Knee pain in nursing home workers after implementation of a safe resident handling program.

PURPOSE: Approximately 25-30% of nursing personnel experience knee pain (KP). We sought to identify physical and psychosocial work exposures, and personal factors related to prevalent, incident, and persistent KP 5-8 years after safe resident handing program (SRHP) implementation in nursing homes. METHODS: Health and exposure information was obtained from worker surveys 5-6 years ("F5") and 7-8 years ("F6") post-SRHP implementation. Prevalent KP correlates were examined at F5; persistent and incident KP predictors were analyzed at F6, utilizing robust Poisson multivariable regression. RESULTS: F5 KP prevalence (19.7%) was associated with combined physical exposures, and with either high job strain or low social support, in separate models. Two-year persistent KP was similarly associated with these psychosocial exposures. Being overweight was associated with KP in all analyses. CONCLUSIONS: The SRHP program did not eliminate knee physical loading, which should be reduced to prevent nursing home worker KP. Workplace psychosocial exposures (high job strain, low social support) also appeared germane.

Systematic review of quantitative imaging biomarkers for neck and shoulder musculoskeletal disorders.

BACKGROUND: This study systematically summarizes quantitative imaging biomarker research in non-traumatic neck and shoulder musculoskeletal disorders (MSDs). There were two research questions: 1) Are there quantitative imaging biomarkers associated with the presence of neck and shoulder MSDs?, 2) Are there quantitative imaging biomarkers associated with the severity of neck and shoulder MSDs? METHODS: PubMed and SCOPUS were used for the literature search. One hundred and twenty-five studies met primary inclusion criteria. Data were extracted from 49 sufficient quality studies. RESULTS: Most of the 125 studies were cross-sectional and utilized convenience samples of patients as both cases and controls. Only half controlled for potential confounders via exclusion or in the analysis. Approximately one-third reported response rates. In sufficient quality articles, 82% demonstrated at least one statistically significant association between the MSD(s) and biomarker(s) studied. The literature synthesis suggested that neck muscle size may be decreased in neck pain, and trapezius myalgia and neck/shoulder pain may be associated with reduced vascularity in the trapezius and reduced trapezius oxygen saturation at rest and in response to upper extremity tasks. Reduced vascularity in the supraspinatus tendon may also be a feature in rotator cuff tears. Five of eight studies showed an association between a quantitative imaging marker and MSD severity. CONCLUSIONS: Although research on quantitative imaging biomarkers is still in a nascent stage, some MSD biomarkers were identified. There are limitations in the articles examined, including possible selection bias and inattention to potentially confounding factors. Recommendations for future studies are provided.

Predictors of low back pain in nursing home workers after implementation of a safe resident handling programme.

OBJECTIVES: Healthcare workers have high rates of low back pain (LBP) related to handling patients. A large chain of nursing homes experienced reduced biomechanical load, compensation claims and costs following implementation of a safe resident handling programme (SRHP). The aim of this study was to examine whether LBP similarly declined and whether it was associated with relevant self-reported occupational exposures or personal health factors. METHODS: Worker surveys were conducted on multiple occasions beginning with the week of first SRHP introduction (baseline). In each survey, the outcome was LBP during the prior 3 months with at least mild severity during the past week. Robust Poisson multivariable regression models were constructed to examine correlates of LBP cross-sectionally at 2 years (F3) and longitudinally at 5-6 years (F5) post-SRHP implementation among workers also in at least one prior survey. RESULTS: LBP prevalence declined minimally between baseline and F3. The prevalence was 37% at F3 and cumulative incidence to F5 was 22%. LBP prevalence at F3 was positively associated with combined physical exposures, psychological job demands and prior back injury, while frequent lift device usage and 'intense' aerobic exercise frequency were protective. At F5, the multivariable model included frequent lift usage at F3 (relative risk (RR) 0.39 (0.18 to 0.84)) and F5 work-family imbalance (RR=1.82 (1.12 to 2.98)). CONCLUSIONS: In this observational study, resident lifting device usage predicted reduced LBP in nursing home workers. Other physical and psychosocial demands of nursing home work also contributed, while frequent intense aerobic exercise appeared to reduce LBP risk.

Systematic review of biochemical biomarkers for neck and upper-extremity musculoskeletal disorders.

OBJECTIVE: This study systematically summarizes biochemical biomarker research in non-traumatic musculoskeletal disorders (MSD). Two research questions guided the review: (i) Are there biochemical markers associated with neck and upper-extremity MSD? and (ii) Are there biochemical markers associated with the severity of neck and upper-extremity MSD? METHODS: A literature search was conducted in PubMed and SCOPUS, and 87 studies met primary inclusion criteria. Following a quality screen, data were extracted from 44 articles of sufficient quality. RESULTS: Most of the 87 studies were cross-sectional and utilized convenience samples of patients as both cases and controls. A response rate was explicitly stated in only 11 (13%) studies. Less than half of the studies controlled for potential confounding through restriction or in the analysis. Most sufficient-quality studies were conducted in older populations (mean age in one or more analysis group >50 years). In sufficient-quality articles, 82% demonstrated at least one statistically significant association between the MSD and biomarker(s) studied. Evidence suggested that: (i) the collagen-repair marker TIMP-1 is decreased in fibro proliferative disorders, (ii) 5-HT (serotonin) is increased in trapezius myalgia, and (iii) triglycerides are increased in a variety of MSD. Only 5 studies showed an association between a biochemical marker and MSD severity. CONCLUSION: While some MSD biomarkers were identified, limitations in the articles examined included possible selection bias, confounding, spectrum effect (potentially heterogeneous biomarker associations in populations according to symptom severity or duration), and insufficient attention to comorbid conditions. A list of recommendations for future studies is provided.

Mobile input device type, texting style and screen size influence upper extremity and trapezius muscle activity, and cervical posture while texting.

This study aimed to determine the effects of input device type, texting style, and screen size on upper extremity and trapezius muscle activity and cervical posture during a short texting task in college students. Users of a physical keypad produced greater thumb, finger flexor, and wrist extensor muscle activity than when texting with a touch screen device of similar dimensions. Texting on either device produced greater wrist extensor muscle activity when texting with 1 hand/thumb compared with both hands/thumbs. As touch screen size increased, more participants held the device on their lap, and chose to use both thumbs less. There was also a trend for greater finger flexor, wrist extensor, and trapezius muscle activity as touch screen size increased, and for greater cervical flexion, although mean differences for cervical flexion were small. Future research can help inform whether the ergonomic stressors observed during texting are associated with musculoskeletal disorder risk.

A validity study of self-reported daily texting frequency, cell phone characteristics, and texting styles among young adults.

BACKGROUND: Texting is associated with adverse health effects including musculoskeletal disorders, sleep disturbances, and traffic crashes. Many studies have relied on self-reported texting frequency, yet the validity of self-reports is unknown. Our objective was to provide some of the first data on the validity of self-reported texting frequency, cell phone characteristics including input device (e.g. touchscreen), key configuration (e.g., QWERTY), and texting styles including phone orientation (e.g., horizontal) and hands holding the phone while texting. METHODS: Data were collected using a self-administered questionnaire and observation of a texting task among college students ages 18 to 24. To gauge agreement between self-reported and phone bill-derived categorical number of daily text messages sent, we calculated percent of agreement, Spearman correlation coefficient, and a linear weighted kappa statistic. For agreement between self-reported and observed cell phone characteristics and texting styles we calculated percentages of agreement. We used chi-square tests to detect significant differences (α = 0.05) by gender and study protocol. RESULTS: There were 106 participants; 87 of which had complete data for texting frequency analyses. Among these 87, there was 26% (95% CI: 21-31) agreement between self-reported and phone bill-derived number of daily text messages sent with a Spearman's rho of 0.48 and a weighted kappa of 0.17 (95% CI: 0.06-0.27). Among those who did not accurately report the number of daily texts sent, 81% overestimated this number. Among the full sample (n = 106), there was high agreement between self-reported and observed texting input device (96%, 95% CI: 91-99), key configuration (89%, 95% CI: 81-94), and phone orientation while texting (93%, 95% CI: 86-97). No differences were found by gender or study protocol among any items. CONCLUSIONS: While young adults correctly reported their cell phone's characteristics and phone orientation while texting, most incorrectly estimated the number of daily text messages they sent. This suggests that while self-reported texting frequency may be useful for studies where relative ordering is adequate, it should not be used in epidemiologic studies to identify a risk threshold. For these studies, it is recommended that a less biased measure, such as a cell phone bill, be utilized.

Serum and MRI biomarkers in mobile device texting: a pilot study.

OBJECTIVE: We aimed to determine if serum biochemical and MRI biomarkers differed between high volume (> or =230 texts sent/day; n = 5) and low volume (< or =25 texts sent/day; n = 5) texters. A secondary aim was to ascertain what correlations between the biochemical and imaging biomarkers could tell us about the pathophysiology of early onset tendinopathies. BACKGROUND: Text messaging has become widespread, particularly among college-aged young adults. There is concern that high rates of texting may result in musculoskeletal disorders, including tendinopathies. Pathophysiology of tendinopathies is largely unknown. METHOD: Ten females with a mean age of 20 were recruited. We examined serum for 20 biomarkers of inflammation, tissue degeneration, and repair. We used conventional MRI and MRI mean intratendinous signal intensity (MISI) to assess thumb tendons. Correlations between MISI and serum biomarkers were also examined. RESULTS: Three high volume texters had MRI tendinopathy findings as did one low volume texter. Increased serum TNF-RI was found in high volume texters compared to low volume texters, as were nonsignificant increases in MISI in two thumb tendons. Serum TNF-RI and TNF-alpha correlated with MISI in these tendons, as did ILI-RI. CONCLUSION: These results suggest that early onset tendinopathy with concurrent inflammation may be occurring in prolific texters. Further studies with larger sample sizes are needed for confirmation. Application: High volume texting may be a risk factor for thumb tendinopathy in later years. Multidisciplinary research using biochemical and imaging biomarkers may be used to gain insight into pathophysiological processes in musculoskeletal disorders.

Sonographically guided percutaneous needle release of the carpal tunnel for treatment of carpal tunnel syndrome: preliminary report.

OBJECTIVES: The purpose of this study was to evaluate the effectiveness of a novel treatment procedure, sonographically guided percutaneous needle release of the carpal tunnel, for individuals with carpal tunnel syndrome. METHODS: Seventeen patients (89% female; mean age, 62 years; SD, 13.6 years) with a clinical diagnosis of carpal tunnel syndrome who had undergone a sonographically guided percutaneous needle release of the carpal tunnel at least 6 months before follow-up evaluation were retrospectively reviewed. At the follow-up evaluation, to ascertain previous and current symptoms as well as functional impairment, the patients filled out a hand diagram and a questionnaire. In addition, medical records were reviewed, and patients were queried regarding complications such as infection or nerve damage. Median nerve sonographic measurements and a physical evaluation were performed on a subset of 13 patients who came to the office for evaluation. RESULTS: Postprocedure sonography showed that patients had a significantly smaller (P = .03) cross-sectional area of the median nerve compared to pretreatment values. In addition, patients had significantly fewer symptoms (P < .0001), less functional impairment (P = .0002), and an improved hand diagram score (P < .0001). Postprocedure patients had grip strength that was 12 lb below average (≈1 SD below) compared to grip strength norms. However, most patients (84.6%) had negative clinical diagnostic test results for carpal tunnel syndrome, and 86% said they were satisfied with the procedure. There were no procedure-related infections or nerve injuries. CONCLUSIONS: Of the patients with carpal tunnel syndrome who agreed to participate in this study, most had favorable symptomatic and functional outcomes. Sonographically guided percutaneous needle release of the carpal tunnel may be an alternative option to traditional surgical treatment of carpal tunnel syndrome.

Physical and psychosocial ergonomic risk factors for low back pain in automobile manufacturing workers.

OBJECTIVES: To examine the association between ergonomic physical and psychosocial exposures and the risk of prevalent and incident low back pain (LBP) in a longitudinal cohort of automobile manufacturing workers. METHODS: Ergonomic exposure intensity and LBP presence were determined through questionnaires at baseline (n=1181) and to workers in the same job 1 year later (n=505). Models were constructed using log-binomial regression with special attention to interactions between ergonomic exposures. RESULTS: Awkward back posture (prevalence ratio (PR) 1.12, 95% CI 1.07 to 1.17), hand force (PR 1.06, 95% CI 1.02 to 1.10), physical effort (PR 1.10, 95% CI 1.04 to 1.16) and whole body vibration (PR 1.04, 95% CI 1.01 to 1.08) were each associated cross-sectionally with LBP. Awkward back posture (RR 1.13, 95% CI 0.98 to 1.31) and hand force (RR 1.07, 95% CI 0.93 to 1.22) also predicted incident LBP, although estimates were statistically less precise. Neither job control, psychological demands, nor job strain was independently related to risk of incident LBP. Among participants reporting high physical ergonomic exposures and moderate to high job control, increasing job demands was associated with a reduced LBP risk (RR 0.72, 95% CI 0.52 to 1.00). Among participants reporting high physical exposures and low job control, psychological demands was associated with an increased LBP risk (RR 1.30, 95% CI 1.02 to 1.66). CONCLUSIONS: Psychosocial workplace interventions for LBP should prioritise jobs in which there are high physical ergonomic exposures. Future studies of LBP should examine the interactions between physical ergonomic risk factors.

Cluster analysis of symptoms among patients with upper extremity musculoskeletal disorders.

INTRODUCTION: Some musculoskeletal disorders of the upper extremity are not readily classified. The study objective was to determine if there were symptom patterns in self-identified repetitive strain injury (RSI) patients. METHODS: Members (n = 700) of the Dutch RSI Patients Association filled out a detailed symptom questionnaire. Factor analysis followed by cluster analysis grouped correlated symptoms. RESULTS: Eight clusters, based largely on symptom severity and quality were formulated. All but one cluster showed diffuse symptoms; the exception was characterized by bilateral symptoms of stiffness and aching pain in the shoulder/neck. CONCLUSIONS: Case definitions which localize upper extremity musculoskeletal disorders to a specific anatomical area may be incomplete. Future clustering studies should rely on both signs and symptoms. Data could be collected from health care providers prospectively to determine the possible prognostic value of the identified clusters with respect to natural history, chronicity, and return to work.

Skin temperature in the dorsal hand of office workers and severity of upper extremity musculoskeletal disorders.

OBJECTIVE: This study aimed to examine the suitability of using mean dorsal (hand) skin temperature (MDT) before and after a short typing task as an indicator of upper extremity musculoskeletal disorder (UEMSD) severity. In addition, MDT reproducibility in controls was assessed for a pre-typing and three post-typing time periods over three trials. METHODS: Asymptomatic office workers (n = 10) and office workers with distal UEMSD symptoms (n = 35) typed for 9 min at three ambient temperatures (18, 22, and 26 degrees C). Pre- and post-trial MDT was measured by infrared thermography. UEMSD severity was defined anamnestically by symptoms and by a physical examination and symptom-derived case definition. RESULTS: Good to excellent reproducibility (intra-class correlation coefficients = 0.46-0.85) for MDT was found in controls at 22 degrees C. At 18 and 22 degrees C, pre-typing MDT differed between controls and cases by number of symptom sites marked on a hand-arm diagram (ANOVA, P

Specific and non-specific upper extremity musculoskeletal disorder syndromes in automobile manufacturing workers.

OBJECTIVE: A longitudinal cohort of automobile manufacturing workers (n = 1,214) was examined for: (1) prevalence and persistence of specific upper extremity musculoskeletal disorders (UEMSDs) such as lateral epicondylitis and de Quervain's disease, and non-specific disorders (NSDs) defined in symptomatic individuals without any specific disorder, and (2) disorder prognoses based on symptom characteristics and other factors. METHODS: Eight specific disorders were identified through case definitions based on upper extremity physical examinations and symptom surveys administered on three occasions over 6 years. RESULTS: At baseline, 41% of the cohort reported upper extremity symptoms; 18% (n = 214) of these had NSDs. In each survey, tendon-related conditions accounted for over half of the specific morbidity. Twenty-five percent had UEMSDs in multiple anatomical sites, and most with hand/wrist disorders had two or more hand/wrist UEMSDs. Persistence for all specific disorders decreased with length of follow-up. Specific UEMSDs were characterized by greater pain severity and functional impairment, and more lost work days than NSDs. CONCLUSIONS: Upper extremity symptoms and diagnoses vary over time. NSDs may be the early stages of conditions that will eventually become more specific. NSDs and overlapping specific UEMSDs should be taken into account in UEMSD classification. Am. J. Ind. Med. 52:124-132, 2009. (c) 2008 Wiley-Liss, Inc.

Subjective ratings of upper extremity exposures: inter-method agreement with direct measurement of exposures.

This study examined the agreement of subjective ratings of upper extremity exposures with corresponding direct measurements obtained simultaneously from workers. Psychophysical ratings of exposure, based on the Borg CR-10 scale, were obtained for the period of time in which direct measurements were acquired using electrogoniometers (wrist), electroinclinometers (shoulder) and electromyography (grip force). Subjects were selected from workers at two automobile manufacturing plants. Significant relationships between subjective ratings of wrist position and measured wrist posture or motion and between ratings of shoulder position and measured shoulder posture were not found. Ratings of manual effort were significantly correlated with directly measured grip force (% maximum voluntary contraction). Ratings of pace were significantly correlated with directly measured wrist motion and this relationship was strengthened with the addition of relative grip force as a covariate. Workers with hand/wrist symptoms provided ratings that were more strongly related to the directly measured exposures than those without symptoms. Self-report by workers is an alternative to more resource-intensive and invasive exposure assessment methods. However, the validity of workers' self-reported exposure assessments has been questioned. The objective of this study was to examine the agreement of selected questionnaire items with corresponding direct measurements from bioinstrumentation and to provide a better understanding of worker self-reports.

JCQ scale reliability and responsiveness to changes in manufacturing process.

BACKGROUND: The job content questionnaire (JCQ) was administered to automobile manufacturing workers in two interviews, 5 years apart. Between the two interviews, the company introduced substantial changes in production technology in some production areas. The aims were: (1) to describe the impact of these changes on self-reported psychosocial exposures, and (2) to examine test-retest reliability of the JCQ scales, taking into account changes in job assignment and, for a subset of workers, physical ergonomic exposures as assessed through field observations. METHODS: The study population included 790 subjects at the first and 519 at the second interview, of whom 387 were present in both. Differences in demand and control scores between interviews were analyzed by Wilcoxon matched-pairs signed-rank test. Test-retest reliability of these scales was evaluated by the intraclass correlation coefficient (ICC) and the Spearman's rho coefficient. RESULTS: The introduction of more automated technology produced an overall increase in job control but did not decrease psychological demand. The reliability of the control scale was low overall but increased to an acceptable level among workers who had not changed job. The demand scale had high reliability only among workers whose physical ergonomic exposures were similar on both survey occasions. CONCLUSIONS: These results show that 5-year test-retest reliability of self-reported psychosocial exposures is adequate among workers whose job assignment and ergonomic exposures have remained stable over time.

Medium- and long-term reproducibility of self-reported exposure to physical ergonomics factors at work.

INTRODUCTION: The literature is sparse on reproducibility of self-reported exposure to physical ergonomics risk factors for musculoskeletal disorders (MSDs). Aims of this study were to evaluate, in a cohort of workers interviewed up to three times: 1-year test-retest reliability; and 5- and 6-year recall of physical exposures. We also examined whether reproducibility was influenced by the presence of UE MSD or by technological changes introduced between the last two surveys. METHODS: A cohort of automobile manufacturing employees was interviewed at baseline, one and six years later about work history, physical and psychosocial exposures at work, upper limb symptoms, injury and medical history, and demographics. Agreement between interviews was evaluated by intraclass correlation and Spearman coefficients. Differences in exposure between 1- and 6-year follow-up were analyzed by Wilcoxon matched-pairs signed-ranks test. RESULTS: Large and significant decreases in work pace and physical effort were observed from baseline, although an upper extremity composite index was quite stable in the total population. One-year test-retest reliability was fair to good for the composite exposure index (ICC=0.58), whole-body vibration, handling parts, and tool use, but poor for the other variables considered. Long-term reproducibility, from baseline or 1-year follow-up to 6-year follow-up, was poor for the composite index and almost all single items. UE MSD case status influenced 1-year test-retest reliability, with subjects who changed case status from baseline displaying higher reliability, but not reproducibility of recalled exposures. A strong regression to the mean effect was observed on exposures reported at follow-up surveys. CONCLUSIONS: Recalled ergonomics exposures could be employed in retrospective cohort studies as a somewhat reliable and unbiased estimate of the self-reported exposures that would have been obtained up to one year earlier, but not over a longer period (5-6 years). These longer-term results may have been limited by difficulty in matching jobs between interviews; also the regression to the mean effect likely contributed to reduce agreement. Changes in production technology and work organization produced a decrease in physical workload intensity and job pace, but did not have a substantial impact on an exposure index for the upper limb.

Recall of prior musculoskeletal pain.

OBJECTIVES: Patients, as well as healthy people, often fail to remember prior symptoms, illnesses, or treatments. The authors investigated how well people in a workplace recalled their prior musculoskeletal pain and which factors influenced recall accuracy. METHODS: In this prospective study (1992-1998), among a cohort of automobile manufacturing workers (N=464), musculoskeletal pain reported at baseline was compared with recalled pain at follow-up. Two outcomes (ie, forgetting and over-recalling) were examined in relation to several personal and occupational characteristics. RESULTS: Of those who had experienced pain or discomfort in the upper extremities at baseline, 72% did not recall it 6 years later. Symptoms at the time of recall strongly influenced pain recall; forgetting approached 100% among those with no current or recent symptoms. However, forgetting was considerable even among those with current symptoms (45%). Prior pain status was over-recalled by 37% of those with upper-extremity pain at the time of recall, but only by 3% of those without symptoms. Women, those with history of an upper-extremity disorder or systemic disease, who were clinical cases or had more anatomical areas in pain at baseline forgot less often. Over-recalling was related to age, having current symptoms, or being a clinical case. The results were similar for low-back and knee pain. CONCLUSIONS: Prior musculoskeletal symptoms are poorly remembered after some years, and the recall is strongly influenced by current symptoms. Recalled information should not be relied upon when an epidemiologic case definition is being constructed or when an attempt is being made to describe the natural history of a disorder.

Work routinization and implications for ergonomic exposure assessment.

Jobs in many modern settings, including manufacturing, service, agriculture and construction, are variable in their content and timing. This prompts the need for exposure assessment methods that do not assume regular work cycles. A scheme is presented for classifying levels of routinization to inform development of an appropriate exposure assessment strategy for a given occupational setting. Five levels of routinization have been defined based on the tasks of which the job is composed: 1) a single scheduled task with a regular work cycle; 2) multiple cyclical tasks; 3) a mix of cyclical and non-cyclical tasks; 4) one non-cyclical task; 5) multiple non-cyclical tasks. This classification, based primarily on job observation, is illustrated through data from a study of automobile manufacturing workers (n = 1200), from which self-assessed exposures to physical and psychosocial stressors were also obtained. In this cohort, decision latitude was greater with higher routinization level (p < 0.0001), and the least routinized jobs showed the lowest self-reported exposure to physical ergonomic stressors. The job analysis checklist developed for non-routinized jobs is presented, and limitations of the task analysis method utilized in the study are discussed. A work sampling approach to job analysis is recommended as the most efficient way to obtain a comparable unbiased exposure estimate across all routinization levels.

Pressure pain thresholds and musculoskeletal morbidity in automobile manufacturing workers.

OBJECTIVES: Reduced pressure pain thresholds (PPTs) have been reported in occupational groups with symptoms of upper extremity musculoskeletal disorders (UEMSDs). The purpose of this study was to determine whether automobile manufacturing workers (n=460) with signs and symptoms of UEMSDs had reduced PPTs (greater sensitivity to pain through pressure applied to the skin) when compared with unaffected members of the cohort, which served as the reference group. The association of PPTs with symptom severity and localization of PE findings was investigated, as was the hypothesis that reduced thresholds would be found on the affected side in those with unilateral physical examination (PE) findings. METHODS: PPTs were measured during the workday at 12 upper extremity sites. A PE for signs of UEMSDs and symptom questionnaire was administered. After comparison of potential covariates using t tests, linear regression multivariable models were constructed with the average of 12 sites (avgPPT) as the outcome. RESULTS: Subjects with PE findings and/or symptoms had a statistically significant lower avgPPT than non-cases. AvgPPT was reduced in those with more widespread PE findings and in those with greater symptom severity (test for trend, P

Infrared thermography for examination of skin temperature in the dorsal hand of office workers.

Reduced blood flow may contribute to the pathophysiology of upper extremity musculoskeletal disorders (UEMSD), such as tendinitis and carpal tunnel syndrome. The study objective was to characterize potential differences in cutaneous temperature, among three groups of office workers assessed by dynamic thermography following a 9-min typing challenge: those with UEMSD, with ( n=6) or without ( n=10) cold hands exacerbated by keyboard use, and control subjects ( n=12). Temperature images of the metacarpal region of the dorsal hand were obtained 1 min before typing, and during three 2-min sample periods [0-2 min (early), 3-5 min (middle), and 8-10 min (late)] after typing. Mean temperature increased from baseline levels immediately after typing by a similar magnitude, 0.7 (0.3) degrees C in controls and 0.6 (0.2) degrees C in UEMSD cases without cold hands, but only by 0.1 (0.3) degrees C in those with cold hands. Using paired t-tests for within group comparisons of mean dorsal temperature between successive imaging periods, three patterns of temperature change were apparent during 10 min following typing. Controls further increased mean temperature by 0.1 degrees C ( t-test, P=0.001) at 3-5 min post-typing before a late temperature decline of -0.3 degrees C ( t-test, P=0.04), while cases without cold hands showed no change from initial post-typing mean temperature rise during middle or late periods. In contrast, subjects with keyboard-induced cold hands had no change from initial post-typing temperature until a decrease at the late period of -0.3 degrees C ( t-test, P=0.06). Infrared thermography appears to distinguish between the three groups of subjects, with keyboard-induced cold hand symptoms presumably due, at least partially, to reduced blood flow.