Vibration-induced white finger syndrome and carpal tunnel syndrome among Finnish metal workers

Evaluation of the bio-dynamic response of the hand-arm system and hand-tool designs - A brief review

Hand-operated tools transmit a high magnitude of vibration exposure to the hand-arm system that causes occupational diseases. The health effects caused in various countries for the past years due to usage of hand tools are necessary to identify the occupational disorders. Researchers have conducted various studies on biological effects, hand-transmitted vibration exposure and biodynamic responses throughout the years. This article goes over each of these studies in detail, as well as identifying areas where more research is needed. The majority of studies deal with the following topics: general guidelines for hand-transmitted vibrations; assessment techniques of vibration exposure; hand-tool evaluation methods; influence of hand-tool design to overcome the biomechanical effects; and finite element modelling for quantifying vibration exposure. In response to this, understanding the biodynamic behaviour of the hand-arm system is useful for better ergonomic intervention in hand tools to reduce fatigue and increase comfort.

Carpal Tunnel Syndrome and Hand-Arm Vibration: A Swedish National Registry Case-Control Study

OBJECTIVE

To investigate the increased risk for carpal tunnel syndrome (CTS) in men and women with hand-arm vibration (HAV) exposure.

DESIGN

Case-control study of CTS where 4396 cases was obtained from National Outpatient Register between 2005 through 2016. Cases were matched to controls and exposure was estimated using a job exposure matrix.

RESULTS

Exposure to HAV increased the risk of CTS with an OR of 1.61 (95% CI 1.46-1.77). The risk was highest in men <30 years of age and among women <30 years no increased risk was observed. The risk increased with a mean year exposure above 2.5 m/s2 to OR 1.84 (95% CI 1.38-2.46).

CONCLUSIONS

HAV exposure increase the risk of CTS in both genders, with highest risk increase in younger men. This emphasize identification of HAV exposure in patients with CTS.

An Experimental Study on the Vibration Transmission Characteristics of Wrist Exposure to Hand Transmitted Vibration

This research intends to further improve the understanding of vibration damage mechanisms in the wrist area and to establish a more effective biodynamic model of the hand-arm system. Scholars have conducted some research work around the influencing factors of vibration response and commonly used vibration transmissibility to characterize the local vibration transmission characteristics of the hand-arm system. In this paper, a hand-transmitted vibration test platform was built according to ISO 10819, and a random combination of four ergonomic factors, namely wrist posture, arm posture, grip force, and thrust force, was used to test the vibration response of six subjects’ wrists; the total vibration transmissibility of the wrist was calculated according to the transmissibility formula. The effect of the four factors on the total vibration transmissibility of the wrist part was comprehensively analyzed, in which the wrist posture was proposed for the first time. The results show that (1) vibration transmissibility of the wrist is not only related to the arm posture, thrust force, and grip force but also related to the wrist posture; (2) the total vibration transmissibility and resonance frequency on the wrist has small correlation with large grip force and thrust force, and the vibration transmissibility of grip force 30 N and 60 N are basically equal in the low-frequency band (from 5–10 Hz to 5–20 Hz); (3) the wrist postures have a significant effect on the total vibration transmissibility at the wrist.

Occupational Disease as the Bane of Workers' Lives: A Study of Its Incidence in Slovakia. Part 2

The main objective of this article is to monitor the development of the number of occupational diseases related to selected physical factors in the working environment (noise, vibration and dust). Each region of Slovakia has its own specific social and economic conditions. Due to the existence of a strong correlation between the several regional variables observed, principal component analysis (PCA) was used to determine the new variables. Cluster analysis was used to group regions with similar characteristics. A dendrogram was created using the average linkage method, which illustrated the similarity of the regions studied. The value of the cophenetic correlation coefficient (CC = 0.90) confirms the validity of the average linkage method. The result of the cluster analysis is the grouping of the eight regions into five homogenic groups (clusters). An analysis of the data shows that Slovakia’s regional differences significantly influence the incidence of occupational diseases in individual regions. It is shown that, in Slovakia, the development of the number of occupational diseases has seen a favourable trend in the long term.

A comparative study of the dose-dependent effects of low level and high intensity photobiomodulation (laser) therapy on pain and electrophysiological parameters in patients with carpal tunnel syndrome

BACKGROUND

Carpal tunnel syndrome (CTS) is a common peripheral nerve disorder of the wrist. Nonsurgical treatments e.g. laser therapy may cause potential beneficial effects.

AIM

To compare the dose dependent effects of low level laser therapy (LLLT) and high intensity laser therapy (HILT) on pain and electrophysiology studies in patients with CTS.

DESIGN

Double-blind randomized controlled trial.

SETTING

Outpatient physiotherapy clinic.

POPULATION

Ninety-eight participants with CTS, aged between 20 to 60 years, were randomly assigned to five groups.

METHODS

All participants undertook four standard exercises, with one group serving as exercise-only controls. Patients were randomly allocated to either high or low fluence LLLT or high or low fluence HILT received over 5 sessions. All patients were assessed by visual analogue scale, median compound muscle action potential (CMAP) and sensory nerve conduction studies before and 3 weeks after the interventions.

RESULTS

VAS was significantly lower in all groups after 3 weeks (P<0.05). CMAP latency decreased in all groups. The interaction of group and time (5×2) was significant for pain (P<0.001), the latency of CMAP (P=0.001) and CMAP amplitude (P=0.02). The interaction of group and time was not significant for the CMAP conduction velocity, sensory nerve latency and amplitude (P>0.05).

CONCLUSIONS

HILT with a power of 1.6 W and low fluence of 8 J/cm² was superior in reduction of pain and improvement of the median motor nerve electrophysiological studies compared to LLLT and exercise-only control groups.

CLINICAL REHABILITATION IMPACT

LLLT and HILT in conjunction with exercise program are effective in reducing pain and improving median motor nerve conduction studies of the patients with CTS. It seems that high power and low fluence laser therapy is better than LLLT and exercise interventions to treat these patients.

Limitations of periodical health examinations in detecting occupational chronic solvent encephalopathy

OBJECTIVES

Occupational diseases (ODs) are globally underdetected, and chronic solvent encephalopathy (CSE) is no exception. The aim was to study how the recommended policies and protocols were followed in occupational health services (OHS) periodical health examinations where symptomatic CSE cases have remained undetected.

METHODS

We retrospectively studied the medical records of occupational CSE cases (n=18) found in a screening project, which had not been detected in preceding OHS health examinations. We collected data from three sources: OHS units, the screening project and the Finnish Institute of Occupational Health. We analysed the health examinations conducted between symptom onset and the detection of CSE: regularity, content, use of recommended screening tools, exposure estimation and whether a physician was involved in the examinations, as recommended.

RESULTS

The mean duration of symptoms before OD identification was 7.3 years (range 3-13), and 36 health examinations had been conducted. Fifteen workers had attended these (1-9 times each) while suffering from CSE symptoms, and two before symptoms. Only one had not had access to OHS. The recommended symptom screening questionnaire, Euroquest, was used in five (14%) examinations, and previous solvent exposure inquired once. A physician was involved in 24 (67%) examinations, whereas the rest were carried out by a nurse.

CONCLUSIONS

Although health examinations are conducted, guidelines are not followed. This may be due to a lack of awareness concerning CSE, and may apply to other ODs. In addition to legislation and policies, OH professionals must be continuously educated to improve awareness, prevention and detection of ODs.

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.

Health-care barriers for workers with HAVS in Ontario, Canada

BACKGROUND

Hand-arm vibration syndrome (HAVS) becomes irreversible unless it is identified early and progression prevented.

AIMS

To describe the health-care-seeking behaviours of workers with HAVS and barriers to health care.

METHODS

We invited all patients assessed for HAVS between 15 January and 27 March 2013 at a hospital-based occupational health clinic (OHC) in Ontario, Canada, to complete a questionnaire asking why and from whom they sought health care, reasons they waited to seek care and barriers they encountered in accessing care. We analysed the data using descriptive statistics.

RESULTS

Forty-one (82%) patients agreed to participate. Thirty-seven had confirmed HAVS; 30 (84%) were Stockholm workshop vascular stage 2 or greater and 35 (97%) were sensorineural stage 1 or greater. The commonest employment sectors were construction [21 (57%)] and mining [6 (17%)]. The main reasons for seeking treatment were pain [11 (30%)], finger numbness [8 (22%)] and functional limitations [5 (14%)]. The commonest initial point of health care was the family physician [23 (66%)]. The mean wait between symptom onset and seeking treatment was 3.4 years, while the mean time between onset and OHC assessment was 9 years. Reasons for delay in seeking care were ignorance of the seriousness and irreversibility of HAVS and ability to continue to work. Family physicians suspected HAVS in 17% of cases and recommended job modification in 34%.

CONCLUSIONS

Workers with HAVS in Ontario delay seeking health care. Primary care physicians often fail to recognize HAVS. Barriers to health care include ignorance of HAVS and of the importance of prevention.

A comparison of hand-arm vibration syndrome between Malaysian and Japanese workers

OBJECTIVES

The aim of this study was to investigate the clinical characteristics of HAVS in a tropical environment in comparison with a temperate environment.

METHODS

We conducted a series medical examinations among the forestry, construction and automobile industry workers in Malaysia adopting the compulsory medical examination procedure used by Wakayama Medical University for Japanese vibratory tools workers. We matched the duration of vibration exposure and compared our results against the Japanese workers. We also compared the results of the Malaysian tree fellers against a group of symptomatic Japanese tree fellers diagnosed with HAVS.

RESULTS

Malaysian subjects reported a similar prevalence of finger tingling, numbness and dullness (Malaysian=25.0%, Japanese=21.5%, p=0.444) but had a lower finger skin temperature (FST) and higher vibrotactile perception threshold (VPT) values as compared with the Japanese workers. No white finger was reported in Malaysian subjects. The FST and VPT of the Malaysian tree fellers were at least as bad as the Japanese tree fellers despite a shorter duration (mean difference=20.12 years, 95%CI=14.50, 25.40) of vibration exposure.

CONCLUSIONS

Although the vascular disorder does not manifest clinically in the tropical environment, the severity of HAVS can be as bad as in the temperate environment with predominantly neurological disorder. Hence, it is essential to formulate national legislation for the control of the occupational vibration exposure.

Hand-arm vibration syndrome: clinical characteristics, conventional electrophysiology and quantitative sensory testing

OBJECTIVE

Workers exposed to vibrating tools may develop hand-arm vibration syndrome (HAVS). We assessed the somatosensory phenotype using quantitative sensory testing (QST) in comparison to electrophysiology to characterize (1) the most sensitive QST parameter for detecting sensory loss, (2) the correlation of QST and electrophysiology, and (3) the frequency of a carpal tunnel syndrome (CTS) in HAVS.

METHODS

QST, cold provocation tests, fine motor skills, and median nerve neurography were used. QST included thermal and mechanical detection and pain thresholds.

RESULTS

Thirty-two patients were examined (54 ± 11 years, 91% men) at the more affected hand compared to 16 matched controls. Vibration detection threshold was the most sensitive parameter to detect sensory loss that was more pronounced in the sensitivity range of Pacinian (150 Hz, x12) than Meissner's corpuscles (20 Hz, x3). QST (84% abnormal) was more sensitive to detect neural dysfunction than conventional electrophysiology (37% abnormal). Motor (34%) and sensory neurography (25%) were abnormal in HAVS. CTS frequency was not increased (9.4%).

CONCLUSION

Findings are consistent with a mechanically-induced, distally pronounced motor and sensory neuropathy independent of CTS.

SIGNIFICANCE

HAVS involves a neuropathy predominantly affecting large fibers with a sensory damage related to resonance frequencies of vibrating tools.

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.