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Background: Patent foramen ovale (PFO) is a congenital anatomical variant which is associated with strokes in young adults. Contrary to vascular risk factors and atherosclerosis, a PFO is present from birth. However, it is completely unknown how an anatomical structure that is already present at birth in a large proportion of the population can convert into a PFO that causes stroke in a few. Recent studies reported a significant association between certain trigger factors and ischemic stroke in young adults. This study aims to investigate these triggers in PFO-associated stroke., Methods: The ODYSSEY study, a multicenter prospective cohort study between 2013 and 2021, included patients aged 18-49 years experiencing their first-ever ischemic event. Participants completed a questionnaire about exposure to potential trigger factors. A case-crossover design was used to assess the relative risks (RR) with 95% confidence intervals (95% CI). The primary outcome was the RR of potential trigger factors for PFO-associated stroke., Results: Overall, 1043 patients completed the questionnaire and had an ischemic stroke, of which 124 patients had a PFO-associated stroke (median age 42.1 years, 45.2% men). For patients with PFO-associated stroke, the RR was 26.0 (95% CI 8.0-128.2) for fever, 24.2 (95% CI 8.5-68.7) for flu-like disease, and 3.31 (95% CI 2.2-5.1) for vigorous exercise., Conclusion: In conclusion, flu-like disease, fever, and vigorous exercise may convert an asymptomatic PFO into a stroke-causing PFO in young adults., Data Access Statement: The raw and anonymized data used in this study can be made available to other researchers on request. Written proposals can be addressed to the corresponding author and will be assessed by the ODYSSEY investigators for appropriateness of use, and a data sharing agreement in accordance with Dutch regulations will be put in place before data are shared., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background and Objectives: Wearing-off symptoms during natalizumab treatment in multiple sclerosis are characterized by an increase of MS-related symptoms prior to natalizumab administration. The influence of extended interval dosing (EID) on wearing-off symptoms are important to consider, as this might cause hesitancy in initiating or continuing EID., Methods: Participants of the NEXT-MS trial, in which treatment intervals are adjusted based on drug concentrations, were divided into two groups: an extended group containing participants with at least one week of additional interval extension, and a group with a fixed interval during the trial (range 4-7 weeks). Changes in the occurrence, frequency, onset, and severity of wearing-off symptoms were evaluated., Results: 255 participants were included (extended group n = 171, fixed group n = 84). The odds on occurrence of wearing-off symptoms in the extended group did not increase after extending the treatment interval. Additional analyses for frequency, onset, and severity of wearing-off symptoms showed no changes over time. Mean decrease in natalizumab drug concentration did not influence the frequency of wearing-off symptoms., Discussion: Wearing-off symptoms were not reinforced by further extending the natalizumab interval. Wearing-off symptoms might increase in a minority of patients after EID, although our data support the view that wearing-off symptoms appear to be unrelated to the decrease in natalizumab trough drug concentrations., Competing Interests: Declaration of competing interest A.A. Toorop: nothing to disclose. M.H.J. Wessels: nothing to disclose. L.M.Y. Gelissen: nothing to disclose. E. Hoitsma: has accepted (speaker and congress) fees from Merck Serono, Biogen Idec, Roche, and Sanofi Genzyme. E.M.P.E. Zeinstra: reports advisory boards/consultancy fees for Merck, Novartis, Genzyme and Roche. L.C. van Rooij: nothing to disclose. C.E.P. van Munster: nothing to disclose. A. Vennegoor: nothing to disclose. J.P. Mostert: nothing to disclose. B.H.A. Wokke: nothing to disclose. N.F. Kalkers: nothing to disclose. E.L.J. Hoogervorst: nothing to disclose. J.J.J. van Eijk: reports honoraria for advisory boards and/or speakers fee from Merck Serono, Biogen Idec, Sanofi Genzyme, Roche and Novartis. C.M. Roosendaal: nothing to disclose. J.J. Kragt: nothing to disclose. M. Eurelings: nothing to disclose. J. Nielsen: nothing to disclose. J. van Genugten: nothing to disclose. L.G.F. Sinnige: nothing to disclose. M.E. Kloosterziel: nothing to disclose. E.P.J. Arnoldus: nothing to disclose. G.W. van Dijk: nothing to disclose. W.H. Bouvy: nothing to disclose. E.M.M. Strijbis: nothing to disclose. B.W. van Oosten: nothing to disclose. B.A. de Jong: nothing to disclose. B.I. Lissenberg-Witte: nothing to disclose. T. Rispens received funding for research from Genmab and consultancy fees from Novartis. B.M.J. Uitdehaag: reports research support and/or consultancy fees from Genzyme, Biogen Idec, Novartis, Teva Pharmaceutical Industries, Merck Serono, Roche, and Immunic Therapeutics. J. Killestein: received research grants for multicentre investigator initiated trials DOT-MS trial, ClinicalTrials.gov Identifier: NCT04260711 (ZonMW) and BLOOMS trial (ZonMW and Treatmeds), ClinicalTrials.gov Identifier: NCT05296161); received consulting fees for F. Hoffmann-La Roche Ltd., Biogen, Teva, Merck, Novartis and Sanofi/Genzyme (all payments to institution); reports speaker relationships with F. Hoffmann-La Roche Ltd., Biogen, Immunic, Teva, Merck, Novartis and Sanofi/Genzyme (all payments to institution); adjudication committee of MS clinical trial of Immunic (payments to institution only). Z.L.E. van Kempen: nothing to disclose., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Limited data exists on cognitive recovery in young stroke patients. We aimed to investigate the longitudinal course of cognitive performance during the first year after stroke at young age and identify predictors for cognitive recovery., Methods: We conducted a multicentre prospective cohort study between 2013 and 2021, enrolling patients aged 18-49 years with first-ever ischaemic stroke. Cognitive assessments were performed within 6 months and after 1 year following the index event, covering seven cognitive domains. Composite Z-scores using normative data determined cognitive impairment (Z-score<-1.5). A Reliable Change Index (RCI) assessed cognitive recovery (RCI>1.96) or decline (RCI<-1.96)., Results: 393 patients (median age 44.3 years, IQR 38.4-47.2) completed cognitive assessments with a median time interval of 403 days (IQR 364-474) between assessments. Based on RCI, a similar proportion of patients showed improvement and decline in each cognitive domain, while the majority exhibited no cognitive change. Among cognitively impaired patients at baseline, improvements were observed in processing speed (23.1%), visuoconstruction (40.1%) and executive functioning (20.0%). Younger age was associated with better cognitive recovery in visuoconstruction, and larger lesion volume was related to cognitive recovery in processing speed. No other predictors for cognitive recovery were identified., Conclusions: Cognitive impairment remains prevalent in young stroke even 1 year after the event. Most patients showed no cognitive change, however, recovery may have occurred in the early weeks after stroke, which was not assessed in our study. Among initially cognitively impaired patients, cognitive recovery is observed in processing speed, visuoconstruction and executive functioning. It is still not possible to predict cognitive recovery in individual patients., Competing Interests: Competing interests: AMT is a junior staff member of the Dutch Heart Foundation (grant number 2016T044). F-EDL is a clinical established investigator of the Dutch Heart Foundation (2014 T060). MJHW has received a VIDI grant (9171337) of the ZonMw/NWO and the clinical established investigator Dutch Heart Foundation grant (2016T86)., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Extended interval dosing (EID) of natalizumab is a promising strategy to optimise treatment in multiple sclerosis (MS). Personalised EID by therapeutic drug monitoring can enable further extension of treatment intervals., Methods: The NEXT-MS trial is an investigator-initiated prospective phase IV non-randomised study. Adults with a diagnosis of relapsing-remitting MS who received ≥6 natalizumab infusions were included in three groups: personalised EID with a target drug trough concentration of 10 µg/mL (EID10), an exploratory group of personalised EID with a target of 5 µg/mL (EID5) and standard interval dosing (SID) of 4 weeks. The primary outcome is radiological disease activity (new/newly enlarged T2 lesions) comparing the EID10 group to a historical cohort of SID (HSID)., Results: Results of the first phase of the NEXT-MS trial are reported here (n=376) as the study will continue with an amended protocol. In the EID10 group (n=251), incidence rate of radiological activity was 10.0 per 1000 person-years, which was non-inferior to the HSID cohort (24.7 per 1000 person-years (n=87), incidence rate difference 14.7, 90% CI -4.5 to 34.0). Incidence rate of radiological activity was 10.0 per 1000 person-years in the EID5 group (n=65), and 47.0 per 1000 person-years in the SID group (n=60). Serum neurofilament light levels did not increase over time within the EID groups. There were no cases of progressive multifocal leukoencephalopathy., Conclusions: MS disease activity is adequately controlled with personalised natalizumab EID. Interval extension to a drug trough concentration of 5 µg/mL is likely a safe target to extend natalizumab treatment intervals >6 weeks., Trial Registration Number: NCT04225312., Competing Interests: Competing interests: EH: has accepted (speaker and congress) fees from Merck Serono, Biogen Idec, Roche and Sanofi Genzyme. EMPEZ: reports advisory boards/consultancy fees for Merck, Novartis, Genzyme and Roche. JvE: reports honoraria for advisory boards and/or speakers fee from Merck Serono, Biogen Idec, Sanofi Genzyme, Roche and Novartis. FB: Steering committee and iDMC for Biogen, Merck, Roche, EISAI. Consultant to Roche, Biogen, Merck, IXICO, Jansen, Combinostics. Research agreements with Novartis, Merck, Biogen, GE, Roche. Co-founder of Queen Square Analytics. Funding by NIHR-UCLH-BRC, Novartis, GE, UKMSS, MAGNIMS-ECTRIMS, EC-H2020, EC-JU (IMI), EPSRC. Editorial board member for Brain, MSJ, Neurology, Radiology and Neuroradiology (section editor). CET: reports funding from National MS Society (Progressive MS alliance) and Innovative Medicines Initiatives 3TR (Horizon 2020, grant no 831434); has a research contract with Celgene; serves on editorial boards of Medidact Neurologie/Springer, Neurology: Neuroimmunology and Neuroinflammation, and is editor of a Neuromethods book Springer. TR received funding for research from Genmab and consultancy fees from Novartis. BMJU: reports research support and/or consultancy fees from Genzyme, Biogen Idec, Novartis, Teva Pharmaceutical Industries, Merck Serono, Roche, and Immunic Therapeutics. JK: received research grants for multicentre investigator initiated trials DOT-MS trial, ClinicalTrials.gov Identifier: NCT04260711 (ZonMW) and BLOOMS trial (ZonMW and Treatmeds), ClinicalTrials.gov Identifier: NCT05296161); received consulting fees for F. Hoffmann-La Roche Ltd, Biogen, Teva, Merck, Novartis and Sanofi/Genzyme (all payments to institution); reports speaker relationships with F. Hoffmann-La Roche, Biogen, Immunic, Teva, Merck, Novartis and Sanofi/Genzyme (all payments to institution); adjudication committee of MS clinical trial of Immunic (payments to institution only)., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Importance: Cause of ischemic stroke in young people is highly variable; however, the risk of recurrence is often presented with all subtypes of stroke grouped together in classification systems such as the Trial of ORG (danaparoid sodium [Orgaran]) 10172 in Acute Stroke Treatment (TOAST) criteria, which limits the ability to individually inform young patients with stroke about their risk of recurrence., Objective: To determine the short-term and long-term risk of recurrent vascular events after ischemic stroke at a young age by stroke cause and to identify factors associated with recurrence., Design, Setting, and Participants: This cohort study used data from the Observational Dutch Young Symptomatic Stroke Study, a prospective, multicenter, hospital-based cohort study, conducted at 17 hospitals in the Netherlands between 2013 and 2021. Eligible participants included 30-day survivors of an initial, neuroimaging-proven ischemic stroke (aged 18-49 years). Data analysis was conducted from June to July 2023., Exposure: Diagnosis of a first-ever, ischemic stroke via neuroimaging., Main Outcome and Measures: The primary outcome was short-term (within 6 months) and long-term (within 5 years) recurrence risk of any vascular event, defined as fatal or nonfatal recurrent ischemic stroke, transient ischemic attack, myocardial infarction, and revascularization procedure. Predefined characteristics were chosen to identify factors associated with risk of recurrence (cause of stroke, age, sex, stroke severity, and cardiovascular health factors)., Results: A total of 1216 patients (median [IQR] age, 44.2 [38.4-47.7] years; 632 male [52.0%]; 584 female [48.0%]) were included, with a median (IQR) follow-up of 4.3 (2.6-6.0) years. The 6-month risk of any recurrent ischemic event was 6.7% (95% CI, 5.3%-8.1%), and the 5-year risk was 12.2% (95% CI, 10.2%-14.2%)The short-term risk was highest for patients with cervical artery dissections (13.2%; 95% CI, 7.6%-18.7%). Other factors associated with a recurrent short-term event were atherothrombotic stroke, rare causes of stroke, and hypertension. The long-term cumulative risk was highest for patients with atherothrombotic stroke (22.7%; 95% CI, 10.6%-34.7%) and lowest for patients with cryptogenic stroke (5.8%; 95% CI, 3.0%-8.5%). Cardioembolic stroke was associated with a recurrent long-term event, as were diabetes and alcohol abuse., Conclusions and Relevance: The findings of this cohort study of 1216 patients with an ischemic stroke at a young age suggest that the risk of recurrent vascular events was high and varied by cause of stroke both for short-term and long-term follow-up, including causes that remained concealed when combined into 1 category in the routinely used TOAST criteria. This knowledge will allow for more personalized counseling of young patients with stroke.

Background: Lambert-Eaton myasthenic syndrome (LEMS) is a neuromuscular junction disorder and the clinical triad consists of proximal muscle weakness, autonomic symptoms and reduced tendon reflexes. Sluggish pupillary reflexes are common but dilated fixed pupils are rare., Case Presentation: We report a patient with a rare clinical course of LEMS. The patient was hospitalised due to progressive dyspnoea. She was ambulant and independent of oxygen at hospitalisation. The following day she suffered an in-hospital cardiac arrest based on hypoxia due to sputum stasis. The neurology department was consulted since the patient did not trigger on the ventilator after cessation of sedation. On neurological examination, the patient had dilated and fixed pupils, severe muscle weakness and areflexia, but a normal consciousness. Finally, she was diagnosed with LEMS. In this case report, the clinical course and diagnostic workup including anti-VGCC antibody testing, imaging and the results of electrophysiological studies are discussed. We also emphasise the importance of malignancy screening since the conventional chest CT was negative for lung carcinoma, but PET-CT raised a high suspicion for small-cell lung carcinoma., Conclusions: A rare course of LEMS, with early respiratory failure and wide, fixed pupils. Regarding repetitive nerve stimulation, it is important to stimulate long enough to see the incremental response. Furthermore, this study illustrated the importance of malignancy screening with PET-CT when there is a high suspicion of small-cell lung carcinoma with negative conventional CT., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Objectives: To investigate CSF findings in relation to clinical and electrodiagnostic subtypes, severity, and outcome of Guillain-Barré syndrome (GBS) based on 1,500 patients in the International GBS Outcome Study., Methods: Albuminocytologic dissociation (ACD) was defined as an increased protein level (>0.45 g/L) in the absence of elevated white cell count (<50 cells/μL). We excluded 124 (8%) patients because of other diagnoses, protocol violation, or insufficient data. The CSF was examined in 1,231 patients (89%)., Results: In 846 (70%) patients, CSF examination showed ACD, which increased with time from weakness onset: ≤4 days 57%, >4 days 84%. High CSF protein levels were associated with a demyelinating subtype, proximal or global muscle weakness, and a reduced likelihood of being able to run at week 2 (odds ratio [OR] 0.42, 95% CI 0.25-0.70; p = 0.001) and week 4 (OR 0.44, 95% CI 0.27-0.72; p = 0.001). Patients with the Miller Fisher syndrome, distal predominant weakness, and normal or equivocal nerve conduction studies were more likely to have lower CSF protein levels. CSF cell count was <5 cells/μL in 1,005 patients (83%), 5-49 cells/μL in 200 patients (16%), and ≥50 cells/μL in 13 patients (1%)., Discussion: ACD is a common finding in GBS, but normal protein levels do not exclude this diagnosis. High CSF protein level is associated with an early severe disease course and a demyelinating subtype. Elevated CSF cell count, rarely ≥50 cells/μL, is compatible with GBS after a thorough exclusion of alternative diagnoses., Classification of Evidence: This study provides Class IV evidence that CSF ACD (defined by the Brighton Collaboration) is common in patients with GBS., (© 2023 American Academy of Neurology.)

Introduction: We aimed to investigate the prevalence of cognitive impairment in the subacute phase after transient ischemic attack (TIA) and ischemic stroke (IS), factors associated with a vascular cognitive disorder, and the prevalence of subjective cognitive complaints and their relation with objective cognitive performance., Patients and Methods: In this multicenter prospective cohort study, we recruited patients with first-ever TIA and IS, aged 18-49 years, between 2013 and 2021 for cognitive assessment up to 6 months after index event. We calculated composite Z-scores for seven cognitive domains. We defined cognitive impairment as a composite Z-score < -1.5. We defined major vascular cognitive disorder as a Z-score < -2.0 in one or more cognitive domains., Results: Fifty three TIA and 545 IS patients completed cognitive assessment with mean time to assessment of 89.7 (SD 40.7) days. The median NIHSS at admission was 3 (interquartile range, 1-5). Cognitive impairment was common in five domains (up to 37%), with similar proportion in TIA and IS patients. Patients with major vascular cognitive disorder had a lower education level, higher NIHSS scores and more frequent lesions in the left frontotemporal lobe than without vascular cognitive disorder ( p  < 0.05 FDR-corrected). Subjective memory and executive cognitive complaints were present in about two-thirds of the patients, but were weakly associated with objective cognitive performance (β: -0.32 and -0.21, respectively)., Discussion and Conclusion: In the subacute phase after TIA or stroke in young adults, cognitive impairment and subjective cognitive complaints are prevalent, but they are weakly associated with each other., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: AT is a junior staff member of the Dutch Heart Foundation (grant number 2016T044). FEL has received a VIDI grant (016-126-351); and the Clinical established investigator Dutch Heart Foundation grant (2014 T060). MW has received a VIDI grant (9171337) of the ZonMw/NWO and the Clinical established investigator Dutch Heart Foundation grant (2016T86)., (© European Stroke Organisation 2022.)

Background: Identification of risk factors and causes of stroke is key to optimize treatment and prevent recurrence. Up to one-third of young patients with stroke have a cryptogenic stroke according to current classification systems (Trial of ORG 10172 in Acute Stroke Treatment [TOAST] and atherosclerosis, small vessel disease, cardiac pathology, other causes, dissection [ASCOD]). The aim was to identify risk factors and leads for (new) causes of cryptogenic ischemic stroke in young adults, using the pediatric classification system from the IPSS study (International Pediatric Stroke Study)., Methods: This is a multicenter prospective cohort study conducted in 17 hospitals in the Netherlands, consisting of 1322 patients aged 18 to 49 years with first-ever, imaging confirmed, ischemic stroke between 2013 and 2021. The main outcome was distribution of risk factors according to IPSS classification in patients with cryptogenic and noncryptogenic stroke according to the TOAST and ASCOD classification., Results: The median age was 44.2 years, and 697 (52.7%) were men. Of these 1322 patients, 333 (25.2%) had a cryptogenic stroke according to the TOAST classification. Additional classification using the ASCOD criteria reduced the number patients with cryptogenic stroke from 333 to 260 (19.7%). When risk factors according to the IPSS were taken into account, the number of patients with no potential cause or risk factor for stroke reduced to 10 (0.8%)., Conclusions: Among young adults aged 18 to 49 years with a cryptogenic ischemic stroke according to the TOAST classification, risk factors for stroke are highly prevalent. Using a pediatric classification system provides new leads for the possible causes in cryptogenic stroke, and could potentially lead to more tailored treatment for young individuals with stroke.

Background and Objectives: Causes of stroke in young adults differ from those in the elderly individuals, and in a larger percentage, no cause can be determined. To gain more insight into the etiology of (cryptogenic) stroke in the young population, we investigated whether trigger factors, such as short-lasting exposure to toxins or infection, may play a role., Methods: Patients aged 18-49 years with a first-ever ischemic stroke or intracerebral hemorrhage (ICH) in 17 participating centers in the Netherlands completed a questionnaire about exposure to 9 potential trigger factors in hazard periods and on a regular yearly basis. A case-crossover design was used to assess relative risks (RRs) with 95% confidence intervals (95% CIs) by the Mantel-Haenszel case-crossover method, for any stroke (ischemic stroke and ICH combined) and for different etiologic subgroups of ischemic stroke., Results: One thousand one hundred forty-six patients completed the questionnaire (1,043 patients with an ischemic stroke and 103 with an ICH, median age 44.0 years, 52.6% men). For any stroke, an increased risk emerged within 1 hour of cola consumption (RR 2.0, 95% CI 1.5-2.8) and vigorous physical exercise (RR 2.6, 95% CI 2.2-3.0), within 2 hours after sexual activity (RR 2.4, 95% CI 1.6-3.5), within 4 hours after illicit drug use (RR 2.8, 95% CI 1.7-4.9), and within 24 hours after fever or flu-like disease (RR 14.1, 95% CI 10.5-31.2; RR 13.9, 95% CI 8.9-21.9). Four trigger factors increased the risk of other determined and cryptogenic ischemic stroke, 3 that of cardioembolic stroke, 2 that of large vessel atherosclerosis and likely atherothrombotic stroke combined and stroke with multiple causes, and none that of stroke due to small vessel disease., Discussion: We identified cola consumption, vigorous physical exercise, sexual activity, illicit drug use, fever, and flu-like disease as potential trigger factors for stroke in the young population and found differences in the type and number of trigger factors associated with different etiologic subgroups of ischemic stroke. These findings might help in better understanding the pathophysiologic mechanisms of (cryptogenic) stroke in the young population., (© 2022 American Academy of Neurology.)

Background: Pooled analyses of previous randomised studies have suggested that very early treatment with glyceryl trinitrate (also known as nitroglycerin) improves functional outcome in patients with acute ischaemic stroke or intracerebral haemorrhage, but this finding was not confirmed in a more recent trial (RIGHT-2). We aimed to assess whether patients with presumed acute stroke benefit from glyceryl tr initrate started within 3 h after symptom onset., Methods: MR ASAP was a phase 3, randomised, open-label, blinded endpoint trial done at six ambulance services serving 18 hospitals in the Netherlands. Eligible participants (aged ≥18 years) had a probable diagnosis of acute stroke (as assessed by a paramedic), a face-arm-speech-time test score of 2 or 3, systolic blood pressure of at least 140 mm Hg, and could start treatment within 3 h of symptom onset. Participants were randomly assigned (1:1) by ambulance personnel, using a secure web-based electronic application with random block sizes stratified by ambulance service, to receive either transdermal glyceryl trinitrate 5 mg/day for 24 h plus standard care (glyceryl trinitrate group) or to standard care alone (control group) in the prehospital setting. Informed consent was deferred until after arrival at the hospital. The primary outcome was functional outcome assessed with the modified Rankin Scale (mRS) at 90 days. Safety outcomes included death within 7 days, death within 90 days, and serious adverse events. Analyses were based on modified intention to treat, and treatment effects were expressed as odds ratios (ORs) or common ORs, with adjustment for baseline prognostic factors. We separately analysed the total population and the target population (ie, patients with intracerebral haemorrhage, ischaemic stroke, or transient ischaemic attack). The target sample size was 1400 patients. The trial is registered as ISRCTN99503308., Findings: On June 24, 2021, the MR ASAP trial was prematurely terminated on the advice of the data and safety monitoring board, with recruitment stopped because of safety concerns in patients with intracerebral haemorrhage. Between April 4, 2018, and Feb 12, 2021, 380 patients were randomly allocated to a study group. 325 provided informed consent or died before consent could be obtained, of whom 170 were assigned to the glyceryl trinitrate group and 155 to the control group. These patients were included in the total population. 201 patients (62%) had ischaemic stroke, 34 (10%) transient ischaemic attack, 56 (17%) intracerebral haemorrhage, and 34 (10%) a stroke-mimicking condition. In the total population (n=325), the median mRS score at 90 days was 2 (IQR 1-4) in both the glyceryl trinitrate and control groups (adjusted common OR 0·97 [95% CI 0·65-1·47]). In the target population (n=291), the 90-day mRS score was 2 (2-4) in the glyceryl trinitrate group and 3 (1-4) in the control group (0·92 [0·59-1·43]). In the total population, there were no differences between the two study groups with respect to death within 90 days (adjusted OR 1·07 [0·53-2·14]) or serious adverse events (unadjusted OR 1·23 [0·76-1·99]). In patients with intracerebral haemorrhage, 12 (34%) of 35 patients allocated to glyceryl trinitrate versus two (10%) of 21 allocated to the control group died within 7 days (adjusted OR 5·91 [0·78-44·81]); death within 90 days occurred in 16 (46%) of 35 in the glyceryl trinitrate group and 11 (55%) of 20 in the control group (adjusted OR 0·87 [0·18-4·17])., Interpretation: We found no sign of benefit of transdermal glyceryl trinitrate started within 3 h of symptom onset in the prehospital setting in patients with presumed acute stroke. The signal of potential early harm of glyceryl trinitrate in patients with intracerebral haemorrhage suggests that glyceryl trinitrate should be avoided in this setting., Funding: The Collaboration for New Treatments of Acute Stroke consortium, the Brain Foundation Netherlands, the Ministry of Economic Affairs, Stryker, Medtronic, Cerenovus, and the Dutch Heart Foundation., Competing Interests: Declaration of interests HR reports financial support from the European Union's Horizon 2020 research and innovation program, paid to his institution. BJE reports financial support from Health Holland Top Sector Life Sciences & Health (via the Top Consortia for Knowledge and Innovation's public–private partnership), paid to his institution; and unpaid board membership of UEMS Neuroradiology and the Dutch Society of Radiology, Division of Neuroradiology. CBLMM, DWJD, PJN and HBvdW report funding from the Dutch Heart Foundation and Stryker, all paid to their institutions or the CONTRAST consortium. CBLMM reports financial support from the TWIN Foundation and Health Evaluation Netherlands, all paid to his institution. CBLMM and HBvdW report financial support from the European Commission, all paid to their institutions. CBLMM and YBWEMR are minor shareholders of Nicolab. DWJD reports grants from Medtronic, Cerenovus, Penumbra, Brain Foundation Netherlands, ZON MW–The Netherlands Organisation for Health Research and Development, and Health Holland Top Sector Life Sciences & Health, all paid to his institution. HBvdW reports honoraria for consultancy from Bayer and LivaNova, all paid to his institution. All other authors declare no competing interests., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background and Objectives: The clinical course and outcome of the Guillain-Barré syndrome (GBS) are diverse and vary among regions. The modified Erasmus GBS Outcome Score (mEGOS), developed with data from Dutch patients, is a clinical model that predicts the risk of walking inability in patients with GBS. The study objective was to validate the mEGOS in the International GBS Outcome Study (IGOS) cohort and to improve its performance and region specificity., Methods: We used prospective data from the first 1,500 patients included in IGOS, aged ≥6 years and unable to walk independently. We evaluated whether the mEGOS at entry and week 1 could predict the inability to walk unaided at 4 and 26 weeks in the full cohort and in regional subgroups, using 2 measures for model performance: (1) discrimination: area under the receiver operating characteristic curve (AUC) and (2) calibration: observed vs predicted probability of being unable to walk independently. To improve the model predictions, we recalibrated the model containing the overall mEGOS score, without changing the individual predictive factors. Finally, we assessed the predictive ability of the individual factors., Results: For validation of mEGOS at entry, 809 patients were eligible (Europe/North America [n = 677], Asia [n = 76], other [n = 56]), and 671 for validation of mEGOS at week 1 (Europe/North America [n = 563], Asia [n = 65], other [n = 43]). AUC values were >0.7 in all regional subgroups. In the Europe/North America subgroup, observed outcomes were worse than predicted; in Asia, observed outcomes were better than predicted. Recalibration improved model accuracy and enabled the development of a region-specific version for Europe/North America (mEGOS-Eu/NA). Similar to the original mEGOS, severe limb weakness and higher age were the predominant predictors of poor outcome in the IGOS cohort., Discussion: mEGOS is a validated tool to predict the inability to walk unaided at 4 and 26 weeks in patients with GBS, also in countries outside the Netherlands. We developed a region-specific version of mEGOS for patients from Europe/North America., Classification of Evidence: This study provides Class II evidence that the mEGOS accurately predicts the inability to walk unaided at 4 and 26 weeks in patients with GBS., Trial Registration Information: NCT01582763., (© 2021 American Academy of Neurology.)