Neurotoxicity of European viperids in Italy: Pavia Poison Control Centre case series 2001–2011

Abstract

Neurotoxicity may appear late (11 hours after the bite in 58.3% of cases), in contrast with the data reported in medical literature. Neurotoxic effects have been reversible in all cases and may be the unique systemic manifestation of envenomation. Neurotoxic effects are shorter in treated group. The antidotic treatment of patients considered as GSS 2 only for neurotoxic effects (with mild local effects) may not be necessary. Variable factors such as different amount of venom injected, concentration of PLA2 component, and individual susceptibility may explain the less percentage of patients presenting neurotoxic effects.

Variability in venom composition of European viper subspecies limits the cross-effectiveness of antivenoms

“…Clinical data suggest that the main neurological symptom on humans upon V . aspis envenomation is a neuromuscular blockade 5 . An accurate read out to assay the neurotoxicity of SPANs is the electrophysiological measurement of Evoked Junction Potential (EJP) amplitudes on isolated soleus muscles, following in vivo injection of the venom in the mouse hind limb 15 , 16 .…”

“…However, in most severe cases, especially in children, local effects may be very serious and systemic symptoms like gastrointestinal issues, hypotension, coagulopathy and neurotoxicity can occur as well. Neurotoxic manifestations mainly affect cranial nerves, leading to botulinum-like symptoms as ptosis, ophthalmoplegia, diplopia, dysphonia, paresthesia, dyspnea and deficit of masticatory, sternocleidomastoid, and nuchal muscles 5 . Treatment is based on hospitalization (if necessary) and on antivenom administration to prevent clinical worsening of envenomation, thus reducing long-term effects and the hospital stay.…”

“…Currently, no antivenoms have been officially licensed by the European Medicines Agency and no standardized protocols for clinical intervention are available 3 . Moreover, very little is known about the relative effectiveness of each antivenom against the viper’s venoms of a specific area, which often display highly heterogeneous compositions and cause variable clinical symptoms 5 – 7 . This limitation is particularly relevant considering the neurotoxic effects exerted by some species.…”

“…Even though it occurs rarely, neurotoxicity has historically been associated with V . ammodytes 4 , 5 , as its venom contains “snake presynaptic PLA 2 (phospholipase A2) neurotoxins” (SPANs), like vipoxin, vaspin and ammodytoxin. More recently, genetic and proteomic analyses have shown that also V .…”

“…More recently, genetic and proteomic analyses have shown that also V . aspis venom contains PLA 2 components which may be responsible for the neurological symptoms developed by bitten patients 5 , 6 , 8 . Interestingly, although PLA 2 s have been detected also in V .…”