Expanding the Neurological Phenotype of Anderson-Fabry Disease: Proof of Concept for an Extrapyramidal Neurodegenerative Pattern and Comparison with Monogenic Vascular Parkinsonism.

Anderson-Fabry disease (AFD) is a genetic sphingolipidosis involving virtually the entire body. Among its manifestation, the involvement of the central and peripheral nervous system is frequent. In recent decades, it has become evident that, besides cerebrovascular damage, a pure neuronal phenotype of AFD exists in the central nervous system, which is supported by clinical, pathological, and neuroimaging data. This neurodegenerative phenotype is often clinically characterized by an extrapyramidal component similar to the one seen in prodromal Parkinson's disease (PD). We analyzed the biological, clinical pathological, and neuroimaging data supporting this phenotype recently proposed in the literature. Moreover, we compared the neurodegenerative PD phenotype of AFD with a classical monogenic vascular disease responsible for vascular parkinsonism and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). A substantial difference in the clinical and neuroimaging features of neurodegenerative and vascular parkinsonism phenotypes emerged, with AFD being potentially responsible for both forms of the extrapyramidal involvement, and CADASIL mainly associated with the vascular subtype. The available studies share some limitations regarding both patients' information and neurological and genetic investigations. Further studies are needed to clarify the potential association between AFD and extrapyramidal manifestations.

Presentation and Outcome in S1P-RM and Natalizumab-Associated Progressive Multifocal Leukoencephalopathy: A Multicenter Cohort Study.

BACKGROUND AND OBJECTIVES: Progressive multifocal leukoencephalopathy (PML) is a severe neurologic disease resulting from JC virus reactivation in immunocompromised patients. Certain multiple sclerosis (MS) disease-modifying therapies (DMTs) are associated with PML risk, such as natalizumab and, more rarely, sphingosine-1-phosphate receptor modulators (S1P-RMs). Although natalizumab-associated PML is well documented, information on S1P-RM-associated PML is limited. The aim of this study is to compare clinical presentations and outcomes between the 2 groups. METHODS: A retrospective multicenter cohort study included patients with PML from 2009 to 2022 treated with S1P-RMs or natalizumab. Data on clinical and radiologic presentation, outcomes, immune reconstitution inflammatory syndrome (IRIS), survival, disability (using the modified Ranking scale-mRS), and MS relapses post-PML were analyzed. RESULTS: Of 88 patients, 84 were analyzed (20 S1P-RM, 64 natalizumab). S1P-RM-associated PML was diagnosed in older patients (median age 52 vs 44 years, p < 0.001) and after longer treatment duration (median 63.9 vs 40 months, p < 0.001). Similarly, S1P-RM patients were more prone to show symptoms at diagnosis (100 vs 80.6%, p = 0.035), had more disseminated lesions (80% vs 34.9%, p = 0.002), and had higher gadolinium enhancement (65% vs 39.1%, p = 0.042). Natalizumab patients had a higher IRIS development rate (OR: 8.3 [1.92-33.3]). Overall, the outcome (mRS) at 12 months was similar in the 2 groups (OR: 0.81 [0.32-2.0]). Yet, post-treatment MS activity was higher in S1P-RM cases (OR: 5.7 [1.4-22.2]). DISCUSSION: S1P-RM-associated PML shows reduced IRIS risk but higher post-treatment MS activity. Clinicians should tailor post-PML treatment based on pre-PML medication.

Muscle hypertrophy following acquired neurogenic injury: systematic review and analysis of existing literature.

OBJECTIVES: Neurogenic muscle hypertrophy (NMH) is a rare condition characterized by focal muscle hypertrophy caused by chronic partial nervous injury. Given its infrequency, underlying mechanisms remain poorly understood. Inspired by two clinical cases, we conducted a systematic review to gain insights into the different aspects of NMH. METHODS: We systematically searched online databases up until May 30, 2023, for reports of muscle hypertrophy attributed to acquired neurogenic factors. We conducted an exploratory analysis to identify commonly associated features. We also report two representative clinical cases. RESULTS: Our search identified 63 reports, describing 93 NMH cases, to which we added our two cases. NMH predominantly affects patients with compressive radiculopathy (68.4%), negligible muscular weakness (93.3%), and a chronic increase in muscle bulk. A striking finding in most neurophysiological studies (60.0%) is profuse spontaneous discharges, often hindering the analysis of voluntary traces. Some patients exhibited features consistent with more significant muscle damage, including higher creatine phosphokinase levels, muscle pain, and inflammatory muscle infiltration. These patients are sometimes referred to in literature as "focal myositis." Treatment encompassed corticosteroid, Botulinum Toxin A, decompressive surgery, antiepileptic medications, and nerve blocks, demonstrating varying degrees of efficacy. Botulinum Toxin A yielded the most favorable response in terms of reducing spontaneous discharges. INTERPRETATION: This systematic review aims to provide a clear description and categorization of this uncommon presentation of an often-overlooked neurological disorder. Though questions remain about the underlying mechanism, evidence suggests that aberrant fiber overstimulation along with increased workload that promotes focal damage may result in muscle hypertrophy. This may serve as a guide for therapeutic interventions.

Antisense Morpholino-Based In Vitro Correction of a Pseudoexon-Generating Variant in the SGCB Gene.

Limb-girdle muscular dystrophies (LGMD) are clinically and genetically heterogenous presentations displaying predominantly proximal muscle weakness due to the loss of skeletal muscle fibers. Beta-sarcoglycanopathy (LGMDR4) results from biallelic molecular defects in SGCB and features pediatric onset with limb-girdle involvement, often complicated by respiratory and heart dysfunction. Here we describe a patient who presented at the age of 12 years reporting high creatine kinase levels and onset of cramps after strenuous exercise. Instrumental investigations, including a muscle biopsy, pointed towards a diagnosis of beta-sarcoglycanopathy. NGS panel sequencing identified two variants in the SGCB gene, one of which (c.243+1548T>C) was found to promote the inclusion of a pseudoexon between exons 2 and 3 in the SGCB transcript. Interestingly, we detected the same genotype in a previously reported LGMDR4 patient, deceased more than twenty years ago, who had escaped molecular diagnosis so far. After the delivery of morpholino oligomers targeting the pseudoexon in patient-specific induced pluripotent stem cells, we observed the correction of the physiological splicing and partial restoration of protein levels. Our findings prompt the analysis of the c.243+1548T>C variant in suspected LGMDR4 patients, especially those harbouring monoallelic SGCB variants, and provide a further example of the efficacy of antisense technology for the correction of molecular defects resulting in splicing abnormalities.

Out-of-Frame Mutations in ACTN2 Last Exon Cause a Dominant Distal Myopathy With Facial Weakness.

BACKGROUND AND OBJECTIVES: To clinically, genetically, and histopathologically characterize patients presenting with an unusual combination of distal myopathy and facial weakness, without involvement of upper limb or shoulder girdle muscles. METHODS: Two families with a novel form of actininopathy were identified. Patients had been followed up over 10 years. Their molecular genetic diagnosis was not clear after extensive investigations, including analysis of candidate genes and FSHD1-related D4Z4 repeats. RESULTS: Patients shared a similar clinical phenotype and a common pattern of muscle involvement. They presented with a very slowly progressive myopathy involving anterior lower leg and facial muscles. Muscle MRI finding showed complete fat replacement of anterolateral compartment muscles of the lower legs with variable involvement of soleus and gastrocnemius but sparing thigh muscles. Muscle biopsy showed internalized nuclei, myofibrillar disorganization, and rimmed vacuoles. High-throughput sequencing identified in each proband a heterozygous single nucleotide deletion (c.2558del and c.2567del) in the last exon of the ACTN2 gene. The deletions are predicted to lead to a novel but unstructured slightly extended C-terminal amino acid sequence. DISCUSSION: Our findings indicate an unusual form of actininopathy with specific molecular and clinical features. Actininopathy should be considered in the differential diagnosis of distal myopathy combined with facial weakness.

Adoptive Transfer of JC Virus-Specific T Lymphocytes for the Treatment of Progressive Multifocal Leukoencephalopathy.

OBJECTIVE: Progressive multifocal leukoencephalopathy (PML) is still burdened by high mortality in a subset of patients, such as those affected by hematological malignancies. The aim of this study was to analyze the safety and carry out preliminary evaluation of the efficacy of polyomavirus JC (JCPyV)-specific T cell therapy in a cohort of hematological patients with PML. METHODS: Between 2014 and 2019, 9 patients with a diagnosis of "definite PML" according to the 2013 consensus who were showing progressive clinical deterioration received JCPyV-specific T cells. Cell lines were expanded from autologous or allogenic peripheral blood mononuclear cells by stimulation with JCPyV antigen-derived peptides. RESULTS: None of the patients experienced treatment-related adverse events. In the evaluable patients, an increase in the frequency of circulating JCPyV-specific lymphocytes was observed, with a decrease or clearance of JCPyV viral load in cerebrospinal fluid. In responsive patients, transient appearance of punctate areas of contrast enhancement within, or close to, PML lesions was observed, which was interpreted as a sign of immune control and which regressed spontaneously without the need for steroid treatment. Six of 9 patients achieved PML control, with 5 alive and in good clinical condition at their last follow-up. INTERPRETATION: Among other novel treatments, T cell therapy is emerging as a viable treatment option in patients with PML, particularly for those not amenable to restoration of specific immunity. Neurologists should be encouraged to refer PML patients to specialized centers to allow access to this treatment strategy. ANN NEUROL 2021;89:769-779.

The risk of infection in patients with multiple sclerosis treated with disease-modifying therapies: A Delphi consensus statement.

The risk of infection associated with immunomodulatory or immunosuppressive disease-modifying drugs (DMDs) in patients with multiple sclerosis (MS) has been increasingly addressed in recent scientific literature. A modified Delphi consensus process was conducted to develop clinically relevant, evidence-based recommendations to assist physicians with decision-making in relation to the risks of a wide range of infections associated with different DMDs in patients with MS. The current consensus statements, developed by a panel of experts (neurologists, infectious disease specialists, a gynaecologist and a neuroradiologist), address the risk of iatrogenic infections (opportunistic infections, including herpes and cryptococcal infections, candidiasis and listeria; progressive multifocal leukoencephalopathy; human papillomavirus and urinary tract infections; respiratory tract infections and tuberculosis; hepatitis and gastrointestinal infections) in patients with MS treated with different DMDs, as well as prevention strategies and surveillance strategies for the early identification of infections. In the discussion, more recent data emerged in the literature were taken into consideration. Recommended risk reduction and management strategies for infections include screening at diagnosis and before starting a new DMD, prophylaxis where appropriate, monitoring and early diagnosis.

Should frequent MRI monitoring be performed in natalizumab-treated MS patients? A contribution to a recent debate.

BACKGROUND: Brain magnetic resonance imaging (MRI) is the most effective surveillance tool for the detection of asymptomatic progressive multifocal leukoencephalopathy (PML). However, the optimal frequency for routine MRI surveillance is under-investigated. OBJECTIVE: To understand whether, upon their first MRI appearance, PML lesions present a difference in volume when comparing patients who frequently underwent MRI surveillance (3/4 months) with those who were assessed at longer intervals (6/12 months) and to understand the impact of the volume of lesions on clinical outcome. METHODS: The data of patients included in the Italian PML cohort were retrospectively analysed. Patients who had all the pre-diagnostic MRI scans available (n = 37) were included. The volume of PML lesion was calculated by manually outlining the PML lesion. RESULTS: Compared with patients who underwent MRI examination at least every 4 months, patients who were assessed less frequently had a lesion of significantly higher volume (median: 2567 (883-3583) vs. 664 mm3 (392-963) p = 0.006) and suffered a higher rate of disability (median: 2.25 expanded disability status scale points (-2.5 to 8) vs. 0.5 (-1 to 2.5) p = 0.004). CONCLUSION: The positive clinical outcome of patients undergoing frequent MRI surveillance and the small volume of the PML lesion upon first appearance justify a frequent surveillance using MRI in patients at high risk of PML.

Symptomatic cerebrospinal fluid escape.

: Cerebrospinal fluid (CSF) viral escape is defined by detectable HIV-RNA in CSF despite undetectable or lower-than-CSF level in plasma of patients receiving combination antiretroviral therapy (cART). This condition may occasionally be associated with neurological problems, consisting of new and progressive cognitive decline and/or focal symptoms and signs, defining the 'symptomatic CSF escape'. Brain MRI usually shows diffuse white matter hyperintensities that recall the presentation of HIV encephalopathy in the precART era. However, patients develop symptomatic CSF escape with relatively high CD4 cell counts and suppressed or low systemic virus replication. In addition, the frequent CSF pleocytosis and the pathological demonstration of CD8 T-cell brain infiltrates in some cases of symptomatic escape indicate that inflammation is an important component in the pathogenesis of this condition. Low nadir CD4 cells are common, likely reflecting the establishment of a HIV reservoir in the central nervous system (CNS). CSF escape seems to result from reactivation of CNS infection when cART potency is lowered, because of low patient's adherence, drug resistance, or use of drug combinations that are poorly effective in the CNS and cART optimization is key to revert escape and neurological disease in the great majority of cases.

Four cases of natalizumab-related PML: a less severe course in extended interval dosing?

BACKGROUND: Progressive multifocal leukoencephalopathy (PML) is a severe adverse event of natalizumab (NTZ). The administration of NTZ with extended interval dosing (EID) has been proposed as a strategy to potentially reduce the incidence of PML while maintaining its therapeutic efficacy. METHODS: In the current paper, we describe 4 cases of NTZ-PML in EID included in the Italian PML cohort. RESULTS: The patients developed PML after at least 38 NTZ infusions. Their John Cunningham virus (JCv) index was > 1.5, and patients had not previously used immunosuppressant. Two patients were asymptomatic at PML onset, while two had mild motor impairment of the right hand and anomia, respectively. All of them had undetectable viral load but one (37 JCv copies/ml). In all patients, MRI revealed unilobar lesions with deferred contrast enhancement suggestive of immune reconstitution. The clinical course ended with a favorable clinical outcome (ΔEDSS up to 1). CONCLUSIONS: Although PML in EID seems to occur less frequently than in conventional dosing regimen, strict monitoring of high-risk patients contributed to the indolent course observed in the four described cases, characterized by a prolonged pre-symptomatic phase, paucisymptomatic onset, low JCv load, less severe functional impairment during immune reconstitution, and a mild disability burden.

Immune profiling of a patient with alemtuzumab-associated progressive multifocal leukoencephalopathy.

A 31-year-old woman affected by multiple sclerosis (MS) experienced generalized tonic-clonic seizures 2 months after the second alemtuzumab cycle. Positive JC virus (JCV)-DNA in cerebrospinal fluid (CSF) and lesion iconography at magnetic resonance imaging (MRI) were suggestive of progressive multifocal leukoencephalopathy (PML). After 1 month, during full-blown immune reconstitution inflammatory syndrome, JCV-DNA became negative and symptoms gradually improved. New T- and B-cell output and T- and B-cell diversity were low and lymphocytes poorly responded to stimulation. This is the first case of an alemtuzumab-treated patient with clinical symptoms and radiological features compatible with PML. The lack of large T- and B-cell diversity, necessary for JCV recognition, is likely to have concurred to PML insurgence.

Value of structured reporting in neuromuscular disorders.

OBJECTIVE: To assess whether structured reports (SRs) of MRI in patients with inherited neuromuscular disorders (IND) provide more clinically relevant information than non-structured reports (NSRs) and whether neuroradiologists' expertise affects completeness of reports. MATERIAL AND METHODS: Lower limbs' MRI reports of patients with IND produced by neuroradiologists with different level of expertise (> 15 years vs. < 15 years of experience in reading IND-MRI) before and after implementation of a SR template were included. Reports were assessed for the presence of 9 key features relevant for IND management. Reports and images were evaluated by neurologists who assessed: disease-specific muscular involvement pattern; presence of sufficient information to order the appropriate genetic/diagnostic tests; presence of sufficient information to make therapeutic decision/perform biopsy and necessity to review MRI images. Mann-Whitney and Fisher's exact tests were used to compare the number of key features for NSR and SR and neurologists' answers for reports produced by neuroradiologists with different experience. RESULTS: Thirty-one SRs and 101 NSRs were reviewed. A median of 8 and 6 key features was present in SR and NSR, respectively (p value < 0.0001). When reports were produced by less expert neuroradiologists, neurologists recognized muscular involvement pattern, had sufficient information for clinical decision-making/perform biopsy more often with SR than NSR (p values: < 0.0001), and needed to evaluate images less often with SR (p value: 0.0001). When reports produced by expert neuroradiologists were evaluated, no significant difference in neurologists' answers was observed. CONCLUSION: SR of IND-MRI contained more often clinically relevant information considered important for disease management than NSR. Radiologist's expertise affects completeness of NSR reports.

Early diagnosis of progressive multifocal leucoencephalopathy: longitudinal lesion evolution.

OBJECTIVE: Early diagnosis of natalizumab-related progressive multifocal leucoencephalopathy (NTZ-PML) in multiple sclerosis has been deemed a major priority by the regulatory agencies but has yet to become a reality. The current paper aims to: (1) investigate whether patients with NTZ-PML pass through a prolonged presymptomatic phase with MRI abnormalities, (2) estimate the longitudinal PML lesion volume increase during the presymptomatic phase and (3) estimate the presymptomatic phase length and its impact on therapy duration as a risk stratification parameter. METHODS: All Italian patients who developed NTZ-PML between 2009 and 2018 were included. The data of patients with available prediagnostic MRI were analysed (n=41). Detailed clinical and neuroradiological information was available for each participant. RESULTS: (1) PML lesions were detectable in the presymptomatic phase in 32/41 (78%) patients; (ii) the lesion volume increased by 62.8 % for each month spent in the prediagnostic phase; (3) the prediagnostic phase length was 150.8±74.9 days; (4) PML MRI features were detectable before the 24th month of therapy in 31.7 % of patients in our cohort. CONCLUSIONS: Considering the latency of PML clinical manifestation, the presymptomatic phase length supports the usefulness of MRI surveillance every 3-4 months. Early diagnosis could prompt a better outcome for patients due to the relationship between lesion volume and JC virus infection. The insight from this study might also have an impact on risk stratification algorithms, as therapy duration as a parameter of stratification appears to need reassessment.

PET Evaluation of Late Cerebral Effect in Advanced Radiation Therapy Techniques for Cranial Base Tumors.

BACKGROUND AND OBJECTIVE: Even though the benefits of radiation therapy are well established, it is important to recognize the broad spectrum of radiation-induced changes, particularly in the central nervous system. The possible damage to the brain parenchyma may have clinical consequences and in particular cognitive impairment might be one of the major complications of radiotherapy. To date, no studies have investigated the effects of focal radiation therapy on brain structure and function together with the assessment of their clinical outcomes at a long follow-up. METHODS: In this prospective study, we evaluated in six patients the possible brain late effects after radiation therapy, using a standardized neuropsychological battery, MRI and 18F-FDG PET using SPM and semi-quantitative methods, in patients affected by cranial base tumors who underwent gamma knife or tomotherapy. RESULTS: Neuropsychological examinations showed no cognitive impairment after the treatment. In all patients, both MRI assessment and 18F-FDG-PET did not reveal any local or distant anatomical and metabolic late effects. CONCLUSION: The present study support the safety of advanced radiation therapy techniques. 18F-FDGPET, using SPM and semi-quantitative methods, might be a valuable tool to evaluate the cerebral radiotoxicity in patients treated for brain neoplasms.

Diagnostic and Prognostic Value of JC Virus DNA in Plasma in Progressive Multifocal Leukoencephalopathy.

Background: Progressive multifocal leukoencephalopathy (PML) is a severe demyelinating disease caused by the polyomavirus JC (John Cunningham; JCV) that affects patients with impaired immune systems. While JCV-DNA detection in cerebrospinal fluid (CSF) is diagnostic of PML, the clinical significance of plasma JCV-DNA is uncertain. Methods: We retrospectively analyzed plasma samples from PML patients that were drawn close to disease onset and from controls without PML. In PML patients, we compared plasma JCV-DNA detection and levels to clinical and laboratory parameters, and patient survival. Results: JCV-DNA was detected in plasma of 49/103 (48%) patients with PML (20/24, 83%, human immunodeficiency virus [HIV] negative; 29/79, 37%, HIV-positive) and of 4/144 (3%) controls without PML (0/95 HIV-negative; 4/49, 8%, HIV-positive), yielding a diagnostic sensitivity and specificity of 48% and 97% (83% and 100% in HIV-negative; 37% and 92% in HIV-positive), respectively. Among 16 PML patients with undetectable CSF JCV-DNA, 4 (25%) had detectable plasma JCV-DNA. Plasma JCV-DNA levels were independently associated with CSF levels (P < .0001) and previous corticosteroid treatment (P = .012). Higher plasma JCV-DNA levels were associated with disease progression in HIV-negative patients (P = .005); in HIV-positive patients, there was an increased risk of progression only in those treated with combination antiretroviral therapy (cART; P < .0001). Conclusions: Testing JCV-DNA in plasma might complement PML diagnosis, especially when CSF is unavailable or JCV-DNA not detectable in CSF. In addition, JCV-DNA plasma levels could be useful as a marker of disease progression in both HIV-negative and cART-treated, HIV-positive PML patients.

Adult leukoencephalopathies with prominent infratentorial involvement can be caused by Erdheim-Chester disease.

BACKGROUND: Leukoencephalopathies with prominent involvement of cerebellum and brainstem, henceforward called prominent infratentorial leukoencephalopathies (PILs), encompass a variety of inherited and acquired white matter diseases. Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis likely under-diagnosed as cause of adult PIL. METHODS: We reviewed the clinical and laboratory information of ten consecutive sporadic adult patients with PIL of unknown origin, who were investigated for ECD. RESULTS: There were seven males and three females; mean age at clinical onset was 49.6 years (range 38-59); cerebellar ataxia with or without other neurological symptoms was the only or the main clinical manifestation; diabetes insipidus was present in three individuals. Eight patients had white matter focal supratentorial abnormalities, in addition to the infratentorial white matter changes. Six out of eight patients had spinal cord lesions. Thoraco-abdominal CT showed periaortic sheathing in two patients, whole-body FDG-PET revealed increased glucose uptake in the long bones of the legs in five patients, brain FDG-PET showed overt infratentorial hypermetabolism in one patient. In eight patients, ECD was confirmed by bone scintigraphy, pathological data, or both. Two ECD patients treated with vemurafenib showed a marked improvement of neurological symptoms and brain MRI abnormalities at 1 year follow-up. CONCLUSIONS: Symptoms of PIL can be the only clinical manifestation of ECD. Adult patients with PIL of unknown origin should undergo investigations aimed at unveiling ECD, including bone scintigraphy and whole-body FDG-PET. The early diagnosis allows starting disease-modifying therapies of an otherwise life-threatening disease.

To do or not to do? plasma exchange and timing of steroid administration in progressive multifocal leukoencephalopathy.

OBJECTIVE: To retrospectively analyze the effect of plasma exchange (PLEX; yes = PLEX+ , no = PLEX- ) and steroids administration timing (prophylactically [proST] or therapeutically [therST]) on the longitudinal clinical course of patients with natalizumab-related progressive multifocal leukoencephalopathy (PML) and full-blown immune reconstitution inflammatory syndrome (PML-IRIS). METHODS: Clinical and radiological data of 42 Italian patients with PML were analyzed. Patient's data are available until 12 months after PML diagnosis. PLEX and steroids treatment as time-dependent covariates were entered in: (1) a Cox model to investigate their impact on full-blown PML-IRIS latency; (2) an analysis of variance ANOVA to investigate their impact on IRIS duration; and (3) a linear mixed model to assess their impact on the longitudinal clinical course (measured by means of Expanded Disability Status Scale [EDSS]). RESULTS: Treatment with PLEX was not associated to PML-IRIS latency (hazard ratio [HR] = 1.05; p = 0.92), but once IRIS emerged, its duration was significantly longer in patients who underwent PLEX (101 vs 54 days in PLEX+ and PLEX- patients; p = 0.028). Receiving proST versus therST was not associated to IRIS latency (HR = 0.67; p = 0.39) or duration (p = 0.95). Patients who underwent proST had a significantly higher EDSS increase during PML (0.09 EDSS points per month; p = 0.04) as compared to those who had therST. INTERPRETATION: This study highlights that: (1) caution on the use of PLEX should be considered as the current data do not support a beneficial effect of PLEX and (2) caution on the early use of steroids is suggested because their prophylactic use to prevent full-blown PML-IRIS seems to negatively impact on the longitudinal disability course. Ann Neurol 2017;82:697-705.

Is maraviroc useful in multiple sclerosis patients with natalizumab-related progressive multifocal leukoencephalopathy?

BACKGROUND: Despite the recent advances in the understanding of natalizumab (NTZ) related progressive multifocal leukoencephalopathy (PML) and its associated immune reconstitution inflammatory syndrome (PML-IRIS), the therapeutic options are still under investigated. In this context, the beneficial use of maraviroc is still an anecdotal observation. OBJECTIVE: To evaluate the impact of maraviroc in modifying the course of PML preventing IRIS or blunting IRIS manifestations. METHODS: Three patients with NTZ PML included in the Italian dataset of PML were treated with maraviroc. Their longitudinal clinical and radiological course was described in detail. RESULTS: The three patients were characterized by a steady clinical worsening not controlled by maraviroc. All the three patients manifested PML-IRIS, which emerged, respectively, at 62, 64 and 90days post NTZ withdrawal. This is in accordance with the data of the Italian dataset. Clinical and radiological stabilization of PML-IRIS occurred only after corticosteroids administration. CONCLUSION: In these three cases, maraviroc did not show any clear effect in modulating the clinical course of PML preventing IRIS. Moreover, once PML-IRIS emerged, the clinical stabilization was achieved only with the use of corticosteroids. Thus, the use of maraviroc should be regarded with extreme caution due the potential adverse events associated with its use.