What are the treatment options for neuritis and numbness in hands extending to arms after weeks of welding?

Occupational Peripheral Neuropathy from Welding Exposure

Immediate Management Priority

For neuritis and numbness in hands extending to arms after weeks of welding, immediately cease welding exposure and implement comprehensive nerve protection strategies, as manganese-containing welding fumes can cause irreversible neurological damage requiring urgent occupational medicine evaluation. 1

Initial Assessment and Risk Factor Identification

Critical History Elements

• Body habitus, preexisting neurologic symptoms, diabetes mellitus, peripheral vascular disease, alcohol dependency, and arthritis must be reviewed as these increase susceptibility to peripheral neuropathies 2
• Duration and intensity of welding exposure, specifically to manganese-containing fumes which bypass the blood-brain barrier via olfactory nerve transport 1
• Specific welding positions used, as prolonged arm abduction >90° or excessive elbow flexion increases brachial plexus and ulnar nerve injury risk 2

Physical Examination Focus

• Distribution of numbness and weakness to differentiate between specific nerve territories (ulnar, median, radial, brachial plexus) versus toxic neuropathy 3, 4
• Two-point discrimination testing, as impaired 2-PD indicates significant sensory nerve damage 5
• Assessment of hand coordination and muscular function 5

Diagnostic Workup

Electrodiagnostic Studies (Priority Testing)

• Nerve conduction studies and electromyography should be performed 3-4 weeks after symptom onset to allow abnormal spontaneous activity to develop and provide maximal diagnostic information 6
• Studies differentiate between demyelinating versus axonal injury patterns and establish prognosis 4
• The "sural sparing pattern" helps differentiate focal entrapment from toxic polyneuropathy 3

Imaging When Indicated

• MRI with T2-weighted neurography is reference standard if focal entrapment suspected, showing high signal intensity and nerve enlargement 3, 4
• Ultrasound provides effective alternative with 77-79% sensitivity and 94-98% specificity for nerve assessment 3, 4

Treatment Algorithm

Phase 1: Immediate Occupational Intervention (Days 1-7)

• Complete cessation of welding exposure as manganese neurotoxicity can progress to irreversible manganism 1
• Implement engineering controls including ventilation and respiratory protection if return to welding considered 1
• Document 78 cases of probable/possible occupational manganism have been identified in welding literature 1

Phase 2: Positioning and Ergonomic Modifications (Ongoing)

For upper extremity protection:

• Limit arm abduction to ≤90° during any activities 2, 3
• Maintain neutral or supinated forearm position to decrease pressure on ulnar groove 2, 3
• Avoid elbow flexion >90° as this significantly increases ulnar neuropathy risk 2, 4
• Apply foam or gel padding at elbows, but ensure not too tight as excessive compression paradoxically increases nerve injury 3

Phase 3: Pharmacologic Management

For neuropathic pain and numbness:

• Duloxetine 30mg daily for first week, then increase to 60mg daily provides 30-50% pain reduction and improves numbness/tingling 2
• This represents the highest quality evidence for neuropathic symptom management in peripheral neuropathy 2

For localized pain:

• Paracetamol up to 4g/day as first-line oral analgesic 3, 4
• Topical NSAIDs for localized areas with fewer systemic effects 3, 4
• Oral NSAIDs at lowest effective dose if inadequate paracetamol response 4

Phase 4: Physical Rehabilitation

• Range of motion and strengthening exercises to maintain function 3, 4
• Local heat application before exercise 4
• Physical activity has demonstrated improvement in neuropathy symptoms in multiple RCTs 2

Phase 5: Alternative Therapies (If Standard Treatment Insufficient)

• Acupuncture may provide benefit with statistically significant improvements in physical and function domains (P=.03 and P=.04) 2
• However, electro-acupuncture showed no superiority over sham in one trial 2
• Scrambler therapy showed twice as many patients achieving ≥50% improvement versus TENS 2

Critical Pitfalls to Avoid

• Do not continue welding exposure while awaiting diagnostic workup, as manganese neurotoxicity can become irreversible 1
• Avoid acetyl-L-carnitine as ASCO guidelines specifically recommend against its use for peripheral neuropathy prevention 2
• Do not delay electrodiagnostic studies beyond 3-4 weeks as earlier testing may miss critical findings 6
• Avoid vitamin E supplementation as high-quality trials show no benefit (RR 1.03,95% CI 0.59-1.80, P=.92) 2
• Do not apply padding too tightly at pressure points as this creates tourniquet effect worsening nerve compression 3

Prognosis and Monitoring

• Proximal nerve injuries have poorer prognosis for neurological recovery 6
• Regular follow-up monitoring is essential to assess for progression versus improvement 3
• Recovery from occupational neuropathy is typically slow but can be complete if exposure ceased early 7
• Some patients may develop permanent neurological deficits if exposure continues 6