Impact of diagnostic investigations in the management of CAR T-cell-associated neurotoxicity

ABSTRACT

International guidelines regarding the management of immune effector cell-associated neurotoxicity syndrome (ICANS) recommend several diagnostic investigations, including magnetic resonance imaging (MRI), lumbar puncture (LP), and electroencephalogram (EEG) based on ICANS grade. However, the impact of these investigations has not yet been evaluated. Here, we aimed to describe the role of MRI, LP, and EEG in the management of ICANS in a cohort of real-life patients treated with chimeric antigen receptor (CAR) T cells at the University Hospital of Rennes, France. Between August 2018 and January 2023, a total of 190 consecutive patients were treated with CAR T cells. Among those, 91 (48%) developed ICANS. MRI was performed in 71 patients (78%) with ICANS, with a therapeutic impact in 4% of patients, despite frequent abnormal findings. LP was performed in 43 patients (47%), which led to preemptive antimicrobial agents in 7% of patients, although no infection was eventually detected. Systematic EEG was performed in 51 patients (56%), which led to therapeutic modifications in 16% of patients. Our study shows that EEG is the diagnostic investigation with the greatest therapeutic impact, whereas MRI and LP appear to have a limited therapeutic impact. Our results emphasize the role of EEG in the current guidelines but question the need for systematic MRI and LP, which might be left to the discretion of the treating physician.

Neurotoxicity and management of primary and secondary central nervous system lymphoma after adoptive immunotherapy with CD19-directed chimeric antigen receptor T-cells

BACKGROUND

Chimeric antigen receptor (CAR) T-cells targeting CD19 have been established as a leading engineered T-cell therapy for B-cell lymphomas; however, data for patients with central nervous system (CNS) involvement are limited.

METHODS

We retrospectively report on CNS-specific toxicities, management, and CNS response of 45 consecutive CAR T-cell transfusions for patients with active CNS lymphoma at the Massachusetts General Hospital over a 5-year period.

RESULTS

Our cohort includes 17 patients with primary CNS lymphoma (PCNSL; 1 patient with 2 CAR T-cell transfusions) and 27 patients with secondary CNS lymphoma (SCNSL). Mild ICANS (grade 1-2) was observed after 19/45 transfusions (42.2%) and severe immune effector cell-associated neurotoxicity syndrome (ICANS) (grade 3-4) after 7/45 transfusions (15.6%). A larger increase in C-reactive protein (CRP) levels and higher rates of ICANS were detected in SCNSL. Early fever and baseline C-reactive protein levels were associated with ICANS occurrence. CNS response was seen in 31 cases (68.9%), including a complete response of CNS disease in 18 cases (40.0%) which lasted for a median of 11.4 ± 4.5 months. Dexamethasone dose at time of lymphodepletion (but not at or after CAR T-cell transfusion) was associated with an increased risk for CNS progression (hazard ratios [HR] per mg/d: 1.16, P = .031). If bridging therapy was warranted, the use of ibrutinib translated into favorable CNS-progression-free survival (5 vs. 1 month, HR 0.28, CI 0.1-0.7; P = .010).

CONCLUSIONS

CAR T-cells exhibit promising antitumor effects and a favorable safety profile in CNS lymphoma. Further evaluation of the role of bridging regimens and corticosteroids is warranted.

Delayed-Onset Psychosis Secondary to Tacrolimus Neurotoxicity After Lung Transplant: A Case Report and Systematic Review

BACKGROUND

Tacrolimus is the most common immunosuppressant used after transplant, yet it can result in moderate-to-severe neurotoxicity in up to 32% of patients. Signs of neurotoxicity can vary from mild (tremor or headache) to severe (posterior reversible encephalopathy syndrome or psychosis. Prompt recognition and management is needed to lead to symptom resolution.

OBJECTIVE

The objective of this study is to describe the clinical presentation of tacrolimus-induced psychosis, a type of tacrolimus-inducted neurotoxicity, and distinguish it from other central nervous system disturbances, including delirium.

METHODS AND RESULTS

We present a case of delayed onset tacrolimus-induced psychosis with focus on unique clinical features and management strategies. We conducted a systematic review of cases of tacrolimus-induced psychosis using the PubMed database and included 15 manuscripts in our review.

CONCLUSIONS

Tacrolimus-induced psychosis is a unique presentation of tacrolimus-related neurotoxicity and can present without the cardinal symptoms of delirium. The data on isolated psychotic symptoms are limited with current literature focusing on more common presentations of tacrolimus-induced neurotoxicity, such as delirium and tremor. Development of psychosis can occur later in the treatment course and at normal tacrolimus serum levels. It can improve with antipsychotic therapies, but primary management should include cross-titration to an alternate immunosuppressant regimen.

Post-CART-T Cell Infection: Etiology, pathogenesis, and therapeutic approaches

Chimeric antigen receptor (CAR) T cell therapy targeting CD-19 has revolutionized the treatment of refractory B-cell malignancies. However, patients undergoing this therapy face an increased risk of infections due to compromised immune function, lymphodepleting chemotherapy, hospitalization, and therapy-related complications such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome. Patients with systemic corticosteroid use, low immunoglobulin levels, and severe CRS, are at higher risk of infection. This review article highlights the spectrum of infections encountered in CAR T cell therapy, including bacterial, viral, and fungal infections. Following consensus guidelines for vaccination and immunoglobulin replacement is recommended. Clear criteria for antibiotic usage and vaccinating household members against respiratory viruses are crucial. Understanding the risk factors, spectrum of infections, and implementing appropriate prophylactic measures are essential to optimize outcomes in patients undergoing CAR T cell therapy. By prioritizing infection prevention strategies, healthcare professionals can effectively improve patient care.

Complete spectrum of adverse events associated with chimeric antigen receptor (CAR)-T cell therapies

Chimeric antigen receptor (CAR)-T cell therapies have been approved by FDA to treat relapsed or refractory hematological malignancies. However, the adverse effects of CAR-T cell therapies are complex and can be challenging to diagnose and treat. In this review, we summarize the major adverse events, including cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and CAR T-cell associated HLH (carHLH), and discuss their pathophysiology, symptoms, grading, and diagnosis systems, as well as management. In a future outlook, we also provide an overview of measures and modifications to CAR-T cells that are currently being explored to limit toxicity.

Valproate overdose leading to hyperammonaemic encephalopathy

Sodium valproate is a commonly prescribed anticonvulsant medication; however, it can cause uncommon side effects such as hyperammonaemia and encephalopathy. We present the case of a male in his early 50s brought to the emergency department after being found collapsed by his wife, with an empty bottle of sodium valproate tablets. The patient developed hyperammonaemic encephalopathy due to sodium valproate overdose and was treated with supportive care and renal replacement therapy. This case highlights the importance of recognising the potential complications of sodium valproate and its prompt treatment.

How I treat unique and difficult-to-manage cases of CAR T-cell therapy-associated neurotoxicity

With growing indications for chimeric antigen receptor (CAR) T-cell therapy, toxicity profiles are evolving. There is an urgent and unmet need of approaches to optimally manage emerging adverse events that extend beyond the standard paradigm of cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome (ICANS). Although management guidelines exist for ICANS, there is little guidance on how to approach patients with neurologic comorbidities, and how to manage rare neurotoxicity presentations, such as CAR T-cell therapy-related cerebral edema, severe motor complications or late-onset neurotoxicity. In this study, we present 3 scenarios of patients treated with CAR T cells who develop unique types of neurotoxicity, and we describe an approach for the evaluation and management based on experience because objective data are limited. The goal of this study is to develop an awareness of emerging and unusual complications, discuss treatment approaches, and help institutions and health care providers establish frameworks to navigate how to best address unusual neurotoxicities to ultimately improve patient outcomes.

Multifocal demyelinating leukoencephalopathy and oligodendroglial lineage cell loss with immune effector cell-associated neurotoxicity syndrome (ICANS) following CD19 CAR T-cell therapy for mantle cell lymphoma

Immune effector cell-associated neurotoxicity syndrome (ICANS) is a prevalent condition seen after treatment with chimeric antigen receptor T-cell (CAR T) therapy and other cancer cell therapies. The underlying pathophysiology and neuropathology of the clinical syndrome are incompletely understood due to the limited availability of brain tissue evaluation from patient cases, and a lack of high-fidelity preclinical animal models for translational research. Here, we present the cellular and tissue neuropathologic analysis of a patient who experienced grade 4 ICANS after treatment with anti-CD19 CAR T therapy for mantle cell lymphoma. Our pathologic evaluation reveals a pattern of multifocal demyelinating leukoencephalopathy associated with a clinical course of severe ICANS. A focused analysis of glial subtypes further suggests region-specific oligodendrocyte lineage cell loss as a potential cellular and pathophysiologic correlate in severe ICANS. We propose a framework for the continuum of neuropathologic changes thus far reported across ICANS cases. Future elucidation of the mechanistic processes underlying ICANS will be critical in minimizing neurotoxicity following CAR T-cell and related immunotherapy treatments across oncologic and autoimmune diseases.

Immune effector cell-associated neurotoxicity syndrome: A therapeutic approach in the critically ill

Immunotherapy with chimeric antigen-specific receptor modified T cells, known as CAR-T, is emerging as a promising approach to hematological malignancies. In this regard, CAR-T against human cluster of differentiation (CD) 19 has demonstrated antitumor efficacy in application to B cell neoplasms resistant to conventional therapy. However, activation of the immune system induces severe and specific complications which can prove life-threatening. These include cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome (known as ICANS) - the latter being the subject of the present review. Although the physiopathological mechanisms underlying ICANS are not well known, a number of clinical and biological factors increase the risk of developing neurotoxicity associated to CAR-T therapy. Treatment is based on close monitoring, measures of support, anticonvulsivants, corticosteroids, and early admission to intensive care. The present study offers a comprehensive review of the available literature from a multidisciplinary perspective, including recommendations from intensivists, neurologists and hematologists dedicated to the care of critically ill adults.

Critical care management of chimeric antigen receptor T-cell therapy recipients

Chimeric antigen receptor (CAR) T-cell therapy is a promising immunotherapeutic treatment concept that is changing the treatment approach to hematologic malignancies. The development of CAR T-cell therapy represents a prime example for the successful bench-to-bedside translation of advances in immunology and cellular therapy into clinical practice. The currently available CAR T-cell products have shown high response rates and long-term remissions in patients with relapsed/refractory acute lymphoblastic leukemia and relapsed/refractory lymphoma. However, CAR T-cell therapy can induce severe life-threatening toxicities such as cytokine release syndrome, neurotoxicity, or infection, which require rapid and aggressive medical treatment in the intensive care unit setting. In this review, the authors provide an overview of the state-of-the-art in the clinical management of severe life-threatening events in CAR T-cell recipients. Furthermore, key challenges that have to be overcome to maximize the safety of CAR T cells are discussed.

Managing therapy-associated neurotoxicity in children with ALL

Several chemotherapeutic agents and novel immunotherapies provide excellent control of systemic and central nervous system (CNS) leukemia but can be highly neurotoxic. The manifestations of subacute methotrexate neurotoxicity are diverse and require vigilant management; nonetheless, symptoms are transient in almost all patients. As methotrexate is a crucial drug to prevent CNS relapse, it is important to aim to resume it after full neurologic recovery. Most children tolerate methotrexate rechallenge without significant delays or prophylactic medications. Neurotoxicity is more frequent with newer immunotherapies such as CD19- chimeric antigen receptor T (CAR T) cells and blinatumomab. A uniform grading system for immune effector cell-associated neurotoxicity syndrome (ICANS) and algorithms for management based on severity have been developed. Low-grade ICANS usually resolves within a few days with supportive measures, but severe ICANS requires multispecialty care in the intensive care unit for life-threatening seizures and cerebral edema. Pharmacologic interventions include anticonvulsants for seizure control and glucocorticoids to reduce neuroinflammation. Anticytokine therapies targeted to the pathophysiology of ICANS are in development. By using illustrative patient cases, we discuss the management of neurotoxicity from methotrexate, CAR T cells, and blinatumomab in this review.

Cellular and Molecular Mechanisms Mediating Methylmercury Neurotoxicity and Neuroinflammation

Methylmercury (MeHg) toxicity is a major environmental concern. In the aquatic reservoir, MeHg bioaccumulates along the food chain until it is consumed by riverine populations. There has been much interest in the neurotoxicity of MeHg due to recent environmental disasters. Studies have also addressed the implications of long-term MeHg exposure for humans. The central nervous system is particularly susceptible to the deleterious effects of MeHg, as evidenced by clinical symptoms and histopathological changes in poisoned humans. In vitro and in vivo studies have been crucial in deciphering the molecular mechanisms underlying MeHg-induced neurotoxicity. A collection of cellular and molecular alterations including cytokine release, oxidative stress, mitochondrial dysfunction, Ca²⁺ and glutamate dyshomeostasis, and cell death mechanisms are important consequences of brain cells exposure to MeHg. The purpose of this review is to organize an overview of the mercury cycle and MeHg poisoning events and to summarize data from cellular, animal, and human studies focusing on MeHg effects in neurons and glial cells. This review proposes an up-to-date compendium that will serve as a starting point for further studies and a consultation reference of published studies.

A Neurotoxic Snake Venom without Phospholipase A2: Proteomics and Cross-Neutralization of the Venom from Senegalese Cobra, Naja senegalensis (Subgenus: Uraeus)

The Senegalese cobra, Naja senegalensis, is a non-spitting cobra species newly erected from the Naja haje complex. Naja senegalensis causes neurotoxic envenomation in Western Africa but its venom properties remain underexplored. Applying a protein decomplexation proteomic approach, this study unveiled the unique complexity of the venom composition. Three-finger toxins constituted the major component, accounting for 75.91% of total venom proteins. Of these, cardiotoxin/cytotoxin (~53%) and alpha-neurotoxins (~23%) predominated in the venom proteome. Phospholipase A₂, however, was not present in the venom, suggesting a unique snake venom phenotype found in this species. The venom, despite the absence of PLA₂, is highly lethal with an intravenous LD₅₀ of 0.39 µg/g in mice, consistent with the high abundance of alpha-neurotoxins (predominating long neurotoxins) in the venom. The hetero-specific VINS African Polyvalent Antivenom (VAPAV) was immunoreactive to the venom, implying conserved protein antigenicity in the venoms of N. senegalensis and N. haje. Furthermore, VAPAV was able to cross-neutralize the lethal effect of N. senegalensis venom but the potency was limited (0.59 mg venom completely neutralized per mL antivenom, or ~82 LD₅₀ per ml of antivenom). The efficacy of antivenom should be further improved to optimize the treatment of cobra bite envenomation in Africa.

Downregulation of microRNA-199a-5p alleviated lidocaine-induced sensory dysfunction and spinal cord myelin lesions in a rat model

Lidocaine induces neurotoxicity in the spinal cord, but the underlying mechanisms remain unclear. In this study, we evaluated the effects of miR-199a-5p on 10 % lidocaine neurotoxicity. Increased expression of miR-199a-5p in the spinal cord of rats treated with 10 % lidocaine was assessed by qRT-PCR. Furthermore, after miR-199a-5p antagomir administration, the sensory dysfunction and myelin sheath lesions (evaluated by semithin sections stained with toluidine blue, electron microscopy, g-ratios and myelin thickness) induced by 10 % lidocaine were alleviated. Myelin regulatory factor (MYRF), a key molecule of myelin sheath development, was predicted to be a target gene of miR-199a-5p by the TargetScan and miRBase databases. MYRF and its downstream factors myelin basic protein (MBP), proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG) were significantly decreased after intrathecal 10 % lidocaine administration. Moreover, these changes were reversed after miR-199a-5p antagomir administration. FISH-immunofluorescence showed coexpression of miR-199a-5p and MYRF in the spinal cord white matter of rats. A luciferase reporter assay further demonstrated the functional association between miR-199a-5p and MYRF. Overall, miR-199a-5p upregulation is involved in 10 % lidocaine-induced spinal cord toxicity through regulation of MYRF. Therefore, downregulating miR-199a-5p expression may be a potential strategy to ameliorate spinal cord neurotoxicity induced by 10 % lidocaine.

Exotic Snakebites Reported to Pennsylvania Poison Control Centers: Lessons Learned on the Demographics, Clinical Effects, and Treatment of These Cases

Exotic snakebites (i.e. from non-native species) are a rare occurrence, but they present a unique challenge to clinicians treating these patients. Poison control centers are often contacted to assist in the management and care of these medical emergencies. In this study, we analyzed case records of the two Pennsylvania poison control centers from 2004 to 2018 to describe clinical features reported as a result of exotic snakebite envenomation. For the 15-year period reviewed, 18 exotic snakebites were reported with effects ranging from mild local tissue injury to patients who were treated with mechanical ventilation due to respiratory failure. The mean age of the patients was 35 years and males accounted for 83% of the cases. Antivenom, the only specific treatment, was administered in seven of 18 patients within an average of four h of envenomation. The procurement of antivenom against these exotic species may require substantial logistical efforts due to limited stocking of this rarely used treatment. Newer, targeted, small molecule treatments that are being currently investigated may aid in the treatment of snakebites in general. However, people should be cautious when handling these exotic species, and clinicians should be aware of these bites and relevant clinical effects in order to manage these when reported.

Chemical and Genetic Zebrafish Models to Define Mechanisms of and Treatments for Dopaminergic Neurodegeneration

The zebrafish (Danio rerio) is routinely used in biological studies as a vertebrate model system that provides unique strengths allowing applications in studies of neurodevelopmental and neurodegenerative diseases. One specific advantage is that the neurotransmitter systems are highly conserved throughout vertebrate evolution, including between zebrafish and humans. Disruption of the dopaminergic signaling pathway is linked to multiple neurological disorders. One of the most common is Parkinson’s disease, a neurodegenerative disease associated with the loss of dopaminergic neurons, among other neuropathological characteristics. In this review, the development of the zebrafish’s dopaminergic system, focusing on genetic control of the dopaminergic system, is detailed. Second, neurotoxicant models used to study dopaminergic neuronal loss, including 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), the pesticides paraquat and rotenone, and 6-hydroxydopamine (6-OHDA), are described. Next, zebrafish genetic knockdown models of dj1, pink1, and prkn established for investigating mechanisms of Parkinson’s disease are discussed. Chemical modulators of the dopaminergic system are also highlighted to showcase the applicability of the zebrafish to identify mechanisms and treatments for neurodegenerative diseases such as Parkinson’s disease associated with the dopaminergic system.

Critical Illness Secondary to Synthetic Cannabinoid Ingestion

IMPORTANCE

Synthetic cannabinoids (SCs), commonly known as K2, spice, or fake weed, are cheap, artificially manufactured recreational drugs that have emerged as a major public health threat in various regions of the US.

OBJECTIVE

To describe the clinical manifestations of SC intoxication.

DESIGN, SETTING, AND PARTICIPANTS

This case series assessed adults admitted to the intensive care unit from 2014 to 2016 with acute life-threatening complications of SC use. Data analysis was completed in October 2016.

EXPOSURES

Use of SCs such as K2, spice, or other synthetic versions of cannabinoids.

MAIN OUTCOMES AND MEASURES

Data collected included patient demographic data, medical history, presenting symptoms, physical findings, laboratory and imaging data, and intensive care unit and hospital course.

RESULTS

Thirty patients (mean age, 41 years [range, 21-59 years]; 24 men [80%]) with SC ingestion were admitted to the intensive care unit over a 2-year period. Thirteen patients were undomiciled. The majority had a history of polysubstance abuse, psychiatric illness, or personality disorder. The admission diagnoses were coma (10 patients [33%]), agitation (10 patients [33%]), and seizure (6 patients [20%]). Eighteen patients (60%) had acute respiratory failure, and tracheal intubation was required in 21 patients (70%) for either airway protection or acute respiratory failure. Rhabdomyolysis was noted in 8 patients (26%). A man developed transient cerebral edema with loss of gray-white differentiation but had complete recovery. A woman with history of asthma died of acute respiratory distress syndrome. All patients underwent routine toxicology testing, which was unrevealing in 16 cases and revealed coingestion in the remainder. Sixteen patients (53%) left the hospital against medical advice.

CONCLUSIONS AND RELEVANCE

Ingestion of SCs can lead to life-threatening complications, including severe toxic encephalopathy, acute respiratory failure, and death. Synthetic cannabinoids are undetectable in routine serum and urine toxicology testing but can be suspected on the basis of history and clinical presentation, which may include extreme agitation or coma. Frontline clinicians must be aware of the presentation and be vigilant in suspecting SC intoxication.

Vinca alkaloids, thalidomide and eribulin-induced peripheral neurotoxicity: From pathogenesis to treatment

Vinca alkaloids, thalidomide, and eribulin are widely used to treat patients with childhood acute lymphoblastic leukemia (ALL), adults affected by multiple myeloma and locally invasive or metastatic breast cancer, respectively. However, soon after their introduction into clinical practice, chemotherapy-induced peripheral neurotoxicity (CIPN) emerged as their main non-hematological and among dose-limiting adverse events. It is generally perceived that vinca alkaloids and the antiangiogenic agent thalidomide are more neurotoxic, compared to eribulin. The exposure to these chemotherapeutic agents is associated with an axonal, length-dependent, sensory polyneuropathy of mild to moderate severity, whereas it is considered that the peripheral nerve damage, unless severe, usually resolves soon after treatment discontinuation. Advanced age, high initial and prolonged dosing, coadministration of other neurotoxic chemotherapeutic agents and pre-existing neuropathy are the common risk factors. Pharmacogenetic biomarkers might be used to define patients at increased susceptibility of CIPN. Currently, there is no established therapy for CIPN prevention or treatment; symptomatic treatment for neuropathic pain and dose reduction or withdrawal in severe cases is considered, at the cost of reduced cancer therapeutic efficacy. This review critically examines the pathogenesis, epidemiology, risk factors (both clinical and pharmacogenetic), clinical phenotype and management of CIPN as a result of exposure to vinca alkaloids, thalidomide and its analogue lenalidomide as also eribulin.

Individually tailored whole-body vibration training to reduce symptoms of chemotherapy-induced peripheral neuropathy: study protocol of a randomised controlled trial-VANISH

INTRODUCTION

Chemotherapy-induced peripheral neuropathy (CIPN) is a prevalent and clinically meaningful side effect of cancer treatment. CIPN is induced by neurotoxic agents, causing severe sensory and/or motor deficits, resulting in disability and poor recovery, reducing patients' quality of life and limiting medical therapy. To date, effective treatment options are lacking. Whole-body vibration (WBV) training can attenuate motor and sensory deficits. We are conducting a two-armed, multicentre, assessor-blinded, randomised controlled trial, to investigate the effects of WBV on relevant symptoms of CIPN and determine the training characteristics.

METHODS AND ANALYSIS

In this ongoing study, 44 patients who have completed therapy in the past 3 months, with a neurologically confirmed CIPN are assessed before and after a 12-week intervention and follow-up. The intervention group receives WBV twice a week. Exercises are individually tailored according to the initially determined optimal neuromuscular response. The control group receives care as usual.Primary endpoint is the patient reported reduction of CIPN-related symptoms (Functional Assessment of Cancer Therapy/Gynaecology Oncology Group-Neurotoxicity). Secondary endpoints are compound muscle action potentials, distal motor latency, conduction velocity, F-waves from the tibial and peroneal nerve, antidromic sensory nerve conduction studies of the sural nerve, normalised electromyographic activity, peripheral deep sensitivity, proprioception, balance, pain, the feasibility of training settings, quality of life and the level of physical activity.

AIM, ETHICS AND DISSEMINATION

The study was approved by both responsible ethics committees. (1) Our results may contribute to a better understanding of the effects of WBV on motor and sensory functions and (2) may provide information whether WBV at the most effective setting, is feasible for neuropathic patients. (3) Our results may also contribute to improve supportive care in oncology, thereby enhancing quality of life and enabling the optimal medical therapy. All results will be published in international peer-reviewed journals as well as a manual for clinical practice.

TRIAL REGISTRATION NUMBER

NCT03032718.

Successful treatment of a patient with severe thallium poisoning in a coma using Prussian blue and plasma exchange: A case report

RATIONALE

This is the first reported severe thallium poisoning patient successfully treated with Prussian blue (PB) and plasma exchange (PE).

PATIENT CONCERNS

A 42-year-old woman in a coma owing to severe thallium poisoning was admitted to our department after day 44 of poisoning. At admission, blood and urine thallium concentrations were 380.0 and 2580.0 ng/mL, respectively.

DIAGNOSIS

The patient was diagnosed with toxic encephalopathy induced by thallium poisoning; in addition, she was also diagnosed with bilateral pneumonia, respiratory failure, moderate anemia, hypoproteinemia, and electrolyte imbalance based on her chest X-ray, blood gas analysis, Hb level, albumin levels, and serum electrolyte results.

INTERVENTIONS

The patient was intubated and treated with PB (6600 mg/d, 15 days in total) combined with PE (once daily, 5 days in total) as well as other symptomatic supportive care measures.

OUTCOMES

After treatments, her blood and urinary thallium concentrations gradually decreased and on the 13th day after admission, the blood thallium concentration decreased to 0 ng/mL. The oxygenation index gradually improved, meantime, the patient gradually regained consciousness, and on the 50th day of admission, the patient's consciousness reverted to a clear-headed state. The patient recovered mostly after 37 months of follow-up.

LESSONS

Through this case, we learned that the gradual reduction in blood and urine thallium concentration and the patient's improved condition is correlated with PB and PE treatment. For patients with severe thallium poisoning, this treatment method might be effective; but the exact curative effect is unconfirmed, requiring further research to verify.

Mechanisms and Management of Chimeric Antigen Receptor T-Cell Therapy-Related Toxicities

Chimeric antigen receptor T-cell (CAR-T) therapy has proven to be a very effective cancer immunotherapy. Axicabtagene ciloleucel and tisagenlecleucel are the first-in-class anti-CD19 CAR-T currently available for relapsed/refractory adult large B-cell lymphoma. Tisagenlecleucel is also available for pediatric and young adult (up to age 25 years) patients with relapsed/refractory B-acute lymphoblastic leukemia. Cytokine release syndrome (CRS) and CAR-T-associated encephalopathy syndrome (neurotoxicity) are the most common adverse effects associated with CAR-T therapy. They can lead to significant morbidity and preclude widespread use of this treatment modality. Treatment-related deaths from severe CRS and cerebral edema have been reported. There is a significant heterogeneity in the side-effect profile of different CAR-T products under investigation and there is a need to develop standardized guidelines for toxicity grading and management. Here, we summarize the current literature on pathogenesis, clinical presentation, and management of CRS and neurotoxicity. The different grading systems of CRS and management protocols used in different trials have made it difficult to compare the outcomes of different CAR-T therapies. Several prevention strategies such as predictive biomarkers of CRS and neurotoxicity and modified CAR-T with 'built-in' safety mechanisms are being studied, with the potential to greatly expand the safety and applicability of CAR-T treatment across various malignancies.

Best Practices for Postoperative Brain Health: Recommendations From the Fifth International Perioperative Neurotoxicity Working Group

As part of the American Society of Anesthesiology Brain Health Initiative goal of improving perioperative brain health for older patients, over 30 experts met at the fifth International Perioperative Neurotoxicity Workshop in San Francisco, CA, in May 2016, to discuss best practices for optimizing perioperative brain health in older adults (ie, >65 years of age). The objective of this workshop was to discuss and develop consensus solutions to improve patient management and outcomes and to discuss what older adults should be told (and by whom) about postoperative brain health risks. Thus, the workshop was provider and patient oriented as well as solution focused rather than etiology focused. For those areas in which we determined that there were limited evidence-based recommendations, we identified knowledge gaps and the types of scientific knowledge and investigations needed to direct future best practice. Because concerns about perioperative neurocognitive injury in pediatric patients are already being addressed by the SmartTots initiative, our workshop discussion (and thus this article) focuses specifically on perioperative cognition in older adults. The 2 main perioperative cognitive disorders that have been studied to date are postoperative delirium and cognitive dysfunction. Postoperative delirium is a syndrome of fluctuating changes in attention and level of consciousness that occurs in 20%-40% of patients >60 years of age after major surgery and inpatient hospitalization. Many older surgical patients also develop postoperative cognitive deficits that typically last for weeks to months, thus referred to as postoperative cognitive dysfunction. Because of the heterogeneity of different tools and thresholds used to assess and define these disorders at varying points in time after anesthesia and surgery, a recent article has proposed a new recommended nomenclature for these perioperative neurocognitive disorders. Our discussion about this topic was organized around 4 key issues: preprocedure consent, preoperative cognitive assessment, intraoperative management, and postoperative follow-up. These 4 issues also form the structure of this document. Multiple viewpoints were presented by participants and discussed at this in-person meeting, and the overall group consensus from these discussions was then drafted by a smaller writing group (the 6 primary authors of this article) into this manuscript. Of course, further studies have appeared since the workshop, which the writing group has incorporated where appropriate. All participants from this in-person meeting then had the opportunity to review, edit, and approve this final manuscript; 1 participant did not approve the final manuscript and asked for his/her name to be removed.

Is quantitative sensory testing helpful in the management of oxaliplatin neuropathy? a two-year clinical study

PURPOSE

To better understand how quantitative sensory testing could help the clinician in the management of oxaliplatin-induced peripheral neuropathy in terms of earlier and more reliable detection, we conducted a two-year prospective study.

METHODS

Thermal sensory assessment, tactile sensory assessment, neuropathic pain assessment and adverse events gradation (NCI-CTC) were performed during treatment and 6 months after treatment completion.

RESULTS

35 patients were enrolled and followed-up during one year. Cold and Warm Detection Thresholds were higher 6 months after treatment completion than at enrollment. Mechanical detection thresholds didn't change significantly. Neurotoxicity was mostly grade-1, only 18% grade-2 and no grade-3. Grade-2 patients received lower oxaliplatin cumulative dose than grade-1, which reveals effective dose adaptation and grade-2 patients were more likely to develop painful neuropathy.

CONCLUSION

Thermal thresholds impairment emerges too late to help the clinician in the prophylaxis of neuropathy. Management of OXA-treatment based on NCI-CTC, as currently recommended, remains the best way to detect neuropathy and ensure treatment adaptation.

Examining the Impact of a Web-Based Intervention to Promote Patient Activation in Chemotherapy-Induced Peripheral Neuropathy Assessment and Management

Lack of activation in self-care can compromise a patient's ability to monitor and manage cancer treatment-related side effects, such as chemotherapy-induced peripheral neuropathy (CIPN). The web-based Carevive® Care Planning System (CPS) was developed to promote evidence-based symptom assessment and treatment by enhancing patients' involvement in their own care. The purpose of this single-arm, pre-test/post-test, prospective study was to examine whether the CPS can promote patient activation in CIPN symptom assessment and management. Seventy-five women with breast cancer receiving neurotoxic chemotherapy were recruited from a Comprehensive Cancer Center. Using standardized neuropathy measures embedded within the CPS, patients reported their CIPN symptoms over three consecutive clinical visits and completed the Patient Activation Measure (PAM) at the first and third visits. Mean changes in PAM scores between visits were compared using repeated measure analysis of covariance, adjusting for age. At baseline, patients were diagnosed with cancer within the past year (94.7%), highly activated (85% Level III/IV), and had a mean age of 51.3. PAM scores improved significantly from 67.15 (SD = 13.5; range = 47-100) at visit one to 69.29 (SD = 16.18; range = 47-100) (p = 0.02) (n = 62) at visit three. However, patients perceived the CPS to be of minimal value because it solely focused on CIPN and, for many, CIPN was not severe enough to motivate them to seek out symptom management information. Further research is needed to assess the utility of the CPS in promoting activation in the assessment and management of varying cancer treatment-related symptoms.

Chemotherapy-induced peripheral neuropathy: A current review

Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting side effect experienced by patients receiving treatment for cancer. Approximately 30 to 40% of patients treated with neurotoxic chemotherapy will develop CIPN, and there is considerable variability in its severity between patients. It is often sensory-predominant with pain and can lead to long-term morbidity in survivors. The prevalence and burden of CIPN late effects will likely increase as cancer survival rates continue to improve. In this review, we discuss the approach to peripheral neuropathy in patients with cancer and address the clinical phenotypes and pathomechanisms of specific neurotoxic chemotherapeutic agents. Ann Neurol 2017;81:772-781.

Common toxidromes in movement disorder neurology

BACKGROUND

Physicians can come across patients who are exposed to certain prescription drugs or toxins that can result in adverse effects and complications which have high rates of morbidity and mortality.

OBJECTIVE

To summarise the key clinical features and management of the common movement disorder toxidromes relevant to physicians (with an interest in neurology).

METHODS

We searched PUBMED from 1946 to 2016 for papers relating to movement toxidromes and their treatment. The findings from those studies were then summarised and are presented here.

RESULTS

The key features of 6 of the common movement disorder toxidromes and their treatment are tabulated and highlighted. The management of toxidromes with the highest mortality like neuroleptic malignant syndrome and serotonin syndrome are discussed in detail.

CONCLUSION

There are several toxidromes that have the potential to become a serious life-threatening emergency if there is a delay in recognition of key clinical features and instituting the appropriate treatment at the earliest is crucial.

Treatment of cefuroxime-induced neurotoxicity with continuous venovenous haemofiltration

A 61-year-old woman with decreased consciousness, myoclonus, tremors, nystagmus and bradypnoea, due to cefuroxime-induced neurotoxicity, was admitted to the intensive care unit. Continuous venovenous haemofiltration (CVVH) rapidly reduced plasma cefuroxime concentrations and improved neurological manifestations within the next few hours. Retrospective pharmacokinetic assessment showed a total cefuroxime clearance of 166 ml/min during the CVVH.

Altered mental status and end organ damage associated with the use of gacyclidine: a case series

INTRODUCTION

Over the past decade, there has been a sharp increase in the number of newly identified synthetic drugs. These new drugs are often derivatives of previously abused substances but have unpredictable toxicity. One of these drugs is gacyclidine, a derivative of phencyclidine (PCP). Gacyclidine has been studied as a neuroprotective agent in trauma and as a therapy of soman toxicity. There are no previous reports of its use as a drug of abuse.

CASE REPORTS

During a two-month period in the summer of 2013, a series of patients with severe agitation and end-organ injury were identified in an urban academic Emergency Department (ED). A urine drug of abuse screen was performed on all patients, and serum samples were sent for comprehensive toxicology analysis. A total of five patients were identified as having agitation, rhabdomyolysis, and elevated troponin (Table 1). Three of the five patients reported use of methamphetamine, and all five patients had urine drug screens positive for amphetamine. Comprehensive serum analysis identified methamphetamine in three cases, cocaine metabolites in one case, and a potential untargeted match for gacyclidine in all five cases. No other drugs of abuse were identified.

DISCUSSION

This is the first series of cases describing possible gacyclidine intoxication. The possible source of the gacyclidine is unknown but it may have been an adulterant in methamphetamine as all patients who were questioned reported methamphetamine use. These cases highlight the importance of screening for new drugs of abuse when patients present with atypical or severe symptoms. Gacyclidine has the potential to become a drug of abuse both by itself and in conjunction with other agents and toxicity from gacyclidine can be severe. It is the role of the medical toxicology field to identify new agents such as gacyclidine early and to attempt to educate the community on the dangers of these new drugs of abuse.

Acute toxicity associated with the recreational use of the novel dissociative psychoactive substance methoxphenidine

INTRODUCTION

Methoxphenidine is a novel dissociative designer drug of the diarylethylamine class which shares structural features with phencyclidine (PCP), and is not at present subject to restrictive regulations. There is very limited information about the acute toxicity profile of methoxphenidine and the only sources are anonymous internet sites and a 1989 patent of the Searle Company. We report a case of analytically confirmed oral methoxphenidine toxicity.

CASE DETAILS

A 53-year-old man was found on the street in a somnolent and confusional state. Observed signs and symptoms such as tachycardia (112 bpm), hypertension (220/125 mmHg), echolalia, confusion, agitation, opisthotonus, nystagmus and amnesia were consistent with phencyclidine-induced adverse effects. Temperature (99.1°F (37.3°C)) and peripheral oxygen saturation while breathing room air (99%) were normal. Laboratory analysis revealed an increase of creatine kinase (max 865 U/L), alanine aminotransferase (72 U/L) and gamma-glutamyl transpeptidase (123 U/L). Methoxphenidine was identified by a liquid chromatography tandem mass spectrometry toxicological screening method using turbulent flow online extraction in plasma and urine samples collected on admission. The clinical course was favourable and signs and symptoms resolved with symptomatic treatment.

CONCLUSION

Based on this case report and users' web reports, and compatible with the chemical structure, methoxphenidine produces effects similar to those of the arylcyclohexylamines, as PCP.

2-(4-Iodo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25I-NBOMe): clinical case with unique confirmatory testing

INTRODUCTION

2C designer drugs have been in use since the 1970s, but new drugs continue to develop from substitutions to the base phenethylamine structure. This creates new clinical profiles and difficulty with laboratory confirmation. 2-(4-Iodo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25I-NBOMe) is a relatively new 2C drug that is more potent than structural 2C analogs; exposure reports are rare. Testing for 2C drugs is developing; specific testing for new analogs such as 25I-NBOMe is a challenge. These drugs do not reliably trigger a positive result on rapid drug immunoassays. Additionally, most facilities with confirmatory testing capabilities will not identify 25I-NBOMe; methods for detecting 25I-NBOMe in biological samples have not been clearly described nor have optimal metabolic targets for detecting 25I-NBOMe ingestion.

CASE REPORT

An 18-year-old female presented following use of 25I-NBOMe. She had an isolated brief seizure, tachycardia, hypertension, agitation, and confusion. She improved with intravenously administered fluids and benzodiazepines and was discharged 7 h postingestion. Urine was analyzed using quantitative LC-MS/MS methodology for 25I-NBOMe, 2-(4-chloro-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)-methyl]ethanamine (25C-NBOMe), and 2-(2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethanamine (25H-NBOMe). 25I-NBOMe was found at a concentration of 7.5 ng/mL, and 25H-NBOMe was detected as well. Additional testing was pursued to characterize the metabolism of 25I-NBOMe; the sample was reanalyzed with UPLC-time-of-flight mass spectrometry to identify excreted metabolites. The sample was additionally analyzed for the presence of 2,5-dimethoxy-4-iodophenethylamine (2C-I), 4-bromo-2,5-dimethoxyphenethylamine (2C-B), and 1-(2,5-dimethoxy-4-ethylphenyl)-2-aminoethane (2C-E).

DISCUSSION

This is a report of a patient presenting following exposure to 25I-NBOMe, a dangerous member of the evolving 2C drug class. The exposure was confirmed in a unique manner that could prove helpful in guiding further patient analysis and laboratory studies.

Oxidative stress and mitochondrial dysfunction in aluminium neurotoxicity and its amelioration: a review

Aluminium is light weight and toxic metal present ubiquitously on earth which has gained considerable attention due to its neurotoxic effects. The widespread use of products made from or containing aluminium is ensuring its presence in our body. There is prolonged retention of a fraction of aluminium that enters the brain, suggesting its potential for accumulation with repeated exposures. There is no known biological role for aluminium within the body but adverse physiological effects of this metal have been observed in mammals. The generation of oxidative stress may be attributed to its toxic consequences in animals and humans. The oxidative stress has been implicated in pathogenesis of various neurodegenerative conditions including Alzheimer's disease and Parkinson's disease. Though it remains unclear whether oxidative stress is a major cause or merely a consequence of cellular dysfunction associated with neurodegenerative diseases, an accumulating body of evidence implicates that impaired mitochondrial energy production and increased mitochondrial oxidative damage is associated with the pathogenesis of neurodegenerative disorders. Being involved in the production of reactive oxygen species, aluminium may impair mitochondrial bioenergetics and may lead to the generation of oxidative stress. In this review, we have discussed the oxidative stress and mitochondrial dysfunctions occurring in Al neurotoxicity. In addition, the ameliorative measures undertaken in aluminium induced oxidative stress and mitochondrial dysfunctions have also been highlighted.

[Clinical examination of 3 patients with delayed neuropsychiatric encephalopathy induced by carbon monoxide poisoning, who recovered from severe neurocognitive impairment by repetitive hyperbaric oxygen therapy]

We performed hyperbaric oxygen (HBO) therapy for 3 patients with delayed neuropsychiatric encephalopathy induced by carbon monoxide (CO) poisoning. All patients were male and around 50 years old, and they had not received HBO therapy within 24 h after CO poisoning, even though they showed severe consciousness disturbance. In these patients, delayed neuropsychiatric encephalopathy appeared about 25 days after acute CO poisoning, and HBO therapy was initiated within 8 days after disease onset. Although the condition of 2 of the patients worsened initially, they showed significant improvement of neurocognitive impairment after 30 sessions of HBO therapy. The clinical courses of these patients suggest that the effect of HBO therapy can be evaluated after 30 sessions. To evaluate the validity of the indices of the clinical effect of HBO therapy, we performed brain magnetic resonance imaging, single photon emission computed tomography, electroencephalography (EEG), and neurocognitive tests (HDS-R, and Wechsler Adult Intelligence Scale-Revised or III). Our results showed that changes in EEG signals and neurocognitive tests were closely correlated with the patients' clinical courses.

Chemotherapy-induced peripheral neurotoxicity: a critical analysis

With a 3-fold increase in the number of cancer survivors noted since the 1970s, there are now over 28 million cancer survivors worldwide. Accordingly, there is a heightened awareness of long-term toxicities and the impact on quality of life following treatment in cancer survivors. This review will address the increasing importance and challenge of chemotherapy-induced neurotoxicity, with a focus on neuropathy associated with the treatment of breast cancer, colorectal cancer, testicular cancer, and hematological cancers. An overview of the diagnosis, symptomatology, and pathophysiology of chemotherapy-induced peripheral neuropathy will be provided, with a critical analysis of assessment strategies, neuroprotective approaches, and potential treatments. The review will concentrate on neuropathy associated with taxanes, platinum compounds, vinca alkaloids, thalidomide, and bortezomib, providing clinical information specific to these chemotherapies.

[Severe and uncommon complications of anticholinesterase intoxication in children]

BACKGROUND

The Northern region of the Negev desert is an endemic area of organophosphate and carbamate intoxications in Bedouin children. Most victims are intoxicated by drinking the poisonous material kept by the parents in soft drink bottles. Signs and symptoms of intoxication are commonly known and generally include various effects on the central nervous system, usually a decreased level of consciousness in children, cholinergic muscarinic (sweating, rhinorrhea, miosis, vomiting) and nicotinic (weakness) effects. Specific therapy includes Atropine Sulphate and Oximes. PURPOSE AND RESULTS: To describe the course of disease of four (out of 47) children admitted to the Division of Pediatrics with organophosphate or carbamate poisoning during a two-year period. The four children 3-17 years of age ingested the poisonous material: organophosphate chlorpyrifos (2 children); carbamate methomyl (one child) and an unidentified compound in another child. Three of the four patients ingested the poison in a suicide attempt. All 4 children suffered from severe and uncommon complications, including severe respiratory failure from different etiologies. In addition, two of the four suffered from a neurological deficit causing prolonged disability. Three had renal failure necessitating hemofiltration in one case. One child had severe hemodynamic failure and arrhythmias necessitating, among other therapy, the insertion of a temporary pace maker. Two children had (laboratory) pancreatitis. One of the children with severe respiratory failure died after 38 days of extracorporeal membrane oxygenation.

CONCLUSIONS

Intoxications by anticholinesterase compounds are not uncommon among Bedouin children in the Negev. This public health threat should be prevented and completely eradicated by the health authorities. Severe intoxication, especially in cases arising after suicide attempts, wherein the amount of the poisonous material is large, may be complicated by life threatening, multi-organ failure during and after the initial phase of poisoning and may progress into prolonged disability and death.

[Clinical characteristics and treatment of polyneuropathy developed after chemotherapy]

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the main problem of modern cytotoxic therapy. Drug dose reduction, delay or even complete stopping of chemotherapy until the regression of CIPN symptoms impair treatment effectiveness and patients' survival. We studied 44 cancer patients with CIPN developed after polychemotherapy. We suggested a treatment regimen that included a complex of allopathic, homeopathic drugs and hydrotherapy. The treatment resulted in a subjective and objective regression of neuropathy symptoms and improving of quality of life in all patients. Patients who had to delay chemotherapy were able to restart it.

Regenerative effects of umbilical cord matrix cells (UCMCs) in a rodent model of rotenone neurotoxicity

Rotenone is one of the pesticides thought to have neurotoxic effect that could potentially play a role in the development of Parkinson's disease (PD). The neurotoxic effects of rotenone have been used to induce PD model in animals that can help in testing suggested therapies. Cell replacement therapies are suggested as new promising approach for treating PD. This study was done to evaluate the regenerative effect of intrathecal administered umbilical cord matrix cells in a rotenone model of PD in mice. Thirty, male BALB/c mice were used and divided into 3 equal groups. The control group (G.1) received only carboxymethyl cellulose orally once daily at a volume of 10ml/kg. The second group was given a daily rotenone oral dose of 30mg/kg for 28days. The third group received rotenone (30mg/(kgday) orally for 28days) and in the 15th day 1×10(5) of UCMCs were given intrathecally and then they completed the rotenone course. At the 23rd day all the animals were evaluated regarding locomotor incoordination through behavioral tests for monitoring PD development. At the end of the 28days all animals were sacrificed by overdose of phenobarbital and their brain were subjected to immunohistochemical analysis for dopaminergic neurons staining for anti TH antibodies. Intrathecal UCMCs revealed regenerative effects in SNpc as evidenced by immunohistochemical staining; this was in parallel with better performance in behavioral tests. In conclusion, the results of this study revealed the regenerative capacities of UCMCs against rotenone neurotoxicity in mice.

Mechanisms for consideration for intervention in the development of organophosphorus-induced delayed neuropathy

Organophosphorus-induced delayed neuropathy (OPIDN) is a neurodegenerative disorder characterised by ataxia progressing to paralysis with concomitant central and peripheral distal axonopathy. Symptoms of OPIDN in people include tingling of the hands and feet. This tingling is followed by sensory loss, progressive muscle weakness and flaccidity of the distal skeletal muscles of the lower and upper extremities and ataxia, which appear about 8-14 days after exposure. Some organophosphorus compounds (OPs) that are still used in worldwide agriculture have potential to induce OPIDN, including methamidophos, trichlorfon, dichlorvos and chorpyrifos. This review summarizes experimental attempts to prevent and/or treat OPIDN and the different mechanisms involved in each approach. The initial mechanism associated with development of OPIDN is phosphorylation and inhibition of neuropathy target esterase (NTE). The phosphorylated enzyme undergoes a second reaction known as "aging" that results in the loss of one of the "R" groups bound to the phosphorus of the OP. A second mechanism involved in OPIDN is an imbalance in calcium homeostasis. This can lead to the activation of calcium-activated neutral protease and increases in calcium/calmodulin-dependent protein kinases. These events contribute to aberrant phosphorylation of cytoskeletal proteins and protein digestion in the terminal axon that can proceed similarly to Wallerian-type degeneration. Several experimental studies demonstrated alleviation of the signs and symptoms of OPIDN by restoring calcium balance. Other studies have used preadministration of NTE inhibitors, such as carbamates, thiocarbamates, sulfonyl fluorides and phosphinate to prevent OPIDN. Progress is being made, but there is yet no single specific treatment available for use in clinical practice to prevent or alleviate the severe effects of OPIDN.

Anesthetic neurotoxicity

Concerns for toxic effects of anesthesia to the brains of the young and the elderly are mounting. While experimental evidence for such effects in the developing brain is strong, the underlying mechanisms are less well understood and debate continues as to whether young humans are at risk for anesthetic neurotoxicity. The phenomenon of postoperative cognitive deterioration in the elderly remains controversial. Time course, severity, and whether or not it persists long term are under debate. For both patient groups, today's evidence is not sufficient to guide change in clinical practice. Well-designed research is therefore imperative to tackle this critical issue.

Valproate-induced hyperammonemic encephalopathy: a brief review

BACKGROUND

This brief review presents a comprehensive evaluation of valproate-induced encephalopathy (VHE) and also discusses potential mechanisms of the condition.

SCOPE

Sodium valproate (VPA) is an effective antiepileptic drug used in neurology as well as in psychiatry, in adults and children. VHE requires early diagnosis and management. Focused research efforts in understanding the condition will help decrease its incidence. Delay in recognition of VHE can result in the development of potentially life-threatening complications.

FINDINGS

Management options are described. Since VPA frequently causes a modest rise in plasma ammonia levels which is asymptomatic, it is important to recognize the symptoms of VHE promptly and to correlate them with the plasma ammonia levels.

CONCLUSIONS

Although there are several case reports on VHE, this review is a comprehensive evaluation of its causes and potential mechanisms. Rapid diagnosis and management will help in reducing VHE-related morbidity.

Treatment of MDR1 mutant dogs with macrocyclic lactones

P-glycoprotein, encoded by the multidrug resistance gene MDR1, is an ATP-driven drug efflux pump which is highly expressed at the blood-brain barrier of vertebrates. Drug efflux of macrocyclic lactones by P-glycoprotein is highly relevant for the therapeutic safety of macrocyclic lactones, as thereby GABA-gated chloride channels, which are confined to the central nervous system in vertebrates, are protected from high drug concentrations that otherwise would induce neurological toxicity. A 4-bp deletion mutation exists in the MDR1 gene of many dog breeds such as the Collie and the Australian Shepherd, which results in the expression of a non-functional P-glycoprotein and is associated with multiple drug sensitivity. Accordingly, dogs with homozygous MDR1 mutation are in general prone to neurotoxicity by macrocyclic lactones due to their increased brain penetration. Nevertheless, treatment of these dogs with macrocyclic lactones does not inevitably result in neurological symptoms, since, the safety of treatment highly depends on the treatment indication, dosage, route of application, and the individual compound used as outlined in this review. Whereas all available macrocyclic lactones can safely be administered to MDR1 mutant dogs at doses usually used for heartworm prevention, these dogs will experience neurological toxicity following a high dose regimen which is common for mange treatment in dogs. Here, we review and discuss the neurotoxicological potential of different macrocyclic lactones as well as their treatment options in MDR1 mutant dogs.

A novel "molecular tweezer" inhibitor of α-synuclein neurotoxicity in vitro and in vivo

Aggregation of α-synuclein (α-syn) is implicated as being causative in the pathogenesis of Parkinson's disease, multiple system atrophy, and dementia with Lewy bodies. Despite several therapies that improve symptoms in these disorders, none slow disease progression. Recently, a novel "molecular tweezer" (MT) termed CLR01 has been described as a potent inhibitor of assembly and toxicity of multiple amyloidogenic proteins. Here we investigated the ability of CLR01 to inhibit assembly and toxicity of α-syn. In vitro, CLR01 inhibited the assembly of α-syn into β-sheet-rich fibrils and caused disaggregation of pre-formed fibrils, as determined by thioflavin T fluorescence and electron microscopy. α-Syn toxicity was studied in cell cultures and was completely mitigated by CLR01 when α-syn was expressed endogenously or added exogenously. To determine if CLR01 was also protective in vivo, we used a novel zebrafish model of α-syn toxicity (α-syn-ZF), which expresses human, wild-type α-syn in neurons. α-Syn-ZF embryos developed severe deformities due to neuronal apoptosis and most of them died within 48 to 72 h. CLR01 added to the water significantly improved zebrafish phenotype and survival, suppressed α-syn aggregation in neurons, and reduced α-syn-induced apoptosis. α-Syn expression was found to inhibit the ubiquitin proteasome system in α-syn-ZF neurons, resulting in further accumulation of α-syn. Treatment with CLR01 almost completely mitigated the proteasome inhibition. The data suggest that CLR01 is a promising therapeutic agent for the treatment of Parkinson's disease and other synucleinopathies.