Severe Leukoencephalopathy Following Acute Oxycodone Intoxication

Strong opioids-induced cardiac, neurologic, and respiratory disorders: a real-world study from 2004 to 2023 based on FAERS

Opioids are mainly used as adjuncts to the induction and maintenance of general anesthesia, postoperative analgesia, and treating moderate to severe cancer pain and chronic pain. However, the hazards of these drugs to various organ organs still need to be further explored. This study used the US FDA Adverse Event Reporting System (FAERS) database to determine whether commonly receiving opioids was higher than the baseline risk for all other medications. FAERS was asked about adverse events (AEs) for the opioids "morphine," "fentanyl," "oxycodone," "hydromorphone," "sufentanil," and "remifentanil" from the first quarter of 2004 (2004Q1) through the second quarter of 2023 (2023Q2). Disproportionality signaling analysis was performed by calculating reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network (BCPNN), and Empirical Bayesian Geometric Mean (EBGM). AEs with system organ classes (SOCs) of "cardiac disease," "neurologic disease," and "respiratory, thoracic, and mediastinal disease" were then screened. The statistical analysis included 12,819,518 reports in the FAERS database from 2004Q1 to 2023Q2, of which 236,619 AEs were reported as "primary suspect" for the six drugs mentioned above, which were selected as "cardiac disorders," "nervous system disorders," and "respiratory, thoracic and mediastinal disorders." Some AEs identified in this study are consistent with the drug labeling, such as bradycardia, respiratory depression, and somnolence. In addition, some unexpected and significant acute adverse drug reactions (ADRs), such as toxic leukoencephalopathy and coma, may occur. This study identified potential new and unexpected ADRs for opioids, providing valuable evidence for safety studies of opioids.

Inverse pattern of GABAergic system impairment in the external versus internal globus pallidus in male heroin addicts

Opioid addiction is a global problem that has been exacerbated in the USA and Europe by the COVID-19 pandemic. The globus pallidus (GP) plays a prominent neurobiological role in the regulation of behaviour as an output station of the striato-pallidal system. GABAergic large projection neurons are the main neuronal type in the external (EGP) and internal (IGP) parts of the GP, where addiction-specific molecular and functional abnormalities occur. In these neurons, glutamate decarboxylase (GAD) with isoforms GAD 65 and 67 is a key enzyme in GABA synthesis, and experimental studies suggest GAD dysregulation in the GP of heroin addicts. Our study, which was performed on paraffin-embedded brains from the Magdeburg Brain Bank, aimed to investigate abnormalities in the GABAergic function of large GP neurons by densitometric evaluation of their GAD 65/67-immunostained thick dendrites. The study revealed a bilaterally decreased fibres density in the EGP paralleled by the increase in the IGP in 11 male heroin addicts versus 11 healthy controls (significant U-test P values). The analysis of confounding variables found no interference of age, brain volume, and duration of formalin fixation with the results. Our findings suggest a dysregulation of GABAergic activity in the GP of heroin addicts, which is consistent with experimental data from animal models and plays potentially a role in the disturbed function of basal ganglia circuit in opioid addiction.

Chronic Voluntary Morphine Intake Is Associated with Changes in Brain Structures Involved in Drug Dependence in a Rat Model of Polydrug Use

Chronic opioid intake leads to several brain changes involved in the development of dependence, whereby an early hedonistic effect (liking) extends to the need to self-administer the drug (wanting), the latter being mostly a prefrontal-striatal function. The development of animal models for voluntary oral opioid intake represents an important tool for identifying the cellular and molecular alterations induced by chronic opioid use. Studies mainly in humans have shown that polydrug use and drug dependence are shared across various substances. We hypothesize that an animal bred for its alcohol preference would develop opioid dependence and further that this would be associated with the overt cortical abnormalities clinically described for opioid addicts. We show that Wistar-derived outbred UChB rats selected for their high alcohol preference additionally develop: (i) a preference for oral ingestion of morphine over water, resulting in morphine intake of 15 mg/kg/day; (ii) marked opioid dependence, as evidenced by the generation of strong withdrawal signs upon naloxone administration; (iii) prefrontal cortex alterations known to be associated with the loss of control over drug intake, namely, demyelination, axonal degeneration, and a reduction in glutamate transporter GLT-1 levels; and (iv) glial striatal neuroinflammation and brain oxidative stress, as previously reported for chronic alcohol and chronic nicotine use. These findings underline the relevance of polydrug animal models and their potential in the study of the wide spectrum of brain alterations induced by chronic morphine intake. This study should be valuable for future evaluations of therapeutic approaches for this devastating condition.

Partial Recovery in Toxic Leukoencephalopathy: Is It Really a Slow Improvement or a Warning Sign?

A 55-year-old African American man who was found down by a friend nine hours after being last seen at the same place was brought to the emergency department (ED) with encephalopathy, lactic acidosis, rhabdomyolysis, elevated troponin, acute kidney injury (AKI), and transaminitis. His urine drug screen (UDS) was positive for cocaine. Intravenous (IV) Narcan was given with minimal improvement in mental status. A computed tomography (CT) scan of the head and a CT scan of the cervical spine in the ED showed no acute findings. Due to hypoxia, the patient was eventually intubated. The patient also required a fasciotomy and eventually hyperbaric oxygen (HBO) therapy due to the left lower extremity wound. He was transferred to our facility for further care. Due to incomplete cognitive recovery, as the patient was oriented to self only, further neurological workup, including magnetic resonance imaging (MRI) of the brain, was obtained, which showed bilateral symmetric T2 FLAIR (Fluid attenuated inversion recovery) hyperintensity in the globus pallidus. The patient had slow and gradual deterioration with worsening encephalopathy, akinetic mutism, parkinsonian features, and seizures, which prompted further evaluation from neurology. The patient eventually underwent extensive workup, including a continuous video electroencephalogram (cvEEG), repeat MRI brain with and without contrast, lumbar puncture for cerebrospinal fluid (CSF) analysis, MRI brain with diffusion tensor imaging (DTI), and magnetic resonance spectroscopy (MRS). The patient was treated with multivitamin therapy and coenzyme Q10, but there was no significant benefit. We report a case of cocaine-induced leukoencephalopathy with findings like 'chasing the dragon encephalopathy' with a possible component of delayed post-hypoxic injury with underlying neuroinflammation.

Association between toxic drug events and encephalopathy in British Columbia, Canada: a cross-sectional analysis

BACKGROUND

Encephalopathy can occur from a non-fatal toxic drug event (overdose) which results in a partial or complete loss of oxygen to the brain, or due to long-term substance use issues. It can be categorized as a non-traumatic acquired brain injury or toxic encephalopathy. In the context of the drug toxicity crisis in British Columbia (BC), Canada, measuring the co-occurrence of encephalopathy and drug toxicity is challenging due to lack of standardized screening. We aimed to estimate the prevalence of encephalopathy among people who experienced a toxic drug event and examine the association between toxic drug events and encephalopathy.

METHODS

Using a 20% random sample of BC residents from administrative health data, we conducted a cross-sectional analysis. Toxic drug events were identified using the BC Provincial Overdose Cohort definition and encephalopathy was identified using ICD codes from hospitalization, emergency department, and primary care records between January 1st 2015 and December 31st 2019. Unadjusted and adjusted log-binomial regression models were employed to estimate the risk of encephalopathy among people who had a toxic drug event compared to people who did not experience a toxic drug event.

RESULTS

Among people with encephalopathy, 14.6% (n = 54) had one or more drug toxicity events between 2015 and 2019. After adjusting for sex, age, and mental illness, people who experienced drug toxicity were 15.3 times (95% CI = 11.3, 20.7) more likely to have encephalopathy compared to people who did not experience a drug toxicity event. People who were 40 years and older, male, and had a mental illness were at increased risk of encephalopathy.

CONCLUSIONS

There is a need for collaboration between community members, health care providers, and key stakeholders to develop a standardized approach to define, screen, and detect neurocognitive injury related to drug toxicity.

A pilot study investigating cognitive impairment associated with opioid overdose

BACKGROUND

In 2021, while overdose (OD) deaths were at the highest in recorded history, it is estimated that >80% of ODs do not result in a fatality. While several case studies have indicated that opioid-related ODs can result in cognitive impairment, the possible association has not yet been systematically investigated.

METHODS

78 participants with a history of OUD who reported experiencing an OD in the past year (n=35) or denied a lifetime history of OD (n=43) completed this study. Participants completed cognitive assessments including the Test of Premorbid Functioning (TOPF) and the NIH Toolbox Cognition Battery (NIHTB-CB). Comparisons were made between those who experienced an opioid-related OD in the past year versus those who denied a lifetime OD history while controlling for factors including age, premorbid functioning, and number of prior ODs.

RESULTS

When comparing those who experienced an opioid-related OD within the past year to those without a history of OD, uncorrected standard scores were generally comparable; however, differences emerged in the multivariable model. Specifically, compared to those without a history of OD, those who experienced a past year OD evidenced significantly lower total cognition composite scores (coef. = -7.112; P=0.004), lower crystalized cognition composite scores (coef. = -4.194; P=0.009), and lower fluid cognition composite scores (coef. = -7.879; P=0.031).

CONCLUSIONS

Findings revealed that opioid-related ODs may be associated with, or contribute to, reduced cognition. Extent of the impairment appears contingent upon individuals' premorbid intellectual functioning and the cumulative number of past ODs. While statistically significant, clinical significance may be limited given that performance differences (∼4 - 8 points) were not particularly robust. More rigorous investigation is warranted, and future studies must also account for the many other variables possibly contributing to cognitive impairment.

Fatal fentanyl-associated cerebellitis in a young man

A 22-year-old man was brought in by EMS for coma and respiratory failure. The initial diagnosis was an opioid overdose but the patient did not respond to naloxone. A head CT revealed findings consistent with cerebellitis. The patient developed obstructive hydrocephalus and herniation. Despite neurosurgical and ICU care, the patient did not recover. Cerebellitis is a seldom-discussed complication of opioid use which may become more common as the opioid and fentanyl epidemic evolves.

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.

Posterior Reversible Encephalopathy Syndrome (PRES) in a Patient with Opioid Use Disorder

Posterior Reversible Encephalopathy Syndrome (PRES) is a characteristic clinical radiographic syndrome with diffuse structural alteration of cerebral white matter secondary to myelin damage with diverse and multifactorial etiologies. It can present with acutely altered mentation, somnolence or occasionally stupor, vision impairment, seizures, and sudden or chronic headaches that are not focal. The pathophysiology remains unclear, but mechanisms involving endothelial injury and dysregulation of cerebral autoregulation have been purported. We report the case of a 36-year-old male with a history of heroin use disorder, who was admitted to our hospital for opioid withdrawal. CT head without contrast and MRI with and without gadolinium showed significant white matter disease in both cerebral hemispheres and cerebellum. He was diagnosed with Posterior Reversible Encephalopathy Syndrome secondary to heroin use and managed on the medical floor in collaboration with the neurology team. His clinical symptoms improved and he was discharged after six weeks. To our knowledge, this case did not present with the risk factors for PRES reported in the literature. For patients with heroin use disorder who present with an altered mental status, PRES should be highly suspected. The diagnosis and management require collaboration between psychiatry and neurology.

Endogenous and exogenous opioid effects on oligodendrocyte biology and developmental brain myelination

The elevated presence of opioid receptors and their ligands throughout the developing brain points to the existence of maturational functions of the endogenous opioid system that still remain poorly understood. The alarmingly increasing rates of opioid use and abuse underscore the urgent need for clear identification of those functions and the cellular bases and molecular mechanisms underlying their physiological roles under normal and pathological conditions. This review is focused on current knowledge on the direct and indirect regulatory roles that opioids may have on oligodendrocyte development and their generation of myelin, a complex insulating membrane that not only facilitates rapid impulse conduction but also participates in mechanisms of brain plasticity and adaptation. Information is examined in relation to the importance of endogenous opioid function, as well as direct and indirect effects of opioid analogues, which like methadone and buprenorphine are used in medication-assisted therapies for opioid addiction during pregnancy and pharmacotherapy in neonatal abstinence syndrome. Potential opioid effects are also discussed regarding late myelination of the brain prefrontal cortex in adolescents and young adults. Such knowledge is fundamental for the design of safer pharmacological interventions for opioid abuse, minimizing deleterious effects in the developing nervous system.

Lesson of the month: Oxycodone-induced leukoencephalopathy: a rare diagnosis

Oxycodone-induced leukoencephalopathy is a rare diagnosis that should be considered in unconscious patients with appropriate history. We describe a case of a 57-year-old unconscious woman who required intubation and did not respond to naloxone infusion. The unconsciousness was initially thought to be due to hypoxic brain injury. However, a further review of brain imaging showed characteristic features of oxycodone-induced leukoencephalopathy. We describe the pathological and radiological features of this condition, and provide a concise review of the limited literature on this condition. Accurate diagnosis of this condition will be valuable to clinicians and patients in terms of their medium-term and long-term prognosis, and potential for rehabilitation.

Diffuse subcortical white matter injury and bilateral basal ganglia neuronal loss after acute opioid overdose

Opiate intoxication has been associated with life-threatening effects of sympathetic suppression and respiratory depression, but current literature is limited in describing its neurotoxic effects on the central nervous system. Here, we present the case of an otherwise high-functioning adolescent male who was found unresponsive after ingestion of approximately 3-4 fake oxycodone 10-325 mg pills laced with fentanyl. Magnetic resonance imaging showed evidence of diffuse T2 hyperintensities in the corpus callosum and bilateral frontal, parietal, and cerebellum indicative of diffuse white matter injury. In addition, there were distinct areas of restricted diffusion in the bilateral basal ganglia concerning for oxidative stress-mediated neuronal loss. His neurological exam improved with supportive treatment over the course of his hospitalization. Although limited literature has shown leukoencephalopathy to be associated with opioid overdose, we present a case of additional involvement of subcortical gray matter.

Brain cell-derived exosomes in plasma serve as neurodegeneration biomarkers in male cynomolgus monkeys self-administrating oxycodone

Background

The United States is currently facing an opioid crisis. Novel tools to better comprehend dynamic molecular changes in the brain associated with the opioid abuse are limited. Recent studies have suggested the usefulness of plasma exosomes in better understanding CNS disorders. However, no study has ever characterized exosomes (small extracellular vesicles of endocytic origin) secreted by brain cells to understand the potential neurodegenerative effects of long-term oxycodone self-administration (SA).

Methods

MRI of Cynomolgus monkeys (Macaca fascicularis) was performed to assess alterations in gray matter volumes with oxycodone SA. We isolated total exosomes (TE) from the plasma of these monkeys; from TE, we pulled-out neuron-derived exosomes (NDE), astrocytes-derived exosomes (ADE), and microglia-derived exosomes (MDE) using surface biomarkers L1CAM (L1 cell adhesion molecule), GLAST (Glutamate aspartate transporter) and TMEM119 (transmembrane protein119), respectively.

Findings

We observed a significantly lower gray matter volume of specific lobes of the brain (frontal and parietal lobes, and right putamen) in monkeys with ∼3 years of oxycodone SA compared to controls. Higher expression of neurodegenerative biomarkers (NFL and α-synuclein) correlates well with the change in brain lobe volumes in control and oxycodone SA monkeys. We also identified a strong effect of oxycodone SA on the loading of specific miRNAs and proteins associated with neuro-cognitive disorders. Finally, exosomes subpopulation from oxycodone SA group activated NF-κB activity in THP1- cells.

Interpretation

These results provide evidence for the utility of brain cells-derived exosomes from plasma in better understanding and predicting the pro-inflammatory and neurodegenerative consequence of oxycodone SA.

Funding

NIH

The molecular neurobiology and neuropathology of opioid use disorder

The number of people diagnosed with opioid use disorder has skyrocketed as a consequence of the opioid epidemic and the increased prescribing of opioid drugs for chronic pain relief. Opioid use disorder is characterized by loss of control of drug taking, continued drug use in the presence of adverse consequences, and repeated relapses to drug taking even after long periods of abstinence. Patients who suffer from opioid use disorder often present with cognitive deficits that are potentially secondary to structural brain abnormalities that vary according to the chemical composition of the abused opioid. This review details the neurobiological effects of oxycodone, morphine, heroin, methadone, and fentanyl on brain neurocircuitries by presenting the acute and chronic effects of these drugs on the human brain. In addition, we review results of neuroimaging in opioid use disorder patients and/or histological studies from brains of patients who had expired after acute intoxication following long-term use of these drugs. Moreover, we include relevant discussions of the neurobiological mechanisms involved in promoting abnormalities in the brains of opioid-exposed patients. Finally, we discuss how novel strategies could be used to provide pharmacological treatment against opioid use disorder.

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Brain abnormalities caused by opioid intoxication.

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Intoxication of opioids leads to defects in brain neurocircuitries.

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Insight into the molecular mechanisms associated with craving in heroin addicts.

Opioid and neuroHIV Comorbidity - Current and Future Perspectives

With the current national opioid crisis, it is critical to examine the mechanisms underlying pathophysiologic interactions between human immunodeficiency virus (HIV) and opioids in the central nervous system (CNS). Recent advances in experimental models, methodology, and our understanding of disease processes at the molecular and cellular levels reveal opioid-HIV interactions with increasing clarity. However, despite the substantial new insight, the unique impact of opioids on the severity, progression, and prognosis of neuroHIV and HIV-associated neurocognitive disorders (HAND) are not fully understood. In this review, we explore, in detail, what is currently known about mechanisms underlying opioid interactions with HIV, with emphasis on individual HIV-1-expressed gene products at the molecular, cellular and systems levels. Furthermore, we review preclinical and clinical studies with a focus on key considerations when addressing questions of whether opioid-HIV interactive pathogenesis results in unique structural or functional deficits not seen with either disease alone. These considerations include, understanding the combined consequences of HIV-1 genetic variants, host variants, and μ-opioid receptor (MOR) and HIV chemokine co-receptor interactions on the comorbidity. Lastly, we present topics that need to be considered in the future to better understand the unique contributions of opioids to the pathophysiology of neuroHIV. Graphical Abstract Blood-brain barrier and the neurovascular unit. With HIV and opiate co-exposure (represented below the dotted line), there is breakdown of tight junction proteins and increased leakage of paracellular compounds into the brain. Despite this, opiate exposure selectively increases the expression of some efflux transporters, thereby restricting brain penetration of specific drugs.

Cerebellar Hippocampal and Basal Nuclei Transient Edema with Restricted diffusion (CHANTER) Syndrome

Background

Abnormal restricted diffusion on magnetic resonance imaging is often associated with ischemic stroke or anoxic injury, but other conditions can present similarly. We present six cases of an unusual but consistent pattern of restricted diffusion in bilateral hippocampi and cerebellar cortices. This pattern of injury is distinct from typical imaging findings in ischemic, anoxic, or toxic injury, suggesting it may represent an under-recognized clinicoradiographic syndrome. Despite initial presentation with stupor or coma in the context of obstructive hydrocephalus, patients may have acceptable outcomes if offered early intervention.

Methods

We identified an ad hoc series of patients at our two institutions between years 2014 and 2017 who presented to the neurocritical care unit with severe, otherwise unexplained cerebellar edema and retrospectively identified several commonalities in history, presentation, and imaging.

Results

Between two institutions, we identified six patients—ages 33–59 years, four male—with similar presentations of decreased level of consciousness in the context of intoxicant exposure, with acute cytotoxic edema of the cerebellar cortex, hippocampi, and aspects of the basal nuclei. All patients presented with severe cerebellar edema which led to obstructive hydrocephalus requiring aggressive medical and/or surgical management. The five patients who survived to discharge demonstrated variable degrees of physical and memory impairment on discharge and at follow-up.

Conclusions

We present findings of a potentially novel syndrome involving a distinct pattern of cerebellar and hippocampal restricted diffusion, with imaging and clinical characteristics distinct from ischemic stroke, hypoxic injury, and known toxidromes and leukoencephalopathies. Given the potential for favorable outcome despite early obstructive hydrocephalus, early identification and treatment of this syndrome are critical.

Opioid-induced toxic leukoencephalopathy: A case report and review of the literature

Importance

Reports of toxic leukoencephalopathy (TLE) due to opioids have been extensively documented within the adult literature. There is a paucity of literature with respect to the incidence, complications, and outcomes of TLE in the pediatric population.

Objective

To describe a rare complication of opioid ingestion in the pediatric population and serve as the first large review of published cases of opioid-induced leukoencephalopathy. Thirteen case reports with varying treatments are herein reviewed in addition to our own case. The range of treatment modalities, morbidity and mortality are broad and outcomes secondary to supportive care versus neurosurgical intervention is explored.

Evidence review

All cases of pediatric opioid-induced toxic leukoencephalopathy published on pubmed and google scholar were included in this review.

Findings

We report the case of a 4-year old male surgically treated for acute oxycodone-induced TLE who initially presented with Glascow Coma Scale of 4 and a comatose state for weeks. Over the next several months he recovered with spasticity of all extremities, oral aversion, substantial vision loss, and the ability to speak in short sentences. In addition, we found thirteen other reported cases of opioid-induced leukoencephalopathy reported in the literature. The treatment approaches described range from supportive care alone, to invasive neurosurgical interventions including placement of extraventricular drains, removal of hemorrhagic tissue, and craniectomy. The outcomes of patients with opioid-induced leukoencephalopathy is also variable. Reports demonstrate a range of outcomes that include patients who died to those with no residual neurologic deficits.

Conclusions

This review of reported pediatric cases of opioid-induced leukoencephalopathy highlights the importance of early neurosurgical intervention for prevention of devastating outcomes.

The Emerging Role of Inhaled Heroin in the Opioid Epidemic: A Review

Importance

Opioid addiction affects approximately 2.4 million Americans. Nearly 1 million individuals, including a growing subset of 21 000 minors, abuse heroin. Its annual cost within the United States amounts to $51 billion. Inhaled heroin use represents a global phenomenon and is approaching epidemic levels east of the Mississippi River as well as among urban youth. Chasing the dragon (CTD) by heating heroin and inhaling its fumes is particularly concerning, because this method of heroin usage has greater availability, greater ease of administration, and impressive intensity of subjective experience (high) compared with sniffing or snorting, although it also has a safer infectious profile compared with heroin injection. This is relevant owing to peculiar and often catastrophic brain complications. Following the American Medical Association Opioid Task Force mandate, we contribute a description of the pharmacology, pathophysiology, clinical spectrum, neuroimaging, and neuropathology of CTD leukoencephalopathy, as distinct from other heroin abuse modalities.

Observations

The unique spectrum of CTD-associated health outcomes includes an aggressive toxic leukoencephalopathy with pathognomonic neuropathologic features, along with sporadic instances of movement disorders and hydrocephalus. Clinical CTD severity is predominantly moderate at admission, frequently unmodified at discharge, and largely improved in the long term. Mild cases survive with minor sequelae, while moderate to severe presentations might deteriorate and progress to death. Other methods of heroin use may complicate with stroke, seizure, obstructive hydrocephalus, and (uncharacteristically) leukoencephalopathy.

Conclusions and Relevance

The distinct pharmacology of CTD correlates with its specific clinical and radiological features and prompts grave concern for potential morbidity and long-term disability costs. Proposed diagnostic criteria and standardized reporting would ameliorate the limitations of CTD literature and facilitate patient selection for a coenzyme Q10 therapeutic trial.

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

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Recognition the etiologies of ATL is important due to its potentially reversible nature after treatment or removal of the toxin.

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“CHOICES” is useful to memorize etiologies associated with PVWM injury in non-metabolic and non-infectious ATL patients.

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Reduced diffusion is an early and important imaging finding to evaluate patients with non-metabolic and non-infectious ATL patients.

Purpose

To describe non-metabolic, non-infectious etiologies of acute toxic leukoencephalopathy (ATL) on DWI MRI, and provide a useful acronym to remember them.

Material and Methods

Our PACS archive was reviewed, yielding 185 patients with suspected ATL per MRI reports and clinical follow up; infectious or metabolic causes were excluded.

Result/Discussion

The 87 included non-infectious, non-metabolic ATL patients' etiologies are represented by the acronym 'CHOICES': chemotherapy ('C',n = 34); heroin-induced ('H',n = 6), opioid analogues ('O',n = 14); immunosuppressant ('I',n = 11) or imidazole (n = 2); cocaine ('C',n = 1); environmental or ethanol abuse ('E',n = 5), splenial lesions ('S',n = 9), and 'other' (n = 5).

Conclusion

The "CHOICES" acronym delineates various toxic etiologies of ATL.

Outcomes associated with hospital admissions for accidental opioid overdose in British Columbia: a retrospective cohort study

OBJECTIVES

To study the association between accidental opioid overdose and neurological, respiratory, cardiac and other serious adverse events and whether risk of these adverse events was elevated during hospital readmissions compared with initial admissions.

DESIGN

Retrospective cohort study.

SETTING

Population-based study using linked administrative data in British Columbia, Canada.

PARTICIPANTS

The primary analysis included 2433 patients with 2554 admissions for accidental opioid overdose between 2006 and 2015, including 121 readmissions within 1 year of initial admission. The secondary analysis included 538 patients discharged following a total of 552 accidental opioid overdose hospitalizations and 11 040 matched controls from a cohort of patients with ≥180 days of prescription opioid use.

OUTCOME MEASURES

The primary outcome was encephalopathy; secondary outcomes were adult respiratory distress syndrome, respiratory failure, pulmonary haemorrhage, aspiration pneumonia, cardiac arrest, ventricular arrhythmia, heart failure, rhabdomyolysis, paraplegia or tetraplegia, acute renal failure, death, a composite outcome of encephalopathy or any secondary outcome and total serious adverse events (all-cause hospitalisation or death). We analysed these outcomes using generalised linear models with a logistic link function.

RESULTS

3% of accidental opioid overdose admissions included encephalopathy and 25% included one or more adverse events (composite outcome). We found no evidence of increased risk of encephalopathy (OR 0.57; 95% CI 0.13 to 2.49) or other outcomes during readmissions versus initial admissions. In the secondary analysis, <5 patients in each cohort experienced encephalopathy. Risk of the composite outcome (OR 2.15; 95% CI 1.48 to 3.12) and all-cause mortality (OR 2.13; 95% CI 1.18 to 3.86) were higher for patients in the year following overdose relative to controls.

CONCLUSIONS

We found no evidence that risk of encephalopathy or other adverse events was higher in readmissions compared with initial admissions for accidental opioid overdose. Risk of serious morbidity and mortality may be elevated in the year following an accidental opioid overdose.

Methadone-induced Toxic Encephalopathy In Pediatric Patients: Two Case Reports

Toxic encephalopathy is a wide spectrum of encephalopathy secondary to insult from toxic substances, with variable clinical presentations from minor cognitive impairment to severe neurological dysfunction and death. Methadone-induced toxic encephalopathy is an extremely rare form of toxic encephalopathy which typically demonstrates abnormal imaging findings in the dentate nuclei or cerebellum. This is a report of methadone-induced toxic encephalopathy in two toddlers secondary to accidental ingestion. They were brought in unconscious to the emergency department of a tertiary hospital and were found to be cyanotic and pulseless, requiring cardiopulmonary resuscitation and mechanical ventilation. Magnetic resonance imaging (MRI) of the brain of both patients showed similar findings of symmetrical hyperintense foci in bilateral cerebellar hemispheres on T2-weighted and fluid-attenuated inversion recovery (FLAIR) sequences. These areas also demonstrated diffusion restriction on diffusion weighted imaging (DWI). Blood and urine toxicology results confirmed the presence of methadone in both patients. As the exact substance of accidental ingestion may not be known at the time of presentation, early radiological diagnosis of methadone-induced encephalopathy may prompt early initiation of treatment to prevent further life-threatening complications, particularly in vulnerable pediatric population.

Chronic oxycodone induces axonal degeneration in rat brain

BACKGROUND

Chronic opioid therapy for non-malignant pain conditions has significantly increased over the last 15 years. Recently, the correlation between opioid analgesics and alternations in brain structure, such as leukoencephalopathy, axon demyelination, and white matter lesions, has been demonstrated in patients with a history of long-term use of prescription opioids. The exact mechanisms underlying the neurotoxic effect of opioids on the central nervous system are still not fully understood. We investigated the effect of chronic opioids using an animal model in which female rats were orally gavaged with 15 mg/kg of oxycodone every 24 h for 30 days. In addition we tested oxycodone, morphine and DAMGO in breast adenocarcinoma MCF7 cells, which are known to express the μ-opioid receptor.

RESULTS

We observed several changes in the white matter of animals treated with oxycodone: deformation of axonal tracks, reduction in size of axonal fascicles, loss of myelin basic protein and accumulation of amyloid precursor protein beta (β-APP), suggesting axonal damages by chronic oxycodone. Moreover, we demonstrated activation of pro-apoptotic machinery amid suppression of anti-apoptotic signaling in axonal tracks that correlated with activation of biomarkers of the integrated stress response (ISR) in these structures after oxycodone exposure. Using MCF7 cells, we observed induction of the ISR and pro-apoptotic signaling after opioid treatment. We showed that the ISR inhibitor, ISRIB, suppresses opioid-induced Bax and CHOP expression in MCF7 cells.

CONCLUSIONS

Altogether, our data suggest that chronic opioid administration may cause neuronal degeneration by activation of the integrated stress response leading to induction of apoptotic signaling in neurons and also by promoting demyelination in CNS.

Acute brain injury following illicit drug abuse in adolescent and young adult patients: spectrum of neuroimaging findings

The use of illicit drugs is currently a major medical problem among adolescents. Several illicit drugs have a high abuse potential and can be neurotoxic causing high morbidity and mortality. The clinical manifestation of adolescents with acute drug-induced neurotoxicity is often characterized by non-specific symptoms and findings. Early diagnosis is important to prevent death and permanent long-term neurological impairments. We report on clinical and neuroimaging findings in five adolescents with acute brain imaging following illicit drug intoxication to highlight the role of neuroimaging findings in the diagnostic work-up of pediatric acute drug-induced neurotoxicity. Our patients reveal two main neuroimaging patterns of brain injury: diffuse symmetric subcortical white matter injury with preferential cerebellar involvement (leukoencephalopathy pattern) or multiple foci of ischemic infarctions in a non-arterial territory distribution (ischemic pattern). Familiarity with these two neuroimaging patterns of findings in the evaluation of magnetic resonance imaging studies in adolescents with acutely altered mental status may suggest the correct diagnosis, narrow the differential diagnosis, and consequently allow early initiation of targeted laboratory investigations and treatment, potentially improving outcome.

Pyrolysis of drugs of abuse: a comprehensive review

This review summarizes the literature to date relating to pyrolysis and heated vapour ingestion of drugs of abuse. In this context, heating is referred to as smoking or pyrolysis, but these are generic descriptors that encompass numerous methods of vapour generation and inhalation. Depending on the amount of drug used, diluents and contaminants present, heating conditions, and the oxidative/reductive environment, many thermal decomposition products can be formed. In addition to the recognized hazard of rapid onset of pharmacological effects of the parent drug, thermal decomposition products may be pharmacologically active as well as acutely/chronically toxic. For example, several published reports have linked heroin smoking to a form of brain encephalopathy and to the development of movement disorders. Early qualitative studies focusing on the thermal decomposition of drugs have evolved into more complex investigations employing mass spectral identification, confirmation, and elucidation of formation mechanism. In most cases, thermal decomposition begins with cleavage of the weakest bond (often C-N) to generate free radicals that then form the most stable sterically favoured products. Several reports of rearrangements at higher temperatures have been identified and hint at an underlying complexity that arises from the variety of smoking methods and conditions. Given that many designer drugs such as synthetic cannabinoids are ingested primarily through smoking, this issue has taken on new importance.

Toxic Leukoencephalopathy in the Intensive Care Unit

In this article, we report two cases of acute toxic leukoencephalopathy to highlight this acute clinicoradiological syndrome as an important, although uncommon, consideration in the undifferentiated comatose patient who fails to wake following drug overdose or has unexplained neurology with a history of drug exposure. We then review the current literature and discuss potential differential diagnoses in this setting, along with proposed treatments for this condition. The cases presented demonstrate a more fulminant onset than previously well-defined acute toxic leukoencephalopathy subtypes and highlight the prognostic importance of magnetic resonance imaging in diagnosing a condition from which significant functional recovery seems possible.

Delayed-onset movement disorder and encephalopathy after oxycodone ingestion

We present the case of a 14-year-old girl with a biphasic course after oxycodone ingestion. Clinically, she had a rapid return to baseline after initial ingestion and presented a week later with new-onset ballism, akathisia, and encephalopathy. Neuroimaging demonstrated bilateral globi pallidi and cerebellar lesions with a relative decrease of metabolite peaks on magnetic resonance spectroscopy. Her movement disorder was treated successfully with valproic acid and clonidine. Her cognitive functioning returned to baseline 3 months after ingestion.

Methadone-induced toxic brain damage

A 29-year-old man presented with comatose after methadone intoxication. Cerebral tomography only showed cortico-subcortical hypodense signal in the right cerebellar hemisphere. Brain MRI showed a rare imaging of FLAIR and DWI hyperintensities in the two cerebellar hemispheres as well as basal ganglia (globi pallidi), compatible with methadone overdose. To our knowledge this is the first reported case of both cerebellar and basal ganglia involvement in methadone overdose.

Chasing the Dragon: A Review of Toxic Leukoencephalopathy

The report begins with the case of an 18-year-old male who presented to a community hospital with difficulty walking and speaking. His illicit drug use history included smoking heroin. After admission to the hospital, a thorough workup was consistent with toxic heroin related leukoencephalopathy. The young man continued to decline and died approximately 2 months after his initial presentation and diagnosis. An autopsy and a thorough neuropathology examination were completed. Sections through the cerebral hemispheres and the cerebellum revealed diffuse and profound softening and discoloration of the white matter, most prominently in the occipital lobes. Microscopically, there was vacuolization and spongiosis of the white matter. The pathologic findings were consistent with the diagnosis of toxic or heroin related leukoencephalopathy. Toxic leukoencephalopathy is a rare disorder of unknown etiology linked to the smoking of heroin, known as “chasing the dragon.” The exact mechanism of the disorder is unknown, but it is thought that impurities cut into the heroin may become toxic substances upon sublimation, as the disorder is not seen with injected heroin. Currently, therapy is supportive with no effective cures available. The natural history of the disorder is variable, with an approximately 25% mortality rate. The popularity of smoking heroin is growing in the United States, and it is particularly seen with increasing frequency in new heroin users. Thus, this is an important, and likely increasingly common, effect of illicit drug use that should be recognized by forensic pathologists.