"CHOICES": An acronym to aid in delineating potential causes of non-metabolic, non-infectious acute toxic leukoencephalopathy

Cough elixir overdose causing toxic leuco-encephalopathy and serotonin syndrome

Acute toxic leukoencephalopathy and serotonin syndrome are rare neurological complications associated with various drugs and toxins, some of which overlap. However, the co-occurrence of these conditions is poorly documented. We present the case of a 14-year-old boy who suddenly developed altered consciousness and autonomic dysfunction after consuming excessive quantities of cough remedies containing dextromethorphan, chlorphenamine, dichlorobenzyl alcohol, and amylmetacreson. Magnetic resonance imaging of the brain revealed distinct white matter lesions. With supportive care, the patient rapidly improved, and the magnetic resonance imaging abnormalities disappeared. The swift resolution, typical magnetic resonance imaging findings, and a history of exposure to drugs affecting the central nervous system's serotonergic system suggested concurrent acute toxic leukoencephalopathy and serotonin syndrome. The components of cough medications can be hazardous in overdose due to their potential to enhance serotonin toxicity and cause direct or indirect central nervous system white matter damage. Early recognition and appropriate treatment are essential for recovery.

Toxic leukoencephalopathy versus delayed post-hypoxic leukoencephalopathy after oral morphine sulphate overdose

Toxic leukoencephalopathy (TLE) is a rare pathology caused by various substances including opioids (notably heroin), immunosuppressants, chemotherapy agents, cocaine, alcohol and carbon monoxide. However, although heroin is metabolised by the body into morphine, there is a striking paucity in cases of primary oral morphine-induced TLE, especially in the adult population. We present the case of a man in his 40s admitted to hospital in respiratory depression with a Glasgow Coma Scale (GCS) score of 6 after taking an overdose of oral morphine sulphate. Following a complete recovery to baseline, he was then readmitted with an acute deterioration in his neurobehavioural condition. Initial investigations returned normal but MRI showed changes characteristic for TLE.In cases of opioid toxicity such as ours, TLE is difficult to differentiate from delayed post-hypoxic leukoencephalopathy, due to their similar clinical presentation, disease progression and radiological manifestation. We explore how clinicians can approach this diagnostic uncertainty.

Case Report: MRI, Clinical, and Pathological Correlates of Bromethalin Toxicosis in Three Dogs

Bromethalin toxicosis is an increasingly common clinical presentation in dogs that may be fatal depending on the extent of intoxication. Antemortem diagnosis of bromethalin toxicosis was achieved in three dogs by demonstration of the active metabolite desmethylbromethalin in fat or serum. Magnetic resonance imaging (MRI) findings were consistent with a diffuse leukoencephalopathy with restricted diffusion and prominent involvement of the corticospinal motor tracts on T2-weighted and diffusion-weighted sequences. Imaging findings were confirmed in one non-surviving dog at necropsy. Resolution of MRI abnormalities was demonstrated in one surviving dog that was consistent with the associated resolution of clinical signs. Initial findings in these dogs support further investigation of specific MRI patterns in cases of leukoencephalopathy to aid differential diagnosis. While antemortem detection of bromethalin and its metabolites confirms exposure, quantitation may be informative as a prognostic biomarker.

Central Nervous System Systemic Lupus Erythematosus: Pathophysiologic, Clinical, and Imaging Features

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by multiple immunologic abnormalities and has the potential to involve the central nervous system (CNS). The prevalence of SLE seems to be growing, possibly because of earlier diagnosis and improved survival; however, the associated mortality is still high. The mortality is associated with disease-related risk factors such as lupus disease activity, young age, and organ damage or with antiphospholipid syndrome (APS). Neuropsychiatric SLE (NPSLE), which is caused by SLE-related CNS involvement, comprises a broad range of neurologic and psychiatric manifestations with varying severity, which can make this disease indistinguishable from other conditions that are unrelated to SLE. No unifying pathophysiology has been found in the etiology of NPSLE, suggesting that this condition has multiple contributors such as various immune effectors and the brain-intrinsic neuroimmune interfaces that are breached by the immune effectors. The postulated neuroimmune interfaces include the blood-brain barrier, blood-cerebrospinal fluid barrier, meningeal barrier, and glymphatic system. On the basis of the immunologic, pathologic, and imaging features of NPSLE, the underlying pathophysiology can be classified as vasculitis and vasculopathy, APS, demyelinating syndrome, or autoimmune antibody-mediated encephalitis. Each pathophysiology has different imaging characteristics, although the imaging and pathophysiologic features may overlap. Moreover, there are complications due to the immunocompromised status caused by SLE per se or by SLE treatment. Radiologists and clinicians should become familiar with the underlying mechanisms, radiologic findings, and complications of NPSLE, as this information may aid in the diagnosis and treatment of NPSLE. Online supplemental material is available for this article. ^©RSNA, 2022.

Neurocognitive impairments and brain abnormalities resulting from opioid-related overdoses: A systematic review

BACKGROUND

Non-fatal opioid-related overdoses have increased significantly over the past two decades and there have been increasing reports of brain injuries and/or neurocognitive impairments following overdose events. Limited preclinical research suggests that opioid overdoses may cause brain injury; however, little is known about such injuries in humans. The purpose this systematic review is to summarize existing studies on neurocognitive impairments and/or brain abnormalities associated with an opioid-related overdose in humans.

METHODS

PubMed, Web of Science, Ovid MEDLINE and PsyINFO were searched, without year restrictions, and identified 3099 articles. An additional 24 articles were identified by reviewing references. Articles were included if they were published in English, reported study findings in humans, included individuals 18 years of age or older, and reported an objective measure of neurocognitive impairments and/or brain abnormalities resulting from an opioid-related overdose. Six domains of bias (selection, performance, attrition, detection (two dimensions) and reporting were evaluated and themes were summarized.

RESULTS

Seventy-nine journal articles, published between 1973-2020, were included in the review. More than half of the articles were case reports (n = 44) and there were 11 cohort studies, 18 case series, and 6 case-control studies. All of the studies were categorized as at-risk of bias, few controlled for confounding factors, and methodological differences made direct comparisons difficult. Less than half of the studies reported toxicology results confirming an opioid-related overdose; 64.6 % reported brain MRI results and 27.8 % reported results of neuropsychological testing. Only two studies had within subject comparative data to document changes in the brain possibly associated with an overdose. Despite these limitations, existing publications suggest that brain injuries and neurocognitive impairments are associated with opioid overdose. Additional research is needed to establish the incidence of overdose-related brain injuries and the potential impact on functioning, as well as engagement in treatment of substance use disorders.

CONCLUSIONS

Respiratory depression is a defining characteristic of opioid overdose and prolonged cerebral hypoxia may cause brain injuries and/or neurocognitive impairments. The onset, characteristics, and duration of such injuries is variable and additional research is needed to understand their clinical implications.

Leukoencephalopathy with transient splenial lesions related to 5-fluorouracil or capecitabine

BACKGROUND

5-Fluorouracil (5-FU) and its oral prodrug capecitabine have been rarely but consistently associated with acute central nervous system toxicity, including transient leukoencephalopathies involving the splenium of the corpus callosum.

METHODS

We performed a retrospective search in the French Pharmacovigilance database (FPDB) (January 1985-July 2020) for adult patients affected by solid cancers who developed acute toxic leukoencephalopathies with splenial lesions following treatment with 5-FU or capecitabine. A comprehensive review of the literature helped to circumstantiate our findings.

RESULTS

Our research in the FPDB identified six patients who, within 3 days from their first cycle of 5-FU or capecitabine, developed acute neurological symptoms, including gait ataxia (n = 4), dysarthria (n = 3), dysmetria (n = 2), headache (n = 2), and confusion (n = 2). Brain magnetic resonance imaging (MRI) showed T2/FLAIR (fluid-attenuated inversion recovery) hyperintensities in the corpus callosum, with diffusion restriction and no contrast enhancement, generally accompanied by additional alterations in the bilateral supratentorial white matter (n = 5). All patients discontinued the agent supposedly responsible for the toxicity and experienced full recovery after a median of 8.5 days from symptom onset. Control MRI showed a progressive normalization of acute MRI abnormalities. Literature review identified 26 cases with similar clinical and paraclinical characteristics. A single patient from the literature resumed 5-FU at a lower dose, with no recurrent toxicity.

CONCLUSIONS

5-FU and capecitabine might be responsible for acute leukoencephalopathies with transient splenial lesions that are generally reversible upon drug discontinuation. Resuming the agent responsible for toxicity might be feasible in selected cases, after having excluded dihydropyrimidine dehydrogenase deficiency, if expected benefits outweigh the risks.

Potentially Reversible and Recognizable Acute Encephalopathic Syndromes: Disease Categorization and MRI Appearances

"Encephalopathy" is a vague term that encompasses varying definitions, often with a nonspecific clinical presentation and numerous possible pathophysiologic causes. Hence, MR imaging plays a crucial role in the early diagnosis and treatment by identifying imaging patterns when there is limited clinical history in such patients with acute encephalopathy. The aim of this review was to aid in remembrance of etiologies of potentially reversible acute encephalopathic syndromes on MR imaging. The differential includes vascular (reversible cerebral vasoconstriction syndrome, transient global amnesia, disseminated intravascular coagulation, and thrombotic microangiopathy), infection (meningitis, encephalitis), toxic (posterior reversible encephalopathy syndrome, acute toxic leukoencephalopathy; carbon monoxide, alcohol-related, medication- and illicit drug-related toxic encephalopathies), autoimmune, metabolic (osmotic demyelination syndrome, uremic, acute hepatic encephalopathy), idiopathic/inflammatory (stroke-like migraine attacks after radiation therapy syndrome), neoplasm-related encephalopathy, and seizure-related encephalopathy.

Pediatric Acute Toxic Leukoencephalopathy: Prediction of the Clinical Outcome by FLAIR and DWI for Various Etiologies

BACKGROUND AND PURPOSE

Pediatric acute toxic leukoencephalopathy is a clinicoradiologic entity comprising various etiologies. This study aimed to identify the MR imaging appearance of pediatric acute toxic leukoencephalopathy from various etiologies and determine whether the etiology correlates with clinical outcome.

MATERIALS AND METHODS

We retrospectively reviewed the electronic records of patients with pediatric acute toxic leukoencephalopathy younger than 19 years of age who had MR imaging within <2 weeks of presentation, including DWI and FLAIR sequences. Two neuroradiologists scored the DWI and FLAIR severity and measured the percentage ADC reduction within the visibly affected regions and normal-appearing WM. The percentage ADC reduction and DWI and FLAIR severity were correlated with clinical outcome using the Spearman correlation.

RESULTS

Of 22 children, 3 were excluded due to a nontoxic cause or incomplete examination. Regarding the included 19 children (mean age, 13 years), the etiologies of pediatric acute toxic leukoencephalopathy were the following: methotrexate (n = 6), bone marrow transplantation (n = 4), fludarabine (n = 3), cytarabine (n = 1), carboplatin (n = 1), vincristine (n = 1), cyclosporine (n = 1), uremia (n = 1), and bevacizumab (n = 1). Three subgroups were analyzed (chemotherapy, n = 12; immunosuppression, n = 5; others, n = 2). There was a strong correlation of FLAIR (r  = 0.773, P < .001) and DWI (r = 0.851, P < .001) severity with clinical outcome, and patients treated with fludarabine had the worst outcomes. High percentage ADC reduction values were associated with adverse outcomes, and lower percentage ADC reduction values were associated with favorable outcomes (r = 0.570, P = .011).

CONCLUSIONS

The DWI and FLAIR severity scores appear highly prognostic, whereas percentage ADC reduction is moderately prognostic for clinical outcomes in pediatric acute toxic leukoencephalopathy. Immunosuppressive pediatric acute toxic leukoencephalopathy tends toward favorable outcomes, and fludarabine tends toward worse outcomes.