Vibration-Induced White Finger

Vibration induced white finger is the vascular component of hand arm vibration syndrome. It is secondary Raynaud phenomenon caused by repeated exposure to hand transmitted vibration, with attacks of finger blanching on exposure to cold.

Exposure. Chainsaws, grinders, pneumatic and rotary hammers, drills, sanders, riveters and vibrating tools in forestry, construction, mining, metal and stone work. Risk rises with vibration magnitude and daily and cumulative use.

Epidemiology. Prevalence ranges from about 6 to 50% in exposed groups, depending on tool and exposure. Latency is months to years.

Staging. Stage 1 (mild): occasional blanching of the tips of one or more fingers. Stage 2 (moderate): occasional blanching of the distal and middle phalanges, rarely proximal. Stage 3 (severe): frequent blanching of all phalanges. Stage 4 (very severe): all of stage 3 with skin changes at the fingertips.

Course. Early disease can improve after exposure reduces. Advanced disease often persists.

Pathophysiology.

Repeated vibration injures vascular endothelium and causes smooth muscle hypertrophy, with an exaggerated sympathetic vasoconstrictor response. Local cold exposure and smoking add to digital vasospasm.

Structural changes in digital arteries reduce flow. Sensorineural damage often coexists.

• Episodic blanching of fingers triggered by cold, then cyanosis and painful reddening on recovery.
• Numbness and tingling, reduced dexterity and grip, often with night pain.
• Thumbs are usually spared.
• Fingertip ulceration and trophic change in stage 4.

Red flags.

• Digital ulceration, gangrene or persistent ischaemia.
• Asymmetric or unilateral disease, or systemic features suggesting an alternative cause.

• Detailed work history including tools, vibration magnitude, daily exposure and years of work.
• Examination: Allen test, capillary refill and skin changes.
• Cold provocation with finger systolic pressure measurement, thermal and vibration perception tests.
• Nail fold capillaroscopy to separate from connective tissue disease.
• Blood tests: full blood count, inflammatory markers, ANA, rheumatoid factor and other autoantibodies when atypical.
• Duplex ultrasound or angiography for unilateral disease.

Differential diagnosis. Primary Raynaud phenomenon, systemic sclerosis, other connective tissue disease, hypothenar hammer syndrome, thoracic outlet syndrome, carpal tunnel syndrome, cryoglobulinaemia, drug induced vasospasm (beta blockers, ergot derivatives).

• Reduce vibration exposure by using low vibration tools, limiting trigger time, rest breaks and job rotation; transfer from vibration work in moderate or severe disease.
• Keep the hands and body warm using insulated gloves and clothing; stop smoking; avoid caffeine and vasoconstrictor drugs.
• Nifedipine modified release 30 mg orally once daily, increased after 2 weeks to 60 mg daily if needed. Usual maximum 60 mg daily. Give for the cold season or long term. Monitor blood pressure, ankle oedema and headache. Reduce dose in hepatic impairment; no renal adjustment; avoid in pregnancy unless benefit outweighs risk.
• Severe or ulcerating disease: specialist vasodilator infusion and wound care.
• Evidence for drug therapy in this condition is limited.

Monitoring. Review every 6 to 12 months with symptom staging; yearly screening for exposed workers.

Referral and escalation. Occupational physician; vascular or rheumatology review for digital ulcers, asymmetric disease or diagnostic doubt; notification and compensation where required.