Venom ophthalmia caused by venoms of spitting elapid and other snakes: Report of ten cases with review of epidemiology, clinical features, pathophysiology and management

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.

Wilderness Medical Society practice guidelines for treatment of eye injuries and illnesses in the wilderness

A panel convened to develop an evidence-based set of guidelines for the recognition and treatment of eye injuries and illnesses that may occur in the wilderness. These guidelines are meant to serve as a tool to help wilderness providers accurately identify and subsequently treat or evacuate for a variety of ophthalmologic complaints. Recommendations are graded based on the quality of their supporting evidence and the balance between risks and benefits according to criteria developed by the American College of Chest Physicians.

Frog saliva-induced toxic keratopathy: a case report

Corneal toxicity due to exposure to many chemicals and medications have been described in the literature. We present a case of toxic keratopathy by corneal exposure to salivary secretion of a frog. A 40-year-old male patient reported a sudden splash of frog saliva in his right eye while he was examining it at a close distance. Corneal punctate epitheliopathy and stromal oedema and Descemet folds were the initial clinical findings, which completely recovered on the 2nd control day of topical dexamethasone and ofloxacin treatment. We aimed to show the toxic effects of animal-derived secretions on the cornea as a rare cause of toxic keratopathy.

Ventricular bigeminy following a cobra envenomation

CONTEXT

Envenoming by some species of cobras (Naja species) may include cardiotoxic effects including various dysrhythmias. However, dysrhythmias leading specifically to ventricular bigeminy have not been previously documented. We report a case of cardiotoxicity and the development of ventricular bigeminy following a cobra envenomation.

CASE DETAILS

The patient was a 23-year-old man who presented to an emergency department following an alleged cobra bite. There was transient episode of nausea, vomiting, hypotension and tachycardia. The ECG showed infrequent ventricular ectopics that progressed to ventricular bigeminy and persisted even after the vital signs normalized. Complete resolution and resumption of normal sinus rhythm occurred following an empirical administration of monovalent antivenom against Naja kaouthia venom. The patient was discharged after 24 hours of uneventful observation.

DISCUSSION

The patient's concomitant local effects, episodic cardiovascular instability and evolution of ventricular bigeminy support the likelihood of a venom-induced disease. Ventricular bigeminy can develop following a cobra envenomation. Thorough clinical evaluation, close serial observation of vital signs and early continuous cardiac monitoring are important in Naja spp. bites.

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.

Toxin ophthalmia caused by nuchal gland secretion of the Taiwan tiger keelback (Rhabdophis tigrinus formosanus)

Rhabdophis tigrinus is a common colubrid snake that can be found in an extensive geographical region in East Asia. It consists of two subspecies: R.t. tigrinus (yamakagashi) and R.t. formosanus (Taiwan tiger keelback). R. tigrinus possesses two different sets of poisonous glands: the Duvernoy's glands in the maxilla, and the nuchal glands in the dorsal skin of the neck. We report the first case in current English literature of toxin ophthalmia caused by the nuchal gland secretion of R.t. formosanus. The patient was a 40-year-old man whose right eye was sprayed by the nuchal gland fluid of R.t. formosanus. He presented with symptoms of foreign body sensation, progressive burning pain, and blurred vision. Ophthalmologic examination revealed diffuse superficial punctate keratitis, corneal stromal edema with Descemet folds, and conjunctival congestion. The patient responded well to topical treatment with a corticosteroid, antihistamine, and antibiotic, and had a favorable clinical course and outcome.

Clinical toxinology

Clinical toxinology is a specialized area of clinical medicine focused on the pathophysiology, diagnosis, treatment, and prevention of diseases caused by animal, plant, and fungal toxins. This review focuses on recent developments in snakebite. Snakebite is newly recognized as a Neglected Tropical Disease by the World Health Organization (WHO), reflecting the large human and economic cost of this disease. New WHO guidelines on antivenom production are available. The methods of producing antivenom and dosing are changing as understanding of envenoming improves. Lower antivenom doses in some regions are delivering equal outcomes, but antivenom cannot fully treat all envenoming types. Early antivenom treatment may reduce local tissue damage in some types of snakebite.