Acute painful neuropathy in thallium poisoning.

Dysesthesia, allodynia, distal muscle weakness, and sensory impairment were noted in two patients with acute thallium intoxication. Two months later, nerve conduction studies showed an axonal degeneration. Sural nerve biopsy disclosed a decreased fiber density in the large myelinated fibers. Quantitative sensory testing also revealed an impairment of pinprick, temperature, and touch sensations. Cutaneous nerve biopsy confirmed a loss of epidermal nerves indicating an involvement of the small sensory nerves.