Background and objectivesThe severity of the phenotype of spinal muscular atrophy (SMA) is highly variable, yet little is known about the phenotypic variation among siblings. We systematically investigated the phenotypic variability of therapy-naïve 5q-SMA siblings leveraging a large multicentre cohort from the SMArtCARE registry.ResultsClinical information was available from 132 siblings of 65 families. There were 24 (18.2%) type 1, 38 (28.7%) type 2, 54 (40.9%) type 3 patients, and 16 (12.1%) presymptomatic individuals. In 17 families (32.1%), there was discordance in the type of SMA among symptomatic siblings. We found no influence of gender on discordance in SMA type among siblings (p = 0.528). The median age at disease onset within all sibships varied by 6 months (interquartile range (IQR) = 1-30). There was no correlation in age of onset among siblings (r = 0.405; p = 0.052). Among siblings who lost ambulation, the median interval between the start of wheelchair use was 12 months, but the maximal interval was 18 years. In one pair of siblings, one sibling lost the ability to walk at the age of 13, whereas the other sibling was still ambulatory at the age of 54. In 6 sibling pairs (9.5%), only one of both siblings had a history of scoliosis surgery. Analysing SMN2 copy numbers, in one sibling pair (1.8%) 1 SMN2 gene copy was detected, while 10 (17.5%) had 2 copies, 23 (40.4%) had 3 copies, and 17 (29.8%) had 4 copies. Concordance in SMN2 copy numbers across siblings was observed in 90% of families. With increasing SMN2 copy number, the median differences in age of onset among siblings increased without reaching statistical significance.ConclusionThis study reports considerable phenotypic variability in therapy-naïve SMA sibships that cannot solely be explained by differences in SMN2 copy numbers.

OBJECTIVE:To investigate self-assessment of the amyotrophic lateral sclerosis functional rating scale-revised (ALSFRS-R) using the patient's smartphone and to analyze non-inferiority to clinic assessment. METHODS:In an observational study, ALSFRS-R data being remotely collected on a mobile application (App-ALSFRS-R) were compared to ALSFRS-R captured during clinic visits (clinic-ALSFRS-R). ALS progression rate (ALSPR)-as calculated by the monthly decline of ALSFRS-R-and its intrasubject variability (ALSPR-ISV) between ratings were used to compare both cohorts. To investigate non-inferiority of App-ALSFRS-R data, a non-inferiority margin was determined. RESULTS:A total of 691 ALS patients using the ALS-App and 1895 patients with clinic assessments were included. Clinical characteristics for the App-ALSFRS-R and clinic-ALSFRS-R cohorts were as follows: Mean age 60.45 (SD 10.43) and 63.69 (SD 11.30) years (p < 0.001), disease duration 38.7 (SD 37.68) and 56.75 (SD 54.34) months (p < 0.001) and ALSPR 0.72 and 0.59 (p < 0.001), respectively. A paired sample analysis of ALSPR-ISV was applicable for 398 patients with clinic as well as app assessments and did not show a significant difference (IQR 0.12 [CI 0.11, 0.14] vs 0.12 [CI 0.11, 0.14], p = 0.24; Cohen's d = 0.06). CI of IQR for App-ALSFRS-R was below the predefined non-inferiority margin of 0.15 IQR, demonstrating non-inferiority. CONCLUSIONS:Patients using a mobile application for remote digital self-assessment of the ALSFRS-R revealed younger age, earlier disease course, and faster ALS progression. The finding of non-inferiority of App-ALSFRS-R assessments underscores, that data collection using the ALS-App on the patient's smartphone can serve as additional source of ALSFRS-R in ALS research and clinical practice.

Aging is characterized by a decreased autophagic activity contributing to the intracellular deposition of damaged organelles and macromolecules. Autophagy is particularly challenging in neurons since autophagic vesicles are formed at the axonal tip and must be transported to the soma where final degradation occurs. Here, we examined if axonal transport of autophagic vesicles is altered during aging. We employed two-photon microscopy for in vivo imaging in the optic nerve of young and aged rats. In old animals (> 18 months old), retrograde autophagic vesicle transport was significantly reduced with regard to motility and velocity. While activation of autophagy was decreased, expression of key proteins of the autophagy-lysosomal pathway including p62 and procathepsin D and the number of autophagolysosomes was increased. Maturation of autophagic vesicles was shifted to more distal regions of the axon and axonal lysosomal clearing was impaired. In a pull-down assay, the protein binding between dynein and dynactin was decreased by half, which could explain the retrograde axonal transport effects. Taken together, retrograde axonal autophagic vesicle transport in vivo is diminished during aging accompanied by decreased autophagy activation, alterations of the lysosomal pathway, and a reduced dynein-dynactin binding.

Background and purposeIn the differential diagnostic workup of amyotrophic lateral sclerosis (ALS), magnetic resonance imaging (MRI) is primarily used to rule out significant differential diagnoses. So far, whole-brain T1-mapping has not been assessed as a diagnostic tool in this patient population.MethodsWe investigated the diagnostic potential of a novel T1-mapping method based on real-time MRI with 0.5 mm in-plane resolution and 4s acquisition time per slice. The study included patients aged 18 to 90 years who met the revised El Escorial criteria for at least possible ALS. T1-relaxation times were measured along the corticospinal tract in predefined regions of interest.ResultsTwenty-nine ALS-patients and 43 control group patients (CG) were included in the study. Median ALS Functional Rating Scale revised (ALSFRS-R) was 37 (IQR, 35–44) points and the mean duration from symptom onset to MRI was 21 ± 17 (SD) months. ALS patients showed significantly higher T1-relaxation times in all ROIs compared to CG with mean differences in the hand knob of 50 ms (p < 0.001), corona radiata 24 ms (p = 0.034), internal capsule 27 ms (p = 0.002) and midbrain peduncles 48 ms (p < 0.001). There was a consistent negative correlation between the ALSFRS-R and T1-relaxation times in all ROIs.ConclusionsT1-relaxation times along the corticospinal tract are significantly elevated in ALS patients compared to CG and associated with lower ALSFRS-R. These results imply the analysis of T1-relaxation times as a promising diagnostic tool that can distinguish ALS patients from the control group. Ongoing longitudinal studies may provide deeper insights into disease progression and the effects of therapeutic interventions.

In patients with amyotrophic lateral sclerosis (ALS), mechanical insufflation-exsufflation (MI-E) addresses cough deficiency to achieve major therapeutic goals: improving costal muscle and joint function, reducing atelectasis through insufflation, and clearing bronchial secretions via exsufflation. Despite its perceived benefits, there is limited systematic research on MI-E provision, symptom alleviation, or patient satisfaction. The research platform Ambulanzpartner coordinated this longitudinal observational study conducted in 12 German ALS centers from July 2018 to September 2023. Patients were enrolled based on ALS-related cough deficiency requiring MI-E therapy. The study recorded provision, reasons for withholding MI-E, clinical parameters, therapy frequency, subjective cough deficiency, and symptomatic relief. Satisfaction with MI-E therapy was determined by the likelihood of recommendation. Out of 694 ALS patients indicated for MI-E, 527 (75.9%) received the therapy. The primary reason for non-provision was that the patient had died before provision (n = 66 of 167; 39.5%). These patients were significantly more affected as represented by higher progression rates and lower cough peak flows (CPF) at the time of MI-E indication (p < 0.05). Most patients who received MI-E used it daily (n = 290 of 370; 78.4%). Self-assessed cough deficiency correlated with clinical measurements, especially for patients with higher deficits. At follow-up visits, patients reported reduced cough deficiency (p < 0.001). Frequent MI-E use was linked to greater symptom relief and higher likelihood of recommending the therapy. This study highlights the symptomatic and palliative potential of MI-E therapy for ALS patients.

Background and Objectives The availability of disease-modifying therapies for 5q-associated spinal muscular atrophy (SMA) has heightened the need to identify suitable biomarkers. This study investigates neurofilament light chain (NfL) concentrations during long-term nusinersen treatment in adult SMA. Methods In a retrospective study of prospectively collected data, NfL concentrations in the CSF (cNfL) and serum (sNfL) were measured in patients with SMA from 8 German centers and in neurologic controls using a single-molecule array (Simoa) assay. NfL concentrations and clinical characteristics, including the clinical scores Hammersmith Functional Motor Scale Expanded (HFMSE), Revised Upper Limb Module (RULM), and Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R), were analyzed for defined treatment intervals (T1-T4 [loading phase until 4 months], T5-T8 [until 23 months], T9-T12 [until 37 months], and T13-T19 [until 60 months]). Linear mixed models with a random intercept were used to assess the changes in NfL levels during treatment, considering time and covariates as fixed effects. Results One hundred thirteen adult patients with SMA (median age 35, 46% female), with a treatment duration of maximum 60 months, and 52 controls were included. At baseline, NfL concentrations were significantly higher in SMA {cNfL median, 585 (interquartile range [IQR] 428-787) pg/mL; sNfL, 11 (IQR 8-14) pg/mL} than in controls (cNfL, 420 [IQR 323-662] pg/mL; sNfL, 8 [IQR 6-12] pg/mL) (cNfL, p = 0.021; sNfL, p = 0.030). Median differences for all clinical scores were the highest for T5-T8 compared with the loading phase (Delta HFMSE, 0.6 [IQR 0.1-1.4], p = 0.017; Delta RULM, 0.9 [IQR 0.4-1.3], p < 0.001; Delta ALSFRS-R, 0.7 [IQR 0.4-1.0], p < 0.001), but not for subsequent intervals. Longitudinal analysis revealed a significant decrease of NfL concentrations during each treatment interval compared with the loading phase (p < 0.05, respectively) except for sNfL in T13-T19. Even among patients with no measurable clinical improvement (Delta HFMSE <= 0), more than 50% showed declining cNfL and sNfL levels up to T13-T19. Discussion NfL decreased during nusinersen treatment, suggesting its potential as a pharmacodynamic response marker in adult SMA. However, in patients without detectable clinical improvement, our study cannot determine whether they represent a more sensitive outcome measure or are not clinically meaningful.

Studying changes in molecular conformations of cerebrospinal fluid (CSF) in neurological diseases and identifying disease-related secondary structure changes are promising potential biomarkers for early diagnosis and contribute to a better understanding of the pathophysiology. This protocol demonstrates that Fourier transform infrared spectroscopy (FTIR) characterization of CSF is a powerful analytical tool. When combined with chemometric analysis, infrared spectroscopy becomes an essential method for revealing central features of molecular structural changes, especially of protein secondary structure conformations associated with neurodegenerative diseases. This chapter describes a protocol for collecting FTIR spectra from CSF samples, and it covers instrumental options, sample preparation, and recent advancements in spectral data acquisition and interpretation.

BACKGROUND:Amyotrophic lateral sclerosis (ALS) is a disease that still has to be primarily treated symptomatically or palliatively. It is therefore all the more important, in addition to initiating treatment, such as percutaneous endoscopic gastrostomy (PEG), noninvasive ventilation therapy (NIVT) and invasive ventilation therapy via tracheotomy (IVT), to discuss the possible termination of these measures early on. QUESTION:What is the importance of advance directives for those affected and where are possible deficits in therapy planning for the end of life? MATERIAL AND METHOD:Between March 2017 and January 2019 patients with a clinically confirmed diagnosis of ALS at six treatment centers were asked to fill out a questionnaire. A total of 328 people returned the completed forms. RESULTS:Of the participants 72% had already made an advance directive (AD), 25% planned to fill one out and only 3% refused to do so. In composing the AD most patients (90%) had support, although 56% lacked medical counselling and only 18% had drawn up the will together with the doctor and relatives, with the majority of the rest also wanting support from a doctor. A total of 37% of all patients wanted a contact person to talk about their illness but only 40% of them had such a contact person. Of the patients 22% stated that they had considered suicide and of these only 55% stated that they had no contact person for the psychological stress caused by the illness but 31% wished to have such a person. DISCUSSION AND CONCLUSION:A coordinated care of ALS patients, which also takes the psychosocial aspects into account is urgently needed.

Neurons pose a particular challenge to degradative processes like autophagy due to their long and thin processes. Autophagic vesicles (AVs) are formed at the tip of the axon and transported back to the soma. This transport is essential since the final degradation of the vesicular content occurs only close to or in the soma. Here, we established an in vivo live-imaging model in the rat optic nerve using viral vector mediated LC3-labeling and two-photon-microscopy to analyze axonal transport of AVs. Under basal conditions in vivo, 50% of the AVs are moving with a majority of 85% being transported in the retrograde direction. Transport velocity is higher in the retrograde than in the anterograde direction. A crush lesion of the optic nerve results in a rapid breakdown of retrograde axonal transport while the anterograde transport stays intact over several hours. Close to the lesion site, the formation of AVs is upregulated within the first 6 h after crush, but the clearance of AVs and the levels of lysosomal markers in the adjacent axon are reduced. Expression of p150Glued, an adaptor protein of dynein, is significantly reduced after crush lesion. In vitro, fusion and colocalization of the lysosomal marker cathepsin D with AVs are reduced after axotomy. Taken together, we present here the first in vivo analysis of axonal AV transport in the mammalian CNS using live-imaging. We find that axotomy leads to severe defects of retrograde motility and a decreased clearance of AVs via the lysosomal system.

Background:Evidence for the efficacy of nusinersen in adults with 5q-associated spinal muscular atrophy (SMA) has been demonstrated up to a period of 16 months in relatively large cohorts but whereas patients reach a plateau over time is still to be demonstrated. We investigated the efficacy and safety of nusinersen in adults with SMA over 38 months, the longest time period to date in a large cohort of patients from multiple clinical sites. Methods:Our prospective, observational study included adult patients with SMA from Germany, Switzerland, and Austria (July 2017 to May 2022). All participants had genetically-confirmed, 5q-associated SMA and were treated with nusinersen according to the label. The total Hammersmith Functional Motor Scale Expanded (HFMSE) and Revised Upper Limb Module (RULM) scores, and 6-min walk test (6 MWT; metres), were recorded at baseline and 14, 26, and 38 months after treatment initiation, and pre and post values were compared. Adverse events were also recorded. Findings:Overall, 389 patients were screened for eligibility and 237 were included. There were significant increases in all outcome measures compared with baseline, including mean HFMSE scores at 14 months (mean difference 1.72 [95% CI 1.19-2.25]), 26 months (1.20 [95% CI 0.48-1.91]), and 38 months (1.52 [95% CI 0.74-2.30]); mean RULM scores at 14 months (mean difference 0.75 [95% CI 0.43-1.07]), 26 months (mean difference 0.65 [95% CI 0.27-1.03]), and 38 months (mean difference 0.72 [95% CI 0.25-1.18]), and 6 MWT at 14 months (mean difference 30.86 m [95% CI 18.34-43.38]), 26 months (mean difference 29.26 m [95% CI 14.87-43.65]), and 38 months (mean difference 32.20 m [95% CI 10.32-54.09]). No new safety signals were identified. Interpretation:Our prospective, observational, long-term (38 months) data provides further real-world evidence for the continuous efficacy and safety of nusinersen in a large proportion of adult patients with SMA. Funding:Financial support for the registry from Biogen, Novartis and Roche.

INTRODUCTION:Amyotrophic lateral sclerosis (ALS) is an inevitably fatal condition that leads to a progressive loss of physical functioning, which results in a high psychosocial burden and organizational challenges related to medical care. Multidimensional and multiprofessional care is advised to meet the complex needs of patients and their families. Many healthcare systems, including Germany, may not be able to meet these needs because non-medical services such as psychological support or social counselling are not regularly included in the care of patients with ALS (pwALS). Specialised neuropalliative care is not routinely implemented nor widely available. Caregivers of pwALS are also highly burdened, but there is still a lack of support services for them. METHODS:This project aims to assess the perceptions and satisfaction with ALS care in Germany in pwALS and their caregivers. This will be achieved by means of a cross-sectional, multicentre survey. The examination will assess, to which extend the patients' needs in the six domains of physical, psychological, social, spiritual, practical and informational are being met by current care structures. This assessment will be linked to mental well-being, subjective quality of life, attitudes toward life-sustaining measures and physician-assisted suicide, and caregiver burden. The study aims to recruit 500 participants from nationwide ALS centres in order to draw comprehensive conclusions for Germany. A total of 29 centres, mostly acquired via the clinical and scientific German Network for Motor Neuron Diseases (MND-NET), will take part in the project, 25 of which have already started recruitment. PERSPECTIVE:It is intended to provide data-based starting points on how current practice of care in Germany is perceived pwALS and their caregivers and how it can be improved according to their needs. Planning and initiation of the study has been completed. TRIAL REGISTRATION:The study is registered at ClinicalTrails.gov; NCT06418646.

BACKGROUND:Fasudil is a small molecule inhibitor of Rho-associated kinase (ROCK) and is approved for the treatment of subarachnoid haemorrhage. In preclinical studies, fasudil has been shown to attenuate neurodegeneration, modulate neuroinflammation, and foster axonal regeneration. We aimed to investigate the safety, tolerability, and efficacy of fasudil in patients with amyotrophic lateral sclerosis. METHODS:ROCK-ALS was a phase 2, randomised, double-blind, placebo-controlled trial conducted at 19 amyotrophic lateral sclerosis centres in Germany, France, and Switzerland. Individuals (aged 18-80 years) with at least probable amyotrophic lateral sclerosis (as per the revised El Escorial criteria), a disease duration of 6-24 months, and a slow vital capacity greater than 65% of predicted normal were eligible for inclusion. Patients were randomly assigned (1:1:1) to receive 30 mg (15 mg twice daily) or 60 mg (30 mg twice daily) fasudil or matched placebo intravenously for 20 days over a 4-week period. Follow-up assessments were performed at 45, 90, and 180 days after treatment initiation. The co-primary endpoints were safety until day 180 (defined as the proportion without drug-related serious adverse events) and tolerability during the treatment period (defined as the proportion who did not discontinue treatment due to suspected drug-related adverse events). The primary analyses were carried out in the intention-to-treat population, which included all participants who entered the treatment phase. This trial is registered at ClinicalTrials.gov (NCT03792490) and Eudra-CT (2017-003676-31) and is now completed. FINDINGS:Between Feb 20, 2019, and April 20, 2022, 120 participants were enrolled and randomised; two individuals assigned fasudil 30 mg withdrew consent before the baseline visit. Thus, the intention-to-treat population comprised 35 in the fasudil 30 mg group, 39 in the fasudil 60 mg group, and 44 in the placebo group. The estimated proportion without a drug-related serious adverse event was 1·00 (95% CI 0·91 to 1·00) with placebo, 1·00 (0·89 to 1·00) with fasudil 30 mg, and 1·00 (0·90 to 1·00) with fasudil 60 mg; the difference in proportions was 0·00 (95% CI -0·11 to 0·10; p>0·99) for fasudil 30 mg versus placebo and 0·00 (-0·10 to 0·10; p>0·99) for fasudil 60 mg versus placebo. Treatment tolerability (the estimated proportion who did not discontinue) was 0·93 (95% CI 0·81 to 0·99) with placebo, 1·00 (0·90 to 1·00) with fasudil 30 mg, and 0·90 (0·76 to 0·97) with fasudil 60 mg; the difference in proportions was 0·07 (95% CI -0·05 to 0·20; p=0·25) for fasudil 30 mg versus placebo, and -0·03 (-0·18 to 0·10; p=0·70) for fasudil 60 mg versus placebo. Eight deaths occurred: two in the placebo group, four in the fasudil 30 mg group, and two in the fasudil 60 mg group. The most common serious adverse events were respiratory failure (seven events), gastrostomy (five events), pneumonia (four events), and dysphagia (four events). No serious adverse events or deaths were attributed to study treatment. Adverse events, which were mainly related to disease progression, occurred in 139 participants in the placebo group, 108 in the fasudil 30 mg group, and 105 in the fasudil 60 mg group. INTERPRETATION:Fasudil was well tolerated and safe in people with amyotrophic lateral sclerosis. The effect of fasudil on efficacy outcomes should be explored in larger clinical trials with a longer treatment duration, oral administration, and potentially higher dose of the trial drug. FUNDING:Framework of the E-Rare Joint Transnational Call 2016 "Clinical research for new therapeutic uses of already existing molecules (repurposing) in rare diseases".

In patients with amyotrophic lateral sclerosis (ALS), mechanical insufflation-exsufflation (MI-E) addresses cough deficiency to achieve major therapeutic goals: improving costal muscle and joint function, reducing atelectasis through insufflation, and clearing bronchial secretions via exsufflation. Despite its perceived benefits, there is limited systematic research on MI-E provision, symptom alleviation, or patient satisfaction. The research platform Ambulanzpartner coordinated this longitudinal observational study conducted in 12 German ALS centers from July 2018 to September 2023. Patients were enrolled based on ALS-related cough deficiency requiring MI-E therapy. The study recorded provision, reasons for withholding MI-E, clinical parameters, therapy frequency, subjective cough deficiency, and symptomatic relief. Satisfaction with MI-E therapy was determined by the likelihood of recommendation. Out of 694 ALS patients indicated for MI-E, 527 (75.9%) received the therapy. The primary reason for non-provision was that the patient had died before provision (n = 66 of 167; 39.5%). These patients were significantly more affected as represented by higher progression rates and lower peak cough flows (PCF) at the time of MI-E indication (p < 0.05). Most patients who received MI-E used it daily (n = 290 of 370; 78.4%). Self-assessed cough deficiency correlated with clinical measurements, especially for patients with higher deficits. At follow-up visits, patients reported reduced cough deficiency (p < 0.001). Frequent MI-E use was linked to greater symptom relief and higher likelihood of recommending the therapy. This study highlights symptomatic and palliative potential of MI-E therapy for ALS patients.

Die amyotrophe Lateralsklerose (ALS) ist eine Erkrankung, die weiterhin vorwiegend symptomatisch bzw. palliativ behandelt werden muss. Umso wichtiger ist es, neben der Initiierung von Therapien wie Perkutane endoskopische Gastrostomie (PEG), nichtinvasiver Beatmungstherapie (NIBT), invasiver Beatmungstherapie mit Tracheotomie (IBT), beizeiten über die mögliche Beendigung dieser Maßnahmen zu sprechen. Welche Bedeutung haben Patientenverfügungen für die Betroffenen und wo liegen eventuelle Defizite der Therapieplanung für das Lebensende? An sechs Behandlungszentren wurden im Zeitraum zwischen März 2017 und Januar 2019 Patienten mit der klinisch sicheren Diagnose ALS gebeten, einen Fragebogen auszufüllen. Insgesamt haben 328 Personen diese Bögen ausgefüllt zurückgegeben. Insgesamt 72

Background Since the antisense oligonucleotide tofersen has recently become available for the treatment of amyotrophic lateral sclerosis (ALS) caused by mutations in SOD1, determining the causality of the over 230 SOD1 variants has become even more important. The most common SOD1 variant worldwide is p.D91A (c.272A > C), whose causality for ALS is contested when in a heterozygous state. The reason is the high allele frequency of SOD1(D91A) in Europe, exceeding 1% in Finno-Scandinavia. Methods We present the clinical disease course and serum neurofilament light chain (NfL) results of treating 11 patients either homo- or heterozygous for the SOD1(D91A) allele for up to 16 months with tofersen. Results Tofersen decreases serum neurofilament levels (sNFL), which are associated with the ALS progression rate, in the 6 ALS patients homozygous for SOD1(D91A). We observe significantly lower sNfL levels in the 5 patients heterozygous for SOD1(D91A). The results indicate that both mono- and bi-allelic SOD1(D91A) are causally relevant targets, with a possibly reduced effect size of SOD1(D91Ahet). Conclusions The finding is relevant for decision making regarding tofersen treatment, patient counseling and inclusion of SOD1(D91A) patients in drug trials. As far as we are aware, the approach is conceptually new since it provides evidence for the causality of an ALS variant based on a biomarker response to gene-specific treatment.

OBJECTIVE:To assess the performance of serum neurofilament light chain (sNfL) in clinical phenotypes of amyotrophic lateral sclerosis (ALS). METHODS:In 2949 ALS patients at 16 ALS centers in Germany and Austria, clinical characteristics and sNfL were assessed. Phenotypes were differentiated for two anatomical determinants: (1) upper and/or lower motor involvement (typical, typMN; upper/lower motor neuron predominant, UMNp/LMNp; primary lateral sclerosis, PLS) and (2) region of onset and propagation of motor neuron dysfunction (bulbar, limb, flail-arm, flail-leg, thoracic onset). Phenotypes were correlated to sNfL, progression, and survival. RESULTS:Mean sNfL was - compared to typMN (75.7 pg/mL, n = 1791) - significantly lower in LMNp (45.1 pg/mL, n = 413), UMNp (58.7 pg/mL n = 206), and PLS (37.6 pg/mL, n = 84). Also, sNfL significantly differed in the bulbar (92.7 pg/mL, n = 669), limb (64.1 pg/mL, n = 1305), flail-arm (46.4 pg/mL, n = 283), flail-leg (53.6 pg/mL, n = 141), and thoracic (74.5 pg/mL, n = 96) phenotypes. Binary logistic regression analysis showed highest contribution to sNfL elevation for faster progression (odds ratio [OR] 3.24) and for the bulbar onset phenotype (OR 1.94). In contrast, PLS (OR 0.20), LMNp (OR 0.45), and thoracic onset (OR 0.43) showed reduced contributions to sNfL. Longitudinal sNfL (median 12 months, n = 2862) showed minor monthly changes (<0.2%) across all phenotypes. Correlation of sNfL with survival was confirmed (p < 0.001). CONCLUSIONS:This study underscored the correlation of ALS phenotypes - differentiated for motor neuron involvement and region of onset/propagation - with sNfL, progression, and survival. These phenotypes demonstrated a significant effect on sNfL and should be recognized as independent confounders of sNfL analyses in ALS trials and clinical practice.

Electrophysiologic investigations play a central role in the diagnosis of suspected amyotrophic lateral sclerosis (ALS). Electromyography and electroneurography, frequently complemented by motor evoked potentials, are commonly used to substantiate the diagnosis of ALS and to work-up differential diagnosis. A survey of the German Network for Motor Neuron Diseases revealed considerable differences in electrodiagnostic strategies between individual centres. In view of the great interest in harmonizing their diagnostic methods, the present recommendations were agreed upon by all centers of the MND-Net, aiming at their clinical implementation and subsequent multicentric validation. We present here recommendations for a basic routine diagnostic work-up in case of suspected ALS with high sensitivity, specificity and a minimal number of examinations.