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Background and Purpose: In October 2020, the European Academy of Neurology (EAN) consensus statement for management of patients with neurological diseases during the coronavirus disease 2019 (COVID-19) pandemic was published. Due to important changes and developments that have happened since then, the need has arisen to critically reassess the original recommendations and address new challenges., Methods: In step 1, the original items were critically reviewed by the EAN COVID-19 Task Force. In addition, new recommendations were defined. In step 2, an online survey with the recommendations forged in step 1 was sent to the Managing Groups of all Scientific and Coordinating Panels of EAN. In step 3, the final set of recommendations was made., Results: In step 1, out of the original 36 recommendations, 18 were judged still relevant. They were edited to reflect the advances in knowledge and practice. In addition, 21 new recommendations were formulated to address the new knowledge and challenges. In step 2, out of the 39 recommendations sent for the survey, nine were approved as they were, whilst suggestions for improvement were given for the rest. In step 3, the recommendations were further edited, and some new items were formed to accommodate the participants' suggestions, resulting in a final set of 41 recommendations., Conclusion: This revision of the 2020 EAN Statement provides updated comprehensive and structured guidance on good clinical practice in people with neurological disease faced with SARS-CoV-2 infection. It now covers the issues from the more recent domains of COVID-19-related care, vaccine complications and post-COVID-19 conditions., (© 2024 The Author(s). European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)

Objective: To evaluate: (1) the distribution of gray matter (GM) atrophy in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4+NMOSD), and relapsing-remitting multiple sclerosis (RRMS); and (2) the relationship between GM volumes and white matter lesions in various brain regions within each disease., Methods: A retrospective, multicenter analysis of magnetic resonance imaging data included patients with MOGAD/AQP4+NMOSD/RRMS in non-acute disease stage. Voxel-wise analyses and general linear models were used to evaluate the relevance of regional GM atrophy. For significant results (p < 0.05), volumes of atrophic areas are reported., Results: We studied 135 MOGAD patients, 135 AQP4+NMOSD, 175 RRMS, and 144 healthy controls (HC). Compared with HC, MOGAD showed lower GM volumes in the temporal lobes, deep GM, insula, and cingulate cortex (75.79 cm 3 ); AQP4+NMOSD in the occipital cortex (32.83 cm 3 ); and RRMS diffusely in the GM (260.61 cm 3 ). MOGAD showed more pronounced temporal cortex atrophy than RRMS (6.71 cm 3 ), whereas AQP4+NMOSD displayed greater occipital cortex atrophy than RRMS (19.82 cm 3 ). RRMS demonstrated more pronounced deep GM atrophy in comparison with MOGAD (27.90 cm 3 ) and AQP4+NMOSD (47.04 cm 3 ). In MOGAD, higher periventricular and cortical/juxtacortical lesions were linked to reduced temporal cortex, deep GM, and insula volumes. In RRMS, the diffuse GM atrophy was associated with lesions in all locations. AQP4+NMOSD showed no lesion/GM volume correlation., Interpretation: GM atrophy is more widespread in RRMS compared with the other two conditions. MOGAD primarily affects the temporal cortex, whereas AQP4+NMOSD mainly involves the occipital cortex. In MOGAD and RRMS, lesion-related tract degeneration is associated with atrophy, but this link is absent in AQP4+NMOSD. ANN NEUROL 2024;96:276-288., (© 2024 The Author(s). Annals of Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)

Introduction: Recent evidence suggests the blood-to-brain influx rate ( K 1 ) in TSPO PET imaging as a promising biomarker of blood-brain barrier ( BBB ) permeability alterations commonly associated with peripheral inflammation and heightened immune activity in the brain. However, standard compartmental modeling quantification is limited by the requirement of invasive and laborious procedures for extracting an arterial blood input function. In this study, we validate a simplified blood-free methodologic framework for K 1 estimation by fitting the early phase tracer dynamics using a single irreversible compartment model and an image-derived input function ( 1T1K-IDIF )., Methods: The method is tested on a multi-site dataset containing 177 PET studies from two TSPO tracers ([ 11 C]PBR28 and [ 18 F]DPA714). Firstly, 1T1K-IDIF K 1 estimates were compared in terms of both bias and correlation with standard kinetic methodology. Then, the method was tested on an independent sample of [ 11 C]PBR28 scans before and after inflammatory interferon- α challenge, and on test-retest dataset of [ 18 F]DPA714 scans., Results: Comparison with standard kinetic methodology showed good-to-excellent intra-subject correlation for regional 1T1K-IDIF-K 1 ( ρ intra  = 0.93 ± 0.08), although the bias was variable depending on IDIF ability to approximate blood input functions (0.03-0.39 mL/cm 3 /min). 1T1K-IDIF-K 1 unveiled a significant reduction of BBB permeability after inflammatory interferon- α challenge, replicating results from standard quantification. High intra-subject correlation ( ρ  = 0.97 ± 0.01) was reported between K 1 estimates of test and retest scans., Discussion: This evidence supports 1T1K-IDIF as blood-free alternative to assess TSPO tracers' unidirectional blood brain clearance. K 1 investigation could complement more traditional measures in TSPO studies, and even allow further mechanistic insight in the interpretation of TSPO signal., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Maccioni, Carranza Mellana, Brusaferri, Silvestri, Bertoldo, Schubert, Nettis, Mondelli, Howes, Turkheimer, Bottlaender, Bodini, Stankoff, Loggia and Veronese.)

Background: Exploring the relationship between oxygen supply and myelin damage would benefit from a simultaneous quantification of myelin and cerebral blood flow (CBF) in the brain's white matter (WM). To validate an analytical method for quantifying both CBF and myelin content in the WM using dynamic [ 11 C]PiB positron emission tomography (PET)., Methods: A test-retest study was performed on eight healthy subjects who underwent two consecutive dynamic [11 C]PiB-PET scans. Three quantitative approaches were compared: simplified reference tissue model 2 (SRTM2), LOGAN graphical model, and standardized uptake value ratio (SUVR). The sensitivity of methods to the size of the region of interest was explored by simulating lesion masks obtained from 36 subjects with multiple sclerosis. Reproducibility was assessed using the relative difference and interclass correlation coefficient. Repeated measures correlations were used to test for cross-correlations between metrics., Results: Among the CBF measures, the relative delivery (R1) of the simplified reference tissue model 2 (SRTM2) displayed the best reproducibility in the white matter, with a strong influence of the size of regions analyzed, the test-retest variability being below 10% for regions above 68 mm 3 in the supratentorial white matter. [ 11 C]PiB PET-derived proxies of CBF demonstrated lower perfusion of white matter compared to grey matter with an overall ratio equal to 1.71 ± 0.09 when the SRTM2-R1 was employed. Tissue binding in the white matter was well estimated by the Logan graphical model through estimation of the distribution volume ratio (LOGAN-DVR) and SRTM2 distribution volume ratio (SRTM2-DVR), with test-retest variability being below 10% for regions exceeding 106 mm 3 for LOGAN-DVR and 300 mm 3 for SRTM2-DVR. SRTM2-DVR provided a better contrast between white matter and grey matter. The interhemispheric variability was also dependent on the size of the region analyzed, being below 10% for regions above 103 mm 3 for SRTM2-R1 and above 110 mm 3 for LOGAN-DVR. Whereas the 1 to 8-minute standardized uptake value ratio (SUVR1-8) showed an intermediary reproducibility for CBF assessment, SUVR0-2 for perfusion or SUVR50-70 for tissue binding showed poor reproducibility and correlated only mildly with SRTM2-R1 and LOGAN-DVR estimations respectively., Conclusions: [ 11 C]PiB PET imaging can simultaneously quantify perfusion and myelin content in WM diseases associated with focal lesions. For longitudinal studies, SRTM2-R1 and DVR should be preferred over SUVR for the assessment of regional CBF and myelin content, respectively., Trial Registration: European Union Clinical Trials Register EUDRACT; EudraCT Number: 2008-004174-40; Date: 2009-03-06; https//www.clinicaltrialsregister.eu ; number 2008-004174-40., (© 2024. The Author(s).)

Background: Respiratory disorders remain incompletely described in multiple sclerosis (MS), even though they are a frequent cause of death., Methods: The objective was to describe respiratory disorders in MS patients with Expanded Disability Status Score (EDSS) ⩾ 6.5. Diaphragm dysfunction was defined by at least two of the seven criteria: clinical signs, inspiratory recruitment of neck muscles during wakefulness, reduced upright vital capacity (VC) < 80%, upright-to-supine VC ⩾ 15% of upright VC, decrease in Maximal Inspiratory Pressure < 60%, phasic activation of inspiratory neck muscles during sleep, and opposition of thoracic and abdominal movements during sleep. Cough weakness was defined by a peak cough flow < 270 L/min and/or need for cough assist. Sleep apnea syndrome was defined by an apnea-hypopnea index ⩾ 15., Results: Notably, 71 MS patients were included: median age 54 [48, 61] years; median disease duration 21.4 [16.0, 31.4] years. Of these, 52 patients had one or more respiratory disorders; diaphragm dysfunction was the most frequent ( n = 34). Patients with diaphragm dysfunction and cough weakness were more disabled. The fatigue score and the cognitive evaluations did not differ between the groups. Five patients required non-invasive ventilation., Conclusion: Respiratory disorders are frequent in severe MS, mostly diaphragm dysfunction. Of interest, instrumental interventions are available to address these disorders., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: No disclosure relevant to the manuscript. E.M. reports research support from Biogen and personal fees for lectures and advisory boards from Alexion, Biogen, Horizon, Janssen, Merck, Novartis, Roche, Sanofi, and Teva. C.Lo. has received consulting, speaker or travel fees from Merck, Roche, Biogen, Novartis, Teva, and Sanofi, and an IIT grant from Biogen. S.R., M.H., E.C., P.L., A.U., and I.A. report no disclosure. B.S. reports research support from Roche, Sanofi, and Merck and personal fees for lectures or advisory boards from Novartis, Sanofi, Biogen, Janssen, and Merck. C.P. reports research personal fees for lectures and advisory boards from Alexion, Biogen, Horizon, Merck, Novartis, Roche, and Sanofi. B.B. reports research support from Biogen and personal fees for lectures and advisory boards from Novartis, Roche, Sanofi, and Merck. C.Lu. reports research support from Merck and participates in advisory boards for Biogen, Merck, Rewind, and Roche. T.S. reports personal fees for consulting and teaching activities from AstraZeneca France, Chiesi France, KPL consulting, Lungpacer Inc., OSO-AI, TEVA France, and Vitalaire; he is a shareholder of startups Hephaï and Austral Dx. C.M.P. reports personal fees from AstraZeneca, Chiesi, ADEP Assistance, SOS Oxygène, ISIS, ResMed, Menarini, GSK, Fisher & Paykel, Vivisol, Air Liquide, Lowenstein, and Orkyn outside the submitted work.

Cortical myelin loss and repair in multiple sclerosis (MS) have been explored in neuropathological studies, but the impact of these processes on neurodegeneration and the irreversible clinical progression of the disease remains unknown. Here, we evaluated in vivo cortical demyelination and remyelination in a large cohort of people with all clinical phenotypes of MS followed up for 5 years using magnetization transfer imaging (MTI), a technique that has been shown to be sensitive to myelin content changes in the cortex. We investigated 140 people with MS (37 clinically isolated syndrome, 71 relapsing-MS, 32 progressive-MS), who were clinically assessed at baseline and after 5 years and, along with 84 healthy controls, underwent a 3 T-MRI protocol including MTI at baseline and after 1 year. Changes in cortical volume over the radiological follow-up were computed with a Jacobian integration method. Magnetization transfer ratio was employed to calculate for each patient an index of cortical demyelination at baseline and of dynamic cortical demyelination and remyelination over the follow-up period. The three indices of cortical myelin content change were heterogeneous across patients but did not significantly differ across clinical phenotypes or treatment groups. Cortical remyelination, which tended to fail in the regions closer to CSF (-11%, P < 0.001), was extensive in half of the cohort and occurred independently of age, disease duration and clinical phenotype. Higher indices of cortical dynamic demyelination (β = 0.23, P = 0.024) and lower indices of cortical remyelination (β = -0.18, P = 0.03) were significantly associated with greater cortical atrophy after 1 year, independently of age and MS phenotype. While the extent of cortical demyelination predicted a higher probability of clinical progression after 5 years in the entire cohort [odds ratio (OR) = 1.2; P = 0.043], the impact of cortical remyelination in reducing the risk of accumulating clinical disability after 5 years was significant only in the subgroup of patients with shorter disease duration and limited extent of demyelination in cortical regions (OR = 0.86, P = 0.015, area under the curve = 0.93). In this subgroup, a 30% increase in cortical remyelination nearly halved the risk of clinical progression at 5 years, independently of clinical relapses. Overall, our results highlight the critical role of cortical myelin dynamics in the cascade of events leading to neurodegeneration and to the subsequent accumulation of irreversible disability in MS. Our findings suggest that early-stage myelin repair compensating for cortical myelin loss has the potential to prevent neuro-axonal loss and its long-term irreversible clinical consequences in people with MS., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain.)

Purpose: MP2RAGE parameter optimization is redefined to allow more time-efficient MR acquisitions, whereas the T 1 -based synthetic imaging framework is used to obtain on-demand T 1 -weighted contrasts. Our aim was to validate this concept on healthy volunteers and patients with multiple sclerosis, using plug-and-play parallel-transmission brain imaging at 7 T., Methods: A "time-efficient" MP2RAGE sequence was designed with optimized parameters including TI and TR set as small as possible. Extended phase graph formalism was used to set flip-angle values to maximize the gray-to-white-matter contrast-to-noise ratio (CNR). Several synthetic contrasts (UNI, EDGE, FGATIR, FLAWS MIN , FLAWS HCO ) were generated online based on the acquired T 1 maps. Experimental validation was performed on 4 healthy volunteers at various spatial resolutions. Clinical applicability was evaluated on 6 patients with multiple sclerosis, scanned with both time-efficient and conventional MP2RAGE parameterizations., Results: The proposed time-efficient MP2RAGE protocols reduced acquisition time by 40%, 30%, and 19% for brain imaging at (1 mm) 3 , (0.80 mm) 3 and (0.65 mm) 3 , respectively, when compared with conventional parameterizations. They also provided all synthetic contrasts and comparable contrast-to-noise ratio on UNI images. The flexibility in parameter selection allowed us to obtain a whole-brain (0.45 mm) 3 acquisition in 19 min 56 s. On patients with multiple sclerosis, a (0.67 mm) 3 time-efficient acquisition enhanced cortical lesion visualization compared with a conventional (0.80 mm) 3 protocol, while decreasing the scan time by 15%., Conclusion: The proposed optimization, associated with T 1 -based synthetic contrasts, enabled substantial decrease of the acquisition time or higher spatial resolution scans for a given time budget, while generating all typical brain contrasts derived from MP2RAGE., (© 2023 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

The inability of the mammalian central nervous system (CNS) to undergo spontaneous regeneration has long been regarded as a central tenet of neurobiology. However, while this is largely true of the neuronal elements of the adult mammalian CNS, save for discrete populations of granule neurons, the same is not true of its glial elements. In particular, the loss of oligodendrocytes, which results in demyelination, triggers a spontaneous and often highly efficient regenerative response, remyelination, in which new oligodendrocytes are generated and myelin sheaths are restored to denuded axons. Yet remyelination in humans is not without limitation, and a variety of demyelinating conditions are associated with sustained and disabling myelin loss. In this work, we will (1) review the biology of remyelination, including the cells and signals involved; (2) describe when remyelination occurs and when and why it fails, including the consequences of its failure; and (3) discuss approaches for therapeutically enhancing remyelination in demyelinating diseases of both children and adults, both by stimulating endogenous oligodendrocyte progenitor cells and by transplanting these cells into demyelinated brain., (Copyright © 2024 Cold Spring Harbor Laboratory Press; all rights reserved.)

Background and Purpose: The COVID-19 pandemic has significantly impacted health systems worldwide. Here, we assessed the pandemic's impact on clinical service, curricular training, and financial burden from a neurological viewpoint during the enforced lockdown periods and the assumed recovery by 2023., Methods: An online 18-item survey was conducted by the European Academy of Neurology (EAN) NeuroCOVID-19 Task Force among the EAN community. The survey was online between February and March 2023. Questions related to general, demographic, clinical, work, education, and economic aspects., Results: We collected 430 responses from 79 countries. Most health care professionals were aged 35-44 years, with >15 years of work experience. The key findings of their observations were as follows. (i) Clinical services were cut back in all neurological subspecialties during the most restrictive COVID-19 lockdown period. The most affected neurological subspecialties were services for patients with dementia, and neuromuscular and movement disorders. The levels of reduction and the pace of recovery were distinct for acute emergencies and in- and outpatient care. Recovery was slow for sleep medicine, autonomic nervous system disorders, neurorehabilitation, and dementia care. (ii) Student and residency rotations and grand rounds were reorganized, and congresses were converted into a virtual format. Conferences are partly maintained in a hybrid format. (iii) Affordability of neurological care and medication shortage are emerging issues., Conclusions: Recovery of neurological services up to spring 2023 has been incomplete following substantial disruption of neurological care, medical education, and health economics in the wake of the COVID-19 pandemic. The continued limitations for the delivery of neurological care threaten brain health and call for action on a global scale., (© 2023 The Authors. European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)