Complex regional pain syndrome following viper-bite

Area of Science:

• Neurology
• Toxicology
• Dermatology

Background:

• Complex regional pain syndrome (CRPS) is a debilitating condition typically following trauma, surgery, or fractures.
• While snake bites are common globally, CRPS development post-snakebite is rarely reported, with no prior cases from Western Europe.
• Vipera Berus, a prevalent snake in Europe and Norway, presents a potential, underreported cause of CRPS.

Observation:

• A case study details a young woman who developed CRPS in her right arm after a Vipera Berus snake bite.
• Clinical investigations six months post-bite included sensory and motor evaluations, quantitative sensory testing (QST), resting sweat output (RSO), and quantitative sudomotor axon reflex (QSART).
• The patient met Budapest criteria for CRPS, exhibiting continuous pain, autonomic dysfunction, and altered thermal thresholds.

Findings:

• Quantitative sensory testing revealed elevated warmth and cold thresholds, indicating damage to afferent A-delta and C-fibers.
• Quantitative sudomotor axon reflex testing showed impairment of efferent sympathetic sudomotor C-fibers.
• An increased resting sweat output volume was inversely correlated with decreased QSART results, suggesting complex autonomic involvement.

Implications:

• Viper bites should be recognized as a potential trigger for CRPS, necessitating early diagnosis and treatment.
• CRPS following viper bites may be underdiagnosed due to lack of awareness and patients not realizing they were bitten.
• Unexplained sudden limb pain and swelling warrant consideration of a potential viper bite, especially in endemic areas.