Can snake bite cause ischemic stroke

Snake bite and related complications are common. Bleeding manifestation is one of the dreaded complication mainly IC bleed, but ischemic stroke is rare complication following snake bite.

What is the evidence ?

There are multiple case reports and case series. 

• Sahoo et al (Indian J Crit Care Med. 2018 ) had reported a case of snake bite (hematotoxic) leading to  ischemic stroke.
• Siddalingana et al (Annals of Indian Academy of Neurology.2014) has reported a case of posterior circulation ischemic stroke following russels viper bite.
• Huang et al (Toxins. 2022) in his review article on cerebral complications of snake bite envenoming has reported that ischemic stroke is most frequent CNS complication  following viper envenomation. 
• Jeevagan et al  (Thrombosis Journal.2012) has reported a case of ischemic stroke following humped nose pit viper bite. 

Mechanism

• Viper venom has both anticoagulant and procoagulant effect. the procoagulation and platelet-aggregating properties are due to the presence of cerastobin, factor IVa, cerastocytin, cerastotin, and afaacytin.  These various protein products have thrombin-like enzyme activity; different toxins activate different parts of the coagulation cascade, resulting in the formation of fibrin in the blood stream that leads to small and even large vessel occlusions due to the micro-thrombi which in turn will result in cerebral infarction, or toxin which may cause severe vasospasm.

• Toxic vasculitis may also lead to infract. 

• Hyperviscosity caused by hypovolemia may also lead to vessel occlusion. 

Presumed mechanisms for cerebral complications following snakebite envenoming. SVMPs: Snake-venom metalloproteinases; SVSPs: Snake-venom serine proteases; PLA₂: Phospholipase A2; LAAOs: L-amino-acid oxidase; Snaclecs: Snake C-type lectin-like proteins; N/A: Not applied.

Conclusion

• Ischemic stroke following snake bite is rare complication. multiple mechanism are attributed to developed of ischemic stroke, procoagulation &  platelet aggregation properties of venom is believed to be the main pathway. Russels viper is believed to more associated with ischemic complication.

Reference

• Sahoo AK, Sriramka B. Acute Reversible Ischemic Stroke after Snake Bite. Indian J Crit Care Med. 2018 Aug;22(8):611-612. doi: 10.4103/ijccm.IJCCM_455_17. PMID: 30186014; PMCID: PMC6108302.

• Toxins 2022, 14(7), 436; https://doi.org/10.3390/toxins14070436