Heterogeneity of cognitive impairments in myotonic dystrophy type 1 explained by three distinct cognitive profiles

BACKGROUND

Severity and nature of cognitive impairments in Myotonic dystrophy type 1 (DM1) are heterogeneous among studies. We hypothesized that this heterogeneity is explained by different cognitive profiles in DM1, with different clinical, biological and behavioral features.

METHODS

Adult patients with genetically proven DM1 underwent a clinical, neuropsychological and behavioral assessment. We conducted a k-means clustering analysis on 9 cognitive tests representative of different domains (verbal/non-verbal episodic memory, visuo-constructive abilities, visual gnosis, executive functions, information processing speed).

RESULTS

We included 124 DM1 patients. Mean age was 45.1 ± 13.5 years [19.8-73.2], mean age of onset was 30.4 ± 15.7 years [5-72], and mean CTG triplets' expansion size was 489.7 ± 351.8 [50-1600]. We found 3 cognitive clusters, including, respectively, 84, 29 and 11 patients. The first cluster included patients with more preserved cognitive functions; the second included patients with worse cognitive performances which predominate on executive functions; and the third even more pronounced and diffuse cognitive deficits. Younger patients, with a more recent DM1 clinical onset, higher educational level were more frequently classified in the cluster with more preserved cognitive functions. There were no significant differences between clusters regarding CTG triplets' expansion, neither age at DM1 onset, nor most of behavioral measures.

CONCLUSIONS

We found different cognitive profiles in our DM1 population, which seem influenced by age and DM1 duration. Our findings may explain the heterogeneity of studies about cognition in DM1, and suggest a potential neurodegenerative mechanism in DM1 adults.

Cognitive Impairment Is Part of the Phenotype of Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome (CANVAS)

BACKGROUND

Little is known about the impact of the cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) on cognition.

OBJECTIVE

Our objective was to determine the frequency and severity of cognitive impairment in RFC1-positive patients and describe the pattern of deficits.

METHODS

Participants underwent a comprehensive neuropsychological assessment. Volume of the cerebellum and its lobules was measured in those who underwent a 3 Tesla-magnetic resonance scan.

RESULTS

Twenty-one patients underwent a complete assessment, including 71% scoring lower than the cutoff at the Montreal Cognitive assessment and 71% having a definite cerebellar cognitive affective/Schmahmann syndrome. Three patients had dementia and seven met the criteria of mild cognitive impairment. Severity of cognitive impairment did not correlate with severity of clinical manifestations. Performance at memory and visuospatial functions tests negatively correlated with the severity of cerebellar manifestations.

CONCLUSION

Cognitive manifestations are frequent in RFC1-related disorders. They should be included in the phenotype and screened systematically. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Real-life effectiveness 1 year after switching to avalglucosidase alfa in late-onset Pompe disease patients worsening on alglucosidase alfa therapy: A French cohort study

INTRODUCTION

Late-onset Pompe disease (LOPD) is characterized by a progressive myopathy resulting from a deficiency of acid α-glucosidase enzyme activity. Enzyme replacement therapy has been shown to be effective, but long-term treatment results vary. Avalglucosidase alfa demonstrated non-inferiority to alglucosidase alfa in a phase 3 study, allowing in France compassionate access for advanced LOPD patients unresponsive to alglucosidase alfa.

METHODS

Data from the French Pompe registry were analyzed for patients who benefited from a switch to avalglucosidase alfa with at least 1 year of follow-up. Respiratory (forced vital capacity [FVC]) and motor functions (Six-Minute Walk Test [6MWT]) were assessed before and 1 year after switching. Individual changes in FVC and 6MWT were expressed as slopes and statistical analyses were performed to compare values.

RESULTS

Twenty-nine patients were included (mean age 56 years, 11 years of prior treatment). The FVC and 6MWT values remained stable. The individual analyses showed a stabilization of motor worsening: -1 m/year on the 6MWT after the switch versus -63 m/year the year before the switch (i.e., a worsening of 33%/year before vs. an improvement of 3%/year later). Respiratory data were not statistically different.

DISCUSSION

At the group level, gait parameters improved slightly with a stabilization of previous worsening, but respiratory parameters showed limited changes. At the individual level, results were discordant, with some patients with a good motor or respiratory response and some with further worsening.

CONCLUSION

Switching to avalglucosidase alfa demonstrated varied responses in advanced LOPD patients with failing alglucosidase alfa therapy, with a general improvement in motor stabilization.

Effect of nusinersen after 3 years of treatment in 57 young children with SMA in terms of SMN2 copy number or type

BACKGROUND

Spinal muscular atrophy (SMA) is a rare genetic neuromuscular disorder due to an autosomal recessive mutation in the survival motor neuron 1 gene (SMN1), causing degeneration of the anterior horn cells of the spinal cord and resulting in muscle atrophy. This study aimed to report on the 36-month follow-up of children with SMA treated with nusinersen before the age of 3 years. Changes in motor function, nutritional and ventilatory support, and orthopedic outcomes were evaluated at baseline and 36 months after intrathecal administration of nusinersen and correlated with SMA type and SMN2 copy number.

RESULTS

We found that 93% of the patients gained new motor skills during the 3 years-standing without help for 12 of 37 and walking with help for 11 of 37 patients harboring three SMN2 copies. No patients with two copies of SMN2 can stand alone or walk. Patients bearing three copies of SMN2 are more likely to be spared from respiratory, nutritional, and orthopedic complications than patients with two SMN2 copies.

CONCLUSION

Children with SMA treated with nusinersen continue to make motor acquisitions at 3 years after initiation of treatment. Children with two SMN2 copies had worse motor, respiratory, and orthopedic outcomes after 3 years of treatment than children with three copies.

Hereditary neuropathy associated with liability to pressure palsies: a 24-year experience with carpal and cubital tunnel surgery

The aim of this single-centre retrospective study was to evaluate the outcomes of carpal tunnel release surgery in patients with hereditary neuropathy with pressure palsies (HNPP). The secondary aims were to identify prognostic factors for the outcome of carpal tunnel release and to assess the outcome of cubital tunnel release. Our primary hypothesis was postoperative improvement. In total, 18 patients (26 carpal tunnel releases) with at least one symptomatic carpal tunnel syndrome were included. At a median follow-up of 8.5 years, more than 73% of the patients were satisfied with the results. The visual analogue scale (0 to 10) for discomfort decreased by 2.2 points (p < 0.001). The Boston Carpal Tunnel Questionnaire symptom severity scale decreased by 1.3 points (p < 0.001). The decrease in the Functional Status Scale was not significant. No significant prognostic factor for outcome was identified. A total of 12 patients also underwent cubital tunnel release, and three patients underwent just this procedure (23 procedures). Despite the lack of preoperative data, cubital tunnel release provided encouraging results. Level of evidence: III.

Characterization of theory of mind performance in patients with myotonic dystrophy type 1

INTRODUCTION

Myotonic dystrophy type 1 (DM1) is associated with motor dysfunction as well as psychological and cognitive impairments, including altered social cognition. Theory of mind (ToM) impairments have been reported in this disease but their nature and their cognitive/cerebral correlates have yet to be determined.

METHODS

Fifty DM1 patients and 50 healthy controls were assessed using the Movie for the Assessment of Social Cognition, which quantifies impairments in affective and cognitive components of ToM through the depiction of everyday situations. We also measured the study participants' cognitive, behavioral and social abilities, quality of life, and brain MRI characteristics.

RESULTS

DM1 patients presented a significant impairment in ToM performance compared to controls (p < .001). The patients' errors were related to hypomentalizations (p < .001 vs controls) but not to hypermentalizations (p = .95). The affective component was affected (p < .001 vs controls) but not the cognitive component (p = .09). The ToM impairment was associated with demographic variables (older age and a lower educational level), genetic findings (a larger CTG triplets repeat expansion) and cognitive scores (slower information processing speed). Associations were also found with brain MRI variables (lower white matter and supratentorial volumes) but not with behavioral or social variables.

DISCUSSION

DM1 patients display a ToM impairment, characterized by predominant hypomentalizations concerning the affective component. This impairment might result from structural brain abnormalities observed in DM1.

Comparison of biomarker for diagnosis of nitrous oxide abuse: challenge of cobalamin metabolic parameters, a retrospective study

BACKGROUND

Recreational use of nitrous oxide (N₂O) leads to neurological disorders including combined subacute degeneration of spinal cord, psychological disorders, and thrombosis. Serum or urine N₂O assays could not be routinely performed. Hence, it is necessary to investigate other biological markers such as metabolic markers. We aimed here to challenge the three main biological markers used for the diagnosis of nitrous oxide abuse as total vitamin B12, homocysteine, and methylmalonic acid.

METHODS

We retrospectively collected clinical and biological data from 52 patients with known, documented chronic N₂O abuse and associated clinical signs (peripheral neuropathy disability score or thrombosis event). Sera and plasma total vitamin B12, methylmalonic acid (MMA), and homocysteine were performed to identify the most specific marker of chronic N₂O intoxication and related clinical outcomes.

RESULTS

Plasma homocysteine was almost consistently increased in case of N₂O chronic consumption, whereas MMA increase and total vitamin B12 decrease are not systematically found. Our results showed that none of the markers are correlated with levels of N₂O consumptions. However, homocysteine and MMA are correlated with clinical severity, but MMA seems to be a better marker of clinical severity.

CONCLUSION

There is no specific marker of nitrous oxide abuse according to levels of consumption, total vitamin B12 decrease could not be used either as consumption or as severity marker. However, we showed that homocysteine is consistently increased and could be used as marker of recent N₂O consumption. On the other hand, we showed that MMA could be used as a marker of clinical gravity.

A new score combining compound muscle action potential (CMAP) amplitudes and motor score is predictive of motor outcome after AVXS-101 (Onasemnogene Abeparvovec) SMA therapy

Spinal muscular atrophy 1 (SMA1) is a severe early genetic disease with degeneration of motor neurons. Motor development is still suboptimal after gene replacement therapy in symptomatic patients. In this study, compound muscle action potential (CMAP) amplitudes were explored as predictors of motor recovery after gene therapy. Thirteen symptomatic SMA1 patients were prospectively included at the Necker Enfants Malades Hospital, Paris, France (Cohort 1) and 12 at the other pediatric neuromuscular reference centers of the French Filnemus network (Cohort 2). In Cohort 1, median CMAP amplitudes showed the best improvement between baseline and the 12 months visit compared to the other tested nerves (ulnar, fibular and tibial). High median CMAP amplitudes at baseline was associated with unaided sitting achievement at M6 (AUC 90%). None of the patients with CHOPINTEND at M0 < 30/64 and median CMAP < 0.5 mV achieved unaided sitting at M6 and this result was confirmed on Cohort 2 used as an independent validation data. Thus, median CMAP amplitude is a valid biomarker for routine practice to predict sitting at M6. A median CMAP amplitude over 0.5 mV at baseline may predict better motor recovery.

Relation between retina, cognition and brain volumes in MS: a consequence of asymptomatic optic nerve lesions

INTRODUCTION

Asymptomatic optic nerve lesions are frequent in multiple sclerosis (MS) and their impact on cognition and/or brain volume has never been taken into account.

PATIENTS AND METHODS

We used the data from the cross-sectional Visual Ways in MS (VWIMS) study including relapsing remitting MS. All patients underwent brain and optic nerve Magnetic Resonance Imaging (MRI) including Double Inversion Recuperation (DIR) sequence, retinal OCT, and cognitive evaluation with the Brief International Cognitive Assessment in MS (BICAMS). We measured the association between OCT findings (thickness/volume of retinal layers) and extra-visual parameters (cerebral volumes and BICAMS scores) in optic nerves with and/or without the presence of DIR asymptomatic optic nerve hypersignal.

RESULTS

Between March and December 2017, we included 98 patients. Two patients were excluded. Over the 192 eyes, 73 had at least one clinical history of optic neuritis (ON-eyes) whereas 119 were asymptomatic (NON-eyes). Among the 119 NON-eyes, 58 had 3D-DIR optic nerve hypersignal (48.7%). We confirmed significant associations between some retinal OCT measures and some extra-visual parameters (cerebral volumes, cognitive scores) in NON-eyes. Unexpectedly, these associations were found when an asymptomatic optic nerve DIR-hypersignal was present on MRI, but not when it was absent.

CONCLUSION

Our study showed a relation between OCT measures and extra-visual parameters in NON-eyes MS patients. As a confusion factor, asymptomatic optic nerve lesions may be the explanation of the relation between OCT measures and extra-visual parameters. Retinal OCT seems to be far more a "window over the optic nerve" than a "window over the brain".

Factors impacting performance on the 6-minute walk test by people with late-onset Pompe disease

INTRODUCTION/AIMS

Pompe disease is a progressive myopathy that combines motor, respiratory, and cardiac impairments. The 6-min walk test is the gold standard for assessing disease severity at the motor level. The objective of this study was to better determine the parameters that influence the total distance covered in patients with Pompe disease.

METHODS

We performed a retrospective review of 15 patients with late-onset Pompe disease who were followed regularly at a single referral center. Logistic regression was used to investigate the links between motor, respiratory and cardiac variables and 6-min walk test performance.

RESULTS

When considering baseline clinical and demographic variables, a seven-step backward elimination regression analysis yielded a model with two predictors (age and the use of an assistive device) that explained 85.5% of the variance. When considering the cardiorespiratory variables monitored during gait, a three-step backward elimination regression analysis showed that two predictors (heart rate recovery and the baseline partial pressure of carbon dioxide) explained 42.2% of the variance.

DISCUSSION

Our results highlighted the importance of respiratory and cardiac adaptation during exercise (along with motor ability) during the 6-min walk test in patients with Pompe disease. Further studies of larger cohorts are necessary to validate the model, which might enable investigators to determine whether intra-individual fluctuations in 6-min walk test performance are related to physiological parameters and/or to other variables such as the patient's level of motivation during the test.

Rituximab Therapy in the Treatment of Juvenile Myasthenia Gravis: The French Experience

OBJECTIVE

Corticosteroids are the first-line immunosuppressants in the management of juvenile myasthenia gravis despite their adverse effects. The place of new immunosuppressive therapies is not clearly defined by the last international consensus held in March 2019, due to the lack of clinical trials. The aim of this study is to describe the use of rituximab, its efficacy and safety in 8 main pediatric centers of the French neuromuscular reference network in order to propose a new place in the therapeutic strategy of juvenile myasthenia gravis.

METHOD

We conducted a retrospective multicenter study from January 1, 2009 to April 30, 2020, including a large cohort of children with myasthenia gravis in 8 main French pediatric reference centers of the Filnemus network. The type of myasthenia, the different lines of immunosuppressive treatment and the clinical course of the patients were collected. To evaluate the efficacy of rituximab, we studied the clinical course of patients on immunosuppressive therapy. Outcome was defined as the clinical and therapeutic status of patients at the last visit: stable without immunosuppressants, stable with immunosuppressants or unstable.

RESULTS

We included 74 patients: 18 children with ocular form and 56 children with generalized form. Of the 37 patients who required immunosuppressive therapy, 27 were treated with rituximab. Patients treated with rituximab had a better outcome than patients treated with conventional immunosuppressants (p = 0.006). The use of rituximab as a first-line immunosuppressant showed a better efficacy with a discontinuation of immunosuppressants in 75% of patients (vs. 25%, p=0.04) and resulted cortisone sparing (42% vs. 92%, p=0.03) compared with rituximab treatment as a second or third-line immunosuppression. Rituximab was well tolerated; no adverse effect was observed.

CONCLUSION

The use of rituximab has increased in France over the last 10 years as first line immunosuppressant. This study suggests a good tolerability and efficacy of rituximab in juvenile myasthenia gravis. Early use appears to improve outcomes and facilitate cortisone-sparing in antibody-positive generalized juvenile myasthenia.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that for children with MG rituximab is effective and well tolerated.

Motor neuron pathology in CANVAS due to RFC1 expansions

CANVAS caused by RFC1 biallelic expansions is a major cause of inherited sensory neuronopathy. Detection of RFC1 expansion is challenging and CANVAS can be associated with atypical features.

We clinically and genetically characterized 50 patients, selected based on the presence of sensory neuronopathy confirmed by EMG. We screened RFC1 expansion by PCR, repeat-primed PCR, and Southern blotting of long-range PCR products, a newly developed method. Neuropathological characterization was performed on the brain and spinal cord of one patient.

Most patients (88%) carried a biallelic (AAGGG)n expansion in RFC1. In addition to the core CANVAS phenotype (sensory neuronopathy, cerebellar syndrome, and vestibular impairment), we observed chronic cough (97%), oculomotor signs (85%), motor neuron involvement (55%), dysautonomia (50%), and parkinsonism (10%). Motor neuron involvement was found for 24 of 38 patients (63.1%). First motor neuron signs, such as brisk reflexes, extensor plantar responses, and/or spasticity, were present in 29% of patients, second motor neuron signs, such as fasciculations, wasting, weakness, or a neurogenic pattern on EMG in 18%, and both in 16%. Mixed motor and sensory neuronopathy was observed in 19% of patients. Among six non-RFC1 patients, one carried a heterozygous AAGGG expansion and a pathogenic variant in GRM1. Neuropathological examination of one RFC1 patient with an enriched phenotype, including parkinsonism, dysautonomia, and cognitive decline, showed posterior column and lumbar posterior root atrophy. Degeneration of the vestibulospinal and spinocerebellar tracts was mild. We observed marked astrocytic gliosis and axonal swelling of the synapse between first and second motor neurons in the anterior horn at the lumbar level. The cerebellum showed mild depletion of Purkinje cells, with empty baskets, torpedoes, and astrogliosis characterized by a disorganization of the Bergmann's radial glia. We found neuronal loss in the vagal nucleus. The pars compacta of the substantia nigra was depleted, with widespread Lewy bodies in the locus coeruleus, substantia nigra, hippocampus, entorhinal cortex, and amygdala.

We propose new guidelines for the screening of RFC1 expansion, considering different expansion motifs. Here, we developed a new method to more easily detect pathogenic RFC1 expansions. We report frequent motor neuron involvement and different neuronopathy subtypes. Parkinsonism was more prevalent in this cohort than in the general population, 10% versus the expected 1% (p &lt; 0.001). We describe, for the first time, the spinal cord pathology in CANVAS, showing the alteration of posterior columns and roots, astrocytic gliosis and axonal swelling, suggesting motor neuron synaptic dysfunction.

Childhood-onset progressive dystonia associated with pathogenic truncating variants in CHD8

Originally described as a risk factor for autism, CHD8 loss‐of‐function variants have recently been associated with a wider spectrum of neurodevelopmental abnormalities. We further expand the CHD8‐related phenotype with the description of two unrelated patients who presented with childhood‐onset progressive dystonia. Whole‐exome sequencing conducted in two independent laboratories revealed a CHD8 nonsense variant in one patient and a frameshift variant in the second. The patients had strongly overlapping phenotypes characterized by generalized dystonia with mild‐to‐moderate neurodevelopmental comorbidity. Deep brain stimulation led to clinical improvement in both cases. We suggest that CHD8 should be added to the growing list of neurodevelopmental disorder‐associated genes whose mutations can also result in dystonia‐dominant phenotypes.

Adalimumab and myositis: A case report and review of the French and international Pharmacovigilance Databases

TNFα inhibitors, including adalimumab, are widely used in inflammatory rheumatologic and bowel diseases. Well-known adverse effects include: opportunistic infections, immunogenicity and new inflammatory manifestations. Myositis is an inflammatory disease, which manifests with muscle symptoms and can be life-threatening. Little is known about drug-induced myositis. We aimed to describe a case of myositis induced by adalimumab and reviewed national and international pharmacovigilance databases for other cases until 01/02/2019. This was a 63 years old woman with Crohn's disease, who developed muscle weakness, and rhabdomyolysis 3 months after starting adalimumab. Diagnosis of myositis was suspected and confirmed with electromyography and muscle biopsy. Improvement in muscle symptoms was observed after stopping adalimumab and starting corticosteroids. Muscular adverse effects are well-known and usually benign with adalimumab. However, five cases of myositis during treatment with adalimumab were registered in French PharmacoVigilance Database (FPVD) with muscle symptoms observed 3 months to 7 years after starting adalimumab. In VigiBase^Ⓡ, 90 cases of myositis associated with adalimumab with some similar characteristics were registered. When a patient treated with adalimumab complains of muscular symptoms, inflammatory myopathies should be considered. This adverse effect should be mentioned in a 'Summary of Product Characteristics' to alert healthcare professionals.

Low hormone levels during an attack of systemic capillary leak syndrome normalizing after treatment

We report herein the case of a patient with low blood levels of different hormones during a systemic capillary leak syndrome (Clarkson's disease) attack.

Asymptomatic optic nerve lesions: An underestimated cause of silent retinal atrophy in MS

OBJECTIVE

To evaluate the frequency of asymptomatic optic nerve lesions and their role in the asymptomatic retinal neuroaxonal loss observed in multiple sclerosis (MS).

METHODS

We included patients with remitting-relapsing MS in the VWIMS study (Analysis of Neurodegenerative Process Within Visual Ways In Multiple Sclerosis) (ClinicalTrials.gov Identifier: 03656055). Included patients underwent optical coherence tomography (OCT), optic nerve and brain MRI, and low-contrast visual acuity measurement. In eyes of patients with MS without optic neuritis (MS-NON), an optic nerve lesion on MRI (3D double inversion recovery [DIR] sequence) was considered as an asymptomatic lesion. We considered the following OCT/MRI measures: peripapillary retinal nerve fiber layer thickness, macular ganglion cell + inner plexiform layer (mGCIPL) volumes, optic nerve lesion length, T2 lesion burden, and fractional anisotropy within optic radiations.

RESULTS

An optic nerve lesion was detected in half of MS-NON eyes. Compared to optic nerves without any lesion and independently of the optic radiation lesions, the asymptomatic lesions were associated with thinner inner retinal layers (p < 0.0001) and a lower contrast visual acuity (p ≤ 0.003). Within eyes with asymptomatic optic nerve lesions, optic nerve lesion length was the only MRI measure significantly associated with retinal neuroaxonal loss (p < 0.03). Intereye mGCIPL thickness difference (IETD) was lower in patients with bilateral optic nerve DIR hypersignal compared to patients with unilateral hypersignal (p = 0.0317). For the diagnosis of history of optic neuritis, sensitivity of 3D DIR and of mGCIPL IETD were 84.9% and 63.5%, respectively.

CONCLUSIONS

Asymptomatic optic nerve lesions are an underestimated and preponderant cause of retinal neuroaxonal loss in MS. 3D DIR sequence may be more sensitive than IETD measured by OCT for the detection of optic nerve lesions.

A Fully Automatic Method for Optic Radiation Tractography Applicable to Multiple Sclerosis Patients

The optic radiations (OR) are white matter tracts forming the posterior part of the visual ways. As an important inter-individual variability exists, atlases may be inefficient to locate the OR in a given subject. We designed a fully automatic method to delimitate the OR on a magnetic resonance imaging using tractography. On 15 healthy subjects, we evaluated the validity of our method by comparing the outputs to the Jülich post-mortem histological atlas, and its reproducibility. We also evaluated its feasibility on 98 multiple sclerosis (MS) patients. We correlated different visual outcomes with the inflammatory lesions volume within the OR reconstructed with different methods (our method, atlas, TractSeg). Our method reconstructed the OR bundle in all healthy subjects (< 2 h for most of them), and was reproducible. It demonstrated good classification indexes: sensitivity up to 0.996, specificity up to 0.993, Dice coefficient up to 0.842, and an area under the receiver operating characteristic (ROC) curve of 0.981. Our method reconstructed the OR in 91 of the 98 MS patients (92.9%, < 6 h for most of patients). Compared to an atlas-based approach and the TractSeg method, the inflammatory lesions volume in the OR measured with our method better correlated with the visual cortex volume, visual acuity and mean peripapillar retinal nerve fiber layer thickness. Our method seems to be efficient to reconstruct the OR in healthy subjects, and seems applicable to MS patients. It may be more relevant than an atlas based approach.

Two cases of relapses in primary progressive multiple sclerosis after fingolimod withdrawal

We report two cases of primary progressive multiple sclerosis (PPMS) included in the INFORMS cohort, experiencing a relapse related to a single MRI gadolinium-enhancing lesion 3 months after fingolimod withdrawal. These two patients share similarities with relapsing-remitting multiple sclerosis cases described in the same situation, suggesting that the initiating process of the active demyelinating plaques is also present in PPMS, even without relapses, but may be triggered as fingolimod is withdrawn. Although the results of the INFORMS study suggest that fingolimod may not slow down the progression, some PPMS patients might still benefit from a disease-modifying treatment.