Fatal acute disseminated encephalomyelitis following treated snake bite in India

Snakebite Envenoming a Challenging Diagnosis for the Forensic Pathologist: A Systematic Review

Snakebite envenoming (SBE) is a public health issue in developing countries. The estimated annual global incidence of snakebites is about 5.4 million snakebites per year, resulting from 1.8 to 2.7 million cases of SBE and from 81,000 to 138,000 deaths with 400,000 survivors suffering permanent physical and psychological disabilities. There are more than 3000 species of snakes around the world: 600 are venomous and over 200 are considered to be medically important because of their clinical effects. The severity of SBE depends on several factors among which bite localization, snake's size, condition of glands and teeth, bite angle and bite duration, the microflora of the snake's mouth and victim's skin, age of the victim, weight, health status, and victim's activity after a bite. Snake venoms are mixtures of protein families, and each of these families contains many different toxins or toxin isoforms. Based on their effects, snake venoms can be classified as hemotoxic, neurotoxic, or cytotoxic and they can all act together involving multiple tissues and organs. When the bite is fatal, the mechanism of death is primarily related to the paralysis of respiratory muscles, which causes asphyxia and hypoxic-ischemic encephalopathy, but also anaphylactic shock, hemorrhagic shock, cardiomyopathy, acute tubular necrosis (ATN). The purpose of this literature review is to evaluate epidemiological and post-mortem examination findings in fatal SBEs in order to better understand the pathophysiological mechanisms, thus helping pathologists in defining the correct diagnosis.

Multiple thromboembolic strokes in a toddler associated with Australian Eastern Brown snake envenomation

Venomous snakes are found in every state and territory in Australia and are amongst the most dangerous in the world. Of Australia's snakes the Eastern Brown snake (Pseudonaja textilis) is responsible for the majority of the cases of envenomation and death. We describe a case of thromboembolic stroke associated with Eastern Brown snake envenomation in a 2-year-old boy. Following the incident, the boy has made a good recovery.

Non-fatal acute haemorrhagic leukoencephalitis following snake bite: A case report

Acute haemorrhagic leukoencephalitis (AHL) is a fulminant inflammatory disease of cerebral white matter, characterised by demyelination and haemorrhagic necrosis. The outcome is usually fatal with only few survivors. An unusual presentation of a 44-year-old South Indian farmer who developed AHL following a snake bite is reported. Though the initial brain imaging showed extensive involvement of the white matter with multiple haemorrhagic foci, the patient improved spontaneously with no specific therapy. A repeat magnetic resonance imaging of the brain 28 days after the snake bite confirmed radiological improvement.

Unusual late neurological complication in a child after an Indian krait bite

BACKGROUND

Neurological manifestations of elapid snakebites include neuromuscular paralysis and cerebrovascular complications. Autonomic manifestations are observed in almost two third of patients following moderate to severe envenomation.

PATIENT SUMMARY

A 10-year-old boy presented with acute onset flaccid quadriparesis with encephalopathy, cranial neuropathy, and respiratory failure after bite of a common Indian krait. He also had features of autonomic instability in the form of hypertension and variable heart rate. Within 10 days, he was weaned from the ventilator and discharged on multiple oral antihypertensives. Within a week, he returned with focal status epilepticus. MRI of the brain suggested posterior reversible leukoencephalopathy. He recovered completely within 2 days with visual impairments while recovering. Within next 1 month, his antihypertensives were tapered completely. MRI of the brain, repeated after 3 months, confirmed complete resolution.

CONCLUSIONS

This patient highlights the fact that posterior reversible leukoencephalopathy can be a late complication of Indian krait bite secondary to autonomic instability with systemic hypertension.

Snake bite-induced leucoencephalopathy

Snake bite is an important cause of mortality and morbidity in India with an estimated 35 000-50 000 fatal bites occurring annually. Neurological deficits following vasculotoxic snake bite are either due to intracranial haemorrhage or subarachnoid bleed as a result of consumption coagulopathy. However, ischaemic strokes and acute disseminated encephalomyelitis have been reported occasionally. We hereby report a case of snake bite leading to leucoencephalopathy.

Neurological effects of venomous bites and stings: snakes, spiders, and scorpions

Snake and spider bites, as well as scorpion sting envenoming, are neglected diseases affecting millions of people all over the world. Neurological complications vary according to the offending animal, and are often directly related to toxic effects of the venom, affecting the central nervous system, the neuromuscular transmission, the cardiovascular system, or the coagulation cascade. Snake bite envenoming may result in stroke or muscle paralysis. Metalloproteinases and other substances (common in vipers and colubrids) have anticoagulant or procoagulant activity, and may induce ischemic or hemorrhagic strokes. The venom of elapids is rich in neurotoxins affecting the neuromuscular transmission at either presynaptic or postsynaptic levels. The clinical picture of scorpion sting envenoming is dominated by muscle weakness associated with arterial hypertension, cardiac arrythmias, myocarditis, or pulmonary edema. These manifestations occur as the result of release of catecholamines into the bloodstream or due to direct cardiac toxicity of the venom. Cerebrovascular complications have been reported after the sting of the Indian red scorpion. Intracranial hemorrhages occur in the setting of acute increases in arterial blood pressure related to sympathetic overstimulation, and cerebral infarctions are related to either cerebral hypoperfusion, consumption coagulopathy, vasculitis, or cardiogenic brain embolism. Three main syndromes result from spider bite envenoming: latrodectism, loxoscelism, and funnel-web spider envenoming. Latrodectism is related to neurotoxins present in the venom of widow spiders. Most cases present with headache, lethargy, irritability, myalgia, tremor, fasciculation, or ataxia. Loxoscelism is caused by envenoming by spiders of the family Sicariidae. It may present with a stroke due to a severe coagulopathy. The venom of funnel-web spiders also has neurotoxins that stimulate neurotransmitter release, resulting in sensory disturbances and muscle paralysis. Proper management of the envenomed patient, including prompt transport to the hospital, correction of the hemostatic disorder, ventilatory support, and administration of antivenom, significantly reduce the risk of neurological complications which, in turn, reduce the mortality and improve the functional outcome of survivors.

Neurological complications of venomous snake bites: a review

Snake bite envenoming is a neglected tropical disease affecting millions of people living in the developing world. According to the offending snake species, the clinical picture may be dominated by swelling and soft tissue necrosis in the bitten limb, or by systemic or neurological manifestations. Serious neurological complications, including stroke and muscle paralysis, are related to the toxic effects of the venom, which contains a complex mixture of toxins affecting the coagulation cascade, the neuromuscular transmission, or both. Metalloproteinases, serine proteases, and C-type lentins (common in viper and colubrid venoms) have anticoagulant or procoagulant activity and may be either agonists or antagonists of platelet aggregation; as a result, ischemic or hemorrhagic strokes may occur. In contrast, the venom of elapids is rich in phospholipase A(2) and three-finger proteins, which are potent neurotoxins affecting the neuromuscular transmission at either presynaptic or post-synaptic levels. Presynaptic-acting neurotoxins (called β-neurotoxins) inhibit the release of acetylcholine, while post-synaptic-acting neurotoxins (called α-neurotoxins) cause a reversible blockage of acetylcholine receptors. Proper management of the envenomed patient, including prompt transport to the hospital, correction of the hemostatic disorder, ventilatory support, and administration of antivenom, significantly reduces the risk of neurological complications which, in turn, reduce the mortality and improve the functional outcome of survivors.

Reversible posterior leukoencephalopathy in a venomous snake (Bothrops asper) bite victim

An 18-year-old man developed posterior reversible leukoencephalopaty after being bitten by a venomous snake (Bothrops asper). It is possible that this previously unrecognized neurological complication of snake bite envenoming occurred as the result of endothelial dysfunction induced by the venom of the offending snake. This pathogenetic mechanism has also been implicated as the cause of cerebral infarctions in snake bite victims. Alternatively, the leukoencephalopathy might have been a complication of antivenom therapy.

Acute demyelinating encephalomyelitis after anti-venom therapy in Russell's viper bite

INTRODUCTION

Russell's viper is a commonly encountered venomous snake in India. Morbidity and mortality following envenomation and the treatment thereof are frequent. We report a rarely seen complication after a treated Russell's viper bite.

CASE REPORT

A 36-year-old male farmer received 30 vials polyvalent anti-snake venom after a viper bite to his right leg. Improvement in initial hematemesis and circulatory shock was followed by acute renal failure managed with regular hemodialysis. He displayed no abnormalities on neurological examination at admission. Fourth day onwards his neurologic status started deteriorating with development of behavioral abnormalities, hemi-spatial neglect of left upper limb, paralysis of left facial nerve, left upper limb, and right lower limb. Acute disseminated encephalomyelitis was confirmed on magnetic resonance imaging (MRI) of brain with typical spectroscopic characteristics. High dose methyl prednisolone was administered and a rapid recovery followed.

CONCLUSION

Russell's viper bite followed by treatment with antivenom may be complicated by the development of immune complex mediated demyelination and development of acute disseminated encephalomyelitis. MRI spectroscopy helps in early identification of demyelination and in a definite diagnosis. Treatment with corticosteroids was associated with resolution of symptoms in this case.

Postoperative acute disseminated encephalomyelitis after exposure to microfibrillar collagen hemostat

Microfibrillar collagen hemostat, known by its trade name Avitene, has been used in neurosurgery for decades. Complications with this product have been documented in other surgical specialties and described as mostly immune-mediated foreign-body reactions that can lead to a granulomatous reaction. There has never been a case of disseminated encephalomyelitis associated with this topical hemostatic agent. In this report the authors present a case of postoperative acute disseminated encephalomyelitis after exposure to Avitene. Possible pathophysiological mechanisms are discussed and the pertinent literature is reviewed.