Carpal tunnel syndrome and occupation in U.S. Navy enlisted personnel

An Integrated Review of Carpal Tunnel Syndrome: New Insights to an Old Problem

Carpal tunnel syndrome (CTS) is a common entrapment neuropathy characterized by pain, numbness, and impaired function of the hand due to compression of the median nerve at the level of the wrist. Although CTS can develop from repetitive strain, injury, or medical conditions, there are also congenital and genetic risk factors that can predispose individuals to the condition. With respect to anatomical factors, some individuals are born with a smaller carpal tunnel, which increases their susceptibility to median nerve compression. Variations in specific genes, such as those encoding proteins involved in extracellular matrix remodeling, inflammation, and nerve function, have also been linked to an increased risk for CTS. CTS is associated with a high cost of health care maintenance and loss of work productivity. Therefore, it is vital that primary care physicians fully understand the anatomy, epidemiology, pathophysiology, etiology, and risk factors of CTS, so they can be proactive in prevention, diagnosing, and guiding proper treatment. This integrated review also provides insights into how biological, genetic, environmental, and occupational factors interact with structural elements to determine who is most likely to acquire and suffer from CTS. Keeping health practitioners abreast of all the factors that could impact CTS should go a long way in decreasing the health care and socioeconomic burden of CTS.

How to Differentiate Pronator Syndrome from Carpal Tunnel Syndrome: A Comprehensive Clinical Comparison

The diagnostic process that allows pronator syndrome to be differentiated reliably from carpal tunnel syndrome remains a challenge for clinicians, as evidenced by the most common cause of pronator syndrome misdiagnosis: carpal tunnel syndrome. Pronator syndrome can be caused by compression of the median nerve as it passes through the anatomical structures of the forearm, while carpal tunnel syndrome refers to one particular topographic area within which compression occurs, the carpal tunnel. The present narrative review is a complex clinical comparison of the two syndromes with their anatomical backgrounds involving topographical relationships, morphology, clinical picture, differential diagnosis, and therapeutic options. It discusses the most frequently used diagnostic techniques and their correct interpretations. Its main goal is to provide an up-to-date picture of the current understanding of the disease processes and their etiologies, to establish an appropriate diagnosis, and introduce relevant treatment benefiting the patient.

Patterns of Involvement of Digits in Patients with Multiple Trigger Digits: A Retrospective Study

Background: The involvement of digits in patients with multiple trigger digits often displays specific patterns. We aimed to determine the patterns of involvement of digits in multiple trigger digits and their association with patient-related factors and compare them to those of patients with a single trigger digit. Methods: All patients with trigger digits treated over a 2-year period were retrospectively examined in June 2020. Data regarding the age at occurrence of initial trigger digit, sex, occupation, presence of diabetes mellitus, carpal tunnel syndrome and de Quervain disease, and hand dominance was determined. The data obtained from patients with multiple trigger digits was compared with those with a single trigger digit. Additionally, we investigated the patterns of involvement of the first two affected digits in patients with multiple trigger digits and their association with patient-related factors and compared them to those in patients with a single trigger digit. Results: Three hundred and eighty-seven and 577 patients with multiple and single trigger digits, respectively, were studied. Their median age was 60 (range: 17-92) years. The incidence of concomitant diabetes mellitus was 150% higher in patients with multiple trigger digits than in those with a single trigger digit. Symmetric occurrence and adjacent occurrence patterns were observed in 42.4 % and 28.4% of the 387 patients, respectively. Initial onset in the fifth and sixth decades of life, female sex and a time lag between occurrences were significantly associated with symmetric occurrence. Male sex and simultaneous occurrence in two digits were significantly associated with adjacent occurrence. Diabetes mellitus was not associated with each occurrence pattern. Conclusions: We have confirmed the presence of two involvement patterns in patients with multiple trigger digits: symmetric and adjacent. Our data will help in the prevention, early detection and management of multiple trigger digits. Level of Evidence: Level III (Therapeutic).

Identification of Clinical and Demographic Predictors for Treatment Modality in Patients With Carpal Tunnel Syndrome

BACKGROUND

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy. There are multiple treatment modalities for CTS. This study examines both clinical and demographic predictors for initial treatment modality of CTS.

METHODS

Patients diagnosed with CTS between February 2015 and October 2020 with a hand clinic visit within 6 weeks before treatment were included in our study. Patients completed Patient-Reported Outcomes Measurement Information System Pain Interference, Physical Function, and Depression and had complete data on relevant predictor variables. Primary outcomes were treatment group: (1) injection only; (2) release only; and (3) injection followed by release. Bivariate analyses and multinomial logistic regression was used to identify statistically significant variables and independent predictors associated with the treatment groups, respectively.

RESULTS

A total of 1409 patients fit our inclusion criteria. Sex, age, body mass index (BMI), race, ethnicity, Pain Interference, and Depression were statistically significant predictors for treatment group in bivariate analysis (P < .05). In multivariable analysis, adults older than 65 years were less likely to receive either injection only or injection followed by release (odds ratio [OR]: 0.56 and OR: 0.52, respectively; P < .01). Overweight (BMI: ≥25) individuals were less likely to receive injection only (OR: 0.45; P < .01). Women were more likely to have either injection only or injection followed by released (OR: 1.50 and 1.55; P < .01). Similarly, black, Indigenous, or Persons of Color had an increased odds of injection only and injection followed by release (OR: 1.61 and OR: 1.69, respectively; P < .05).

CONCLUSIONS

Sex, age, BMI, race, and ethnicity were found to be independent predictors of treatment modality for CTS.

Musculoskeletal Injuries Among Females in the Military: A Scoping Review

INTRODUCTION

Musculoskeletal injuries (MSKi) are a common challenge for those in military careers. Compared to their male peers, reports indicate that female military members and recruits are at greater risk of suffering MSKi during training and deployment. The objectives of this study were to identify the types and causes of MSKi among female military personnel and to explore the various risk factors associated with MSKi.

MATERIALS AND METHODS

A scoping review was conducted over a 4-month time frame of English language, peer-reviewed studies published from 1946 to 2019. Search strategies for major biomedical databases (e.g., MEDLINE; Embase Classic + Embase; and the following EBM Reviews-Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Health Technology Assessment, and the NHS Economic Evaluation Database) were developed by a senior medical information specialist and included 2,891 titles/abstracts. Study selection and data collection were designed according to the Population, Concept, and Context framework. Studies were included if the study population provided stratified data for females in a military context.

RESULTS

From a total of 2,287 citations captured from the literature searches, 168 peer-reviewed publications (144 unique studies) were eligible for inclusion. Studies were identified from across 10 countries and published between 1977 and 2019. Study designs were primarily prospective and retrospective cohorts. Most studies assessed both prevalence/incidence and risk factors for MSKi (62.50%), with few studies assessing cause (13.69%). For MSKi of female recruits compared to active female members, the prevalence was higher (19.7%-58.3% vs. 5.5%-56.6%), but the incidence (0.02%-57.7% vs. 13.5%-71.9%) was lower. The incidence of stress fractures was found to be much higher in female recruits than in active members (1.6%-23.9% vs. 2.7%). For anthropometric risk factors, increased body fat was a predictor of MSKi, but not stress fractures. For physiological risk factors for both female military groups, being less physically fit, later menarche, and having no/irregular menses were predictors of MSKi and stress fractures. For biomechanical risk factors, among female recruits, longer tibial length and femoral neck diameter increased the risk of stress fractures, and low foot arch increased risk of an ankle sprain. For female active military members, differences in shoulder rotation and bone strength were associated with risk of MSKi. For biological sex, being female compared to male was associated with an increased risk of MSKi, stress fractures, and general injuries. The consequences of experiencing MSKi for active military included limited duties, time off, and discharge. For recruits, these included missed training days, limited duty days, and release.

CONCLUSIONS

This scoping review provides insight into the current state of the evidence regarding the types and causes of MSKi, as well as the factors that influence MSKi among females in the military. Future research endeavors should focus on randomized controlled trials examining training paradigms to see if women are more susceptible. The data presented in the scoping review could potentially be used to develop training strategies to mitigate some of the identified barriers that negatively impact women from pursuing careers in the military.

Carpal Tunnel Syndrome in Military Aviators

INTRODUCTION

The incidence of carpal tunnel syndrome (CTS) is increased in occupations exposed to repetitive motion, poor wrist posture, and vibration exposure. While all pilots are exposed to these factors, helicopter pilots are especially exposed to vibration. The study is to identify the incidence and risk factors for CTS in military aviators.

MATERIALS AND METHODS

Clearance was obtained from Tripler Army Medical Center IRB. The Defense Medical Epidemiological Database was queried for all new cases of CTS from 2006 to 2015. Incidence rates (IRs) were determined for helicopter pilots, fixed-wing pilots, and nonpilot officers. Poisson regression analysis was used to calculate adjusted IR in order to control for demographic factors. Race was also taken into account, where pilots would classify themselves into a white or non-white race, defined by each individual. Race was assessed in the study to see if there were any differences in IR of CTS between white and non-white pilots.

RESULTS

We identified 7,398 new cases of CTS among 2,319,352 person-years within the study period. Increasing age, female gender, and non-white race were significantly correlated with higher IR. Fixed-wing pilots demonstrated significantly lower adjusted IR than nonpilot officers in each age group. Helicopter pilots demonstrated higher IR than fixed-wing pilots in each age group. Helicopter pilots had lower incidence of CTS early in their career compared to nonpilot officers, but by age 40+, their IR ratio was significantly higher (1.21).

CONCLUSION

Analysis of the database indicates that fixed-wing pilot status is a protective factor against development of CTS among U.S. military officers. In contrast, helicopter pilots were found to be at an increased rate of CTS than their fixed-wing counterparts. Their incidence is comparable to their nonpilot officer peers early in their career, but is significantly increased at the senior level. Increasing age and female gender are risk factors in the military officer population as expected. Non-white race was found to increase risk in the military population, in contrast to reports of the civilian population.

Cubital tunnel syndrome in Noonan syndrome secondary to hypoplasia of the humeral trochlea

This report describes the case of a 45-year-old woman with Noonan syndrome who developed cubital tunnel syndrome secondary to hypoplasia of the humeral trochlea. Cubital tunnel syndrome, the second-most common peripheral compression neuropathy, is caused by compression of the ulnar nerve at the elbow. Noonan syndrome, an autosomal dominant multisystem disorder, is characterized by variable cognitive deficit and skeletal, ectodermal and hematologic anomalies. Results show three distinctive anatomical features such as (1) hypoplasia of the humeral trochlea and medial epicondyle, (2) absence of the medial intermuscular septum and (3) lack of Osborn's ligament.

Incidence of Cubital Tunnel Syndrome in the U.S. Military Population

PURPOSE

Cubital tunnel syndrome (CuTS) is the second most common peripheral nerve entrapment syndrome. However, existing epidemiological evidence regarding the estimated incidence of the CuTS disease burden in specific populations is sparse, especially among the U.S. military. The purpose of this study was to describe the demographics and determine the incidence of CuTS among active duty U.S. military service members.

METHODS

All first-time occurrences for CuTS among military members were identified using International Classification of Diseases, Ninth Revision, clinical modification code 354.2 for ulnar nerve lesions in the U.S. Defense Medical Epidemiology Database. A multivariable Poisson regression analysis was used to estimate the incidence rate ratio (IRR) per 1,000 person-years and 95% confidence intervals (95% CI), while controlling for sex, race, age, rank, and service. Rate-ratios were calculated using different referent factors based on differences in sex, race, age, rank, and service branch.

RESULTS

During the 10-year study period, the total number of incident cases of CuTS was 31,568, and a total of 13,745,456 person-years were documented. The overall unadjusted IRR of CuTS during the study period was 2.3 per 1,000 person-years (95% CI, 2.27-2.33). The 35- to 39-year age group had the highest adjusted IRR of CuTS. In addition, females, Caucasians, and junior enlisted service members showed significantly higher IRRs.

CONCLUSIONS

Our study was able to provide baseline epidemiological data on IRRs and influential risk factors in CuTS. We demonstrated an incidence of CuTS that is comparable with previously reported IRRs, which have varied from 0.08 to 8.0 cases per 1,000 person-years. This study also found significantly higher risk for the development of CuTS with increased age and among U.S. Army service members.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Physical ergonomic risk factors of carpal tunnel syndrome among rubber tappers

This study evaluated physical ergonomic risk factors associated with carpal tunnel syndrome (CTS) among rubber tappers in Thailand. The Boston Carpal Tunnel Syndrome Questionnaire and Phalen's test and Tinel's sign were used to identify 133 cases with CTS and 401 non-CTS controls. Video recordings and Rapid Upper Limb Assessment used to evaluate the level of ergonomic risk in right and left hand postures. Significant physical ergonomic risk factors of CTS were higher number of trees tapped at or below knee level and collecting latex. Among right-handed tappers, tapping at higher than chest level involved significantly higher proportion of right wrist flexion and/or extension, and left wrist radial and/or ulnar deviation and twist than tapping at a lower level.

Importance of Recognizing Carpal Tunnel Syndrome for Neurosurgeons: A Review

Idiopathic carpal tunnel syndrome (CTS) is a common complaint, reflecting entrapment neuropathy of the upper extremity. CTS produces symptoms similar to those of other conditions, such as cervical spondylosis or ischemic or neoplastic intracranial disease. Because of these overlaps, patients with CTS are often referred to a neurosurgeon. Surgical treatment of CTS was started recently in our department. Through this experience, we realized that neurosurgeons should have an increased awareness of this condition so they can knowledgeably assess patients with a differential diagnosis that includes CTS and cervical spinal and cerebral disease. We conducted a literature review to gain the information needed to summarize current knowledge on the clinical, pathogenetic, and therapeutic aspects of CTS. Because the optimal diagnostic criteria for this disease are still undetermined, its diagnosis is based on the patient’s history and physical examination, which should be confirmed by nerve conduction studies and imaging modalities such as magnetic resonance imaging and ultrasonography. Treatment methods include observation, medication, splinting, steroid injections, and surgical intervention. Understanding the clinical features and pathogenesis of CTS, as well as the therapeutic options available to treat it, is important for neurosurgeons if they are to provide the correct management of patients with this disease.

Immediate and durable clinical improvement in the non-operated hand after contralateral surgery for patients with bilateral Carpal Tunnel Syndrome

BACKGROUND

Little is known about clinical improvement in the non-operated hand after unilateral surgery for patients who present with bilateral carpal tunnel syndrome (CTS). In this prospective study of patients with bilateral CTS, we evaluated the clinical effects on the non-operated hand following unilateral contralateral carpal tunnel surgical release.

MATERIAL AND METHODS

During a consecutive period of 22 months, 69 patients with bilateral CTS underwent unilateral open carpal tunnel release. Bilateral subjective and objective evaluations were performed pre-operatively, at days 2, 15 and 180 after surgery. Subjective evaluations, analysed with Student t test, included the Boston-Levine symptom severity score and a visual analogue scale including pain, nocturnal symptoms and numbness. A telephone survey was conducted 12 months after surgery.

RESULTS

The Boston-Levine severity score of the contralateral non-operated hand decreased from 2.70 pre-operatively to 1.70 at 2 days (p < 0.001). The visual analogue pain score decreased at 2 days for 61 patients (88 %), whereas the nocturnal symptoms decreased or disappeared in 63 cases (91 %) and the paresthesia in 52 cases (75 %) (ps < 0.001). These beneficial effects were stable in time with no statistically significant change at 180 days. Overall, 58 patients (84 %) observed a total resolution or a significant improvement in their symptoms at 6 months. At 12 months, 100 % of patients responded to a telephone survey. Fifty one of them (74 %) reported minimal or no symptoms on the non-operated hand. Linear regression (analysis of variance [ANOVA]) showed that gender, age, professional status, duration of pre-operative symptoms and severity of electrophysiological disturbances were not predictive of post-operative evolution in the non-operated hand after unilateral surgery for CTS.

Carpal tunnel syndrome and its relationship to occupation: a meta-analysis

OBJECTIVE

To examine the association between work place exposure and CTS by meta-analysis, including analyses with respect to exposure to hand force, repetition, vibration and wrist posture.

METHODS

All relevant peer-reviewed articles published between January 1980 and December 2009 were identified by a systematic search using the MEDLINE, CINAHL and PubMed databases. Papers were critiqued independently by two researchers and the relevant exposure information was extracted. Using the raw data of exposed and unexposed cases, a cumulative effect of specific exposure risks were calculated for hand force, repetition, a combination of force and repetition, vibration and wrist posture using the statistical program, Stata version 11 (StataCorp, College Station, TX, USA). Heterogeneity, meta-regression, publication bias and subgroup sensitivity analyses were performed.

RESULTS

Thirty-seven studies from English-language literature met the inclusion criteria. Using National Institute for Occupational Health and Safety criteria for case definition, a significant positive association between CTS and hand force, repetition, use of vibratory tools and wrist posture was observed with approximate doubling of risk for all exposures. Significant heterogeneity among studies was observed for most exposures and metaregression analyses identified CTS case definition, study design, country and risk of bias score to be the significant determinants. When a more conservative definition of CTS was employed to include nerve conduction abnormality with symptoms and/or signs, risk factors significantly associated with an increased risk of CTS among exposed workers were: vibration [odds ratio (OR) 5.40; 95% CI 3.14, 9.31], hand force (OR 4.23; 95% CI 1.53, 11.68) and repetition (OR 2.26; 95% CI 1.73, 2.94). There was a non-significant trend for the association between CTS and combined exposure to both force and repetition (OR 1.85; 95% CI 0.99, 3.45) and wrist posture (OR 4.73; 95% CI 0.42, 53.32).

CONCLUSION

Occupational exposure to excess vibration, increased hand force and repetition increase the risk of developing CTS. Workplace strategies to avoid overexposure to these risk factors should be implemented.

Incidence of carpal tunnel syndrome in the US military population

Carpal tunnel syndrome (CTS) is a common disease. Its epidemiology has been evaluated previously, mostly in regional populations or in working groups, with an incidence between 1.5 and 3.5 per 1,000 person-years. We studied this diagnosis in the US military population, with the hypothesis that this young population would have a lower incidence of CTS than previously reported in general populations. The Defense Medical Epidemiology Database notes all medical encounters for all US military personnel and maintains the number of all personnel on active duty each year. We queried the database using the International Classification of Diseases, ninth revision, code 354.0 (CTS) and analyzed the personnel presenting for initial visits for the years 1998-2006. Multivariate Poisson analysis was performed, controlling for rank, gender, age, and race. The raw incidence of CTS in the US military was 3.98 per 1,000 person-years, in a population of 12,298,088 person-years. Females had a significantly higher incidence of CTS than males, with an adjusted incidence rate ratio of 3.29. CTS incidence increased by age, with the age group > or = 40 years having a significantly higher incidence. Additionally, military rank was found to be an independent risk factor for CTS, with rates higher in senior officer and enlisted groups. This suggests that occupational requirements have an effect on CTS within the military. We showed a comparable incidence of CTS between the US military and general population, with a significantly higher female cohort with a diagnosis of CTS. Increased age and advanced rank were risk factors for CTS.

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.

Trends and occupational associations in incidence of hospitalized pulmonary sarcoidosis and other lung diseases in Navy personnel: a 27-year historical prospective study, 1975-2001

STUDY OBJECTIVES

This study examines long-term trends in incidence rates of hospitalized pulmonary sarcoidosis in a large cohort of Navy personnel, and evaluates the possible relationship of sarcoidosis with occupation.

DESIGN

Incidence rates of first hospitalizations were determined for black and white male Navy enlisted personnel on active duty from 1975 to 2001.

SETTING

Navy service includes a potential for exposure to a variety of substances, including nonskid coatings used on ship decks that may be aerosolized during removal. Particulate matter containing aluminum, titanium, and silicates has been identified in nonskid samples. Specific occupational groups may have had greater exposure potential than others.

PATIENTS OR PARTICIPANTS

Hospitalized cases included sarcoidosis (n = 674), asthma (n = 3,536), emphysema and chronic bronchitis (n = 1,103), respiratory conditions due to fumes and vapors (n = 61), and pneumoconiosis (n = 51) observed in 9,953,607 person-years of active-duty service.

INTERVENTIONS

None. However, improvements were made in personal protective gear and other countermeasures to prevent or limit respiratory exposures during service.

MEASUREMENTS AND RESULTS

Annual overall hospitalized sarcoidosis incidence rates per 100,000 were 24.9 for black men and 3.5 for white men (black/white ratio of 7.1, p < 0.0001). Annual incidence rates in blacks declined markedly, particularly since 1989, but the black/white ratio remained high through 1999. Occupational associations were present in blacks and whites. Black ship's servicemen (23 cases) and aviation structural mechanics specializing in structures (12 cases) had more than twice the expected incidence rate compared to all blacks, and white mess management specialists (15 cases) had twice the overall white incidence rate.

CONCLUSIONS

There was a steep decline in incidence of hospitalized sarcoidosis in blacks in the Navy. Occupational associations suggest the possibility that a dust or moisture-related lung disease may have been erroneously classified as sarcoidosis, or, alternatively, that sarcoidosis had a previously unrecognized occupational component.

Work-related cumulative trauma disorders of the upper extremity: navigating the epidemiologic literature

BACKGROUND

Cumulative trauma disorder of the upper extremity (CTDUE) is an umbrella term used to describe disorders resulting from repeated use of the upper extremity over time rather than a specific incident. The primary purpose of this article is to summarize the literature regarding the rate of work-related CTDUE, while drawing attention to the various factors contributing to the wide range of reported findings.

METHODS

The Cumulative Index to Nursing and Allied Health and Medline databases were searched for articles focusing on etiology or rates of occurrence of work-related CTDUE and their findings were summarized.

RESULTS

Potential reasons for rising rates, a gender differential, and the substantial range in rates and rate ratios are delineated and important factors to consider when interpreting rates derived from workers' compensation data are detailed.

CONCLUSIONS

Future research should attempt to correctly identify more specific categories of CTDUE in well-defined and accurately-quantified "at risk" populations to provide more meaningful information regarding the epidemiology of CTDUE and the effectiveness of control activities.