International consensus criteria for diagnosing and staging hand-arm vibration syndrome

[From vibration trauma to pharyngeal muscle instability: A self-sustaining pathophysiological process (circulus vitiosus) in obstructive sleep apnea]

Pharyngeal stability is ensured by both anatomical and non-anatomical factors. In addition to the anatomical width, functional factors are also significant in determining the degree of obstruction of the upper airway. The functionality of the pharyngeal muscles depends on an undisturbed sensorimotor system. In patients with rhonchopathy or obstructive sleep apnea (OSA), sensorimotor function and muscle morphology change progressively. It is hypothesised that long-term snoring leads to vibration-induced sensorimotor neuropathy, resulting in the loss of function and structure of the pharyngeal muscles. Pharyngeal mechanoreceptors lose their sensitivity, and due to neural damage, information can no longer be adequately translated into motor responses. This raises the question of the timeframe within which irreversible vibration-induced receptor damage occurs due to snoring.

Case report: Hand-arm vibration syndrome in a dental technician

Occupational exposure to vibration using hand-held tools may cause hand-arm vibration syndrome (HAVS) among workers. We report the case of a 39-year-old lady with a 5-year work exposure to repetitive wrist movements and vibration from hand tools in the dental fabrication laboratory, working as a dental technician. She presented with a 3-year history of chronic pain over the wrists and positive symptoms of numbness and tingling in the hands, pain and discomfort of the fingers during cold exposure, and poor grip strength. Symptoms over the right hand were worse than the left. She is right-hand dominant. She had bilateral median nerve neuropathy at the wrist. Nerve conductive tests were consistent with minimal bilateral carpal tunnel syndrome. MRI showed evidence of soft tissue damage from repetitive strain injury of the right wrist. Neurosensory grading for hand-vibration syndrome (HAVS) using the Stockholm Workshop Scale (SWS) was performed and she was graded as Stage 1SN with numbness or tingling symptoms. Using the International Consensus Criteria (ICC) grading for HAVS, she was graded Stage N1 with numbness and/or tingling (symptoms) of finger. A workplace risk health assessment (WHRA) was performed, and exposure scores for her work tasks in dental fabrication and risk levels were determined using the HSE (Health and Safety UK) Assessment of Repetitive Tasks (ART) tool. The processes of teeth setting using dental burs (exposure score 23), divestment work with stone clippers (score 20), and use of pneumatic drills (score 21) were deemed high-risk activities for repetitive strain injury. The use of carving tools (score 12), packing with the use of flask clamps, and trimming (score 14) were classified as medium high-risk activities for repetitive strain injuries. Workplace modifications and workplace vibration exposure level monitoring protocols were subsequently established with the stabilization of the patient's symptoms.

Vocational rehabilitative decisions after symptoms and findings consistent with hand-arm vibration syndrome in the Swedish surveillance system - a mixed-method design

BACKGROUND

EU workers exposed to hand-arm vibration should be offered health surveillance to detect early symptoms, and findings, of Hand-Arm Vibration Syndrome (HAVS). To execute the mandatory vocational rehabilitation, the employer needs to be aware of injuries found in the medical check-up. We aimed to analyse: 1) How physicians graded the neurosensory component of HAVS on the Stockholm Workshop Scale (SWS), compared to semi-objective findings. 2) What vocational rehabilitative decisions (VRD) were taken by physicians after examinations. 3) Whether the VRDs differed in relation to the SWS-grading.

METHODS

Data came from 660 medical records - all examinations performed during twelve consecutive months in one large Swedish occupational healthcare company. 572 individuals had data on the SWS from the physician. For the qualitative analysis, we used the inductive-iterative immersion-crystallization method.

RESULTS

60% of the examined workers had symptoms and 32% had semi-objective findings consistent with HAVS. The physicians' SWS gradings were underestimated in 59% of the cases with semi-objective findings. The VRDs were classified, relative to communication with the employer, as: "Adequate" (57%), when no injury was present, communication had already taken place, was planned, or was no longer needed in the absence of further exposure, "Semi-adequate" (18%), if no plan for communication was yet established or only communicated through a document with a shorter time until next check-up, and "Inadequate"(25%), when patients refused (20%), or physicians failed to communicate with the employer, despite findings (80%). Underestimated SWS-gradings of HAVS were significantly associated with more "Inadequate" VRDs in the group with semi-objective findings.

CONCLUSIONS

Occupational physicians underestimate the number of individuals with SWS 2-3 compared with semi-objective findings and regularly fail to communicate to the employer despite findings of HAVS. The underestimation of SWS-grading, followed by inadequate VRDs, excludes many workers from the employer's mandatory protective measures which may lead to aggravation of an untreatable injury in the affected individual and development of HAVS in their similarly exposed colleagues.

Serum levels of biomarkers related to severity staging of Raynaud's phenomenon, neurosensory manifestations, and vibration exposure in patients with hand-arm vibration injury

Our aim was to explore possible relationships between serum levels of biomarkers in patients with hand-arm vibration injury in relation to the severity of the vascular, i.e., Raynaud's phenomenon (RP), and neurosensory manifestations, the current exposure level, and the duration of exposure. This study was of case series design and involved 92 patients diagnosed with hand-arm vibration injury. Jonckheere's trend test was used to assess any association between serum levels of biomarkers and RP as well as neurosensory manifestations, graded by the International Consensus Criteria. Generalized linear models with adjustment for possible confounders were also used for associations between serum levels of biomarkers and; (1) severity of RP recorded as the extent of finger blanching calculated with Griffin score, (2) vibration perception thresholds, (3) magnitude of current exposure as [A(8); (m/s2)] value, and (4) the duration of exposure in years. Serum levels of thrombomodulin, von Willebrand factor, calcitonin gene related peptide (CGRP), heat shock protein 27, and caspase-3 were positively associated with severity of RP. Serum levels of CGRP were positively associated with the neurosensory component. No associations with exposure were shown for these biomarkers. For Intercellular adhesion molecule 1 and monocyte chemoattractant protein 1, no associations were found with neither severity nor exposure. Levels of serum biomarkers associated with endothelial injury or dysfunction, inflammation, vasodilation, neuroprotection, and apoptosis were positively associated with the severity of hand-arm vibration injury.

Mottled Raynaud's phenomenon and hand-arm vibration syndrome: followed up for 10 years

Vibration white finger is a form of secondary Raynaud's phenomenon (RP) caused by the use of handheld vibrating tools. RP usually appears on the extremities of the fingers, and its borders are well recognised. No reports have been published on 'mottled' RP in continuous observation from the onset to the disappearance of RP. A man in his 60s who had been using vibrating tools such as jackhammers and tampers for 30 years presented with sensations of coldness, burning and numbness. Whole-body cold exposure was performed outdoors in winter, and RP was photographed continuously. 'Mottled' RP can be defined as triphasic colour changes: white, blue and red. The patient was taken off work, kept warm and medicated. His symptoms improved slightly after 10 years of follow-up, but the RP did not disappear. 'Mottled' RP is rare and refractory and should be recognised as a form of RP.

Concordance between the Stockholm Workshop Scale and the International Consensus Criteria for grading the severity of neurosensory manifestations in hand-arm vibration syndrome in a Swedish clinical setting

OBJECTIVES

Occupational exposure to vibration using hand-held tools may cause hand-arm vibration syndrome (HAVS). Correct diagnosis and grading of severity are crucial in protecting the individual's health and for workers' compensation claims. The International Consensus Criteria (ICC) has been suggested to replace the widely used Stockholm Workshop Scale (SWS). The aims were to, in a clinical setting, assess the concordance between the SWS and the ICC neurosensory severity grading of vibration injury, and to present the clinical picture according to symptoms, type of affected nerve fibres and the relation between vascular and neurosensory manifestations.

METHODS

Data were collected from questionnaires, clinical examination and exposure assessment of 92 patients with HAVS. The severity of neurosensory manifestations was classified according to both scales. The prevalence of symptoms and findings was compared across groups of patients with increasing severity according to the SWS.

RESULTS

Classification with the ICC resulted in a shift towards lower grades of severity than with the SWS due to a systematic difference between the scales. Affected sensory units with small nerve fibres were far more prevalent than affected units with large nerve fibres. The most prevalent symptoms were numbness (91%) and cold intolerance (86%).

CONCLUSIONS

Using the ICC resulted in lower grades of the severity of HAVS. This should be taken into consideration when giving medical advice and approving workers' compensation. Clinical examinations should be performed to detect affected sensory units with both small and large nerve fibres and more attention should be paid to cold intolerance.

Hand Function After an Electrical Accident-A Case-Control Study

OBJECTIVE

Electrical accidents cause both acute and long-term injuries. The care of acute injuries is somewhat standardized, but currently recommendations or assessment tools are not available for assessing the long-term effects of an accident on hand function.

METHODS

A case-control study of 24 healthy controls and 24 cases, 1 to 5 years after an electrical accident and with self-reported neurosensory symptoms, was performed using three hand-function tests: the Disabilities of the Arm, Shoulder, and Hand questionnaire, the Purdue Pegboard test, and the Shape and Texture Identification test.

RESULTS

Compared with the control group, patients received statistically significantly lower scores for the Disabilities of the Arm, Shoulder, and Hand outcome measure and the Purdue Pegboard and for one finger on the Shape and Texture Identification test.

CONCLUSION

Hand function is affected after an electrical accident in individuals with self-reported neurosensory symptoms.

Evaluation of neurological testing for hand-arm vibration syndrome

BACKGROUND

The neurological component of hand-arm vibration syndrome (HAVS) uses the Stockholm Workshop Scale sensorineural (SWS SN) stages for classification. Proximal compressive neuropathies are common in HAVS and the symptoms are similar to SN HAVS. The SWS may not be a valid staging tool if a patient has comorbid proximal compression neuropathy.

AIMS

To evaluate the prevalence of proximal compression neuropathy in patients presenting for HAVS assessment and examine the association between compressive neuropathies and SWS SN.

METHODS

A standardized assessment protocol was used to assess 431 patients for HAVS at St. Michael's Hospital, Toronto, Ontario. The prevalence of median and ulnar compressive neuropathies was determined. The association between proximal compression neuropathies and SWS SN stage (0/1 versus 2/3) was evaluated using Chi-square and Fisher's exact tests as well as multivariable logistic regression.

RESULTS

Most patients (79%) reported numbness and 20% had reduced sensory perception (SWS SN Stage 2/3). Almost half (45%) had median neuropathy at the wrist and 7% had ulnar neuropathy. There was no association between the SWS SN stage and median or ulnar neuropathy.

CONCLUSIONS

Two neurological lesions should be investigated in patients presenting for HAVS assessment: compressive neuropathy and digital neuropathy. The prevalence of compressive neuropathies is high in patients being assessed for HAVS and therefore nerve conduction studies (NCS) should be included in HAVS assessment protocols. Comorbid proximal neuropathy does not affect the SWS SN stage; therefore, NCS and SWS SN seem to be measuring different neurological outcomes in HAVS patients.

Influence of ergonomic factors on peripheral neuropathy under HAV exposure

BACKGROUND

Hand-arm vibration (HAV) is a risk factor for carpal tunnel syndrome (CTS) and ulnar neuropathy at the elbow (UNE). It is unclear how ergonomic factors influence the relationship between HAV exposure and CTS and UNE.

AIMS

We aimed to assess the relationship between cumulative HAV exposure and CTS and UNE in workers exposed to HAV from two tools with different ergonomic profiles.

METHODS

We performed nerve conduction studies (NCSs) of the sensory and motor median and ulnar nerves and recorded symptoms indicating CTS and UNE in workers exposed to HAV from impact wrenches or from rock drills. Exposure was measured as cumulative lifetime exposure. We used linear regression adjusted for age and body mass index to assess linear relationships.

RESULTS

Sixty-five workers participated (33 rock drill and 32 impact wrench operators). We found inverse linear associations between cumulative HAV exposure and median nerve sensory conduction velocity in impact wrench operators and ulnar nerve motor conduction velocity in rock drill operators (beta of 0.63 and 0.75). Based on NCS findings and symptoms, seven impact wrench operators had CTS and one UNE, and four rock drill operators had CTS and six UNE.

CONCLUSIONS

Our findings indicate that ergonomic factors influence the development of CTS and UNE under HAV exposure. The ergonomic profile seems to influence which type of neuropathy workers exposed to HAV will develop. Design of occupational exposure guidelines and future studies should be based on ergonomic profile and exposure characteristics for different tools and not merely HAV.

Exposure-response relationship between hand-arm vibration exposure and vibrotactile thresholds among rock drill operators: a 4-year cohort study

OBJECTIVES

The risk of developing hand-arm vibration syndrome (HAVS) from occupational hand-arm vibration (HAV) exposure is traditionally determined by the onset of vascular symptoms (white fingers). However, changes in tactile sensibility at the fingertips is a clinical sign of HAVS which in most cases precedes vascular signs. We aimed to assess relationships between occupational HAV exposure and HAVS-related signs including vibration perception thresholds (VPT) and pegboard score on an individual level, using a longitudinal study design with follow-up tests.

METHODS

We followed-up 148 workers exposed to different HAV levels for 4 years, with health examinations including VPT tests and pegboard tests carried out at baseline, 2 years and 4 years. VPT testing included seven frequencies, from 8 to 500 Hz. Second and fifth finger on both hands were tested, thus a total of 28 tests on each subject. We investigated associations using linear mixed models and significance level at p≤0.05.

RESULTS

There was a significant exposure-response relationship on an individual level between HAV exposure from rock drills and VPT for 16 of 28 test frequencies. The highest rise (worsening) in VPT was found at the 500 Hz test frequency with 1.54 dB increased VPT per 10-fold increase in cumulative exposure. We found no deterioration in pegboard performance associated with HAV exposure among the participants.

CONCLUSIONS

Risk predictions of HAVS may be based on exposure-response relationships between HAV exposure and VPT. The 500 Hz test frequency should be included in the VPT test protocols for early detection of signs related to reduced tactile sensibility.

Effect of the level of manual performance disability caused by exposure to vibration among sailors working on sailing speed vessels

BACKGROUND

hand-arm vibration is one of the typical annoying physical factors. Hand-arm vibration syndrome (HAVS) is a disorder caused by vibrating working tools which vibrate hands beyond the threshold. Long-term HAVS may result in damage to blood vessels, chronic numbness in the fingers, bone injury, and muscular weakness. People are exposed to high-rate noise vibration in a variety of situations, including vessel employment and operating in tiny boats. Moreover, the extant study was conducted to examine manual function disability levels caused by Sailing Speed Vessels (SSV) vibration.

METHODS

The extant study was quasi-experimental research in which, 52 male sailors in SSVs were chosen as the experimental group, and 27 office personnel were selected as the control group. The demographic factors questionnaire, DASH questionnaire, grip and pinch strength tests, the neurosensory exam, and the skill-dexterity test were all employed in this study. SPSS23 software was used to analyze the data.

RESULTS

The findings suggested that the experimental group experienced greater vibration disorder symptoms than the control group. Because the experimental group had a higher score, the individuals experienced poorer circumstances in terms of arm, shoulder, and hand impairment as compared to the control group. The mean grip strength of hands and fingers in two hands of the experimental group was lower than the control group (P < 0.05). There was a statistically significant relationship among grip strengths of both experimental and control groups (P < 0.05). There was a reduction in skill and dexterity of both dominant and non-dominant hands of members in the experimental group. According to the statistical tests, there was no significant association between dominant (P = 0.001) skills and non-dominant (P = 0.010) hands in experimental and control groups. There was not also any significant relationship between skill and dexterity of both hands (P = 0.001) and the dominant hand tweezer test (P = 0.001) in two experimental and control groups. There was a statistically significant association between experimental and control groups in terms of assembly skill and dexterity (P = 0.482).

CONCLUSION

Individuals who are at risk of vibration experience less physical and sensory function. DASH score, grip strength, skill, and dexterity could predict the reduction in physical function disability.

The clinical consequence of using less than four sensory perception examination methods in the Swedish surveillance system for Hand-Arm vibration syndrome

OBJECTIVES

The Swedish surveillance system aiming to reveal undetected Hand-Arm Vibration Syndrome (HAVS) in workers exposed for vibrations is regulated by the provision AFS 2019:3. The goal for the surveillance system is to diagnose HAVS, as well as to find workers at risk for developing HAVS due to other conditions. The national guidelines stipulate examination using at least two out of four hand sensory examination methods (SEM); monofilament (touch), two-point discrimination (discriminative), tuning fork (vibrotactile), and Rolltemp (thermotactile). The aim of this study was to examine the clinical consequence of using less than four of these SEMs.

METHODS

We collected data on SEMs from the medical records of all individuals that went through the specific surveillance medical check-up in a large occupational health service for 1 year. We then calculated the number of workers found with HAVS when using one, two, or three SEMs, and compared with the result from using all available SEMs.

RESULTS

Out of 677 examined individuals, 199 had positive findings in at least one SEM. The detection rate for these findings was on average 47% when using one SEM, 71% using two SEMs, and 88% using three SEMs (out of 100% detection when all four SEMs were used).

CONCLUSIONS

If fewer than four sensory examination methods are used for surveillance of HAVS, many workers with incipient injuries may stay undetected. This may lead to further exposure resulting in aggravation of injury.

Upper extremity musculoskeletal disorders and work exposures among railroad maintenance-of-way workers

BACKGROUND

Our objective was to examine occupational risk factors for musculoskeletal disorders of the shoulders, elbows, wrists, and hands among railroad maintenance-of-way (MOW) workers. Little systematic research on musculoskeletal disorders has been conducted in this occupational group.

METHODS

In total, 3995 active members of the Brotherhood of Maintenance of Way Employes Division (BMWED) completed a standardized survey focusing on disorders caused by hand-transmitted vibration. We computed adjusted prevalence ratios (aPRs) using Poisson regression for shoulder, elbow, carpal tunnel syndrome, and vibration white finger musculoskeletal symptoms by work exposures, adjusted for age, region, race/ethnicity, smoking, potential second job, and spare time vehicle vibration exposure, and other work exposures.

RESULTS

Among active male BMWED members, we found associations between >5.2 years (vs. 0.0-0.7 years) duration of full-time equivalent power tool use and shoulder pain (aPR = 2.01; 95% confidence interval [CI], 1.43-2.85), elbow pain (aPR = 2.88; 95% CI, 1.86-4.46), vibration white finger symptoms (aPR = 2.49; 95% CI, 1.06-5.85), hand/wrist pain (aPR = 2.40; 95% CI, 1.74-3.32), finger numbness or tingling (aPR = 1.86; 95% CI, 1.38-2.50) and self-reported carpal tunnel syndrome diagnosis (aPR = 2.16; 95% CI, 1.24-3.77). Associations were not consistent across outcomes for the duration of non-powered hand tool use and "repeated lifting, pushing, pulling, or bending." Positive gradients were observed for most outcomes.

CONCLUSIONS

Hand-arm vibration and some other biomechanical exposures were associated with shoulder, elbow, wrist, hand, and finger symptoms. Prevention programs should address occupational risk factors for upper extremity musculoskeletal disorders among MOW workers.

Vibration Exposure Safety Guidelines for Surgeons Using Power-Assisted Liposuction (PAL)

BACKGROUND

As power-assisted liposuction (PAL) gains in popularity, plastic surgeons operating these devices experience occupational exposure to hand-transmitted vibration, which can result in hand-arm vibration syndrome, a debilitating neurovasculopathy.

OBJECTIVES

The objective of the study was to determine vibration exposure from the utilization of a PAL device during surgery to generate recommendations for safe use.

METHODS

Vibration emission of a commonly utilized PAL system (MicroAire-650, Surgical Instruments, Charlottesville, VA) was examined employing a vibration data logger under both controlled laboratory conditions and during 13 typical liposuction cases. Data were analyzed and compared with established safety limits of vibration exposure.

RESULTS

The experiments demonstrated a mean vibration magnitude of typical liposuction surgeries to be 5.69 ± 0.77 m/s2 (range, 4.59-6.27 m/s2), which is significantly higher than the manufacturer declared value of 3.77 m/s2. Cannula size was shown to be the most significant contributor to vibration magnitude, with larger cannulas causing more vibration transmission.

CONCLUSIONS

These results indicate that recommendations must be made to prevent undue occupational exposure to vibration from PAL. The MicroAire-650 can generally be safely utilized for less than 1.5 h/d. At exposure levels >1.5 h/d, there is increased risk of developing vibration-related injuries, and vibration-reducing strategies should be implemented. At exposure levels >6 h/d, the safety limit is exceeded and there is significantly increased risk of developing hand-arm vibration syndrome and vibration exposure should be halted.

LEVEL OF EVIDENCE: 4

Adverse health manifestations in the hands of vibration exposed carpenters - a cross sectional study

BACKGROUND

Despite EU regulatory standards, many workers suffer injury as a result of working with hand-held vibrating tools. Our aim of this study was to confirm whether carpenters, a highly exposed group, suffer more injuries to their hands than painters, a group assumed to be less exposed to vibration.

METHODS

193 carpenters (participation rate 100%) and 72 painters (participation rate 67%), all men, answered a questionnaire and underwent a clinical examination to identify manifestations of neural and vascular origin in the hands. Neurosensory affection was defined as having at least one symptom in the fingers/hands (impaired perception of touch, warmth, or cold, impaired dexterity, increased sensation of cold, numbness or tingling, or pain in the fingers/hands when cold) and at least one clinical finding (impaired perception of touch, warmth, cold, vibration, or two-point discrimination). Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Neurosensory affection was fulfilled for 31% of the carpenters and 17% of the painters, age-adjusted OR 3.3 (CI 1.6-7.0). Among carpenters with neurosensory affection 18% reported interference with daily life activities, the most common symptoms being increased sensation of cold, numbness and pain in the fingers/hands when cold, the most common clinical findings were impaired perception of touch and vibration. Neurosensory affection was found in 12% of young carpenters (≤ 30 years old). No difference was found in the prevalence of white fingers between carpenters and painters.

CONCLUSIONS

Carpenters showed more symptoms and clinical findings of neurosensory affection than painters, probably due to vibration exposure. Also young carpenters showed signs of neurosensory affection, which indicates that under current conditions workers at these companies are not protected against injury. This underlines the importance of reducing exposure to vibration and conducting regular medical check-ups to detect early signs of neural and vascular manifestations indicating hand-arm vibration injuries. Special attention should be given to symptoms of increased sensation of cold, pain in the fingers when cold, and numbness, as these were the most common initiating ones, and should be addressed as early as possible in the preventive sentinel process. It is also important to test clinically for small- and large-fibre neuropathy, as the individual may be unaware of any pathology.

Vibration Exposure and Transmissibility on Dentist's Anatomy: A Study of Micro Motors and Air-Turbines

The use of dental hand pieces endanger dentists to vibration exposure as they are subjected to very high amplitude and vibration frequency. This paper has envisaged a comparative analysis of vibration amplitudes and transmissibility during idling and drilling with micro motor (MM) and air-turbine (AT) hand pieces. The study aims to identify the mean difference in vibration amplitudes during idling, explore different grasp forces while drilling with irrigant injection by the dentist, and various vibration transmission of these hand pieces. The study utilized 22 separate frequency resonances on two new and eight used MMs and two new and eight used ATs of different brands by observing the investigator at 16 different dentist clinics. The study adopted a descriptive research design with non–probability sampling techniques for selecting dentists and hand pieces. Statistical methods like Levene Test of Homogeneity, Welch ANOVA, independent t-test, and Games–Howell test were utilized with SPSS version 22 and MS-Excel. The results reveal that vibration amplitudes and vibration transmissibility when measured at position 2 are higher than in another position 1. Vibrations during idling for used MMs are more than AT hand pieces, and the used MM (MUD) and used AT (AUA) hand pieces differ due to their obsolescence and over-usage. Vibration amplitudes increase every time with the tightening of grasping of the hand piece. Vibration amplitudes for each grasping style of MM hand piece differ from all other grasping styles of AT hand pieces. Routine exposure to consistent vibrations has ill physical, mental, and psychological effects on dentists. The used hand pieces more hazardous as compared to newer ones. The study suggests that these hand pieces must be replaced periodically, sufficient to break between two operations, especially after every hand piece usage. Hence, the present research work can be further extended by creating some control groups among dentists and then studying the vibration amplitude exposure of various dental hand pieces and subsequent transmissibility to their body parts.

Analysis of factors influencing the productivity of hammer drilling - user forces, human fatigue, drilling direction, and drill bit

In order to be able to develop a hammer drill with which the user can work as ergonomically and productively as possible, the relevant influencing factors must be known. In addition to the unknown influence of the drilling direction, there is a lack of understanding of the relations between user forces, human fatigue, and productivity. To analyze these relations, an experiment was carried out with 15 professional users. First, the influence of feed force, drilling direction, and drill bit on the rate of penetration was examined. Taking into account the rate of penetration and human fatigue, it was then investigated which of the three feed forces produces the highest productivity. Furthermore, the lateral forces applied by the participants during the drilling process were analyzed. Based on the study, it was found that the drilling direction (p < .001, r = -0.198) and the drill bit type (p < .041, r = -0.16) have a significant influence on the rate of penetration. Moreover, it was found that the rate of penetration tends to increase with higher feed forces, however, the theoretical cumulative drilling meters decrease when taking user fatigue into account. Finally, the experiment showed that the participating professionals applied lateral forces (Mdn = 16.7 N) of 13% to the feed force when working with a hammer drill. On the basis of this knowledge, investigations can be done to analyze the influences of lateral forces on the drilling process. The findings help drill and hammer drill manufacturers in testing and development processes. For craftsmen, on the other hand, the knowledge helps to perform the task as ergonomically and time-efficiently as possible.

Tremor measurements in a 22-year cohort study of workers exposed to hand-held vibrating tools

OBJECTIVES

The objectives of this cohort study were to evaluate possible long-term effects of occupational exposure to hand-arm vibration (HAV) in terms of increased tremor. The aims were to evaluate whether exposure during follow-up, baseline hand-arm vibration syndrome (HAVS), baseline manual dexterity or current medical conditions or life-style habits might be associated with increased tremor. A further aim was to compare two different activation conditions: postural vs rest tremor.

METHODS

Forty men (current age: 60.4 years) who had previously worked as manual workers in a specialized engineering and construction company enrolled in the study. Their hand functions had been examined in 1994. At the baseline examination, 27 had been diagnosed with HAVS, while 13 were not exposed. The follow-up examination in 2016-2017 comprised the CATSYS Tremor Pen^® for measuring postural and rest tremor and the Grooved Pegboard Test for assessing manual dexterity. Blood samples were taken for assessing biomarkers that might have impact on tremor.

RESULTS

Neither cumulative exposure to HAV during follow-up nor HAVS at baseline were associated with increased tremor. A test for manual dexterity at baseline was significantly associated with increased tremor (Tremor Intensity) at follow-up. Blood markers of current medical conditions and tobacco consumption were associated with increased tremor. Rest tremor frequency was higher than postural tremor frequency (p < 0.001).

CONCLUSIONS

The main findings of this 22-year cohort study were no indications of long-term effects on tremor related to HAV exposure and previous HAVS status. However, baseline manual dexterity was significantly associated with increased tremor at follow-up. Activation conditions (e.g., hand position) are important when testing tremor.

Organische und funktionelle Durchblutungsstörungen der Hand – differenzialdiagnostische Aspekte

Die Abklärung von venösen und arteriellen Durchblutungsstörungen sowie Lymphödemen gehört zur täglichen Praxisroutine des Gefäßmediziners. Nicht selten werden von chirurgischen Kollegen Patienten mit Beschwerden im Schulter-, Arm- und Handbereich zum Ausschluss einer vaskulären Ursache vorgestellt. Der wohl häufigste Abklärungsgrund im Handbereich ist das Raynaud-Phänomen. Neben arteriosklerotischen Durchblutungsstörungen und der Thrombangiitis obliterans sind das Hypothenar-/Thenar-Hammer-Syndrom und das Vibrationssyndrom in den Fingern eher wenig bekannte Entitäten, deren Kenntnis jedoch neben dem medizinischen Vorgehen auch versicherungsrelevante Konsequenzen haben kann. Während beim Hypothenar-/Thenar-Hammer-Syndrom eine organische Durchblutungsstörung vorliegt, beinhaltet das Vibrationssyndrom der Finger eine funktionell vaskuläre sowie eine nervale Komponente, die eine Trennung vom Karpaltunnelsyndrom erschwert. Bei beiden Entitäten ist eine Berufsanamnese häufig hilfreich. Schon der Verdacht auf eine Berufskrankheit muss nach Gesetzeslage zur Anzeige gebracht werden. Der Artikel beschreibt die wesentlichen pathophysiologischen Mechanismen beider Entitäten und stellt diagnostische und therapeutische Optionen dar. Die Kenntnis beider Erkrankungen erweitert die differenzialdiagnostische Vorgehensweise in der täglichen Praxisroutine bei Patienten mit Schulter-Arm-Hand-Beschwerden und bei Patienten mit Raynaud-Phänomen.

Sensory perception testing by monofilaments in the digits of controls and workers with HAVS

Objective

To determine if heavy manual work affects sensory perception in the digits and whether Semmes–Weinstein monofilaments (SWM) can be used as a screening tool to detect sensory neuropathy in the digits of workers exposed to hand-transmitted vibration (HTV).

Methods

A cross-sectional study of office workers, heavy manual workers not exposed to HTV and workers with hand-arm vibration syndrome (HAVS). Sensory perception was measured in the digits by SWM using a forced-choice method to determine variability by sex, age, hand and digit. Frequency distributions were used to determine limit values and linear weighted kappa for intra-digit variability. Poisson regression was used to explore the relationship between sensory perception by SWM and abnormalities of thermal and vibration perception in the hands of workers with HAVS.

Results

The sensory perception threshold of office workers did not vary by hand or digit. It was significantly lower in women < 30 than women aged ≥ 30 years. The 95th percentile for heavy manual workers was 1.00 (95% CI 0.60–1.00) and significantly higher than for office workers at 0.16 (95% CI 0.16–0.16). Heavy manual workers > 50 years had the highest threshold at 1.40 (95% CI 1.00–2.00). Weighted kappa for reliability was 0.63 (95% CI 0.53–0.70). A mean SWM threshold of ≥ 1.0 gram-force had a 79% sensitivity and 64% specificity for detecting abnormalities of thermal and vibration perception in the ipsilateral index and little fingers of workers with HAVS.

Conclusions

SWM are a useful screening tool for detecting sensory loss in the digits of workers exposed to HTV.

Dose-response relationship between hand-arm vibration exposure and vibrotactile thresholds among roadworkers

BACKGROUND

Testing of vibration perception threshold (VPT) at the fingertips as a quantitative measure of tactile sensitivity is a commonly used tool in diagnosing hand-arm vibration syndrome. There is limited research on dose-response relationships between hand-arm vibration (HAV) exposure and VPT on an individual level.

AIMS

Assess possible dose-response relationships on an individual level between HAV exposure and VPT at the fingertips.

METHODS

We assessed average daily vibration exposure (m/s²A8) and cumulative lifetime HAV exposure for 104 participants from different departments in a road maintenance company based on vibration measurements and questionnaires. VPT was measured based on the technical method described in ISO 13091-1:2005 using octave frequencies 8-500 Hz. We investigated associations using linear regression models with significance level p≤0.05.

RESULTS

The participants were either exposed to rock drills (n=33), impact wrenches (n=52) or none of these tools (n=19). Exposure to rock drills and impact wrenches was associated with elevated VPT for all seven test frequencies in the second and fifth fingers of both hands. A dose-response with the daily exposure measure m/s²(A8) was found based on 1.2 m/s²(A8) for impact wrenches, and 5.4 m/s²(A8) for rock drills. A stronger association was found with the cumulative exposure for rock drills compared with impact wrenches, and for the second finger compared with the fifth finger.

CONCLUSIONS

HAV exposure was associated with elevated VPT, also at exposure levels below the common exposure action value of 2.5 m/s²(A8). Lowering the HAV exposure can contribute to prevent increasing VPTs in these workers.