Long-term effect of hand-arm vibration on thermotactile perception thresholds

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 related symptoms and signs in quarry and foundry workers

Purpose

The development of vascular and neurosensory findings were studied in two groups of long-term exposed quarry and foundry workers with different vibration exposures, working conditions and work tasks.

Methods

The study included 10 quarry workers (mean age 43 yrs., mean exposure time 16 yrs.) and 15 foundry workers (35 yrs.; 11 yrs.) at two plants in Sweden. All participants completed a basic questionnaire and passed a medical examination including a number of neurosensory tests, e.g. the determination of vibration (VPT) and temperature (TPT) perception thresholds as well as a musculoskeletal examination of the neck, shoulders, arms and hands.

Results

A high prevalence of neurosensory findings (40%) was found among the quarry workers. Both groups, however, showed a low prevalence of vibration white fingers (VWF). Foundry workers showed significantly better sensitivity than quarry workers for all monofilament tests (p ≤ 0.016), TPT warmth in dig 2 (p = 0.048) and 5 dexter (p = 0.008), and in dig 5 sinister (p = 0.005). They also showed a better VPT performance in dig 5 dexter (p = 0.031).

Conclusions

Despite high vibration exposure, the prevalence of VWF was low. The high prevalence of neurosensory findings among the quarry workers may depend on higher A(8) vibration exposure and higher exposure to high-frequency vibrations. An age-effect and exposure to cold could also be contributing factors. The nervous system seems to be more susceptible to high-frequency vibrations than the vascular system. For neurosensory injuries, the current ISO 5349-1 standard is not applicable.

Manifestations of cold sensitivity - a case series

Objectives: To characterise cold sensitivity using a semi-structured interview, physical examination, thermal quantitative sensory testing (QST), and laser speckle contrast analysis (LASCA). Methods: Eight women and four men, ages 22-74, with cold sensitivity were interviewed and examined by an occupational physician. Thermal perception thresholds were established using QST, on the pulp of the index and little finger of the most affected hand. Skin perfusion in the dorsum of the hand was measured using LASCA, at baseline, after two-minute 12°C water immersion, and during rewarming. Results: The physical examination yielded few findings indicative of vascular or neurosensory pathology. One subject (8%) had impaired thermal perception thresholds. LASCA at baseline showed absent proximal-distal perfusion gradients in six subjects (50%), and a dyshomogeneous perfusion pattern in five (42%). Perfusion on a group level was virtually unchanged by cold stress testing (median 52.5 PU; IQR 9.0 before versus 51.3 PU; IQR 27.2 afterwards). Conclusions: Physical examination and thermal QST offered little aid in diagnosing cold sensitivity, which challenges the neurosensory pathophysiological hypothesis. LASCA indicated disturbances in microvascular regulation and could prove a useful tool in future studies on cold sensitivity.