensory symptoms, and results of pinprick sensation examination. The prospective evaluation indicated that the clinical point-score rule, overall, performed moderately in predicting electrodiagnostic results (receiver operator characteristic curve = 0.80). The clinical point score was most predictive in a small subset of subjects with very high scores. However, in most subjects, the clinical point score could not accurately predict electrodiagnostic outcome in CTS, particularly in subjects with middle to low clinical point scores.

CONCLUSIONS

The developed clinical point-score rule was most predictive in subjects with high point score; however, the majority of the referrals to the electrodiagnostic laboratory indicated that the electrodiagnostic studies provided additional, independent information beyond what could be obtained by the clinical point score.

Risk factors for carpal tunnel syndrome and median neuropathy in a working population

OBJECTIVE

To assess whether work-related physical activities are associated with Carpal tunnel syndrome (CTS), even when controlling for personal risk factors.

METHODS

A cross-sectional assessment of 1108 workers from eight employers and three unions completed nerve conduction testing, physical examination, and questionnaires. CTS was defined by median neuropathy and associated symptoms.

RESULTS

Eighteen workers had CTS and 131 had evidence of median neuropathy. CTS was highest among construction workers (3.0%) compared to other subjects (<1%). Logistic regression models for median neuropathy both personal and work-related risk factors. Work-related exposures were estimated by two methods: self-report and job title based ratings.

CONCLUSIONS

Both work and personal factors mediated median nerve impairment. Construction workers are at an increased risk of CTS so awareness should be raised and interventions should specifically target this risk group.

A randomized controlled trial evaluating an alternative mouse or forearm support on change in median and ulnar nerve motor latency at the wrist

BACKGROUND

The purpose of this study was to determine the effects of an alternative mouse and/or a forearm support board on nerve function at the wrist among engineers.

METHODS

This randomized controlled intervention trial followed 206 engineers for 1 year. Distal motor latency (DML) at baseline and follow-up was conducted for the median and ulnar nerves at the right wrist.

RESULTS

One hundred fifty-four subjects agreed to a nerve conduction study at the beginning and end of the study period. Those who received the alternative mouse had a protective effect (OR = 0.47, 95% CI 0.22-0.98) on change in the right ulnar DML. There was no significant effect on the median nerve DML. The forearm support board had no significant effect on the median or ulnar nerve DML.

CONCLUSIONS

In engineers who use a computer for more than 20 hr per week, an alternative mouse may have a protective effect for ulnar nerve function at the wrist. No protective effect of a forearm support board was found for the median nerve.

Carpal tunnel syndrome and the use of computer mouse and keyboard: a systematic review

Background

This review examines evidence for an association between computer work and carpal tunnel syndrome (CTS).

Methods

A systematic review of studies of computer work and CTS was performed. Supplementary, longitudinal studies of low force, repetitive work and CTS, and studies of possible pathophysiological mechanisms were evaluated.

Results

Eight epidemiological studies of the association between computer work and CTS were identified. All eight studies had one or more limitation including imprecise exposure and outcome assessment, low statistical power or potentially serious biases. In three of the studies an exposure-response association was observed but because of possible misclassification no firm conclusions could be drawn. Three of the studies found risks below 1. Also longitudinal studies of repetitive low-force non-computer work (n = 3) were reviewed but these studies did not add evidence to an association. Measurements of carpal tunnel pressure (CTP) under conditions typically observed among computer users showed pressure values below levels considered harmful. However, during actual mouse use one study showed an increase of CTP to potentially harmful levels. The long term effects of prolonged or repeatedly increased pressures at these levels are not known, however.

Conclusion

There is insufficient epidemiological evidence that computer work causes CTS.

Disparity between popular (Internet) and scientific illness concepts of carpal tunnel syndrome causation

PURPOSE

To determine whether there are notable disparities between popular (Internet) and scientific (Index Medicus) theories of carpal tunnel syndrome (CTS) causation.

METHODS

Reports from 3 sources were evaluated with regard to support for etiological theories of CTS: 1) patient-oriented information on CTS from the Internet, 2) recent physician-oriented information on CTS from medical journals indexed on Index Medicus, and 3) articles addressing the etiology of CTS from the 1997 National Institute for Occupational Safety and Health report. Multiple logistic regression analyses evaluated differences in etiological theories from the 3 sources.

RESULTS

Internet sites implicated vitamin B(6) deficiency, tenosynovitis, and typing or computer use as causes for idiopathic CTS considerably more often and genetic predisposition considerably less often than recent Index Medicus scientific reports and reports reviewed by the National Institute for Occupational Safety and Health.

CONCLUSIONS

There are notable disparities between popular (Internet) and scientific (Index Medicus) theories of CTS causation.

Effect of wrist posture on carpal tunnel pressure while typing

Long weekly hours of keyboard use may lead to or aggravate carpal tunnel syndrome. The effects of typing on fluid pressure in the carpal tunnel, a possible mediator of carpal tunnel syndrome, are unknown. Twenty healthy subjects participated in a laboratory study to investigate the effects of typing at different wrist postures on carpal tunnel pressure of the right hand. Changes in wrist flexion/extension angle (p = 0.01) and radial/ulnar deviation angle (p = 0.03) independently altered carpal tunnel pressure; wrist deviations in extension or radial deviation were associated with an increase in pressure. The activity of typing independently elevated carpal tunnel pressure (p = 0.001) relative to the static hand held in the same posture. This information can guide the design and use of keyboards and workstations in order to minimize carpal tunnel pressure while typing. The findings may also be useful to clinicians and ergonomists in the management of patients with carpal tunnel syndrome who use a keyboard.

The quality and strength of evidence for etiology: example of carpal tunnel syndrome

PURPOSE

The purpose of this investigation was to evaluate the quality and strength of scientific evidence supporting an etiologic relationship between a disease and a proposed risk factor using a scoring system based on the Bradford Hill criteria for causal association.

METHODS

A quantitative score based on the Bradford Hill criteria (qBHs) was used to evaluate 117 articles presenting original data regarding the etiology of carpal tunnel syndrome: 33 (28%) that evaluated biological (structural or genetic) risk factors, 51 (44%) that evaluated occupational (environment or activity-related) risk factors, and 33 (28%) that evaluated both types of risk factors.

RESULTS

The quantitative Bradford Hill scores of 2 independent observers showed very good agreement, supporting the reliability of the instrument. The average qBHs was 12.2 points (moderate association) among biological risk factors compared with 5.2 points (poor association) for occupational risk factors. The highest average qBHs was observed for genetic factors (14.2), race (11.7), and anthropometric measures of the wrist (11.3 points) with all studies finding a moderate causal association. The highest average qBHs among occupational risk factors was observed for activities requiring repetitive hand use (6.5 points among the 30 of 45 articles that reported a causal association), substantial exposure to vibration (6.3 points; 14 of 20 articles), and type of occupation (5.6 points; 38 of 53 articles), with the findings being much less consistent.

CONCLUSIONS

According to a quantitative analysis of published scientific evidence, the etiology of carpal tunnel syndrome is largely structural, genetic, and biological, with environmental and occupational factors such as repetitive hand use playing a minor and more debatable role. Speculative causal theories should be analyzed through a rigorous approach prior to wide adoption.

Show me the evidence

Reporting outcomes based on clinical evidence is going to set the standards for hand surgery practice. Hand surgeons will be judged by the evidence that their interventions are doing the most good for the most people at a price that patients and/or insurance companies are willing to pay. Evidence-based practice is the integration of the best research evidence with clinical expertise and patient values. The best evidence comes from randomized clinical trials, which are expensive, time consuming, and not always possible. Sometimes we have to settle for good evidence, which may be the best evidence that is available. Nevertheless, if the future demands good evidence, then as hand surgeons and researchers we need to supply that evidence. Thus, first we have to know how and where to look for what's out there and then what we can do to add to this body of knowledge.

Carpal tunnel syndrome and keyboard use at work: a population-based study

OBJECTIVE

To investigate the relationship between carpal tunnel syndrome (CTS) and keyboard use at work in a general population.

METHODS

A health status questionnaire was mailed to 2,465 persons of working age (25-65 years) who were randomly selected from the general population of a representative region of Sweden. The questionnaire required the subjects to provide information about the presence and severity of pain, numbness and tingling in each body region, employment history, and work activities, including average time spent using a keyboard during a usual working day. Those reporting recurrent hand numbness or tingling in the median nerve distribution were asked to undergo a physical examination and nerve conduction testing. The prevalence of CTS, defined as symptoms plus abnormal results on nerve conduction tests, was compared between groups of subjects that differed in their intensity of keyboard use, adjusting for age, sex, body mass index, and smoking status.

RESULTS

Eighty-two percent responded to the questionnaire, and 80% of all symptomatic persons attended the examinations. Persons who had reported intensive keyboard use on the questionnaire were significantly less likely to be diagnosed as having CTS than were those who had reported little keyboard use, with a prevalence that increased from 2.6% in the highest keyboard use group (> or = 4 hours/day), to 2.9% in the moderate use group (1 to <4 hours/day), 4.9% in the low use group (<1 hour/day), and 5.2% in the no keyboard use at work group (P for trend = 0.032). Using > or = 1 hour/day to designate high keyboard use and <1 hour/day to designate low keyboard use, the prevalence ratio of CTS in the groups with high to low keyboard use was 0.55 (95% confidence interval 0.32, 0.96).

CONCLUSION

Intensive keyboard use appears to be associated with a lower risk of CTS.

Postoperative relieve of abnormal vasoregulation in carpal tunnel syndrome

OBJECTIVE

To study the skin temperature changes as a sign of altered blood flow regulation due to abnormal sympathetic nerve function in carpal tunnel syndrome (CTS) and the efficacy of carpal tunnel release (CTR) operation in the alleviation of those signs and other symptoms of CTS.

SUBJECTS AND METHODS

Forty-one healthy hands (n=41) of 22 volunteers and 22 hands (n=22) with clinically diagnosed carpal tunnel syndrome of 16 patients were examined. A series of infrared photos of the hands of each subject were taken and stored by using digital infrared thermography (DIRT) before and 6 months after the CTR. The temperatures of the finger tips from digit 1 (D1) to digit 5 (D5), the center point of thenar (Th) and hypothenar (Ht) eminences were measured, the median nerve index (MI=(D1-D2)+(D1-D3)+(D2-D3)) and the temperature differences between the median and the ulnar nerve distribution area (MED.ULN=(D1-D5)+(D2-D5)+(D3-D5)+(Th-Ht)) were calculated. Absolute values were used when calculating the temperature differences between different points.

RESULTS

All the CTS patients were released from the CTS symptoms, i.e. numbness and pain after the operation, and the results of nerve conduction studies (NCS) were all back to normal. The MI and MED.ULN in CTS hands were significantly smaller before CTR compared to those of healthy control subjects (MI: p<0.001, MED.ULN: p<0.005), and those after CTR (p<0.005 for both parameters). The results also showed that all finger tips of the affected hand including those innervated by the ulnar nerve were cooler before but warmer after the operation. Before the operation, the non-CTS hands of the CTS patients, were also colder (although the difference was not significant) than the healthy control subjects but approached the same level after the CTR operation of the CTS hands.

CONCLUSION

The results of DIRT measurements suggest that the blood flow regulation in CTS is abnormal possibly because of disturbed sympathetic vasomotor regulation and that the circulation gets normal together with the alleviation of the other symptoms of CTS as recorded 6 months after CTR operation.

Carpal tunnel syndrome in male visual display terminal (VDT) workers

BACKGROUND

The association between working at a video display terminal (VDT) and development of carpal tunnel syndrome (CTS) is not well-established. The study surveyed the prevalence of CTS symptoms, explored the risk factors and evaluated the clinical application of hand diagrams, physical tests and electrodiagnosis among male VDT workers.

METHODS

A cross-sectional study was performed in an information and communication technology company. Three-forty questionnaires were completed and 82 volunteers participated in the physical examination and nerve conduction study. The personal and occupational risk factors for CTS were analyzed.

RESULTS

The prevalence of CTS symptoms was 3.8% among 340 subjects, while prolonged median motor distal latency (>4.2 msec) was disclosed in 3.7% of a subgroup receiving examination. Classic/probable CTS symptoms was associated with high body mass index (>28 kg/m(2), odds ratio = 4.1, P = 0.029) and moderate job seniority (3-5 years, odds ratio = 4.6, P = 0.023). Prolonged median motor distal latency was associated with older age (>35 years old). We did not observe correlation between CTS symptoms, abnormal NCS, positive Tinel's sign or Phalen's test.

CONCLUSION

The prevalence of CTS symptoms was not high among the group of male VDT workers studied. Job seniority, but not specific tasks, was associated with CTS symptoms. More reliable and valid methods to quantify the ergonomic exposure are needed to establish the association of VDT tasks and CTS.

Keyboard use and musculoskeletal outcomes among computer users

BACKGROUND

In this review, the epidemiological evidence examining associations between upper extremity musculoskeletal symptoms and disorders and keyboard use intensity (hours of computer use-per day or per-week) and computer user posture was explored.

METHODS

An OVID Medline literature search was conducted to identify papers published in the peer-reviewed medical literature between 1966 and November, 2005. A total of 558 citations were found and reviewed. Those papers in which associations between musculoskeletal outcomes and (1) posture (ascertained by a study investigator) or (2) computer use, in units of hours-per-day, hours-per-week, or as a percent of work-time, were included in the review.

RESULTS

Thirty-nine epidemiological studies examining associations between computer use and MSD outcomes were identified. While the observational epidemiological literature was heterogeneous, some trends did emerge. It appears that the most consistent finding was the association observed between hours keying and hand/arm outcomes. Associations between some postural effects and musculoskeletal outcomes may also be inferred from the literature. In particular, placing the keyboard below the elbow, limiting head rotation, and resting the arms appears to result in reduced risk of neck/shoulder outcomes. Minimizing ulnar deviation and keyboard thickness appears to result in reduced risk of hand/arm outcomes.

CONCLUSIONS

Several methodological limitations, including non-representative samples, imprecise or biased measures of exposure and health outcome, incomplete control of confounding, and reversal of cause and effect, may contribute to the heterogeneity of observed results. Suggestions are made for improving the validity of future investigations.

A randomised controlled trial evaluating the effects of two workstation interventions on upper body pain and incident musculoskeletal disorders among computer operators

BACKGROUND

Call centre work with computers is associated with increased rates of upper body pain and musculoskeletal disorders.

METHODS

This one year, randomised controlled intervention trial evaluated the effects of a wide forearm support surface and a trackball on upper body pain severity and incident musculoskeletal disorders among 182 call centre operators at a large healthcare company. Participants were randomised to receive (1) ergonomics training only, (2) training plus a trackball, (3) training plus a forearm support, or (4) training plus a trackball and forearm support. Outcome measures were weekly pain severity scores and diagnosis of incident musculoskeletal disorder in the upper extremities or the neck/shoulder region based on physical examination performed by a physician blinded to intervention. Analyses using Cox proportional hazard models and linear regression models adjusted for demographic factors, baseline pain levels, and psychosocial job factors.

RESULTS

Post-intervention, 63 participants were diagnosed with one or more incident musculoskeletal disorders. Hazard rate ratios showed a protective effect of the armboard for neck/shoulder disorders (HR = 0.49, 95% CI 0.24 to 0.97) after adjusting for baseline pain levels and demographic and psychosocial factors. The armboard also significantly reduced neck/shoulder pain (p = 0.01) and right upper extremity pain (p = 0.002) in comparison to the control group. A return-on-investment model predicted a full return of armboard and installation costs within 10.6 months.

CONCLUSION

Providing a large forearm support combined with ergonomic training is an effective intervention to prevent upper body musculoskeletal disorders and reduce upper body pain associated with computer work among call centre employees.

Upper extremity mononeuropathy among engineers

OBJECTIVES

The objectives of this study were to estimate the prevalence of mononeuropathy at the wrist among engineers who use computers and to identify associated risk factors.

METHODS

This is a cross-sectional study of 202 engineers using questionnaires and electrophysiological nerve testing. The definition for median or ulnar mononeuropathy required the combination of distal upper extremity discomfort and abnormal distal motor latency.

RESULTS

The prevalence of neuropathy at the wrist among engineers was 10.3% (right median), 3.4% (left median), 1.8% (right ulnar), and 2.9% (left ulnar). Logistic regression analysis identified three variables with positive associations (body mass index, hours of computer use, and antihypertensive medication) and three variables with negative associations (typing speed, driving hours, total break time).

CONCLUSIONS

Mononeuropathies at the wrist occur among computer-using engineers and are related to a number of factors, including hours of computer use.

Sympathetic pathology evidenced by hand thermal anomalies in carpal tunnel syndrome

OBJECTIVE

To clarify sympathetic pathology in carpal tunnel syndrome and the usefulness of digital infrared thermography as a diagnostic aid.

MATERIAL AND METHODS

38 clinically diagnosed carpal tunnel syndrome hands from 30 patients (confirmed by the standard nerve conduction studies) and 41 hands from 22 healthy volunteers (the hands having current finger inflammation were excluded) were studied. A series of hand infrared photos of each subject were taken and stored by using the technique of digital infrared thermography. We studied the infrared pictures and measured the temperatures of finger tips from digit 1 (D1) to digit 5 (D5), the center point of thenar (Th) and hypothenar eminences (Ht), then we calculated the temperature differences (absolute values) between each two of the 7 points, and median index (MI): (D1-D2)+(D2-D3)+(D1-D3). The means of D2 and Th (MD2+Th), D5 and Ht (MD5+Ht) were also calculated.

RESULTS

The results showed that the temperatures of median nerve distribution area in the hands were highly significantly different (Th-Ht, p < 0.001, MI, p < 0.001) between carpal tunnel syndrome (CTS) and the control group. The differences between the median and ulnar nerve distribution area were also highly significantly different in CTS hands (MD2+Th compared to MD5+Ht, p < 0.01). The sensitivity and specificity of digital infrared thermography were 84 and 91%, respectively.

CONCLUSION

Digital infrared thermography suggests sympathetic neural pathology in carpal tunnel syndrome. It may also be useful as an additional non-invasive tool in the diagnosis of CTS especially in the early stage.

Tingling/numbness in the hands of computer users: neurophysiological findings from the NUDATA study

OBJECTIVES

To investigate whether tingling/numbness of the hands and fingers among computer users is associated with elevated vibration threshold as a sign of early nerve compression.

METHODS

Within the Danish NUDATA study, vibratory sensory testing with monitoring of the digital vibration threshold at seven frequencies on the second and fifth fingers of both hands was performed on 20 cases with unilateral tingling/numbness in the hands and fingers, and 20 gender- and age-matched controls. Both cases and controls were identified from questionnaire information about tingling/numbness at least once a week or daily within the last 3 months. Participants with more than slight muscular pain or disorders of the neck and upper extremities, excessive alcohol consumption, previous injuries of the upper extremities, or concurrent medical diseases were excluded. The two groups had a similar amount of work with mouse, keyboard, and computer.

RESULTS

Seven of the 20 cases (35%) had elevated vibration thresholds, compared with 3 of the 20 controls (15%); this difference was not statistically significant (chi2=2.13, P=0.14). Compared with controls, cases had increased perception threshold for all frequencies, but the difference was statistically significant for only 2 out of 14 measurements. Comparison between left and right hand threshold values within the case group did not show any significant difference at any frequency.

CONCLUSIONS

The results indicate that tingling/numbness of the hands and fingers among computer users cannot be explained by nerve compression.

Work-related musculoskeletal disorders of the hand and wrist: epidemiology, pathophysiology, and sensorimotor changes

The purpose of this commentary is to present recent epidemiological findings regarding work-related musculoskeletal disorders (WMSDs) of the hand and wrist, and to summarize experimental evidence of underlying tissue pathophysiology and sensorimotor changes in WMSDs. Sixty-five percent of the 333 800 newly reported cases of occupational illness in 2001 were attributed to repeated trauma. WMSDs of the hand and wrist are associated with the longest absences from work and are, therefore, associated with greater lost productivity and wages than those of other anatomical regions. Selected epidemiological studies of hand/wrist WMSDs published since 1998 are reviewed and summarized. Results from selected animal studies concerning underlying tissue pathophysiology in response to repetitive movement or tissue loading are reviewed and summarized. To the extent possible, corroborating evidence in human studies for various tissue pathomechanisms suggested in animal models is presented. Repetitive, hand-intensive movements, alone or in combination with other physical, nonphysical, and nonoccupational risk factors, contribute to the development of hand/wrist WMSDs. Possible pathophysiological mechanisms of tissue injury include inflammation followed by repair and/or fibrotic scarring, peripheral nerve injury, and central nervous system reorganization. Clinicians should consider all of these pathomechanisms when examining and treating patients with hand/wrist WMSDs.

Design features of alternative computer keyboards: a review of experimental data

Design of computer keyboards no longer is limited to the flat keyboards that are typically shipped with personal computers. Keyboards now exist that are split into halves and these halves can be slanted away from each other (creating a triangle between the halves), sloped downward toward the visual display terminal, tilted upward like a tent, or simply separated. These design features are intended to alleviate discomfort and possible musculoskeletal disorders that have been suggested to be associated with the extensive use of conventional computer keyboards. The geometry of conventional keyboards requires the wrists to be in 10 degrees to 15 degrees of ulnar deviation and 20 degrees of extension and the forearms to be nearly fully pronated while typing. A review of the available experimental data collected on 10-digit touch typists indicates that (1) keyboards with a slant angle (half of the opening angle) of 10 degrees to 12.5 degrees or keyboards with halves separated to approximately shoulder width are both effective in placing the wrist in near neutral (0 degree) ulnar/radial deviation when typing, (2) wrist extension can be reduced to near neutral (0 degrees) when a keyboard with a negative slope of 7.5 degrees is used, contingent on the wrist rest also sloping with the keyboard, and (3) tilting the keyboard halves 20 degrees to 30 degrees is effective in reducing forearm pronation to approximately 45 degrees. These studies also indicate that experienced 10-digit touch typists readily adapt (within 10 minutes) to these individual alternative keyboard features, and can type with approximately the same speed and accuracy as with the conventional keyboard. While placing the wrist and forearm in a more neutral position could, in theory, reduce the incidence of musculoskeletal disorders, randomized controlled trials are necessary before strong recommendations can be made on the effectiveness of alternative keyboards for the prevention and/or treatment of musculoskeletal disorders. In the absence of these randomized controlled trials, the information in this article provides preliminary guidance to clinicians in their evaluation of computer keyboards and workstations and their recommendations to patients.

What can family physicians offer patients with carpal tunnel syndrome other than surgery? A systematic review of nonsurgical management

BACKGROUND

We undertook a literature review to produce evidence-based recommendations for nonsurgical family physician management of carpal tunnel syndrome (CTS).

METHODS

Study design was systematic review of randomized controlled trials (RCTs) on CTS treatment. Data sources were English publications from all relevant databases, hand searches, and guidelines. Outcomes measured were nonsurgical management options for CTS.

RESULTS

We assessed 2 systematic reviews, 16 RCTs, and 1 before-and-after study using historical controls. A considerable percentage of CTS resolves spontaneously. There is strong evidence that local corticosteroid injections, and to a lesser extent oral corticosteroids, give short-term relief for CTS sufferers. There is limited evidence to indicate that splinting, laser-acupuncture, yoga, and therapeutic ultrasound may be effective in the short to medium term (up to 6 months). The evidence for nerve and tendon gliding exercises is even more tentative. The evidence does not support the use of nonsteroidal anti-inflammatory drugs, diuretics, pyridoxine (vitamin B6), chiropractic treatment, or magnet treatment.

CONCLUSIONS

For those who are not able to get surgery or for those who do not want surgery, there are some conservative modalities that can be tried. These modalities include ones for which there is good evidence. It would be reasonable to try some of the techniques with less evidence if the better ones are not successful. Reconsideration of surgery must always be kept in mind to avoid permanent nerve damage.

Occupational and Sport Related Traumatic Neuropathy

BACKGROUND

Sport and occupation related traumatic nerve injury is a common problem in the United States. While the physical requirements of each pursuit place participants at risk for injury to certain peripheral nervous system structures, the vast numbers of professional and recreational pursuits limits the ability to become familiar with nerve injuries specific to each. A more pragmatic approach is to apply knowledge of mechanisms of injury, physiology of nerve injury, regional anatomy, and at-risk peripheral nervous system structures to the routine neurologic history and physical assessment to arrive at a localizing and etiologic diagnosis.

REVIEW SUMMARY

The authors discuss potential mechanisms of nerve injury, the role of electrodiagnostic testing, regional peripheral nervous system anatomic considerations and lesion localization.

CONCLUSIONS

Despite the wide variety of professionally and recreationally induced peripheral nerve injuries, application of anatomic, physiologic and mechanistic considerations allow the neurologist to make an etiologic and localizing diagnosis.

Relationship Between Carpal Tunnel Syndrome and Wrist Angle in Computer Workers

Carpal tunnel syndrome (CTS) is the most widely known entrapment neuropathy. The aim of this study was to assess the incidence of CTS in a group of computer workers by typical symptoms, median nerve conduction studies, and their combinations. The posture of extended wrists while typing on a computer keyboard seems to be a predisposing factor for CTS. However, the correlation between wrist extension angle and the incidence of CTS is not well known. Forty-five subjects (mean age, 38.8 +/- 7.8 years) who used a computer for more than 6 hours daily in a medical center in southern Taiwan were studied. All completed questionnaires to ascertain their age, employment duration, dominant hand, and the severity of symptoms. Physical examinations (Tinel's sign and Phalen's test) were performed by a physician. The maximal wrist extension angle when typing on a computer keyboard was also measured by the same physician. Nerve conduction studies were performed on each subject to determine the severity of CTS. Results showed that the incidence of CTS in the computer workers was 16.7% (15 of 90 hands). Twelve subjects showed electrodiagnostic evidence of CTS: it involved the dominant hand in seven, the non-dominant hand in two, and bilateral hands in three. The severity of clinical symptoms was compatible with the findings of the nerve conduction studies. Among the major predisposing factors, we found significant correlation between CTS development and the wrist extension angle while typing on a computer keyboard. Computer workers who kept their wrists extended by more than 20 degrees were at greater risk of developing CTS.

Computer use related upper limb musculoskeletal (ComRULM) disorders

Computer use has progressed fast in recent years. The symptoms and signs caused by repetitive computer use that is characterized by neck, shoulder, elbow, wrist and hand pain, paresthesia, and numbness can be called 'Computer Related Upper Limb Musculoskeletal (ComRULM) disorders'. Publications of recent 20 years have been reviewed. These disorders are usually multifactorial processes, caused by occupational, personal and social factors. Some suggestions concerning the diagnostics, procedures of prevention, and treatment options have been discussed. Further studies on 'ComRULM disorders' are necessary.

Carpal tunnel syndrome: current theory, treatment, and the use of B6

PURPOSE

To present the current state of the science of pathophysiology, assessment and treatment of carpal tunnel syndrome, including the use of pyridoxine (B6).

DATA SOURCES

Selected research articles, texts, Websites, personal communications with experts, and the authors' own clinical experience.

CONCLUSIONS

Much is yet to be learned about carpal tunnel syndrome. While the basic treatment of NSAIDs and nighttime splints seems universally accepted, much controversy remains. The use of vitamin B6 as a treatment is one such controversy requiring further investigation.

IMPLICATIONS FOR PRACTICE

Current treatment for carpal tunnel syndrome should include NSAIDs, nighttime splinting, ergonomic workstation review, and vitamin B6 200 mg per day.

Carpal tunnel syndrome and workers' compensation: A cross-Canada comparison

Carpal tunnel syndrome (CTS) is the source of substantial workers' compensation claims in industrialized countries. Its pathogenesis, however, continues to be questioned. The purpose of the present study was to assess the attitudes of Canadian plastic surgeons toward Workers' Compensation Board (WCB)-supported claims for CTS and to assess patterns of resource allocation across Canada. Sixty-seven plastic surgeons were asked to read a clinical scenario and respond whether they would support a WCB claim for CTS. Provincial WCB offices were contacted and asked to provide statistics surrounding CTS claims for 1997 to 2001. Fifty-eight per cent (39 of 67) of surgeons surveyed felt that CTS should be covered as a WCB claim, while 42% (28 of 67) felt that it should not be covered by WCB. In British Columbia, 50% (six of 12) of surgeons were in support of the claim compared to 92% (11 of 12) of those from Alberta, 55% (17 of 31) of those from the Central Provinces and 42% (five of 12) of those from the Maritime Provinces. Trends of resource allocation and number of CTS claims per year are presented for the individual provinces for 1997 to 2001. An extensive literature review revealed that there is minimal to no evidence to support the view that CTS should be a compensated claim. As defined by the WCB of Canada, a compensated claim is one that "arises out of, and in the course of, employment and that results from causes and conditions peculiar to the trade, occupation or industry." The ambiguity in the beliefs of Canadian plastic surgeons in supporting CTS as a WCB claim reflects a situation where many of the decisions to cover CTS as a WCB claim are not evidence based.

Carpal tunnel syndrome among apprentice construction workers

BACKGROUND

In terms of lost-work time and restricted workdays, surgery, and rehabilitation, one of the most costly occupational musculoskeletal disorders is carpal tunnel syndrome (CTS). The purpose of this study was to determine the prevalence of CTS among apprentice construction workers.

METHODS

This cross-sectional study included apprentices from four construction trades. Apprentices completed a self-administered questionnaire and received electrophysiologic studies assessing median nerve function across the carpal tunnel. A surveillance case definition for CTS was based on characteristic hand symptoms and the presence of median mononeuropathy across the carpal tunnel.

RESULTS

Of the 1,325 eligible apprentices, 1,142 (86.2%) participated in the study. The prevalence of CTS among apprentices was 8.2%; sheet metal workers had the highest rate (9.2%). In operating engineers, the prevalence of CTS was significantly higher (OR = 6.9; 95% CI = 2.6-18.2) among the heavy equipment mechanics than the drivers of those vehicles. Body mass index, age, and self-reports of working overhead were associated with prevalent CTS. Less than 15% of the apprentices with CTS sought medical attention for their disorder.

CONCLUSIONS

Many construction workers begin developing CTS before or during their apprenticeship. Few apprentices seek medical attention for hand symptoms characteristic of CTS. The results of this study indicate a public health need for the implementation of prevention strategies for CTS in the construction industry.