The Basis of the Paradoxical Disturbance of Temperature Perception in Ciguatera Poisoning

Abstract

The basis of the paradoxical reversal of temperature perception commonly described in ciguatera poisoning has never been defined. The sensations experienced are described as tingling, burning, “dry ice-like”, smarting, and “electric”. Studies have demonstrated that these types of sensations are generated in C-polymodal nociceptor fibers in skin and deep structures and the intensity of these sensations depends on the intensity of discharge in these fibers. Ciguatoxin causes persistent sodium channel opening in nerve membrane resulting in oscillations in membrane potentials and runs of spontaneous discharges. Studies on ciguatera victims in which their hands were immersed in water baths ranging from 0°C to 50°C, suggest the paradoxical sensory discomfort experienced is, most likely, a result of an exaggerated and intense nerve depolarization occurring in peripheral small A-delta myelinated and in particular, C-polymodal nociceptor fibers. Gross temperature perception was found to be intact in ciguatera poisoning and reversal of temperature does not occur.

KEY WORDS:

• ciguatera
• paradoxical sensation
• pruritus
• temperature perception
• nociceptor physiology
• C-polymodal fibers
• A-delta fibers
• fishes
• poisonous