Wrist drop, foot drop, and paresthesias are classic neuropathic features of poisoning with which element?

• A. Arsenic
• B. Lead
• C. Mercury
• D. Cyanide

Answer: (B)

Wrist drop with foot drop and paresthesias reflect a motor and sensory peripheral neuropathy pattern caused by lead poisoning. Lead disrupts nerve function, and the most characteristic effect in adults is a demyelinating-axonal neuropathy that hits the extensor muscles of the wrist and fingers, producing wrist drop; similar weakness can occur in the feet. Paresthesias accompany the weakness as sensory fibers are affected. Among the metals listed, this classic neuropathic presentation is most strongly associated with lead, whereas arsenic, mercury, and cyanide tend to produce different primary toxic effects or neuropathies that do not classically present as wrist drop with paresthesias.