Posterior reversible encephalopathy syndrome following a scorpion sting

Unraveling and profiling Tityus bahiensis venom: Biochemical analyses of the major toxins

Among the scorpions found in Brazil, Tityus bahiensis is one of the species that causes most of the reported human accidents. In spite of this important constatation, the venom composition description is not available in the literature. Thus, this venom remains not properly studied, segregating this particular species into an abandoned, forgotten condition. In the present study, chromatographic separation (RP-HPLC-C18) and proteomic analyses were employed to unravel the diversity, complexity, and proportional distribution of the main peptides and proteins found in the scorpion venom. Moreover, sequence analyses and the presence of new isoforms and toxins are discussed based on a database comparison with other Tityus toxins. Our results show the presence of a wide diversity of potassium and sodium channel toxins and enzymes, such as metallopeptidases and hyaluronidases, as previously described for other species. However, the current work also describes for the first time, at the protein level, phospholipase, angiotensin-converting enzyme, cysteine-rich proteins, serine peptidase inhibitors peptides, and antimicrobial peptides. Finally, thorough data analyses allowed the description of the venom toxins distribution regarding their diversity and relative quantity. SIGNIFICANCE: The work presents the first Tityus bahiensis proteome. We have focused on describing the neurotoxin variability in terms of their isoforms/amino acid substitutions. Understanding the natural variations in the toxins' sequences is essential, once the affinity of these peptides to their respective receptors/ionic channels will vary depending on the specific peptide sequences. Moreover, the current study describes some proteins present in the venom, including enzymes being described for the first time in scorpion venoms, such as PLA2 and ACE. Moreover, we describe the individual relative quantity distribution for the different protein classes identified, as well as their variability in the T.bahiensis venom. Finally, this study also reports the development of a simple straightforward chromatographic method for scorpion venom fractionation.

Cerebral Complications of Snakebite Envenoming: Case Studies

There are an estimated 5.4 million snakebite cases every year. People with snakebite envenoming suffer from severe complications, or even death. Although some review articles cover several topics of snakebite envenoming, a review of the cases regarding cerebral complications, especially rare syndromes, is lacking. Here, we overview 35 cases of snakebite by front-fanged snakes, including Bothrops, Daboia, Cerastes, Deinagkistrodon, Trimeresurus, and Crotalus in the Viperidae family; Bungarus and Naja in the Elapidae family, and Homoroselaps (rare cases) in the Lamprophiidae family. We also review three rare cases of snakebite by rear-fanged snakes, including Oxybelis and Leptodeira in the Colubridae family. In the cases of viper bites, most patients (17/24) were diagnosed with ischemic stroke and intracranial hemorrhage, leading to six deaths. We then discuss the potential underlying molecular mechanisms that cause these complications. In cases of elapid bites, neural, cardiac, and ophthalmic disorders are the main complications. Due to the small amount of venom injection and the inability to deep bite, all the rear-fanged snakebites did not develop any severe complications. To date, antivenom (AV) is the most effective therapy for snakebite envenoming. In the six cases of viper and elapid bites that did not receive AV, three cases (two by viper and one by elapid) resulted in death. This indicates that AV treatment is the key to survival after a venomous snakebite. Lastly, we also discuss several studies of therapeutic agents against snakebite-envenoming-induced complications, which could be potential adjuvants along with AV treatment. This article organizes the diagnosis of hemotoxic and neurotoxic envenoming, which may help ER doctors determine the treatment for unidentified snakebite.

Posterior reversible encephalopathy syndrome (PRES): diagnosis and management

Posterior reversible encephalopathy syndrome (PRES) may present with diverse clinical symptoms including visual disturbance, headache, seizures and impaired consciousness. MRI shows oedema, usually involving the posterior subcortical regions. Triggering factors include hypertension, pre-eclampsia/eclampsia, renal failure, cytotoxic agents and autoimmune conditions. The mechanism underlying PRES is not certain, but endothelial dysfunction is implicated. Treatment is supportive and involves correcting the underlying cause and managing associated complications, such as seizures. Although most patients recover, PRES is not always reversible and may be associated with considerable morbidity and even mortality.

Posterior Reversible Encephalopathy Syndrome in Clinical Toxicology: A Systematic Review of Published Case Reports

Background: Posterior reversible encephalopathy syndrome (PRES) is a rare clinical and radiological entity characterized by a typical brain edema. Although several case reports have described PRES in a context of poisoning, to our knowledge, a comprehensive assessment has not been performed. The aim of this systematic review was to raise awareness on poisoning-specific PRES features and to encourage consistent and detailed reporting of substance abuse–and drug overdose–associated PRES.

Methods: Medline/PubMed, Web of Science, and PsycINFO were screened through May 31, 2019, to systematically identify case reports and case series describing PRES associated with poisoning (i.e., alcohol, drugs, illicit drugs, natural toxins, chemical substances) in accidental context, intentional overdose, and substance abuse. The methodological quality of eligible case reports/series was assessed. Patients and exposure characteristics were recorded; relevant toxicological, radiological, and clinical data were extracted.

Results: Forty-one case reports and one case series reporting 42 unique cases were included. The median time to PRES onset from the start of exposure was 3 days (IQR 2–10). Acute high blood pressure, visual disturbance, and seizure were reported in 70, 55, and 50% of patients, respectively. The initial clinical presentation was alertness disorders in 64% of patients. Nine patients (21%) required mechanical ventilation. One-third of patients had at least one risk factor for PRES such as chronic hypertension (17%) or acute/chronic kidney failure (24%). The main imaging pattern (67%) was the combination of classical parieto-occipital edema with another anatomical region (e.g., frontal, basal ganglia, posterior fossa involvement). Vasogenic edema was found in 86% of patients. Intracranial hemorrhage occurred in 14% of patients. Both brain infarction and reversible cerebral vasoconstriction syndrome were diagnosed in 5% of patients. Three patients (12%, 3/25) had non-reversible lesions on follow-up magnetic resonance imaging. The median time required to hospital discharge was 14 days (IQR 7–18). Mortality and neurological recurrence rate were null.

Conclusions: Comorbidities such as chronic hypertension and kidney failure were less frequent than in patients with other PRES etiologies. Imaging analysis did not highlight a specific pattern for poisoning-induced PRES. Although less described, PRES in the context of poisoning, which shares most of the clinical and radiological characteristics of other etiologies, is not to be ignored.

Effects of Brazilian scorpion venoms on the central nervous system

In Brazil, the scorpion species responsible for most severe incidents belong to the Tityus genus and, among this group, T. serrulatus, T. bahiensis, T. stigmurus and T. obscurus are the most dangerous ones. Other species such as T. metuendus, T. silvestres, T. brazilae, T. confluens, T. costatus, T. fasciolatus and T. neglectus are also found in the country, but the incidence and severity of accidents caused by them are lower. The main effects caused by scorpion venoms - such as myocardial damage, cardiac arrhythmias, pulmonary edema and shock - are mainly due to the release of mediators from the autonomic nervous system. On the other hand, some evidence show the participation of the central nervous system and inflammatory response in the process. The participation of the central nervous system in envenoming has always been questioned. Some authors claim that the central effects would be a consequence of peripheral stimulation and would be the result, not the cause, of the envenoming process. Because, they say, at least in adult individuals, the venom would be unable to cross the blood-brain barrier. In contrast, there is some evidence showing the direct participation of the central nervous system in the envenoming process. This review summarizes the major findings on the effects of Brazilian scorpion venoms on the central nervous system, both clinically and experimentally. Most of the studies have been performed with T. serrulatus and T. bahiensis. Little information is available regarding the other Brazilian Tityus species.

A Horned Viper Bite Victim with PRES

Neurological complications of snake bites have been well documented in the literature as neuromuscular paralysis and cerebrovascular complications; posterior reversible encephalopathy syndrome was rarely described. A 23-year-old lady presented near full term of her pregnancy with a horned snake Cerastes cerastes bite; after successful delivery she started complaining of altered mental status and visual disturbance with ulceration over the site of the snake bite. On admission, the patient had Glasgow Coma Score of 12, blood pressure 130/80 mmHg, temperature 38°C, sinus tachycardia at 120 beats per minute, severe dehydration, and reduction in visual acuity to "hand motion" in both eyes with poor light projection and sluggish pupillary reactions. CT brain was not conclusive; MRI revealed features of PRES. Treatment was mostly supportive within one week; the patient regained consciousness; visual disturbance, however, persisted. This patient as well as the few previously described cases highlights PRES as a possible complication of snake bites.

PRES with asymptomatic spinal cord involvement. Is this scenario more common than we know?

INTRODUCTION

Posterior reversible encephalopathy syndrome (PRES) is an entity characterized by neurologic symptoms such as headaches, altered mental status, seizures and visual changes, and it is associated with white matter vasogenic edema predominantly affecting the posterior occipital and parietal lobes of the brain.

CASE REPORT

A 19-year-old patient developed PRES after the use of chemotherapy for a testicular teratocarcinoma and after the development of a blood pressure elevation.

DISCUSSION

Few cases described the involvement of the spinal cord in this syndrome. In the majority of these cases, the spinal cord involvement was asymptomatic or with few symptoms of spinal cord disease.

Posterior Reversible Encephalopathy Syndrome in a Child Stung by Androctonus mauretanicus Scorpion

Posterior reversible encephalopathy syndrome (PRES) after scorpion sting was very rarely reported in literature. This is an authenticated report of PRES occurring, in a 3-year-old previously healthy girl, as a complication of the Moroccan Androctonus mauretanicus sting. According to the available and recent data, we attempt to discuss the potential mechanisms leading to this neurologic disorder and to determine the possible cause-effect relationship between scorpion venom and its development.

Posterior reversible encephalopathy syndrome: differences between pregnant and non-pregnant patients

Posterior reversible encephalopathy syndrome (PRES) is a clinical-radiologic entity not yet understood, that presents with transient neurologic symptoms and particular radiological findings. Few papers show the differences between pregnant and non-pregnant patients. We review the cases of 38 women diagnosed with PRES, in order to find significant differences between pregnant (18) and non-pregnant (20) patients. We found differences among the age of patients (25.83 years old in pregnant and 29.31 years old in non pregnant; P=0.001); in the mean of highest systolic blood pressure, that was higher in non-pregnant group (185:162 mmHg; P=0.121); and in creatinine levels that was higher in non-pregnant group (3.47:1.04 mg/dL; P=0.001). To our knowledge, just a few papers analyzed whether PRES syndrome presented in the same way in pregnant and non-pregnant patients. The differences and the possible pathophisiology of this syndrome still remain enigmatic.