JC virus infection of the brain

John Cunningham Virus and Progressive Multifocal Leukoencephalopathy: A Falsely Played Diagnosis

Progressive Multifocal Leukoencephalopathy (PML) is a possibly fatal demyelinating disease and John Cunningham Polyomavirus (JCPyV) is believed to cause this condition. The so-called JCPyV was initially reported in lymphoma and Human Immunodeficiency Virus (HIV) cases, whereas nowadays, its incidence is increasing in Multiple Sclerosis (MS) cases treated with natalizumab (Tysabri). However, there are conflicting literature data on its pathology and diagnosis, whereas some misdiagnosed reports exist, giving rise to further questions towards the topic. In reality, the so-called PML and the supposed JCPyV are not what they seem to be. In addition, novel and more frequent PML-like conditions may be reported, especially after the Coronavirus Disease 2019 (COVID-19) pandemic.

Progressive multifocal leukoencephalopathy in a patient with B-cell chronic lymphocytic leukemia after COVID-19 vaccination, complicated with COVID-19 and mucormycosis: a case report

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) is a rare and fatal opportunistic viral demyelinating infectious disease of the central nervous system (CNS). There are various clinical presenting symptoms for the disease.

CASE PRESENTATION

This paper presents a clinical case of PML in a patient with B-Chronic lymphocytic leukemia (B-CLL), previously treated with Chlorambucil, later complicated later with COVID-19 and mucormycosis.

CONCLUSION

PML can develop in the setting of cellular immune dysfunction. Late diagnosis of this disease based on nonspecific symptoms is common, therefore when we face a neurological complication in a CLL or immunocompromised patient, we should consider PML infection. A remarkable feature of this case is the possible triggering effect of COVID-19 vaccination for emergence of PML as the disease can be asymptomatic or sub-clinical before diagnosis.

MRI characteristics of chemotherapy-related central neurotoxicity: a pictorial review

The relentless advancement of chemotherapeutic agents has enhanced survival rates among cancer patients. However, this success comes with an increased prevalence of chemotherapy-induced neurotoxicity, which often mimics the symptoms of metastatic disease or paraneoplastic syndromes and poses a diagnostic challenge for clinicians. Imaging, particularly MRI, plays a pivotal role in unraveling this conundrum.This comprehensive review explores the MRI patterns associated with central neurotoxicities induced by various chemotherapeutic agents. Our objective is to provide radiologists and clinicians with illustrative diagrams that offer a structured approach to diagnosing these conditions. By enhancing the understanding of these distinctive MRI patterns, we aim to facilitate accurate and timely diagnosis, ultimately improving patient care in the context of evolving cancer treatments.Critical relevance statementThis article describes the essential role of MRI in identifying distinct patterns of chemotherapy-induced central neurotoxicity, enabling early diagnosis and improved patient care within the field of clinical radiology.Key points• Chemotherapy-induced neurotoxicity is a growing concern for cancer patients, and MRI is a key tool in diagnosis.• This review highlights distinctive MRI patterns associated with various chemotherapy-induced neurotoxicities.• Understanding these patterns improves patient care, ensuring timely intervention and accurate diagnosis in the complex world of cancer treatment.

Anything but Little: a Pictorial Review on Anatomy and Pathology of the Cerebellum

Despite its small size the cerebellum is an anatomically complex and functionally important part of the brain. Traditionally the cerebellum is viewed as a motor control structure entirely devoted to motor control and learning, but recent functional magnetic resonance imaging (fMRI) studies demonstrated significant involvement of the cerebellum in higher order cognitive functions. The anatomical complexity of the cerebellum is reflected by the several nomenclature systems that exist for the description of cerebellar anatomy. The cerebellum can be affected by a variety of pathological processes, including congenital, infectious and inflammatory, neoplastic, vascular, degenerative and toxic metabolic diseases. The purpose of this pictorial review is to (1) provide a general overview of cerebellar anatomy and function, (2) demonstrate normal cerebellar anatomy on imaging studies, and (3) illustrate both common as well as rare pathological conditions affecting the cerebellum.

CNS Involvement of DLBCL Presenting with an Unusual Non-Enhancing Infiltrative Mass

Central nervous system (CNS) involvement in diffuse large B-cell lymphoma (DLBCL) is relatively uncommon, occurring in approximately 5% of cases, with the majority of instances manifesting during relapse and often associated with poor prognoses. The aim of this case report is to present a unique occurrence of non-enhancing relapse of CNS lymphoma. Significantly, the patient had recently encountered a disease involvement in the axilla region, and subsequent to scheduled chemotherapy, she developed persistent neurological symptoms, leading to the discovery of a relapse of the CNS lymphoma. Our focus will be on delineating the clinical presentation, elucidating the findings observed in clinical imaging, and detailing the therapeutic approaches employed in this specific case. By highlighting these aspects, we aim to provide valuable insights into the diagnosis of the atypical presentation of CNS lymphoma.

Presumptive Progressive Multifocal Encephalopathy in an Immunocompetent Patient: A Rare Case Report

Progressive multifocal encephalopathy (PML) is a rare brain infection caused by the John Cunningham virus (JCV), primarily affecting immunocompromised individuals. This case report presents a unique occurrence of PML in an immunocompetent young man with a history of substance abuse. The patient exhibited progressive neurological symptoms, including weakness and sensory deficits, prompting diagnostic evaluation. Brain imaging and laboratory tests revealed evidence of PML, supported by a positive JCV antibody. Notably, HIV testing was negative. While PML is typically associated with immunosuppression, this case raises questions about potential connections between substance abuse and viral reactivation. The patient received treatment with intravenous methylprednisolone and underwent rehabilitation, emphasizing the challenging nature of PML management. This case highlights the importance of considering PML as a differential diagnosis, even in immunocompetent individuals, and underscores the need for further research into its rare presentations and associated risk factors.

Lymphomas of Central Nervous System

Central nervous system (CNS) lymphoma consists of primary central nervous system lymphoma (PCNSL) and secondary CNS involvement by systemic lymphoma. This chapter focuses on the former. PCNSL is a relative rare disease, accounting for approximately 2.4-4.9% of all primary CNS tumors. It is an extra-nodal variant of non-Hodgkin's lymphoma (NHL), confined to the brain, leptomeninges, spinal cord, and eyes, with no systemic involvement. Recently, elderly patients (≥ 60 years) are increasing. Histologically, B cell blasts, which originate from late germinal center exit B cell, are growing and homing in CNS. Immunohistochemically, these cells are positive for PAX5, CD19, CD20, CD22, and CD79a. PCNSL shows relatively characteristic appearances on CT, MR imaging, and PET. Treatment first line of PCNSL is HD-MTX-based chemotherapy with or without rituximab and irradiation. Severe side-effect of this treatment is delayed onset neurotoxicity, which cause of cognitive impairment. Therefore, combined chemotherapy alone or chemotherapy with reduced-dose irradiation is more recommended for elderly patients. There is no established standard care for relapse of the PCNSLs. Temsirolimus, lenalidomide, temozolomide, and Bruton's tyrosine kinase (BTK) inhibitor ibrutinib are candidates for refractory patients. The prognosis of PCNSL has significantly improved over the last decades (median OS: 26 months, 5-year survival: 31%). Younger than 60 age and WHO performance status less than < or = 1 are associated with a significantly better overall survival.

Changes in Brain Volumes Are Relevant during Natalizumab-Associated Progressive Multifocal Leukoencephalopathy: Lessons from a Case Report

This is a case report concerning a Natalizumab-associated Progressive Multifocal Leukoencephalopathy (PML) with cerebellar localization and wakefulness disturbances. Awakening and clinical improvement dramatically occurred as soon as the immune reconstitution inflammatory syndrome (IRIS) took place, being it mild in nature and colocalizing with the PML lesion. In these ideal experimental conditions, we applied brain magnetic resonance imaging post-analysis in order to know changes in brain volumes underlying the pathological process over the infection period. White matter volume increased with a decrease in grey matter during IRIS. Conversely, we found a constant increase in cerebrospinal fluid volume throughout the duration of PML, suggesting a widespread abiotrophic effect, far from the lesion. Furthermore, brain parenchymal fraction significantly decreased as expected while the total brain volume remained stable at all times. Neurodegeneration is the main contributor to the steady disability in Natalizumab-associated PML. This process is thought to be widespread and inflammatory in nature as well as sustained by IRIS and humoral factors derived from the PML lesion.

CD8 Encephalitis: A Diagnostic Dilemma

CD8+ encephalitis is a subacute encephalopathy associated with HIV infection. Pathophysiology is thought to be auto-reactive CD8+ cells attacking on HIV infected CD4+ cells and ‘viral escape’ phenomena (replication of CD8+ cells in CSF). We present a case of a 45-year-old man with well controlled HIV who developed CD8 encephalitis following Herpes simplex encephalitis. He had persistent encephalopathy for several weeks with status epilepticus and agitated delirium, and diagnosis remained elusive until a brain biopsy confirmed the diagnosis.

Methotrexate induced neurotoxicity in a patient with rheumatoid arthritis on rituximab therapy: a case-based review

Rheumatoid arthritis (RA) is a systemic inflammatory disease treated with conventional and biologic disease-modifying drugs. Methotrexate is the anchor drug for the treatment of RA and is also frequently used for various autoimmune diseases. Adverse events are common and generally easy to manage, involving mainly the gastrointestinal tract and the liver function. However, neurotoxicity is very uncommon in adults with rheumatic diseases. B cell depletion with rituximab is another therapy approach particularly in patients with refractory RA. Whistle leukoencephalopathy - namely progressive multifocal leukoencephalopathy-is an infrequent but well-described side effect of rituximab. In contrast, central nervous system toxicity due to methotrexate is extremely rare especially in RA individuals under oral or subcutaneous low dose on weekly basis. We present a challenging case of a RA patient on treatment with methotrexate and rituximab presenting with leukoencephalopathy. The patient was diagnosed with methotrexate-induced leukoencephalopathy which reversed after treatment discontinuation. We comment on the symptoms and diagnostic workout and we review the available literature on this issue based on recommendations for narrative reviews.

The neurological sequelae of pandemics and epidemics

Neurological manifestations in pandemics frequently cause short and long-term consequences which are frequently overlooked. Despite advances in the treatment of infectious diseases, nervous system involvement remains a challenge, with limited treatments often available. The under-recognition of neurological manifestations may lead to an increase in the burden of acute disease as well as secondary complications with long-term consequences. Nervous system infection or dysfunction during pandemics is common and its enduring consequences, especially among vulnerable populations, are frequently forgotten. An improved understanding the possible mechanisms of neurological damage during epidemics, and increased recognition of the possible manifestations is fundamental to bring insights when dealing with future outbreaks. To reverse this gap in knowledge, we reviewed all the pandemics, large and important epidemics of human history in which neurological manifestations are evident, and described the possible physiological processes that leads to the adverse sequelae caused or triggered by those pathogens.

Understanding progressive multifocal leukoencephalopathy: links between milky-way appearance and mismatch T2/FLAIR

BACKGROUND

Magnetic resonance imaging is essential to diagnose progressive multifocal leukoencephalopathy. The broad radiological spectrum may partially be explained by genetic viral mutations and their differential neurotropism. Recent pharmacovigilance-magnetic resonance imaging studies have provided new insight into pathophysiology and radiological markers of early stages. However, how lesions evolve and why certain anatomical locations are more frequently affected remains unknown. We aim to describe a new sign - T2/fluid-attenutated inversion recovery mismatch - as a complementary marker of cavitated lesions and propose a link with the milky-way appearance, a key early sign. Furthermore, we hypothesise viral dissemination routes.

METHODS

We conducted a retrospective longitudinal study from January 2010 to January 2020, to analyse clinical and magnetic resonance imaging features of 13 progressive multifocal leukoencephalopathy individuals at the symptomatic stage (mean age 58.3 years (SD ± 16.8) - 61.5% were women).

RESULTS

The most prevalent pathology was HIV (61.5%) and motor deficit prevailed regarding other symptoms (76.9%). Frontal lobes (76.9%), middle cerebellar peduncle (61.5%), cerebellum (61.5%), and pons (53.8%) were most commonly affected, and the cortico-ponto-cerebellar pathway seemed involved in these patients. Five patients had a pure radiological pattern. Milky-way appearance was the most frequent radiological sign (58.3%). Five patients with milky-way appearance had concomitantly T2/fluid-attenuated inversion recovery mismatch (P = 0.02). This sign showed high sensitivity and specificity (100-71%, P = 0.02) to assess evolved lesions besides diffusion.

CONCLUSION

The possible tract-dependent spread, as well as clinical and genetic, have implications on the MRI variability of progressive multifocal leukoencephalopathy. The milky-way appearance could reflect a transitional phase towards evolved lesions, the latter demonstrated by T2/fluid-attenuated inversion recovery mismatch. Both could be key magnetic resonance imaging signs to diagnose progressive multifocal leukoencephalopathy at the symptomatic stage.

MRI of Emergent Intracranial Infections and Their Complications

Acute intracranial infections of the central nervous system and skull base are uncommon but time sensitive diagnoses that may present to the emergency department. As symptoms are frequently nonspecific or lack typical features of an infectious process, a high index of suspicion is required to confidently make the diagnosis, and imaging may not only serve as the first clue to an intracranial infection, but is often necessary to completely characterize the disease process and exclude any confounding conditions. Although computed tomography is typically the initial imaging modality for many of these patients, magnetic resonance imaging offers greater sensitivity and specificity in diagnosing intracranial infections, characterizing the full extent of infection, and identifying potential complications. The aim of this article is to serve as a review of the typical and most important imaging manifestations of these infections that can be encountered in the emergent setting.

Imaging Spectrum of Infections in the Setting of Immunotherapy and Molecular Targeted Therapy

Advances in genomics and immunology are revolutionizing our understanding and treatment of cancer with improved treatment outcomes and patient quality of life. With the increasing use of immunotherapy and molecular targeted therapy, a variety of unusual and/or opportunistic infections are also observed. A variety of factors including use of immunosuppression for immune-mediated adverse effects play an important role for increasing the likelihood of these infections and form the basis of this case-based review. Imaging features of infections arising in patients undergoing immunotherapy regimens have not been previously highlighted. Prompt recognition of the spectrum of mycobacterial, bacterial, invasive fungal and viral pathogens can potentially lead to reduction in the high morbidity and mortality in this patient population.

Four cases of progressive multifocal leukoencephalopathy in iatrogenic immunocompromised patients

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system (CNS) caused by John Cunningham Virus (JCV). We report four PML cases in immunocompromised patients, respectively treated with (1) Natalizumab, (2) Rituximab, (3) autologous stem-cell transplantation, and (4) Tacrolimus. All patients underwent neurological examination, magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), JCV-DNA research on biological samples, and lymphocytes subpopulation study. All cases presented with motor, behavioural, and cognitive disorders. Visual, sensitive, and cerebellar deficits developed in three cases. MRI revealed widespread progressive demyelinating areas with active borders; three patients presented contrast enhancement. One patient developed inflammatory reconstitution syndrome (IRIS). At MRS, all cases presented decreased N-acetyl-aspartate (NAA) and three cases showed increased choline (Cho). In one patient, plasma and urine tested positive for JCV-DNA, while cerebrospinal fluid (CSF) analysis confirmed JCV in two patients. The fourth patient had a low JCV-DNA blood titer and brain biopsy showed subacute necrosis. Two patients had abnormal lymphocyte subpopulations. Three patients underwent therapy with Mirtazapine, one of whom received Mefloquine in add-on. No clinical response was registered. Clinical onset, MRI and MRS were highly suggestive of PML in all patients, despite three cases presented contrast enhancement. In three cases JCV-DNA detection in biological samples confirmed the diagnosis. The fourth patient fulfilled diagnosis of “presumptive PML”. Our data confirm the importance to complete the diagnostic workup despite the presence of findings not completely consistent with classical PML. We hypothesize that atypical characteristics could due to the clinical conditions leading to PML.

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Four cases of PML in iatrogenic immunocompromised patients.

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Clinical presentation was typical for PML.

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Diagnostic findings were not completely consistent with classical PML.

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Atypical findings do not exclude diagnosis when clinical data are highly suggestive.

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It is necessary to improve the diagnostic and therapeutic management of patients.

Progressive Multifocal Leukoencephalopathy: Current Insights

Cases of PML should be evaluated according to predisposing factors, as these subgroups differ by incidence rate, clinical course, and prognosis. The three most significant groups at risk of PML are patients with hematological malignancies mostly previously treated with immunotherapies but also untreated, patients with HIV infection, and patients using monoclonal antibody (mAb) treatments. Epidemiological data is scarce and partly conflicting, but the distribution of the subgroups appears to have changed. While there is no specific anti-JCPyV treatment, restoration of the immune function is the most effective approach to PML treatment. Research is warranted to determine whether immune checkpoint inhibitors could benefit certain PML subgroups. There are no systematic national or international records of PML diagnoses or a risk stratification algorithm, except for MS patients receiving natalizumab (NTZ). These are needed to improve PML risk assessment and to tailor better prevention strategies.

CNS Infections in Immunoincompetent Patients : Neuroradiological and Clinical Features

In patients with immunodeficiency the pathogen spectrum of central nervous system (CNS) infections is broader and different from that of immunocompetent patients. Numerous opportunistic infections are characterized by a high prevalence of viral, bacterial and parasitic pathogens, and depend on the type of impaired immune defense, for example impaired T‑cell or monocyte function, monoclonal antibody treatment, and impaired granulocyte function. Neuroradiological features as well as laboratory findings are often different and versatile in comparison to immunocompetent individuals and pathognomonic imaging findings do not exist; however, knowledge of possible pathways of pathogens in the CNS and preferred tissue affection may help in narrowing down differential diagnoses. Therefore, knowledge of the type of patient and the performed immunomodulatory therapy is essential for the neuroradiological assessment and the differential diagnostic considerations. Moreover, parenchymal reactions in the sense of an immune reconstitution inflammatory syndrome (IRIS) can occur when immunocompetence is restored. This review focus on the most common pathologies in immunocompromised patients, and an overview of imaging features but also of pathology and clinical aspects is given. The synopsis of anamnestic information, clinical findings and structured analysis of the lesion pattern, its spread and short-term follow-up may increase the correct diagnostic classification; however, the gold standard is still determination of the pathogen in the cerebrospinal fluid (CSF), blood cultures or biopsies.

Tau-protein concentrations are not elevated in cerebrospinal fluid of patients with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML), caused by infection with John Cunningham polyoma virus (JCPyV) in immune-compromised patients, is a serious demyelinating disease of the central nervous system. This disease often leads to major neurological impairments and consecutive disability. No effective treatment for PML has been found as yet. As JCPyV-PCR of the cerebrospinal fluid (CSF) may be negative in some cases, a reliable diagnosis might prove to be difficult as well. So far, two case reports suggested CSF-tau to be a promising biomarker for PML. Our study included 10 patients with assured diagnosis of PML and varying underlying diseases. In all but one the CSF-tau concentration was normal. Our results indicate that CSF-tau is not an appropriate biomarker for PML.

Development of demyelinating lesions in progressive multifocal leukoencephalopathy (PML): Comparison of magnetic resonance images and neuropathology of post-mortem brain

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disorder caused by opportunistic infection of JC polyomavirus (JCV). Today, increased attention has been focused on PML development in multiple sclerosis (MS) patients under disease-modifying therapies (DMT). Although in the acquired immunodeficiency syndrome (AIDS) era, PML was thought to be a rapidly progressive disease with poor prognosis, drug-associated PML is relatively slow in progress, and a favorable outcome may be expected with early diagnosis. However, early PML diagnosis on magnetic resonance imaging (MRI) is frequently difficult, and JCV DNA copy number in cerebrospinal fluid (CSF) is usually low. To facilitate early PML diagnosis on MRI, the pre-mortem images were compared with neuropathology of the post-mortem brain, and underlying pathology corresponding to the MRI findings was evaluated. As a result, PML lesions of the autopsied brain were divided into three parts, based on the disease extension patterns: (A) Progressive white matter lesion in the right frontoparietal lobe including the precentral gyrus. Huge demyelinated lesions were formed with fusions of numerous small lesions. (B) Central lesion including deep gray matters, such as the putamen and thalamus. The left thalamic lesion was contiguous with the pontine tegmentum. (C) Infratentorial lesion of brainstem and cerebellum. Demyelination in the pontine basilar region and in cerebellar white matter was contiguous via middle cerebellar peduncles (MCPs). In addition, (D) satellite lesions were scattered all over the brain. These observations indicate that PML lesions likely evolve with three steps in a tract-dependent manner: (1) initiation; (2) extension/expansion of demyelinating lesions; and (3) fusion. Understanding of the PML disease evolution patterns would enable confident early diagnosis on MRI, which is essential for favorable prognosis with good functional outcome.

[A case of progressive multifocal leukoencephalopathy in a HIV-infected female patient]

Progressive multifocal leukoencephalopathy (PML) caused by JC virus is a severe central nervous lesion developing in the presence of obvious immunodeficiency. In most cases, the disease results in a fatal outcome within a few months. Antiretroviral therapy is currently considered to be the only method for the prevention and treatment of PML in HIV-infected patients. The paper describes a positive experience in treating the HIV-infected female patient with the established diagnosis of PML.

Neuroimmune Axes of the Blood-Brain Barriers and Blood-Brain Interfaces: Bases for Physiological Regulation, Disease States, and Pharmacological Interventions

Central nervous system (CNS) barriers predominantly mediate the immune-privileged status of the brain, and are also important regulators of neuroimmune communication. It is increasingly appreciated that communication between the brain and immune system contributes to physiologic processes, adaptive responses, and disease states. In this review, we discuss the highly specialized features of brain barriers that regulate neuroimmune communication in health and disease. In section I, we discuss the concept of immune privilege, provide working definitions of brain barriers, and outline the historical work that contributed to the understanding of CNS barrier functions. In section II, we discuss the unique anatomic, cellular, and molecular characteristics of the vascular blood-brain barrier (BBB), blood-cerebrospinal fluid barrier, and tanycytic barriers that confer their functions as neuroimmune interfaces. In section III, we consider BBB-mediated neuroimmune functions and interactions categorized as five neuroimmune axes: disruption, responses to immune stimuli, uptake and transport of immunoactive substances, immune cell trafficking, and secretions of immunoactive substances. In section IV, we discuss neuroimmune functions of CNS barriers in physiologic and disease states, as well as pharmacological interventions for CNS diseases. Throughout this review, we highlight many recent advances that have contributed to the modern understanding of CNS barriers and their interface functions.

[Progressive multifocal encephalopathy in neurological practice]

Progressive multifocal leukoencephalopathy (PML) is considered so far as a rare rapidly progressive demyelinating CNS disease caused by the JC virus activation. Current data suggest that PML developed in people with impaired immunity. However, in some cases PML developed in the absence of severe immunological deficit. In clinical practice, the early diagnosis of PML is difficult because symptoms are mild and, therefore, the physician should be familiar with diagnostic criteria of this disease to make the correct diagnosis and start the symptomatic therapy as soon as possible. This will help to improve patient's state though there is no effective treatment of PML so far. Up to the present moment, antiviral medications, cytostatic drugs, serotonin receptor antagonists, plasmapheresis are widely used. These methods can be used only if the causes of PML have been identified while the patient needs urgent help. Thus, the schemes of pathogenetic treatment with the drugs with pleiotropic effects should be used.

Isolated posterior fossa involvement of progressive multifocal leucoencephalopathy in HIV: A case series with review of the literature

Progressive multifocal leucoencephalopathy (PML) is a progressive demyelinating condition resulting from infection with the John Cunningham virus and precipitated by immunocompromised states. The HIV pandemic, especially in sub-Saharan Africa, has resulted in an increase in the number of patients presenting with PML. Imaging plays an important role in diagnosis and the distribution of the disease is predominantly supratentorial. Isolated posterior fossa involvement is a rare finding with very few cases described in the literature. We present the largest case series of patients described in the literature, with isolated posterior fossa involvement of PML, in HIV-positive patients.

Diagnosis and Treatment of Progressive Multifocal Leukoencephalopathy Associated with Multiple Sclerosis Therapies

Progressive multifocal leukoencephalopathy (PML) is a rare, but serious, complication encountered in patients treated with a select number of disease-modifying therapies (DMTs) utilized in treating multiple sclerosis (MS). PML results from a viral infection in the brain for which the only demonstrated effective therapy is restoring the perturbed immune system-typically achieved in the patient with MS by removing the offending therapeutic agent or, in the case of HIV-associated PML, treatment with highly active antiretroviral therapies. Other therapies for PML remain either ineffective or experimental. Significant work to understand the virus and host interaction has been undertaken, but lack of an animal model for the disorder has significantly hindered progress, especially with respect to development of treatments. Strategies to limit risk of PML with natalizumab, a drug that carries a uniquely high risk for the development of the disorder, have been developed. Identifying factors such as positive JC virus antibody status that increase PML risk, at least in theory, should decrease the incidence rate of the disease. Whether other risk factors for PML can be identified and validated or unique strategies should be employed in association with other DMTs that predispose to PML and whether this has a salutary effect on outcome remains to be demonstrated. Identifying PML early, then promptly eliminating drug in the case of natalizumab-associated PML has demonstrated better outcomes, but the complication of PML continues to carry significant morbidity and mortality. While the scientific community has yet to identify targeted therapy with proven efficacy against JCV or PML there are several candidates being studied.

JC Virus-Related Progressive Multifocal Leukoencephalopathy After Living-Donor Liver Transplant: A Rare Case

Progressive multifocal leukoencephalopathy caused by polyoma JC virus is a rare and severe demyelinating disease of the central nervous system. It occurs in immunocompromised patients and is scarcely reported in liver transplant recipients. Brain biopsy demonstrating demyelination with presence of foamy macrophages, relative preservation of axons, astrogliosis, and typical polyomavirus inclusions in the enlarged oligodendroglial nuclei is essential for diagnosis. Here, we report a case of JC virus-associated progressive multifocal leukoencephalopathy in a living-donor liver transplant recipient who was transplanted for hepatitis C virus-related decompensated cirrhosis. Brain biopsy with immunohistochemistry confirmed the diagnosis of progressive multifocal leukoencephalopathy secondary to JC virus. JC virus related-progressive multifocal leukoencephalopathy is associated with extremely poor prognosis. Awareness and consideration of this entity in liver transplant recipients who present with sudden progressive neurologic manifestations can help in prompt diagnosis and timely treatment.

Fatal ruxolitinib-related JC virus meningitis

We report a possible association between ruxolitinib and JC virus meningitis. A 72-year-old man with myelofibrosis started treatment with ruxolitinib. Fourteen days later, the patient presented to the emergency department with fever and nausea. HIV test was negative. Ruxolitinib was suspended. Symptoms progressed with neck stiffness, cognitive impairment, and motor aphasia. CSF was positive for JC virus. MRI showed nonspecific abnormal findings. Five days after the clinical debut, the patient died. The clinical picture, MRI imaging, and positive JC virus PCR in CSF strongly suggest ruxolitinib-related JC virus meningitis.

Fatal ruxolitinib-related JC virus meningitis

We report a possible association between ruxolitinib and JC virus meningitis. A 72-year-old man with myelofibrosis started treatment with ruxolitinib. Fourteen days later, the patient presented to the emergency department with fever and nausea. HIV test was negative. Ruxolitinib was suspended. Symptoms progressed with neck stiffness, cognitive impairment, and motor aphasia. CSF was positive for JC virus. MRI showed nonspecific abnormal findings. Five days after the clinical debut, the patient died. The clinical picture, MRI imaging, and positive JC virus PCR in CSF strongly suggest ruxolitinib-related JC virus meningitis.

Brain Susceptibility Changes in a Patient with Natalizumab-Related Progressive Multifocal Leukoencephalopathy: A Longitudinal Quantitative Susceptibility Mapping and Relaxometry Study

Background

Brain MRI plays an essential role in both diagnosis and follow-up of the JC virus infection of the brain. Recently, MR studies with susceptibility-weighted imaging (SWI) sequences have shown hypointensities in U-fibers adjacent to white matter (WM) lesions of progressive multifocal leukoencephalopathy (PML). This finding has been confirmed with the use of quantitative susceptibility mapping (QSM), allowing to hypothesize a paramagnetic effect in these regions. Here, we report the first longitudinal assessment of QSM and R2* maps in natalizumab-associated PML to evaluate serial changes in susceptibility contrast images and their role in PML diagnosis and follow-up.

Case presentation

We report the case of a 42-year-old woman with multiple sclerosis (MS) who eventually developed, after the 28th natalizumab infusion, subacute cognitive decline and received a laboratory-confirmed diagnosis of PML, leading to immediate drug discontinuation. Three months later, she suffered a new clinical exacerbation, with a brain scan revealing significant inflammatory activity compatible with the radiological diagnosis of an Immune Reconstitution Inflammatory Syndrome (IRIS). She was then treated with corticosteroids until the clinico-radiological spectrum became stable, with the final outcome of a severe functional impairment. Quantitative maps obtained in the early symptomatic stage clearly showed increased QSM and R2* values in the juxtacortical WM adjacent to PML lesions, which persisted during the subsequent disease course.

Discussion and conclusion

High QSM and R2* values in U-fibers adjacent to WM lesions were early and seemingly time-independent radiological findings in the presented PML case. This, coupled to the known absence of significant paramagnetic effect of new active MS lesions, could support the use of quantitative MRI as an additional tool in the diagnosis and follow-up of natalizumab-related PML in MS.

High b-value diffusion-weighted imaging in progressive multifocal leukoencephalopathy in HIV patients

Objectives

An ill-defined hyperintense edge and hypointense core on diffusion-weighted imaging (DWI) is typical of progressive multifocal leukoencephalopathy (PML). We aimed to investigate whether a b-value of 3,000 s/mm² (b3000) can improve visualisation of PML, or provide different structural information compared to 1,000 s/mm² (b1000).

Methods

We retrospectively identified HIV-positive patients with confirmed PML studied under a clinical protocol including both b1000 and b3000 DWI. The rim and core of each PML lesion and normal-appearing white matter (NAWM) were outlined on trace-weighted DWI. Signal intensities, apparent diffusion coefficient (ADC) values and volumes were measured and compared between b1000 and b3000.

Results

Nine lesions from seven patients were analysed. The rim and core were better visualised on b3000, with higher signal of the rim and lower signal of the core compared to NAWM. The hyperintense rim had non-restricted average ADCs, but included foci of low ADC on both b3000 and b1000. Despite similar total lesion volumes, b3000 displayed significantly larger core and smaller rim volumes than b1000.

Conclusion

b3000 improves visualisation of this important PML hallmark. Moreover, b3000 partly reclassifies tissue from rim into core, and might provide potentially more accurate biomarkers of PML activity and prognosis.

Key Points

• B3000 improves contrast resolution between lesion rim, core and normal-appearing white matter.

• B3000 improves identification of the typical rim-and-core pattern of PML lesions.

• B3000 and b1000 similarly identify lesions, but b3000 results in smaller rims and larger cores.

• B3000 excludes some high diffusion components from rim, reclassifying them into core.

• B3000 DWI may provide more precise PML biomarkers of disease activity and tissue damage.

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-017-4761-8) contains supplementary material, which is available to authorized users.

Progressive Multifocal Leukoencephalopathy in a Multiple Sclerosis Patient Diagnosed after Switching from Natalizumab to Fingolimod

Background. Natalizumab- (NTZ-) associated progressive multifocal leukoencephalopathy (PML) is a severe and often disabling infectious central nervous system disease that can become evident in multiple sclerosis (MS) patients after NTZ discontinuation. Recently, novel diagnostic biomarkers for the assessment of PML risk in NTZ treated MS patients such as the anti-JC virus antibody index have been reported, and the clinical relevance of milky-way lesions detectable by MRI has been discussed. Case Presentation and Conclusion. We report a MS patient in whom PML was highly suspected solely based on MRI findings after switching from NTZ to fingolimod despite repeatedly negative (ultrasensitive) polymerase chain reaction (PCR) testing for JC virus DNA in cerebrospinal fluid. The PML diagnosis was histopathologically confirmed by brain biopsy. The occurrence of an immune reconstitution inflammatory syndrome (IRIS) during fingolimod therapy, elevated measures of JCV antibody indices, and the relevance of milky-way-like lesions detectable by (7 T) MRI are discussed.

Lymphomas-Part 2

There are 2 types of central nervous system lymphoma: primary and secondary. Both have variable imaging features making them diagnostic challenges. Furthermore, a patient's immune status significantly alters the imaging findings. Familiarity with typical appearances, variations, and common mimics aids radiologists in appropriately considering lymphoma in the differential diagnosis. Moreover, special types of lymphoma, such as lymphomatosis cerebri, intravascular lymphoma, and lymphomatoid granulomatosis, also are found. This article discusses uncommon types of lymphoma and the differential diagnosis for focal, multifocal, meningeal, and infiltrative lymphomas.

Rhombencephalitis: pictorial essay

The term rhombencephalitis refers to inflammatory diseases affecting the hindbrain (brainstem and cerebellum). Rhombencephalitis has a wide variety of etiologies, including infections, autoimmune diseases, and paraneoplastic syndromes. Infection with bacteria of the genus Listeria is the most common cause of rhombencephalitis. Primary rhombencephalitis caused by infection with Listeria spp. occurs in healthy young adults. It usually has a biphasic time course with a flu-like syndrome, followed by brainstem dysfunction; 75% of patients have cerebrospinal fluid pleocytosis, and nearly 100% have an abnormal brain magnetic resonance imaging scan. However, other possible causes of rhombencephalitis must be borne in mind. In addition to the clinical aspects, the patterns seen in magnetic resonance imaging can be helpful in defining the possible cause. Some of the reported causes of rhombencephalitis are potentially severe and life threatening; therefore, an accurate initial diagnostic approach is important to establishing a proper early treatment regimen. This pictorial essay reviews the various causes of rhombencephalitis and the corresponding magnetic resonance imaging findings, by describing illustrative confirmed cases.

Isolation of a monoclonal antibody that recognizes the origin binding domain of JCV, but not SV40, large T-antigen

Within immunocompromised populations, the JC polyomavirus is the cause of the often-fatal disease Progressive Multifocal Leukoencephalopathy (PML). JC virus encodes a protein, termed T-antigen (T-ag), which is essential for its replication and pathogenicity. Previous studies of JCV T-ag have, in general, used antibodies raised against SV40 T-ag. Unfortunately, SV40 T-ag is also detected in humans and therefore there have been concerns about cross-reactivity. To address this issue, we have isolated a monoclonal antibody that binds to the JCV, but not the SV40, T-ag origin-binding domain (OBD). Furthermore, the region on the surface of the JCV T-ag OBD that is recognized by the "anti-JCV OBD mAb" has been mapped. We also demonstrate that the "anti-JCV OBD mAb" will be a useful reagent for standard techniques (e.g., Westerns blots and ELISAs). Finally, we note that additional monoclonal Abs that are specific for the T-ags encoded by the other human polyomaviruses could be generated by adopting the approach described herein.

Progressive multifocal leukoencephalopathy with bilateral middle cerebellar peduncle lesions confirmed by repeated CSF-JC virus tests and coexistence of JC virus granule cell neuronopathy. Report of a case

A 65 year-old woman with small lymphocytic leukemia presented with subacute cerebellar ataxia. Six months after rituximab chemotherapy, a cranial MRI revealed lesions in the bilateral middle cerebellar peduncles. Both cerebrospinal fluid (CSF) JC virus (JCV)-DNA PCR test on three occasions and brain biopsy were negative. CSF tests were repeated. The fourth test performed 6 months after the onset showed positive JCV-DNA, and a definite diagnosis of progressive multifocal leukoencephalopathy (PML) was made. Neuroimaging of cerebellar atrophy was considered to be coexistence of granule cell neuronopathy. Medication with mirtazapine and mefloquine was temporarily effective for several months. Little are known solitary bilateral MRI lesions of the middle cerebellar peduncle in PML. JCV-PCR test of CSF may be negative at an earlier stage of PML. Repeated CSF tests should be essential to confirming the diagnosis in such cases.

Central Nervous System Complications of Hematopoietic Stem Cell Transplant

Hematopoietic stem cell transplantation (SCT) is now commonly used to treat several hematologic and nonhematologic diseases. Central nervous system (CNS) complications post-transplantation occur commonly in the first year and result in increased mortality from infectious, toxic, metabolic, or vascular causes. Infections secondary to aspergillus, toxoplasma and viruses cause many of the complications. Drug-related toxicities arising from conditioning regimens and graft-versus-host disease prophylaxis, as well as intraparenchymal hemorrhage, are not uncommon and can result in increased morbidity. Secondary CNS cancers have a higher incidence 5 or more years after allogeneic SCT.

Middle cerebellar peduncles: Magnetic resonance imaging and pathophysiologic correlate

We describe common and less common diseases that can cause magnetic resonance signal abnormalities of middle cerebellar peduncles (MCP), offering a systematic approach correlating imaging findings with clinical clues and pathologic mechanisms. Myelin abnormalities, different types of edema or neurodegenerative processes, can cause areas of abnormal T2 signal, variable enhancement, and patterns of diffusivity of MCP. Pathologies such as demyelinating disorders or certain neurodegenerative entities (e.g., multiple system atrophy or fragile X-associated tremor-ataxia syndrome) appear to have predilection for MCP. Careful evaluation of concomitant imaging findings in the brain or brainstem; and focused correlation with key clinical findings such as immunosuppression for progressive multifocal leukoencephalopahty; hypertension, post-transplant status or high dose chemotherapy for posterior reversible encephalopathy; electrolyte disorders for myelinolysis or suspected toxic-drug related encephalopathy; would yield an appropriate and accurate differential diagnosis in the majority of cases.