Introduction
This topic covers whole-body vibration disease (WBVS), an occupational disease caused by long-term exposure to low-frequency mechanical oscillation transmitted through the seat or floor to the whole body. An exam answer should define it, explain the exposure and mechanism, describe the main clinical syndromes and stages, outline diagnosis and differential diagnosis (especially Raynaud's syndrome), and give treatment, prevention and the principles of medical expertise.
Definition and exposure
Whole-body vibration is mechanical oscillation of the body as a whole, usually in the range of about 1 to 80 Hz, with the most harmful effects in the low-frequency band. The disease develops slowly and is classified as an occupational disease with three stages. It involves vascular, nervous and musculoskeletal disorders, and the latent period from first exposure to clear symptoms is usually several years (the course notes give at least 6 years).
Etiology is the combined effect of several exposure factors:
- Daily dose, combining the amplitude of acceleration and the total duration of exposure per shift
- Duration of exposure in years of work
- Intensity (acceleration level) and frequency, since frequencies close to body resonance (about 4 to 8 Hz for the body as a whole, and roughly 4 to 12 Hz for the spine) are most harmful
- Aggravating factors: prolonged sitting in a fixed posture, poor seat suspension, heavy lifting, trunk twisting, cold, and smoking
At-risk occupations include drivers of trucks, buses, tractors and off-road or construction vehicles, operators of heavy earth-moving and mining equipment, and helicopter and military vehicle crews.