Whole-Body Vibration Syndrome

Whole body vibration syndrome is the set of musculoskeletal and other health effects caused by prolonged vibration transmitted to the body through the seat or the feet. Its commonest consequence is low back pain with accelerated lumbar degeneration.

Exposure. Drivers of trucks, buses, tractors, forklifts, earth moving and mining vehicles, helicopter pilots, and crews of fast boats. Relevant frequencies lie mainly from 0.5 to 80 Hz, and the spine resonates at about 4 to 8 Hz.

Exposure limits. Many jurisdictions use a daily eight hour equivalent action value of about 0.5 m/s2 and a limit of about 1.15 m/s2. Risk rises with magnitude, daily duration and years of exposure.

Epidemiology. Low back pain, disc herniation and sciatica are more frequent in exposed drivers than in unexposed workers, with roughly a 1.5 to 2 fold increase in many cohorts.

Risk modifiers. Sustained seated posture, twisting, manual lifting, poor seat design, shocks from rough ground, cold, smoking and psychosocial stress.

Pathophysiology.

Cyclic loading near spinal resonance overloads vertebral endplates and intervertebral discs. This causes endplate microfracture, impaired disc nutrition and degeneration.

Muscle fatigue and reduced reflex stabilisation add to the load. Gastrointestinal, genitourinary and circulatory complaints are reported, but the evidence for them is weak.

• Low back pain, often worse after long periods of driving, with stiffness.
• Sciatica with leg pain, paraesthesia or weakness when a disc is herniated.
• Neck and shoulder pain, fatigue and headache.

Red flags.

• Saddle anaesthesia, urinary retention or incontinence, or bilateral leg weakness (cauda equina syndrome).
• Progressive motor deficit.
• Fever, weight loss, history of cancer, night pain, or pain after significant trauma.

• Exposure history: vehicle, seat type, hours of driving, road surface, and measured vibration magnitude when available.
• Examination: spinal movement, straight leg raise, power, reflexes and sensation in the legs.
• Imaging is not needed for non-specific pain. MRI of the lumbar spine is indicated for red flags, or for radiculopathy persisting for over 6 weeks.
• Full blood count, inflammatory markers and urinalysis when infection, malignancy or renal disease is suspected.

Differential diagnosis. Non-specific mechanical low back pain, disc herniation, spinal stenosis, facet arthropathy, spondyloarthritis, osteoporotic fracture, spinal infection, spinal malignancy, and referred pain from renal or aortic disease.

• Reduce exposure: seat suspension matched to driver weight, maintenance of vehicle suspension and tyres, smoother routes and lower speed, scheduled breaks with standing and walking, lumbar support, and avoidance of heavy lifting immediately after long drives.
• Stay active; exercise programme and physiotherapy; avoid bed rest.
• Paracetamol 1 g orally every 6 hours as needed, maximum 4 g in 24 hours (3 g if under 50 kg, chronic alcohol excess or liver disease), for the shortest period that controls pain. Monitor liver function with prolonged use. Reduce dose in hepatic impairment; extend dosing interval when eGFR is under 30.
• Ibuprofen 400 mg orally three times daily with food for up to 7 days, maximum 2400 mg daily. Monitor blood pressure, renal function and gastrointestinal symptoms. Avoid if eGFR is under 30, in active peptic ulcer, heart failure or the third trimester; add gastroprotection in older adults or those at risk.
• Radicular pain persisting despite these measures: pregabalin orally, 75 mg twice daily, increased after 3 to 7 days to 300 mg daily and, if needed after a further 7 days, to a maximum of 600 mg daily. Review at 4 weeks and stop if there is no meaningful benefit; withdraw over at least 1 week. Monitor sedation, dizziness, peripheral oedema, weight gain, mood and misuse. Adjust for renal function: creatinine clearance 30 to 60 mL/min, 75 to 300 mg daily in 2 or 3 divided doses; 15 to 30 mL/min, 25 to 150 mg daily; under 15 mL/min, 25 to 75 mg daily. Avoid in pregnancy unless benefit outweighs risk.
• Opioids are not advised for non-specific pain.
• Persistent radiculopathy with motor deficit, or intractable pain, needs surgical assessment.

Monitoring. Review at 4 to 6 weeks, then every 3 months until stable; reassess exposure after any change in vehicle or route.

Referral and escalation. Emergency imaging and surgical referral for suspected cauda equina syndrome; spinal or orthopaedic review for progressive deficit; occupational physician for fitness-for-duty assessment and compensation where required.

Special groups. Pregnancy: paracetamol is preferred and ibuprofen is avoided in the third trimester. Older adults: reduce NSAID exposure and review fall risk with gabapentinoids.