Quantifying disease progression in amyotrophic lateral sclerosis

Changes in saccadic intrusions over time as an objective biomarker to follow ALS disease progression

Objective: Saccadic Intrusions (SIs) are abnormal eye movements during gaze fixation. Studies have indicated the clinical relevance of SIs, especially of square wave jerks (SWJ) in ALS. We used a software-based platform to extract SIs as a part of an interventional drug trial. The objective was to examine SIs' change over time as a potential biomarker of ALS disease progression. Methods: 28 ALS patients (61.95 ± 8.6 years) were assessed with the revised ALS Functional Rating Scale (ALSFRS-R) and with an oculometric test. Changes of SIs over time and correlations with ALSFRS-R and its bulbar subscale were calculated. A power calculation was conducted to understand the practical implications of results. Results: A significant increase of SWJ over trial duration was observed, with an increase in frequency (mean rise of 0.14 ± 0.28, p < 0.01), amplitude (0.001 ± 0.0016 degrees, p < 0.005), overall duration of SWJ (0.13 ± 0.25, in %, p < 0.01), and in their relative part out of all intrusions (0.18 ± 0.32, in %, p < 0.005). Negative correlations were found with the bulbar subscale (R=-0.43, -0.41, -0.39 and -0.47, respectively, p < 0.001). The required sample size for observing a 40% reduction in bulbar aspects when using the oculometric test (α = 0.05 and β = 0.8), was found to be 150 patients per arm, compared with 200 patients using the bulbar subscale. Conclusions: Evaluation of saccadic intrusions during fixation was able to detect disease progression over time, correlated with ALSFRS-R bulbar subscale. Eye movements can potentially serve as an objective biomarker in ALS clinical trials and reduce the required sample size to show clinical effect of therapies.

Describing and characterising variability in ALS disease progression

BACKGROUND, OBJECTIVES

Decrease in the revised ALS Functional Rating Scale (ALSFRS-R) score is currently the most widely used measure of disease progression. However, it does not sufficiently encompass the heterogeneity of ALS. We describe a measure of variability in ALSFRS-R scores and demonstrate its utility in disease characterization.

METHODS

We used 5030 ALS clinical trial patients from the Pooled Resource Open-Access ALS Clinical Trials database to calculate variability in disease progression employing a novel measure and correlated variability with disease span. We characterized the more and less variable populations and designed a machine learning model that used clinical, laboratory and demographic data to predict class of variability. The model was validated with a holdout clinical trial dataset of 84 ALS patients (NCT00818389).

RESULTS

Greater variability in disease progression was indicative of longer disease span on the patient-level. The machine learning model was able to predict class of variability with accuracy of 60.1-72.7% across different time periods and yielded a set of predictors based on clinical, laboratory and demographic data. A reduced set of 16 predictors and the holdout dataset yielded similar accuracy.

DISCUSSION

This measure of variability is a significant determinant of disease span for fast-progressing patients. The predictors identified may shed light on pathophysiology of variability, with greater variability in fast-progressing patients possibly indicative of greater compensatory reinnervation and longer disease span. Increasing variability alongside decreasing rate of disease progression could be a future aim of trials for faster-progressing patients.

Methodological Quality of Clinical Trials in Amyotrophic Lateral Sclerosis: A Systematic Review

Background

More than 200 clinical trials have been performed worldwide in ALS so far, but no agents with substantial efficacy on disease progression have been found.

Objective

To describe the methodological quality of all clinical trials performed in ALS and published before December 31, 2022.

Methods

We conducted a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta Analyses.

Results

213 trials were included. 47.4% manuscripts described preclinical study evaluation, with a positive effect in all. 67.6% of trials were conducted with a parallel-arm design, while 12.7% were cross-over studies; 77% were randomized, while in 5.6% historical-controls were used for comparison. 70% of trials were double blind. Participant inclusion allowed forced vital capacity (or corresponding slow vital capacity)<50% in 15% cases, between 55-65% in 21.6%, between 70-80% in 14.1% reports, and 49.3% of the evaluated manuscripts did not provide a minimum value for respiratory capacity at inclusion. Disease duration was < 6-months in 6 studies, 7-36 months in 68, 37-60 months in 24, 8 trials requested more than 1-month of disease duration, while in 107 reports a disease duration was not described. Dropout rate was ≥20% in 30.5% trials, while it was not reported for 8.5%.

Conclusion

The methodological quality of the included studies was highly variable. Major issues to be addressed in future ALS clinical trials include: the requirement for standard animal toxicology and phase I studies, the resource-intensive nature of phase II-III studies, adequate study methodology and design, a good results reporting.

Exploring Relevant Time Windows in the Association Between PM2.5 Exposure and Amyotrophic Lateral Sclerosis: A Case-Control Study in Denmark

Studies suggest a link between particulate matter less than or equal to 2.5 μm in diameter (PM2.5) and amyotrophic lateral sclerosis (ALS), but to our knowledge critical exposure windows have not been examined. We performed a case-control study in the Danish population spanning the years 1989-2013. Cases were selected from the Danish National Patient Registry based on International Classification of Diseases codes. Five controls were randomly selected from the Danish Civil Registry and matched to a case on vital status, age, and sex. PM2.5 concentration at residential addresses was assigned using monthly predictions from a dispersion model. We used conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for confounding. We evaluated exposure to averaged PM2.5 concentrations 12-24 months, 2-6 years, and 2-11 years pre-ALS diagnosis; annual lagged exposures up to 11 years prediagnosis; and cumulative associations for exposure in lags 1-5 years and 1-10 years prediagnosis, allowing for varying association estimates by year. We identified 3,983 cases and 19,915 controls. Cumulative exposure to PM2.5 in the period 2-6 years prediagnosis was associated with ALS (OR = 1.06, 95% CI: 0.99, 1.13). Exposures in the second, third, and fourth years prediagnosis were individually associated with higher odds of ALS (e.g., for lag 1, OR = 1.04, 95% CI: 1.00, 1.08). Exposure to PM2.5 within 6 years before diagnosis may represent a critical exposure window for ALS.

Hippocampal Metabolic Alterations in Amyotrophic Lateral Sclerosis: A Magnetic Resonance Spectroscopy Study

BACKGROUND

Magnetic resonance spectroscopy (MRS) in amyotrophic lateral sclerosis (ALS) has been overwhelmingly applied to motor regions to date and our understanding of frontotemporal metabolic signatures is relatively limited. The association between metabolic alterations and cognitive performance in also poorly characterised.

MATERIAL AND METHODS

In a multimodal, prospective pilot study, the structural, metabolic, and diffusivity profile of the hippocampus was systematically evaluated in patients with ALS. Patients underwent careful clinical and neurocognitive assessments. All patients were non-demented and exhibited normal memory performance. 1H-MRS spectra of the right and left hippocampi were acquired at 3.0T to determine the concentration of a panel of metabolites. The imaging protocol also included high-resolution T1-weighted structural imaging for subsequent hippocampal grey matter (GM) analyses and diffusion tensor imaging (DTI) for the tractographic evaluation of the integrity of the hippocampal perforant pathway zone (PPZ).

RESULTS

ALS patients exhibited higher hippocampal tNAA, tNAA/tCr and tCho bilaterally, despite the absence of volumetric and PPZ diffusivity differences between the two groups. Furthermore, superior memory performance was associated with higher hippocampal tNAA/tCr bilaterally. Both longer symptom duration and greater functional disability correlated with higher tCho levels.

CONCLUSION

Hippocampal 1H-MRS may not only contribute to a better academic understanding of extra-motor disease burden in ALS, but given its sensitive correlations with validated clinical metrics, it may serve as practical biomarker for future clinical and clinical trial applications. Neuroimaging protocols in ALS should incorporate MRS in addition to standard structural, functional, and diffusion sequences.

A novel quantitative indicator for disease progression rate in amyotrophic lateral sclerosis

OBJECTIVE

The current study sought to develop a new indicator for disease progression rate in amyotrophic lateral sclerosis (ALS).

METHODS

We used a nonparametric method to score diverse patterns of decline in the percentage of predicted forced vital capacity (%FVC) in patients with ALS. This involved 6317 longitudinal %FVC data sets from 920 patients in the Pooled Resource Open-Access ALS Clinical Trials (PRO-ACT) database volunteered by PRO-ACT Consortium members. To assess the utility of the derived scores as a disease indicator, we examined changes over time, the association with prognosis, and correlation with the Risk Profile of the Treatment Research Initiative to Cure ALS (TRICALS). Our local cohort (n = 92) was used for external validation.

RESULTS

We derived scores ranging from 35 to 106 points to construct the FVC Decline Pattern scale (FVC-DiP). Individuals' FVC-DiP scores were determined from a single measurement of %FVC and disease duration at assessment. Although the %FVC declined over the disease course (p < 0.0001), the FVC-DiP remained relatively stable. Low FVC-DiP scores were associated with rapid disease progression. Using our cohort, we demonstrated an association between FVC-DiP and the survival prognosis, the stability of the FVC-DiP per individual, and a correlation between FVC-DiP scores and the TRICALS Risk Profile (r² = 0.904, p < 0.0001).

CONCLUSIONS

FVC-DiP scores reflected patterns of declining %FVC over the natural course of ALS and indicated the disease progression rate. The FVC-DiP may enable easy assessment of disease progression patterns and could be used for assessing treatment efficacy.

Stereological and electrophysiological evaluation of autonomic involvement in amyotrophic lateral sclerosis

OBJECTIVE

Previous studies have identified autonomic dysfunction in amyotrophic lateral sclerosis (ALS) using mostly neurophysiological techniques. In this study, stereological evaluation of autonomic fibers and sweat glands has been performed to identify structural evidence of autonomic denervation in patients with ALS.

METHODS

In this study, 29 ALS patients were compared to 29 controls using COMPASS-31 questionnaire, sympathetic skin response (SSR), and heart rate variability (HRV) at rest. From the same cohorts, 20 ALS patients and 15 controls were further evaluated using staining of autonomic nerve fibers and sweat glands in skin biopsies. SSR and resting HRV were repeated in the ALS patient cohort one year later.

RESULTS

COMPASS-31 total score, gastrointestinal- and urinary-sub scores were higher in ALS patients than controls (P = 0.004, P = 0.005, and P = 0.049, respectively). In the ALS patient cohort, SSR amplitudes in hands and feet were lower than in controls (P<0.0001 and P = 0.0009, respectively), but there was no difference in resting HRV (P>0.05). While there was no change in nerve fibers innervating sweat glands, their density was lower in ALS patients than controls, and semi-quantitative analysis also showed structural damage (P = 0.02 and P = 0.001, respectively). SSR and resting HRV of ALS patients remained stable during the one-year follow-up period (P>0.05).

DISCUSSION

Supporting abnormal neurophysiological tests, stereological analysis revealed direct evidence of autonomic denervation in ALS patients. However, the degenerative process in autonomic nerve fibers is relatively slow, compared to the rate of motor neuron degeneration in this condition.

Identifying patterns in amyotrophic lateral sclerosis progression from sparse longitudinal data

The clinical presentation of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease, varies widely across patients, making it challenging to determine if potential therapeutics slow progression. We sought to determine whether there were common patterns of disease progression that could aid in the design and analysis of clinical trials. We developed an approach based on a mixture of Gaussian processes to identify clusters of patients sharing similar disease progression patterns, modeling their average trajectories and the variability in each cluster. We show that ALS progression is frequently nonlinear, with periods of stable disease preceded or followed by rapid decline. We also show that our approach can be extended to Alzheimer's and Parkinson's diseases. Our results advance the characterization of disease progression of ALS and provide a flexible modeling approach that can be applied to other progressive diseases.

Affection of Respiratory Muscles in ALS and SMA

Respiratory dysfunction is a common cause of morbidity and mortality in motor neuron disease (MND). However, classical volitional measures of respiratory function in these patients are impeded by, e.g., bulbar paralysis or progressive disability. Diaphragm ultrasound imaging might be a valuable tool for assessing respiratory impairment, albeit different ultrasound measures have not been systematically investigated in adult MND patients and, in particular, have not yet been comparatively applied in adult patients with amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). We hypothesized that in contrast to ALS patients, adult SMA patients show a relative sparing of diaphragm function. We retrospectively analyzed diaphragm ultrasound imaging data of 40 patients with ALS and 23 patients with SMA in comparison to a multitude of established parameters of respiratory function. Indeed, ALS patients showed more severe diaphragm dysfunction than adult SMA patients, however, diaphragm dysfunction was also common in adult SMA patients. Notably, dynamic measures of diaphragm function rather than thickness measures were impaired in ALS compared to SMA. Thus, diaphragm ultrasound imaging might be a useful tool to evaluate respiratory dysfunction in adult MND patients. Future larger and prospective studies are needed to validate our initial findings.

Classification of amyotrophic lateral sclerosis by brain volume, connectivity, and network dynamics

Emerging studies corroborate the importance of neuroimaging biomarkers and machine learning to improve diagnostic classification of amyotrophic lateral sclerosis (ALS). While most studies focus on structural data, recent studies assessing functional connectivity between brain regions by linear methods highlight the role of brain function. These studies have yet to be combined with brain structure and nonlinear functional features. We investigate the role of linear and nonlinear functional brain features, and the benefit of combining brain structure and function for ALS classification. ALS patients (N = 97) and healthy controls (N = 59) underwent structural and functional resting state magnetic resonance imaging. Based on key hubs of resting state networks, we defined three feature sets comprising brain volume, resting state functional connectivity (rsFC), as well as (nonlinear) resting state dynamics assessed via recurrent neural networks. Unimodal and multimodal random forest classifiers were built to classify ALS. Out-of-sample prediction errors were assessed via five-fold cross-validation. Unimodal classifiers achieved a classification accuracy of 56.35-61.66%. Multimodal classifiers outperformed unimodal classifiers achieving accuracies of 62.85-66.82%. Evaluating the ranking of individual features' importance scores across all classifiers revealed that rsFC features were most dominant in classification. While univariate analyses revealed reduced rsFC in ALS patients, functional features more generally indicated deficits in information integration across resting state brain networks in ALS. The present work undermines that combining brain structure and function provides an additional benefit to diagnostic classification, as indicated by multimodal classifiers, while emphasizing the importance of capturing both linear and nonlinear functional brain properties to identify discriminative biomarkers of ALS.

Neutrophils-to-Lymphocyte Ratio Is Associated with Progression and Overall Survival in Amyotrophic Lateral Sclerosis

Background: Amyotrophic lateral sclerosis (ALS) is a devastating and untreatable motor neuron disease, with a 3–5-year survival from diagnosis. Possible prognostic serum biomarkers include albumin, C-reactive protein, ferritin, creatinine, uric acid, hemoglobin, potassium, sodium, calcium, glucose, and the neutrophil-to-lymphocyte ratio (NLR), a marker of subclinical inflammation. Objective: To ascertain the influence of NLR on ALS progression rate and survival. Methods: Cross-sectional multicenter study including 146 consecutive incident and prevalent patients (88 males), aged >18 years, diagnosed according to the El Escorial criteria. The exclusion criteria were: (1) patients with tracheostomy or receiving mechanical ventilation; (2) patients with percutaneous endoscopic gastrostomy; and (3) patients who did not sign the informed consent. The rate of disease progression (ΔFS score) represents the monthly decline of the ALSFRS-R score, and was computed as (48 − total ALSFRS-R at recruitment)/symptom duration in months. Patients were followed up to tracheotomy, death, or the end of the follow-up, whichever occurred first. To validate our findings, we used data retrieved from the Pooled Resource Open-Access ALS Clinical Trials (PRO-ACT) Database. Results: The median disease duration was 15 (range = 2–30) months. The mean ALSFRS-R score at recruitment was 35.8 ± 8.0 (range: 10–48), and the median ΔFS was 0.66 (range: 0–5.33). Age at onset, at diagnosis, and at recruitment were significantly lower in the lowest NLR tertile. NLR values positively correlated with ΔFS values (r = 0.28): the regression slope of NLR (log-values) was 0.60 (p < 0.001) before and 0.49 (p = 0.006) after adjustment for age at recruitment. The ΔFS score progressively increased from the lowest to the highest NLR tertile: 0.35 (IQR: 0.18–0.93), 0.62 (IQR: 0.25–1.09), and 0.86 (IQR: 0.53–1.92). Patients were followed for a median of 2 years. The mortality rate passed from 15.9 events per 100 person-years in patients belonging to the lowest NLR tertile to 52.8 in those in the highest tertile. The optimal cut-off value which best classified patients with the lowest and the highest mortality rate was set at the NLR value of 2.315. Indeed, the mortality rate of patients with an NLR value above such cut-off was twice the mortality rate of patients with a value below the cut-off (age adjusted hazard ratio (HR): 2.16, 95% confidence interval (CI): 1.32–3.53). In the PRO-ACT validation sample, patients with an NLR value above the cut-off consistently had a higher mortality rate than those with a value below the cut-off (age adjusted HR: 1.17, 95%CI: 1.01–1.35). Conclusions: NLR could be a candidate easy, fast, and low-cost marker of disease progression and survival in ALS. It may be associated with low-grade inflammation either as a direct mirror of the pathological process of disease progression, or as a consequence of neuronal death (reverse causation). However, prospective studies are needed to understand whether NLR changes during the course of the disease, before using it to monitor disease progression in ALS.

Comparison of CSF and serum neurofilament light and heavy chain as differential diagnostic biomarkers for ALS

OBJECTIVE

Elevated levels of neurofilament light (NfL) and heavy (NfH) chain in amyotrophic lateral sclerosis (ALS) cerebrospinal fluid (CSF) and serum reflect neuro-axonal degeneration and are used as diagnostic biomarkers. However, studies comparing the differential diagnostic potential for ALS of all four parameters are missing. Here, we measured serum NfL/NfH and CSF NfL/NfH in a large cohort of ALS and other neurological disorders and analysed the differential diagnostic potential.

METHODS

In total CSF and serum of 294 patients were analysed. The diagnostic groups comprised: ALS (n=75), frontotemporal lobar degeneration (FTLD) (n=33), Alzheimer's disease (n=20), Parkinson's disease (dementia) (n=18), Creutzfeldt-Jakob disease (n=11), non-neurodegenerative controls (n=77) (Con) and 60 patients who were seen under the direct differential diagnosis of a patient with ALS (Con.DD).

RESULTS

CSF and serum NfL and NfH showed significantly increased levels in ALS (p<0.0001) compared with Con and Con.DD. The difference between ALS and FTLD was markedly stronger for NfH than for NfL. CSF and serum NfL demonstrated a stronger correlation (r=0.84 (95% CI 0.80 to 0.87), p<0.001) than CSF and serum NfH (r=0.68 (95% CI 0.61 to 0.75), p<0.0001). Comparing ALS and Con.DD, receiver operating characteristic analysis revealed the best area under the curve (AUC) value for CSF NfL (AUC=0.94, 95% CI 0.91 to 0.98), followed by CSF NfH (0.93, 95% CI 0.88 to 0.98), serum NfL (0.93, 95% CI 0.89 to 0.97) and serum NfH (0.88, 95% CI 0.82 to 0.94).

CONCLUSION

Our results demonstrate that CSF NfL and NfH as well as serum NfL are equally suited for the differential diagnosis of ALS, whereas serum NfH appears to be slightly less potent.

Sensitivity of brain MRI and neurological examination for detection of upper motor neurone degeneration in amyotrophic lateral sclerosis

OBJECTIVES

To investigate sensitivity of brain MRI and neurological examination for detection of upper motor neuron (UMN) degeneration in patients with amyotrophic lateral sclerosis (ALS).

METHODS

We studied 192 patients with ALS and 314 controls longitudinally. All patients visited our centre twice and underwent full neurological examination and brain MRI. At each visit, we assessed UMN degeneration by measuring motor cortex thickness (CT) and pyramidal tract fibre density (FD) corresponding to five body regions (bulbar region and limbs). For each body region, we measured degree of clinical UMN and lower motor neuron (LMN) symptom burden using a validated scoring system.

RESULTS

We found deterioration over time of CT of motor regions (p≤0.0081) and progression of UMN signs of bulbar region and left arm (p≤0.04). FD was discriminative between controls and patients with moderate/severe UMN signs (all regions, p≤0.034), but did not change longitudinally. Higher clinical UMN burden correlated with reduced CT, but not lower FD, for the bulbar region (p=2.2×10^-10) and legs (p≤0.025). In the arms, we found that severe LMN signs may reduce the detectability of UMN signs (p≤0.043). With MRI, UMN degeneration was detectable before UMN signs became clinically evident (CT: p=1.1×10^-10, FD: p=6.3×10^-4). Motor CT, but not FD, deteriorated more than UMN signs during the study period.

CONCLUSIONS

Motor CT is a more sensitive measure of UMN degeneration than UMN signs. Motor CT and pyramidal tract FD are discriminative between patients and controls. Brain MRI can monitor UMN degeneration before signs become clinically evident. These findings promote MRI as a potential biomarker for UMN progression in clinical trials in ALS.

Amyotrophic lateral sclerosis: Correlations between fluid biomarkers of NfL, TDP-43, and tau, and clinical characteristics

OBJECTIVES

We previously reported the diagnostic and prognostic performance of neurofilament light chain (NfL), TAR DNA-binding protein 43 (TDP-43), and total tau (t-tau) in cerebrospinal fluid (CSF) and plasma as amyotrophic lateral sclerosis (ALS) biomarkers. The present study aimed to elucidate associations between clinical characteristics and the markers as well as mutual associations of the markers in ALS patients using the same dataset.

METHODS

NfL, TDP-43, and t-tau levels in CSF and plasma in 75 ALS patients were analyzed. The associations between those markers and clinical details were investigated by uni- and multivariate analyses. Correlations between the markers were analyzed univariately.

RESULTS

In multivariate analysis of CSF proteins, the disease progression rate (DPR) was positively correlated with NfL (β: 0.51, p = 0.007) and t-tau (β: 0.37, p = 0.03). Plasma NfL was correlated with age (β: 0.53, p = 0.005) and diagnostic grade (β: -0.42, p = 0.02) in multivariate analysis. Plasma TDP-43 was correlated negatively with split hand index (β: -0.48, p = 0.04) and positively with % vital capacity (β: 0.64, p = 0.03) in multivariate analysis. Regarding mutual biomarker analysis, a negative correlation between CSF-NfL and TDP-43 was identified (r: -0.36, p = 0.002).

CONCLUSIONS

Elevated NfL and t-tau levels in CSF may be biomarkers to predict rapid DPR from onset to sample collection. The negative relationship between CSF NfL and TDP-43 suggests that elevation of CSF TDP-43 in ALS is not a simple consequence of its release into CSF during neurodegeneration. The negative correlation between plasma TDP-43 and split hand index may support the pathophysiological association between plasma TDP-43 and ALS.

Quantitative Ultrasound Changes in Echotexture and Functional Parameters after a Multicomponent Training Program in Pre-Frailty Individuals: A Pilot Randomized Clinical Trial

Objective: Currently, ultrasound imaging (USI) is considered a feasible tool in the evaluation of structural and textural muscle differences due to aging. The main aim of this study was to evaluate sonographic changes in muscular structure and function after a 12-week multicomponent training program in pre-frailty individuals. Design: A prospective, randomized, clinical trial was carried out. Participants: Thirty-two pre-frailty subjects were recruited and randomly divided into a multicomponent training program group (n = 16; Multicomponent group) and a conventional care group (n = 14; Control group) with a 12-week follow up. Main outcome measures: Rectus femoris thickness, cross-sectional area (CSA), echointensity, echovariation and vastus lateralis pennation angle tests were carried out to assess the structure and echotexture, and the force-velocity (F-V) profile for muscle power and muscle strength was employed to assess the functional parameters. Results: Statistically significant differences (p < 0.05) were shown for the left rectus femoris echointensity and in the functional parameter of muscle power after a 12-week program for the multicomponent training group compared to the conventional care group. Conclusions: Pre-frailty elderly subjects showed a decrease in rectus femoris echointensity (RF-EI) and an increase in the functional parameter of muscle power after a 12-week multicomponent training program compared to the control group.

MRI DTI and PDFF as Biomarkers for Lower Motor Neuron Degeneration in ALS

Objective

To evaluate the utility of nerve magnetic resonance imaging (MRI), diffusion tensor imaging (DTI), and muscle MRI multi-echo Dixon for assessing lower motor neuron (LMN) degeneration in amyotrophic lateral sclerosis (ALS).

Methods

In this prospective observational cohort study, 14 patients with ALS and 13 healthy controls underwent a multiparametric MRI protocol, including DTI of the sciatic nerve and assessment of muscle proton density fat fraction of the biceps femoris and the quadriceps femoris muscles by a multi-echo Dixon sequence.

Results

In ALS patients, mean fractional anisotropy values of the sciatic nerve were significantly lower than those of healthy controls. The quadriceps femoris, but not the biceps femoris muscle, showed significantly higher intramuscular fat fractions in ALS.

Interpretation

Our study provides evidence that multiparametric MRI protocols might help estimate structural nerve damage and neurogenic muscle changes in ALS.

Gold Coast diagnostic criteria: Implications for ALS diagnosis and clinical trial enrollment

Diagnostic criteria for amyotrophic lateral sclerosis (ALS) are complex, incorporating multiple levels of certainty from possible through to definite, and are thereby prone to error. Specifically, interrater variability was previously established to be poor, thereby limiting utility as diagnostic enrollment criteria for clinical trials. In addition, the different levels of diagnostic certainty do not necessarily reflect disease progression, adding confusion to the diagnostic algorithm. Realizing these inherent limitations, the World Federation of Neurology, the International Federation of Clinical Neurophysiology, the International Alliance of ALS/MND Associations, the ALS Association (United States), and the Motor Neuron Disease Association convened a consensus meeting (Gold Coast, Australia, 2019) to consider the development of simpler criteria that better reflect clinical practice, and that could merge diagnostic categories into a single entity. The diagnostic accuracy of the novel Gold Coast criteria was subsequently interrogated through a large cross-sectional study, which established an increased sensitivity for ALS diagnosis when compared with previous criteria. Diagnostic accuracy was maintained irrespective of disease duration, functional status, or site of disease onset. Importantly, the Gold Coast criteria differentiated atypical phenotypes, such as primary lateral sclerosis, from the more typical ALS phenotype. It is proposed that the Gold Coast criteria should be incorporated into routine practice and clinical trial settings.

Venous creatinine as a biomarker for loss of fat-free mass and disease progression in patients with amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

To establish the utility of venous creatinine as a biomarker to monitor loss of fat-free mass in patients with amyotrophic lateral sclerosis (ALS).

METHODS

In this multicenter natural history study, body composition and venous creatinine were assessed in 107 patients with ALS and 52 healthy controls. Longitudinal patterns of venous creatinine and its association with the risk of death during follow-up were determined in a cohort of patients with ALS from Australia (n = 69) and the Netherlands (n = 38).

RESULTS

The mean levels of venous creatinine were 75.78 ± 11.15 μmol/L for controls, 70.25 ± 12.81 μmol/L for Australian patients, and 59.95 ± 14.62 μmol/L for Dutch patients with ALS. The relationship between measures of venous creatinine and fat-free mass was similar between all groups (r = 0.36, p < 0.001). Within patients, fat-free mass declined by 0.31 (95% confidence interval [CI]: 0.22-0.40) kg/month, and venous creatinine declined by 0.52 (95% CI: 0.38-0.66) μmol/L/month, with a longitudinal correlation of 0.57 (95% CI: 0.35-0.76, p < 0.001). Lower levels of venous creatinine were associated with increased risk for earlier death in patients with ALS (hazard ratio = 0.94, 95% CI: 0.90-0.98, p = 0.007).

CONCLUSIONS

Venous creatinine is decreased in ALS and declines alongside a decline in fat-free mass over the course of the disease, and may serve as a practical marker to monitor the change of fat-free mass in patients with ALS. This could inform clinical care and provide an alternative endpoint for the evaluation of therapeutic interventions that focus on slowing the loss of fat-free mass and disease progression in ALS.

Lipidomic traits of plasma and cerebrospinal fluid in amyotrophic lateral sclerosis correlate with disease progression

Since amyotrophic lateral sclerosis cases exhibit significant heterogeneity, we aim to investigate the association of lipid composition of plasma and CSF with amyotrophic lateral sclerosis diagnosis, its progression and clinical characteristics. Lipidome analyses would help to stratify patients on a molecular basis. For this reason, we have analysed the lipid composition of paired plasma and CSF samples from amyotrophic lateral sclerosis cases and age-matched non-amyotrophic lateral sclerosis individuals (controls) by comprehensive liquid chromatography coupled to mass spectrometry. The concentrations of neurofilament light chain-an index of neuronal damage-were also quantified in CSF samples and plasma. Amyotrophic lateral sclerosis versus control comparison, in a moderate stringency mode, showed that plasma from cases contains more differential lipids (n = 122 for raw P < 0.05; n = 27 for P < 0.01) than CSF (n = 17 for raw P < 0.05; n = 4 for P < 0.01), with almost no overlapping differential species, mainly characterized by an increased content of triacylglyceride species in plasma and decreased in CSF. Of note, false discovery rate correction indicated that one of the CSF lipids (monoacylglycerol 18:0) had high statistic robustness (false discovery rate-P < 0.01). Plasma lipidomes also varied significantly with the main involvement at onset (bulbar, spinal or respiratory). Notably, faster progression cases showed particular lipidome fingerprints, featured by decreased triacylclycerides and specific phospholipids in plasma, with 11 lipids with false discovery rate-P < 0.1 (n = 56 lipids in plasma for raw P < 0.01). Lipid species associated with progression rate clustered in a relatively low number of metabolic pathways, mainly triacylglyceride metabolism and glycerophospholipid and sphingolipid biosynthesis. A specific triacylglyceride (68:12), correlated with neurofilament content (r = 0.8, P < 0.008). Thus, the present findings suggest that systemic hypermetabolism-potentially sustained by increased triacylglyceride content-and CNS alterations of specific lipid pathways could be associated as modifiers of disease progression. Furthermore, these results confirm biochemical lipid heterogeneity in amyotrophic lateral sclerosis with different presentations and progression, suggesting the use of specific lipid species as potential disease classifiers.

Swallowing Safety and Efficiency Impairment Profiles in Individuals with Amyotrophic Lateral Sclerosis

Dysphagia is common in individuals with amyotrophic lateral sclerosis (ALS) and associated with reductions in quality of life and health-related outcomes. Despite the high prevalence of dysphagia in ALS, functional impairment profiles of swallowing safety and efficiency have not been comprehensively examined. We therefore aimed to determine the relative prevalence of unsafe and inefficient swallowing in a large cohort of individuals with ALS. We further sought to examine the impact of global and bulbar disease progression (Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised "ALSFRS-R" total and bulbar scores, respectively), disease duration, and onset type on swallowing impairment profiles. One hundred individuals with ALS completed a standardized videofluoroscopic swallowing examination Two independent and blinded raters performed validated ratings of safety (Penetration-Aspiration Scale, PAS) and efficiency (Analysis of Swallowing Physiology: Events, Kinematics, and Timing, ASPEKT % residue). Binary classifications of safety (unsafe: PAS ≥ 3), efficiency (inefficient: total residue ≥ 3% of C2-4²) and global swallowing status were derived. The ALSFRS-R was completed to derive ALSFRS-R total and bulbar subscale scores. Demographic data (disease duration and onset type) for each participant was also recorded.  Descriptives, 2 × 2 contingency tables with Fishers exact test, and independent samples t-tests were performed (α = 0.05). Prevalence of unsafe and inefficient swallowing was 48% and 73%, respectively. Global swallowing profiles were, in rank order: unsafe and inefficient (39%), inefficient but safe (34%), safe and efficient (18%), and unsafe but efficient (9%). There were no differences in global disease progression or disease duration across swallowing impairment profiles. ALSFRS-R bulbar subscale scores were significantly lower in unsafe versus safe swallowers, p < 0.05. Spinal onset patients had a greater proportion of safe swallowers as compared to bulbar onset patients (p = 0.000, Fisher's exact test). Both spinal and bulbar onset patients demonstrated a higher prevalence of inefficient swallowers as compared to efficient swallowers (p = 0.04, Fisher's exact test). Dysphagia was prevalent in this group of individuals with ALS. Approximately half demonstrated safety impairments and two-thirds had impairments in swallowing efficiency. Inefficient swallowing was approximately four times more likely to be the initial functional impairment in patients with one pathophysiologic functional impairment. A longitudinal study is needed to examine the temporal evolution of dysphagia in ALS.

Patterns of grey and white matter changes differ between bulbar and limb onset amyotrophic lateral sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disease that is characterized by a high heterogeneity in patients' disease course. Patients with bulbar onset of symptoms (b-ALS) have a poorer prognosis than patients with limb onset (l-ALS). However, neuroimaging correlates of the assumed biological difference between b-ALS and l-ALS may have been obfuscated by patients' diversity in the disease course. We conducted Voxel-Based-Morphometry (VBM) and Tract-Based-Spatial-Statistics (TBSS) in a group of 76 ALS patients without clinically relevant cognitive deficits. The subgroups of 26 b-ALS and 52 l-ALS patients did not differ in terms of disease Phase or disease aggressiveness according to the D50 progression model. VBM analyses showed widespread ALS-related changes in grey and white matter, that were more pronounced for b-ALS. TBSS analyses revealed that b-ALS was predominantly characterized by frontal fractional anisotropy decreases. This demonstrates a higher degree of neurodegenerative burden for the group of b-ALS patients in comparison to l-ALS. Correspondingly, higher bulbar symptom burden was associated with right-temporal and inferior-frontal grey matter density decreases as well as fractional anisotropy decreases in inter-hemispheric and long association tracts. Contrasts between patients in Phase I and Phase II further revealed that b-ALS was characterized by an early cortical pathology and showed a spread only outside primary motor regions to frontal and temporal areas. In contrast, l-ALS showed ongoing structural integrity loss within primary motor-regions until Phase II. We therefore provide a strong rationale to treat both onset types of disease separately in ALS studies.

Amide signal intensities may be reduced in the motor cortex and the corticospinal tract of ALS patients

OBJECTIVES

The aim of the study is to assess amide concentration changes in ALS patients compared with healthy controls by using quantitative amide proton transfer (APT) and multiparameter magnetic resonance imaging, and testing its correlation with clinical scores.

METHODS

Sixteen ALS patients and sixteen healthy controls were recruited as part of the Canadian ALS Neuroimaging Consortium, and multimodal magnetic resonance imaging was performed at 3 T, including APT and diffusion imaging. Lorentz fitting was used to quantify the amide effect. Clinical disability was evaluated using the revised ALS functional rating scale (ALSFRS-R), and its correlation with image characteristics was assessed. The diagnostic performance of different imaging parameters was evaluated with receiver operating characteristic analysis.

RESULTS

Our results showed that the amide peak was significantly different between the motor cortex and other gray matter territories within the brain of ALS patients (p < 0.001). Compared with controls, amide signal intensities in ALS were significantly reduced in the motor cortex (p < 0.001) and corticospinal tract (p = 0.046), while abnormalities were not detected using routine imaging methods. There was no significant correlation between amide and ALSFRS-R score. The diagnostic accuracy of the amide peak was superior to that of diffusion imaging.

CONCLUSIONS

This study demonstrated changes of amide signal intensities in the motor cortex and corticospinal tract of ALS patients.

KEY POINTS

• The neurodegenerative disease amyotrophic lateral sclerosis (ALS) has a lack of objective imaging indicators for diagnosis and assessment. • Analysis of amide proton transfer imaging revealed changes in the motor cortex and corticospinal tract of ALS patients that were not visible on standard magnetic resonance imaging. • The diagnostic accuracy of the amide peak was superior to that of diffusion imaging.

Disease aggressiveness signatures of amyotrophic lateral sclerosis in white matter tracts revealed by the D50 disease progression model

Numerous neuroimaging studies in amyotrophic lateral sclerosis (ALS) have reported links between structural changes and clinical data; however phenotypic and disease course heterogeneity have occluded robust associations. The present study used the novel D50 model, which distinguishes between disease accumulation and aggressiveness, to probe correlations with measures of diffusion tensor imaging (DTI). DTI scans of 145 ALS patients and 69 controls were analyzed using tract-based-spatial-statistics of fractional anisotropy (FA), mean- (MD), radial (RD), and axial diffusivity (AD) maps. Intergroup contrasts were calculated between patients and controls, and between ALS subgroups: based on (a) the individual disease covered (Phase I vs. II) or b) patients' disease aggressiveness (D50 value). Regression analyses were used to probe correlations with model-derived parameters. Case-control comparisons revealed widespread ALS-related white matter pathology with decreased FA and increased MD/RD. These affected pathways showed also correlations with the accumulated disease for increased MD/RD, driven by the subgroup of Phase I patients. No significant differences were noted between patients in Phase I and II for any of the contrasts. Patients with high disease aggressiveness (D50 < 30 months) displayed increased AD/MD in bifrontal and biparietal pathways, which was corroborated by significant voxel-wise regressions with D50. Application of the D50 model revealed associations between DTI measures and ALS pathology in Phase I, representing individual disease accumulation early in disease. Patients' overall disease aggressiveness correlated robustly with the extent of DTI changes. We recommend the D50 model for studies developing/validating neuroimaging or other biomarkers for ALS.

Improving clinical trial outcomes in amyotrophic lateral sclerosis

Individuals who are diagnosed with amyotrophic lateral sclerosis (ALS) today face the same historically intransigent problem that has existed since the initial description of the disease in the 1860s - a lack of effective therapies. In part, the development of new treatments has been hampered by an imperfect understanding of the biological processes that trigger ALS and promote disease progression. Advances in our understanding of these biological processes, including the causative genetic mutations, and of the influence of environmental factors have deepened our appreciation of disease pathophysiology. The consequent identification of pathogenic targets means that the introduction of effective therapies is becoming a realistic prospect. Progress in precision medicine, including genetically targeted therapies, will undoubtedly change the natural history of ALS. The evolution of clinical trial designs combined with improved methods for patient stratification will facilitate the translation of novel therapies into the clinic. In addition, the refinement of emerging biomarkers of therapeutic benefits is critical to the streamlining of care for individuals. In this Review, we synthesize these developments in ALS and discuss the further developments and refinements needed to accelerate the introduction of effective therapeutic approaches.

A longitudinal study defined circulating microRNAs as reliable biomarkers for disease prognosis and progression in ALS human patients

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease associated with motor neuron degeneration, muscle atrophy and paralysis. To date, multiple panels of biomarkers have been described in ALS patients and murine models. Nevertheless, none of them has sufficient specificity and thus the molecular signature for ALS prognosis and progression remains to be elucidated. Here we overcome this limitation through a longitudinal study, analyzing serum levels of circulating miRNAs, stable molecules that are recently used as promising biomarkers for many types of human disorders, in ALS patients during the progression of the pathology. We performed next-generation sequencing (NGS) analysis and absolute RT quantification of serum samples of ALS patients and healthy controls. The expression levels of five selected miRNAs were quantitatively analyzed during disease progression in each patient and we demonstrated that high levels of miR-206, miR-133a and miR-151a-5p can predict a slower clinical decline of patient functionality. In particular, we found that miR-206 and miR-151a-5p serum levels were significantly up-regulated at the mild stage of ALS pathology, to decrease in the following moderate and severe stages, whereas the expression levels of miR-133a and miR-199a-5p remained low throughout the course of the disease, showing a diagnostic significance in moderate and severe stages for miR-133a and in mild and terminal ones for miR-199a-5p. Moreover, we found that miR-423–3p and 151a-5p were significantly downregulated respectively in mild and terminal stages of the disease. These data suggest that these miRNAs represent potential prognostic markers for ALS disease.

The use of biotelemetry to explore disease progression markers in amyotrophic lateral sclerosis

OBJECTIVE

To explore novel, real-world biotelemetry disease progression markers in patients with amyotrophic lateral sclerosis (ALS) and to compare with clinical gold-standard measures. Methods: This was an exploratory, non-controlled, non-drug 2-phase study comprising a variable length Pilot Phase (n = 5) and a 48-week Core study Phase (n = 25; NCT02447952). Patients with mild or moderate ALS wore biotelemetry sensors for ∼3 days/month at home, measuring physical activity, heart rate variability (HRV), and speech over 48 weeks. These measures were assessed longitudinally in relation to ALS Functional Rating Scale-Revised (ALSFRS-R) score and forced vital capacity (FVC); assessed by telephone [monthly] and clinic visits [every 12 weeks]). Results: Pilot Phase data supported progression into the Core Phase, where a decline in physical activity from baseline followed ALS progression as measured by ALSFRS-R and FVC. Four endpoints showed moderate or strong between-patient correlations with ALSFRS-R total and gross motor domain scores (defined as a correlation coefficient of ≥0.5 or >0.7, respectively): average daytime active; percentage of daytime active; total daytime activity score; total 24-hour activity score. Moderate correlations were observed between speech endpoints and ALSFRS-R bulbar domain scores; HRV data quality was insufficient for reliable assessment. The sensor was generally well tolerated; 6/25 patients reported mostly mild or moderate intensity skin and subcutaneous tissue disorder adverse events. Conclusions: Biotelemetry measures of physical activity in this Pilot Study tracked ALS progression over time, highlighting their potential as endpoints for future clinical trials. A larger, formally powered study is required to further support activity endpoints as novel disease progression markers.

Triage of Amyotrophic Lateral Sclerosis Patients during the COVID-19 Pandemic: An Application of the D50 Model

Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disease, the management of which requires the continuous provision of multidisciplinary therapies. Owing to the novel coronavirus disease (COVID-19) pandemic, regular contact with ALS patients at our center was severely restricted and patient care was at risk by delay of supportive therapies. We established a triage system based on the D50 disease progression model and were thus able to identify a prospective cohort with high disease aggressiveness (D50 < 30). Thirty-seven patients with highly aggressive disease were actively offered follow-up, either via telephone or on-site, depending on their disease-specific needs and abilities. We describe here the procedures, obstacles, and results of these prescient efforts during the restrictions caused by COVID-19 in the period between March and June 2020. In conclusion, four patients with highly aggressive disease were initiated with non-invasive ventilation and two received a gastrostomy. We could show that a comparable amount of advanced care was induced in a retrospective cohort within a similar time period one year prior to the COVID-19 outbreak. Our workflow to identify high-risk patients via D50 model metrics can be easily implemented and integrated within existing centers. It helped to maintain a high quality of advanced care planning for our ALS patients.

Diaphragmatic CMAP amplitude from phrenic nerve stimulation predicts functional decline in ALS

OBJECTIVE

To evaluate phrenic nerve motor amplitude (PhrenicAmp) as an independent predictor of functional decline in amyotrophic lateral sclerosis (ALS). We also assessed both PhrenicAmp and forced vital capacity (FVC) as predictors of functional loss in patients with bulbar dysfunction.

METHODS

We included consecutive ALS patients with PhrenicAmp and FVC at baseline. Participants were evaluated with the revised ALS Functional Rating Scale (ALSFRS-R) at inclusion and at, at least, one subsequent follow-up visit. The outcome measure of functional decline was the percentage reduction in ALSFRS-R from baseline. Bulbar dysfunction was defined by the presence of any relevant symptom on the ALSFRS-R bulbar sub-score. Correlations and mixed-effects regressions were used to study the relationship between functional decline and both PhrenicAmp and FVC baseline evaluations.

RESULTS

A total of 249 ALS patients were included; 64.2% of these had bulbar dysfunction. At inclusion, significant correlations were found between PhrenicAmp and FVC (p < 0.001), as well as between each respiratory measure and ALSFRS-R (all p < 0.001). The functional decline at first (median 3 months) and second (median 6 months) follow-up visits was significantly correlated with baseline values of both respiratory evaluations (all p < 0.01) in the entire ALS population, but only with baseline PhrenicAmp (all p < 0.05) in bulbar dysfunction cases. Regression analysis revealed that PhrenicAmp (all p < 0.05), but not FVC, was a significant independent predictor of functional decline in ALS patients and in those with bulbar dysfunction.

CONCLUSION

Baseline PhrenicAmp is an independent predictor of functional decline in ALS, whether or not bulbar dysfunction is present.

Intramuscular Injection of Bone Marrow Stem Cells in Amyotrophic Lateral Sclerosis Patients: A Randomized Clinical Trial

Background

Preclinical studies suggest that stem cells may be a valuable therapeutic tool in amyotrophic lateral sclerosis (ALS). As it has been demonstrated that there are molecular changes at the end-plate during the early stages of motorneuron degeneration in animal models, we hypothesize that the local effect of this stem cell delivery method could slow the progressive loss of motor units (MUs) in ALS patients.

Methods

We designed a Phase I/II clinical trial to study the safety of intramuscularly implanting autologous bone marrow mononuclear cells (BMMCs), including stem cells, in ALS patients and their possible effects on the MU of the tibialis anterior (TA) muscle. Twenty-two patients participated in a randomized, double-blind, placebo-controlled trial that consisted of a baseline visit followed by one intramuscular injection of BMNCs, follow-up visits at 30, 90, 180, and 360 days, and an additional year of clinical follow-up. In each patient, one TA muscle was injected with a single dose of BMMCs while the contralateral muscle was given a placebo; the sides were selected randomly. All visits included a complete EMG study of both TA muscles.

Results

Our results show that (1) the intramuscular injection of BMMCs is a safe procedure; (2) ALS patients show heterogeneities in the degree of TA injury; (3) a comparison of placebo-injected muscles with BMMC-injected muscles showed significant differences in only one parameter, the D50 index used to quantify the Compound Muscle Action Potential (CMAP) scan curve. This parameter was higher in the BMMC-injected TA muscle at both 90 days (placebo side: 29.55 ± 2.89, n = 20; experimental side: 39.25 ± 3.21, n = 20; p < 0.01) and 180 days (placebo side: 29.35 ± 3.29, n = 17; experimental side: 41.24 ± 3.34, n = 17; p < 0.01).

Conclusion

This procedure had no effect on the TA muscle MU properties, with the exception of the D50 index. Finding differences in just this index supports the fact that it may be much more sensitive than other electrophysiological parameters when studying treatment effects. Given the low number of patients and their heterogeneity, these results justify exploring the efficacy of this procedure in further patients and other muscles, through Phase II trials.

Clinical Trial Registration

www.clinicaltrials.gov (identifier NCT02286011); EudraCT number 2011-004801-25.

Regional spreading of symptoms at diagnosis as a prognostic marker in amyotrophic lateral sclerosis: a population-based study

OBJECTIVE

The lack of prognostic biomarkers in patients with amyotrophic lateral sclerosis (ALS) induced researchers to develop clinical evaluation tools for stratification and survival prediction. We assessed the correlation between patterns of functional involvement, considered as a cumulative number of body regions involved, and overall survival in a population-based series of patients with ALS (PARALS).

METHODS

We derived the functional involvement of four body regions at diagnosis using ALSFRS-R subscores for bulbar, upper limbs, lower limbs and respiratory/thoracic regions. We analysed the effect of number of body regions involved (NBRI) at diagnosis on overall survival, adjusting for age at onset, sex, site of onset, diagnostic delay, forced vital capacity, body mass index, mutational status, cognition and comparing it with King's staging system.

RESULTS

The NBRI was strongly related to survival, with a progressive increase of death/tracheostomy risk among groups (two body regions HR=1.24, 95% CI 1.06 to 1.45, p=0007; three body regions HR=1.65, 95% CI 1.38 to 1.98, p<0.001; four body regions HR=2.68, 95% CI 2.11 to 3.39, p<0.001). Using ALSFRS-R score, the consistency between the number of regions involved and King's clinical stage at diagnosis was very high (81%). The evaluation of respiratory/thoracic region and cognition allowed to subdivide patients into different prognostic categories. Regional spreading of the disease is associated with survival, independently from the initial region involved.

CONCLUSIONS

The evaluation of NBRI, with the inclusion of initial respiratory/thoracic involvement and cognition, can be useful in many research fields, improving the stratification of patients. Our findings highlight the importance of the spatial spreading of functional impairment in the prediction of ALS outcome.

Multi-dimensional electrical impedance myography of the tongue as a potential biomarker for amyotrophic lateral sclerosis

OBJECTIVE

In amyotrophic lateral sclerosis (ALS) bulbar disease biomarkers are lacking. We evaluated a novel tongue electrical impedance myography (EIM) system, utilising both 2D and 3D electrode configurations for detection of tongue pathology.

METHODS

Longitudinal multi-frequency phase angle spectra were recorded from 41 patients with ALS (baseline, 3 and 6 months) and 30 healthy volunteers (baseline and 6 months). ALS functional rating scale-revised (ALSFRS-R) data and quantitative tongue strength measurements were collected. EIM data were analysed for reliability (intra-class correlation coefficient; ICC) and differences between patients and volunteers ascertained using both univariate (Mann-Whitney U test) and multivariate techniques (feature selection and L2 norm).

RESULTS

The device produced highly reliable data (pooled ICC: 0.836). Significant EIM differences were apparent between ALS patients and healthy volunteers (P < 0.001). EIM data demonstrated a significant relationship to tongue strength and bulbar ALSFRS-R scores (P < 0.015). The EIM recordings revealed a group level longitudinal change over 6 months and consistently identified patients in whom symptoms or tongue strength changed.

CONCLUSIONS

The novel EIM tongue system produces reliable data and can differentiate between healthy muscle and ALS-related disease.

SIGNIFICANCE

Tongue EIM utilising multiple frequencies and electrode configurations has potential as a bulbar disease biomarker in ALS.

Assessing Rat Forelimb and Hindlimb Motor Unit Connectivity as Objective and Robust Biomarkers of Spinal Motor Neuron Function

Sensitive and objective biomarkers of neuronal injury, degeneration, and regeneration can help facilitate translation of experimental findings into clinical testing. Whereas measures of upper motor neuron connectivity have been readily established, functional assessments of lower motor neuron (LMN) innervation of forelimb muscles are lacking. Compound muscle action potential (CMAP) and motor unit (MU) number estimation (MUNE) are well-established methods that allow longitudinal MU integrity monitoring in patients. In analogy we refined CMAP and MUNE methods for assessing spinal MU input in the rat forelimb and hindlimb. Repeated CMAP and MUNE recordings are robust (coefficients of variability: 4.5-11.3%), and MUNE measurements from forelimb wrist flexor muscles (415 ± 8 [SEM]) align with back-traced anatomical LMN counts (336 ± 16 [SEM]). For disease validation, cross-sectional blinded electrophysiological and muscle contractility measurements were obtained in a cohort of G93A SOD1 mutant overexpressing rats and compared with controls. Longitudinal assessment of mutant animals demonstrated progressive motor unit decline in the hindlimb to a greater extent than the forelimb. Hindlimb CMAP and MUNE demonstrated strong correlations with plantarflexion muscle contractility. Cross-species assessment of upper/fore- limb and lower/hind- limb motor units using objective electrophysiological CMAP and MUNE values as biomarkers will guide and improve bi-directional translation.

A speech measure for early stratification of fast and slow progressors of bulbar amyotrophic lateral sclerosis: lip movement jitter

Objective: To assess the utility of novel measures derived from a rapid syllable repetition task (i.e. oral dysdiadochokinesis [DDK]) in early stratification of fast and slow progressive bulbar amyotrophic lateral sclerosis (ALS) and prediction of bulbar disease progression rate. Methods: Fifty-four individuals with ALS were tracked longitudinally on their oral DDK and global bulbar/speech performance (i.e. bulbar subscore on the ALS Functional Rating Scale-Revised [ALSFRS-R]; articulation rate during passage reading) for a four-month average duration. Based on the bulbar deterioration rate over the tracked period, the participants were stratified as 14 fast bulbar progressors and 40 slow bulbar progressors using a posteriori classification approach. To determine if oral DDK performance predicts the differential bulbar disease progression trajectories in these individuals during the early stages of the tracked period (prior to significant bulbar/speech signs), twenty-two measures of lip motor performance in an oral DDK task were derived to (1) differentiate fast and slow bulbar progressors using the Receiver Operating Characteristic analysis and (2) predict bulbar disease progression rates across all individuals using linear regressions. Results: Movement jitter, a measure of temporal variability of alternating lip movement during DDK, showed 80% sensitivity and 95% specificity in differentiating fast and slow bulbar progressors early in the disease, and outperformed the ALSFRS-R bulbar subscore and articulation rate. Movement jitter also predicted bulbar disease progression rates across participants. Conclusion: Findings provided preliminary validation of the clinical value of movement jitter during oral DDK in patient stratification and bulbar disease prognosis.

Genetic Convergence Brings Clarity to the Enigmatic Red Line in ALS

Amyotrophic lateral sclerosis (ALS) is an aggressive neurodegenerative disorder that orchestrates an attack on the motor nervous system that is unrelenting. Recent discoveries into the pathogenic consequences of repeat expansions in C9ORF72, which are the most common genetic cause of ALS, combined with the identification of new genetic mutations are providing novel insight into the underlying mechanism(s) that cause ALS. In particular, the myriad of functions linked to ALS-associated genes have collectively implicated four main pathways in disease pathogenesis, including RNA metabolism and translational biology; protein quality control; cytoskeletal integrity and trafficking; and mitochondrial function and transport. Through the identification of common disease mechanisms on which multiple ALS genes converge, key targets for potential therapeutic intervention are highlighted.

Poor emotional well-being is associated with rapid progression in amyotrophic lateral sclerosis

The study aimed to determine the impact of emotional well-being on disease aggressiveness and survival in amyotrophic lateral sclerosis (ALS). In 224 patients with ALS (without significant cognitive deficits) the revised ALS Functional Rating Scale (physical function), the ALS Assessment Questionnaire (ALSAQ-40) for health-related Quality of Life and survival data were collected. Data analysis comprised logistic regression, Kaplan-Meier curves analyses and Cox regression model. Most patients reported to be worried about how the disease will affect them in the future and 67% reported to feel depressed. Patients with good emotional well-being were characterized by better physical function (higher ALSFRS-R) and lower disease aggressiveness. The association between high emotional well-being and lower disease aggressiveness was confirmed in the univariate analysis and also after adjustment for known predictors of disease progression. In the Kaplan-Meier survival curve analysis the overall 1-year, 2-year and 3-year mortality did not significantly differ between patients with poor and good emotional well-being. Our study demonstrates an association between emotional well-being and disease progression. Knowing that subjective well-being is neither a necessary nor a sufficient cause of health, longitudinal studies are necessary to explore when well-being does and does not influence disease progress and survival in ALS.

Skeletal muscle MRI differentiates SBMA and ALS and correlates with disease severity

OBJECTIVE

To investigate the use of muscle MRI for the differential diagnosis and as a disease progression biomarker for 2 major forms of motor neuron disorders: spinal bulbar muscular atrophy (SBMA) and amyotrophic lateral sclerosis (ALS).

METHODS

We applied quantitative 3-point Dixon and semiquantitative T1-weighted and short tau inversion recovery (STIR) imaging to bulbar and lower limb muscles and performed clinical and functional assessments in ALS (n = 21) and SBMA (n = 21), alongside healthy controls (n = 16). Acquired images were analyzed for the presence of fat infiltration or edema as well as specific patterns of muscle involvement. Quantitative MRI measurements were correlated with clinical measures of disease severity in ALS and SBMA.

RESULTS

Quantitative imaging revealed significant fat infiltration in bulbar (p < 0.001) and limb muscles in SBMA compared to controls (thigh: p < 0.001; calf: p = 0.001), identifying a characteristic pattern of muscle involvement. In ALS, semiquantitative STIR imaging detected marked hyperintensities in lower limb muscles, distinguishing ALS from SBMA and controls. Finally, MRI measurements correlated significantly with clinical scales of disease severity in both ALS and SBMA.

CONCLUSIONS

Our findings show that muscle MRI differentiates between SBMA and ALS and correlates with disease severity, supporting its use as a diagnostic tool and biomarker for disease progression. This highlights the clinical utility of muscle MRI in motor neuron disorders and contributes to establish objective outcome measures, which is crucial for the development of new drugs.

Prognostic analysis of amyotrophic lateral sclerosis based on clinical features and plasma surface-enhanced Raman spectroscopy

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with a wide range of survival times. We aimed to explore prognostic factors related to short survival based on clinical features and plasma metabolic signatures using surface-enhanced Raman spectroscopy (SERS). One hundred and thirty-eight sporadic ALS cases were enrolled serially, including 62 for the short-duration group (≤3 years) and 76 for the long-duration group (>3 years). Multivariate analysis showed that an older age of onset (>60 years; odds ratio [OR] = 3.98, 95% CI: 1.09-14.53), lower body mass index (BMI) (<18.5; OR = 6.80, 95% CI: 1.36-33.92), and lower ALSFRS-R score (<35; OR = 6.03, 95% CI: 1.42-25.63) were associated with higher odds of tracheotomy or death, while a higher uric acid (UA) level showed a protective effect (>356.36 μmol/L; OR = 0.19, 95% CI: 0.05-0.73). SERS analysis showed significant differences between the two groups, and pathway analysis highlighted five main metabolic pathways, including metabolisms of glutathione, pyrimidine, phenylalanine, galactose, and phenylalanine-tyrosine-tryptophan biosynthesis. In conclusion, age of onset, BMI, ALSFRS-R score and UA, together with dysregulation of glucose, amino acid, nucleic acid, and antioxidant metabolism contributed to disease progression, and are therefore potential therapeutic targets for ALS.

Clinical and research applications of neuromuscular ultrasound in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder characterized by dysfunction at multiple levels of the neuraxis. It remains a clinical diagnosis without a definitive diagnostic investigation. Electrodiagnostic testing provides supportive information and, along with imaging and biochemical markers, can help exclude mimicking conditions. Neuromuscular ultrasound has a valuable role in the diagnosis and monitoring of ALS and provides complementary information to clinical assessment and electrodiagnostic testing as well as insights into the underlying pathophysiology of this disease. This review highlights the evidence for ultrasound in the evaluation of bulbar, limb and respiratory musculature and peripheral nerves in ALS. Further research in this evolving area is required.

Extracellular vesicles and their diagnostic potential in amyotrophic lateral sclerosis

Extracellular vesicles, small reservoirs that carry various biomolecules, have gained significant interest from the clinical field in recent years based on the diagnostic, therapeutic and prognostic possibilities they offer. While information abound regarding the clinical potential of such vesicles in diverse conditions, the information demonstrating their likely importance in amyotrophic lateral sclerosis (ALS) is more limited. This review will thus provide a brief introduction to extracellular vesicles, highlight their diagnostic significance in various diseases with a focus on ALS and explore additional applications of extracellular vesicles in the medical field. Overall, this work sheds further light on the clinical importance of extracellular vesicles in diagnostic applications as well as supports the need to better characterize their roles and signatures in patients diagnosed with ALS.

Rapid myelin water imaging for the assessment of cervical spinal cord myelin damage

Background

Rapid myelin water imaging (MWI) using a combined gradient and spin echo (GRASE) sequence can produce myelin specific metrics for the human brain. Spinal cord MWI could be similarly useful, but technical challenges have hindered routine application. GRASE rapid MWI was recently successfully implemented for imaging of healthy cervical spinal cord and may complement other advanced imaging methods, such as diffusion tensor imaging (DTI) and quantitative T₁ (qT₁).

Objective

To demonstrate the feasibility of cervical cord GRASE rapid MWI in multiple sclerosis (MS), primary lateral sclerosis (PLS) and neuromyelitis optica spectrum disorder (NMO), with comparison to DTI and qT₁ metrics.

Methods

GRASE MWI, DTI and qT₁ data were acquired in 2 PLS, 1 relapsing-remitting MS (RRMS), 1 primary-progressive MS (PPMS) and 2 NMO subjects, as well as 6 age (±3 yrs) and sex matched healthy controls (HC). Internal cord structure guided template registrations, used for region of interest (ROI) analysis. Z score maps were calculated for the difference between disease subject and mean HC metric values.

Results

PLS subjects had low myelin water fraction (MWF) in the lateral funiculi compared to HC. RRMS subject MWF was heterogeneous within the cord. The PPMS subject showed no trends in ROI results but had a region of low MWF Z score corresponding to a focal lesion. The NMO subject with a longitudinally extensive transverse myelitis lesion had low values for whole cord mean MWF of 12.8% compared to 24.3% (standard deviation 2.2%) for HC. The NMO subject without lesions also had low MWF compared to HC. DTI and qT₁ metrics showed similar trends, corroborating the MWF results and providing complementary information.

Conclusion

GRASE is sufficiently sensitive to detect decreased myelin within MS spinal cord plaques, NMO lesions, and PLS diffuse spinal cord injury. Decreased MWF in PLS is consistent with demyelination secondary to motor neuron degeneration. GRASE MWI is a feasible method for rapid assessment of myelin content in the cervical spinal cord and provides complementary information to that of DTI and qT₁ measures.

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Downstream myelin changes in motor tracts of primary lateral sclerosis spinal cord.

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Low myelin water fraction in multiple sclerosis and neuromyelitis optica cord lesions.

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Diffuse demyelination evidence in neuromyelitis optica normal-appearing white matter.

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Myelin water imaging provides complementary information to diffusion and T₁ metrics.

Stem cell treatments for amyotrophic lateral sclerosis: a critical overview of early phase trials

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of cortical, brainstem, and spinal motor neurons; it causes progressive muscle weakness and atrophy, respiratory failure, and death. No currently available treatment either stops or reverses this disease. Therapeutics to slow, stop, and reverse ALS are needed. Stem cells may be a viable solution to sustain and nurture diseased motor neurons. Several early-stage clinical trials have been launched to assess the potential of stem cells for ALS treatment. Areas covered: Expert opinion:

AREAS COVERED

This review covers the key advances from early phase clinical trials of stem cell therapy for ALS and identifies promising avenues and key challenges.

EXPERT OPINION

Clinical trials in humans are still in the nascent stages of development. It will be critical to ensure that powered, well-controlled trials are conducted, that optimal treatment windows are identified, and that the ideal cell type, cell dose, and delivery site and method are determined. Several trials have used more invasive procedures, and ethical concerns of sham procedures on patients in the control arm and on their safety should be considered.

Are Circulating Cytokines Reliable Biomarkers for Amyotrophic Lateral Sclerosis?

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that has no effective treatment. The lack of any specific biomarker that can help in the diagnosis or prognosis of ALS has made the identification of biomarkers an urgent challenge. Multiple panels have shown alterations in levels of numerous cytokines in ALS, supporting the contribution of neuroinflammation to the progressive motor neuron loss. However, none of them is fully sensitive and specific enough to become a universal biomarker for ALS. This review gathers the numerous circulating cytokines that have been found dysregulated in both ALS animal models and patients. Particularly, it highlights the opposing results found in the literature to date, and points out another potential application of inflammatory cytokines as therapeutic targets.

ALS blood expression profiling identifies new biomarkers, patient subgroups, and evidence for neutrophilia and hypoxia

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a debilitating disease with few treatment options. Progress towards new therapies requires validated disease biomarkers, but there is no consensus on which fluid-based measures are most informative.

METHODS

This study analyzed microarray data derived from blood samples of patients with ALS (n = 396), ALS mimic diseases (n = 75), and healthy controls (n = 645). Goals were to provide in-depth analysis of differentially expressed genes (DEGs), characterize patient-to-patient heterogeneity, and identify candidate biomarkers.

RESULTS

We identified 752 ALS-increased and 764 ALS-decreased DEGs (FDR < 0.10 with > 10% expression change). Gene expression shifts in ALS blood broadly resembled acute high altitude stress responses. ALS-increased DEGs had high exosome expression, were neutrophil-specific, associated with translation, and overlapped significantly with genes near ALS susceptibility loci (e.g., IFRD1, TBK1, CREB5). ALS-decreased DEGs, in contrast, had low exosome expression, were erythroid lineage-specific, and associated with anemia and blood disorders. Genes encoding neurofilament proteins (NEFH, NEFL) had poor diagnostic accuracy (50-53%). However, support vector machines distinguished ALS patients from ALS mimics and controls with 87% accuracy (sensitivity: 86%, specificity: 87%). Expression profiles were heterogeneous among patients and we identified two subgroups: (i) patients with higher expression of IL6R and myeloid lineage-specific genes and (ii) patients with higher expression of IL23A and lymphoid-specific genes. The gene encoding copper chaperone for superoxide dismutase (CCS) was most strongly associated with survival (HR = 0.77; P = 1.84e-05) and other survival-associated genes were linked to mitochondrial respiration. We identify a 61 gene signature that significantly improves survival prediction when added to Cox proportional hazard models with baseline clinical data (i.e., age at onset, site of onset and sex). Predicted median survival differed 2-fold between patients with favorable and risk-associated gene expression signatures.

CONCLUSIONS

Peripheral blood analysis informs our understanding of ALS disease mechanisms and genetic association signals. Our findings are consistent with low-grade neutrophilia and hypoxia as ALS phenotypes, with heterogeneity among patients partly driven by differences in myeloid and lymphoid cell abundance. Biomarkers identified in this study require further validation but may provide new tools for research and clinical practice.

Dissecting Motor Neuron Disease With Drosophila melanogaster

Motor Neuron Disease (MND) typically affects patients during the later stages of life, and thus, MND is having an increasingly devastating impact on diagnosed individuals, their families and society. The umbrella term MND refers to diseases which cause the progressive loss of upper and/or lower motor neurons and a subsequent decrease in motor ability such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). The study of these diseases is complex and has recently involved the use of genome-wide association studies (GWAS). However, in the case of MND, it has been difficult to identify the complex genetics involved in subtypes, and functional investigation of new candidate disease genes is warranted. Drosophila is a powerful model for addressing these complex diseases. The UAS/Gal4/Gal80 system allows for the upregulation of Drosophila genes, the “knockdown” of genes and the ectopic expression of human genes or mutations in a tissue-specific manner; often resulting in Drosophila models which exhibit typical MND disease pathologies. These can then be further interrogated to identify disease-modifying genes or mutations and disease pathways. This review will discuss two common MNDs and the current Drosophila models which are being used to research their genetic basis and the different pathologies of MND.

The Pathobiology of TDP-43 C-Terminal Fragments in ALS and FTLD

During neurodegenerative disease, the multifunctional RNA-binding protein TDP-43 undergoes a vast array of post-translational modifications, including phosphorylation, acetylation, and cleavage. Many of these alterations may directly contribute to the pathogenesis of TDP-43 proteinopathies, which include most forms of amyotrophic lateral sclerosis (ALS) and approximately half of all frontotemporal dementia, pathologically identified as frontotemporal lobar degeneration (FTLD) with TDP-43 pathology. However, the relative contributions of the various TDP-43 post-translational modifications to disease remain unclear, and indeed some may be secondary epiphenomena rather than disease-causative. It is therefore critical to determine the involvement of each modification in disease processes to allow the design of targeted treatments. In particular, TDP-43 C-terminal fragments (CTFs) accumulate in the brains of people with ALS and FTLD and are therefore described as a neuropathological signature of these diseases. Remarkably, these TDP-43 CTFs are rarely observed in the spinal cord, even in ALS which involves dramatic degeneration of spinal motor neurons. Therefore, TDP-43 CTFs are not produced non-specifically in the course of all forms of TDP-43-related neurodegeneration, but rather variably arise due to additional factors influenced by regional heterogeneity in the central nervous system. In this review, we summarize how TDP-43 CTFs are generated and degraded by cells, and critique evidence from studies of TDP-43 CTF pathology in human disease tissues, as well as cell and animal models, to analyze the pathophysiological relevance of TDP-43 CTFs to ALS and FTLD. Numerous studies now indicate that, although TDP-43 CTFs are prevalent in ALS and FTLD brains, disease-related pathology is only variably reproduced in TDP-43 CTF cell culture models. Furthermore, TDP-43 CTF expression in both transgenic and viral-mediated in vivo models largely fails to induce motor or behavioral dysfunction reminiscent of human disease. We therefore conclude that although TDP-43 CTFs are a hallmark of TDP-43-related neurodegeneration in the brain, they are not a primary cause of ALS or FTLD.