Lithium toxicity and PRES: a novel association

[Neurological complications attributable to lithium: An update]

Lithium intoxication may induce neurological complications, initially characterised by a conscience alteration and an encephalopathy clinical picture with a risk of death or sever long-term consequences. With an occurrence sometimes atypical and possibly without initial hyperlitemia, the diagnosis delay of these complications might be important. Moreover, no specific guidelines focused on these complications are available. The aim of this article is to propose an update on diagnosis and treatment of neurological complications attributable to lithium, as encephalopathy.

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.

Lithium - Pharmacological and Toxicological Aspects: The Current State of the Art

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Lithium is the smallest monovalent cation with many different biological effects. Although lithium is present in the pharmacotherapy of psychiatric illnesses for decades, its precise mechanism of action is still not clarified. Today lithium represents first-line therapy for bipolar disorders (because it possesses both antimanic and antidepressant properties) and the adjunctive treatment for major depression (due to its antisuicidal effects). Beside, lithium showed some protective effects in neurological diseases including acute neural injury, chronic degenerative conditions, Alzheimer's disease as well as in treating leucopenia, hepatitis and some renal diseases. Recent evidence suggested that lithium also possesses some anticancer properties due to its inhibition of Glycogen Synthase Kinase 3 beta (GSK3β) which is included in the regulation of a lot of important cellular processes such as: glycogen metabolism, inflammation, immunomodulation, apoptosis, tissue injury, regeneration etc.

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Although recent evidence suggested a potential utility of lithium in different conditions, its broader use in clinical practice still trails. The reason for this is a narrow therapeutic index of lithium, numerous toxic effects in various organ systems and some clinically relevant interactions with other drugs. Additionally, it is necessary to perform more preclinical as well as clinical studies in order to a precise therapeutic range of lithium, as well as its detailed mechanism of action. The aim of this review is to summarize the current knowledge concerning the pharmacological and toxicological effects of lithium.

Arginine Vasopressin and Posterior Reversible Encephalopathy Syndrome Pathophysiology: the Missing Link?

Posterior reversible encephalopathy syndrome (PRES) is a clinicoradiological entity characterized by a typical brain edema. Its pathogenesis is still debated through hypoperfusion and hyperperfusion theories, which have many limitations. As PRES occurs almost exclusively in clinical situations with arginine vasopressin (AVP) hypersecretion, such as eclampsia and sepsis, we hypothesize that AVP plays a central pathophysiologic role. In this review, we discuss the genesis of PRES and its symptoms through this novel approach. We theorize that AVP axis stimulation precipitates PRES development through an increase in AVP secretion or AVP receptor density. Activation of vasopressin V_1a receptors leads to cerebral vasoconstriction, causing endothelial dysfunction and cerebral ischemia. This promotes cytotoxic edema through hydromineral transglial flux dysfunction and may increase endothelial permeability, leading to subsequent vasogenic brain edema. If our hypothesis is confirmed, it opens new perspectives for better patient monitoring and therapies targeting the AVP axis in PRES.