Electroencephalographic ß-band oscillations in the sensorimotor network reflect motor symptom severity in amyotrophic lateral sclerosis.

BACKGROUND AND PURPOSE: Resting-state electroencephalography (EEG) holds promise for assessing brain networks in amyotrophic lateral sclerosis (ALS). We investigated whether neural ß-band oscillations in the sensorimotor network could serve as an objective quantitative measure of progressive motor impairment and functional disability in ALS patients. METHODS: Resting-state EEG was recorded in 18 people with ALS and 38 age- and gender-matched healthy controls. We estimated source-localized ß-band spectral power in the sensorimotor cortex. Clinical evaluation included lower (LMN) and upper motor neuron scores, Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised score, fine motor function (FMF) subscore, and progression rate. Correlations between clinical scores and ß-band power were analysed and corrected using a false discovery rate of q = 0.05. RESULTS: ß-Band power was significantly lower in people with ALS than controls (p = 0.004), and correlated with LMN score (R = -0.65, p = 0.013), FMF subscore (R = -0.53, p = 0.036), and FMF progression rate (R = 0.52, p = 0.036). CONCLUSIONS: ß-Band spectral power in the sensorimotor cortex reflects clinically evaluated motor impairment in ALS. This technology merits further investigation as a biomarker of progressive functional disability.

Cortico-muscular coherence in primary lateral sclerosis reveals abnormal cortical engagement during motor function beyond primary motor areas.

Primary lateral sclerosis (PLS) is a slowly progressing disorder, which is characterized primarily by the degeneration of upper motor neurons (UMNs) in the primary motor area (M1). It is not yet clear how the function of sensorimotor networks beyond M1 are affected by PLS. The aim of this study was to use cortico-muscular coherence (CMC) to characterize the oscillatory drives between cortical regions and muscles during a motor task in PLS and to examine the relationship between CMC and the level of clinical impairment. We recorded EEG and EMG from hand muscles in 16 participants with PLS and 18 controls during a pincer-grip task. In PLS, higher CMC was observed over contralateral-M1 (α- and γ-band) and ipsilateral-M1 (ß-band) compared with controls. Significant correlations between clinically assessed UMN scores and CMC measures showed that higher clinical impairment was associated with lower CMC over contralateral-M1/frontal areas, higher CMC over parietal area, and both higher and lower CMC (in different bands) over ipsilateral-M1. The results suggest an atypical engagement of both contralateral and ipsilateral M1 during motor activity in PLS, indicating the presence of pathogenic and/or adaptive/compensatory alterations in neural activity. The findings demonstrate the potential of CMC for identifying dysfunction within the sensorimotor networks in PLS.

A theoretical model for the Fåhræus effect in medium-large microvessels.

This paper presents a mathematical model capable to reproduce a celebrated phenomenon in blood microcirculation known as Fåhræus effect, since its discovery by Robin Fåhræus (1929). This consists in a decaying of the relative hematocrit in small vessels as the vessel diameter decreases. The key point of the model is a formula, direct consequence of the basic principles of fluid dynamics, that links the relative hematocrit to the reservoir hematocrit and the vessel diameter, which confirms the observed behavior. To test the model we selected, among the few experiments carried on since then, those performed by Barbee and Cokelet (1971). The agreement is remarkable. An extended comparison is also carried out with a celebrated empirical formula proposed by Pries et al. (1992) to describe the same phenomenon.

Fremanezumab plus plasmapheresis in a patient with chronic migraine and myasthenia gravis: Case report of an effective treatment.

A patient with chronic migraine and generalized myasthenia gravis was concurrently treated with fremanezumab and with therapeutic plasmapheresis (PEX). Fremanezumab was dosed right after a PEX session, or in the midpoint between sessions, and the efficacy of both treatments was maintained. This case broadens the drug's clinical applications and it helps in choosing the appropriate medical regimen in patients requiring both treatments.

Resting-state EEG reveals four subphenotypes of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis is a devastating disease characterized primarily by motor system degeneration, with clinical evidence of cognitive and behavioural change in up to 50% of cases. Amyotrophic lateral sclerosis is both clinically and biologically heterogeneous. Subgrouping is currently undertaken using clinical parameters, such as site of symptom onset (bulbar or spinal), burden of disease (based on the modified El Escorial Research Criteria) and genomics in those with familial disease. However, with the exception of genomics, these subcategories do not take into account underlying disease pathobiology, and are not fully predictive of disease course or prognosis. Recently, we have shown that resting-state EEG can reliably and quantitatively capture abnormal patterns of motor and cognitive network disruption in amyotrophic lateral sclerosis. These network disruptions have been identified across multiple frequency bands, and using measures of neural activity (spectral power) and connectivity (comodulation of activity by amplitude envelope correlation and synchrony by imaginary coherence) on source-localized brain oscillations from high-density EEG. Using data-driven methods (similarity network fusion and spectral clustering), we have now undertaken a clustering analysis to identify disease subphenotypes and to determine whether different patterns of disruption are predictive of disease outcome. We show that amyotrophic lateral sclerosis patients (n = 95) can be subgrouped into four phenotypes with distinct neurophysiological profiles. These clusters are characterized by varying degrees of disruption in the somatomotor (α-band synchrony), frontotemporal (ß-band neural activity and γl-band synchrony) and frontoparietal (γl-band comodulation) networks, which reliably correlate with distinct clinical profiles and different disease trajectories. Using an in-depth stability analysis, we show that these clusters are statistically reproducible and robust, remain stable after reassessment using a follow-up EEG session, and continue to predict the clinical trajectory and disease outcome. Our data demonstrate that novel phenotyping using neuroelectric signal analysis can distinguish disease subtypes based exclusively on different patterns of network disturbances. These patterns may reflect underlying disease neurobiology. The identification of amyotrophic lateral sclerosis subtypes based on profiles of differential impairment in neuronal networks has clear potential in future stratification for clinical trials. Advanced network profiling in amyotrophic lateral sclerosis can also underpin new therapeutic strategies that are based on principles of neurobiology and designed to modulate network disruption.

Modeling of vasomotion in arterioles.

We consider the flow of blood, treated as an incompressible Newtonian fluid, through vessels undergoing periodic oscillations. As remarked by many authors, in the absence of valves oscillations hinder the flow because of the lumen reduction. The underlying biological mechanism is the so-called vasomotion, observed long ago in small blood vessels. Here, we study the vasomotion in arterioles and provide its theoretical justification by analyzing the effect when the network of vessels downstream of the arterioles is considered. We thus explain both quantitatively and qualitatively, why the oscillations of the arteriole walls, a phenomenon that undoubtedly reduces blood flow at the level of the single arteriole, play a fundamental role in microcirculation. In "large" arterioles we analyze also the coupling between the vasomotion and the Fåhræus-Lindqvist effect (the tendency of the erythrocytes to accumulate towards the center). In particular, we prove that the presence of a cell depleted layer close to the vessel walls mitigates the disadvantage caused by the lumen reduction.

Localization of Brain Networks Engaged by the Sustained Attention to Response Task Provides Quantitative Markers of Executive Impairment in Amyotrophic Lateral Sclerosis.

OBJECTIVE: To identify cortical regions engaged during the sustained attention to response task (SART) and characterize changes in their activity associated with the neurodegenerative condition amyotrophic lateral sclerosis (ALS). METHODS: High-density electroencephalography (EEG) was recorded from 33 controls and 23 ALS patients during a SART paradigm. Differences in associated event-related potential peaks were measured for Go and NoGo trials. Sources active during these peaks were localized, and ALS-associated differences were quantified. RESULTS: Go and NoGo N2 and P3 peak sources were localized to the left primary motor cortex, bilateral dorsolateral prefrontal cortex (DLPFC), and lateral posterior parietal cortex (PPC). NoGo trials evoked greater bilateral medial PPC activity during N2 and lesser left insular, PPC and DLPFC activity during P3. Widespread cortical hyperactivity was identified in ALS during P3. Changes in the inferior parietal lobule and insular activity provided very good discrimination (AUROC > 0.75) between patients and controls. Activation of the right precuneus during P3 related to greater executive function in ALS, indicative of a compensatory role. INTERPRETATION: The SART engages numerous frontal and parietal cortical structures. SART-EEG measures correlate with specific cognitive impairments that can be localized to specific structures, aiding in differential diagnosis.

Cognitive dysfunction in amyotrophic lateral sclerosis: can we predict it?

BACKGROUND AND AIM: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by the degeneration of both upper and lower motoneurons in the brain and spinal cord leading to motor and extra-motor symptoms. Although traditionally considered a pure motor disease, recent evidences suggest that ALS is a multisystem disorder. Neuropsychological alterations, in fact, are observed in more than 50% of patients: while executive dysfunctions have been firstly identified, alterations in verbal fluency, behavior, and pragmatic and social cognition have also been described. Detecting and monitoring ALS cognitive and behavioral impairment even at early disease stages is likely to have staging and prognostic implications, and it may impact the enrollment in future clinical trials. During the last 10 years, humoral, radiological, neurophysiological, and genetic biomarkers have been reported in ALS, and some of them seem to potentially correlate to cognitive and behavioral impairment of patients. In this review, we sought to give an up-to-date state of the art of neuropsychological alterations in ALS: we will describe tests used to detect cognitive and behavioral impairment, and we will focus on promising non-invasive biomarkers to detect pre-clinical cognitive decline. CONCLUSIONS: To date, the research on humoral, radiological, neurophysiological, and genetic correlates of neuropsychological alterations is at the early stage, and no conclusive longitudinal data have been published. Further and longitudinal studies on easily accessible and quantifiable biomarkers are needed to clarify the time course and the evolution of cognitive and behavioral impairments of ALS patients.

A continuum mechanics model for the Fåhræus-Lindqvist effect.

The decrease in apparent relative viscosity that occurs when blood is made to flow through a tube whose diameter is less than about 0.3 mm is a well-known and documented phenomenon in physiology, known as the Fåhræus-Lindqvist effect. However, since the historical work of Fåhræus and Lindqvist (Amer. J. Physiol. 96(3): pp. 562-568, 1931), the underlying physical mechanism has remained enigmatic. A widely accepted qualitative explanation was provided by Haynes (Amer. J. Physiol. 198, pp. 1193-1200, 1960) according to which blood flows in microvessels with a core-annulus structure, where the erythrocytes concentrate within a central core surrounded by a plasma layer. Although sustained by observations, this conjecture lacks a rigorous deduction from the basic principles of continuum dynamics. Moreover, relations aimed to reproduce the blood apparent relative viscosity, extensively used in micro-circulation, are all empirical and not derived from the analysis of the fluid mechanical phenomena involved. In this paper, we apply the recent results illustrated in Guadagni and Farina (Int. J. Nonlinear Mech. 126, p. 103587, 2020), with the purpose of showing that Haynes' conjecture, slightly corrected to make it more realistic, can be proved and can be used to reach a sound explanation of the Fåhræus-Lindqvist effect based on continuum mechanics. We propose a theoretical model for the blood apparent relative viscosity which is validated by matching not only the original experimental data reported by Fåhræus and Lindqvist (Amer. J. Physiol. 96(3), pp. 562-568, 1931), but also those provided by several subsequent authors.

Patterned functional network disruption in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease primarily affecting motor function, with additional evidence of extensive nonmotor involvement. Despite increasing recognition of the disease as a multisystem network disorder characterised by impaired connectivity, the precise neuroelectric characteristics of impaired cortical communication remain to be fully elucidated. Here, we characterise changes in functional connectivity using beamformer source analysis on resting-state electroencephalography recordings from 74 ALS patients and 47 age-matched healthy controls. Spatiospectral characteristics of network changes in the ALS patient group were quantified by spectral power, amplitude envelope correlation (co-modulation) and imaginary coherence (synchrony). We show patterns of decreased spectral power in the occipital and temporal (δ- to ß-band), lateral/orbitofrontal (δ- to θ-band) and sensorimotor (ß-band) regions of the brain in patients with ALS. Furthermore, we show increased co-modulation of neural oscillations in the central and posterior (δ-, θ- and γl -band) and frontal (δ- and γl -band) regions, as well as decreased synchrony in the temporal and frontal (δ- to ß-band) and sensorimotor (ß-band) regions. Factorisation of these complex connectivity patterns reveals a distinct disruption of both motor and nonmotor networks. The observed changes in connectivity correlated with structural MRI changes, functional motor scores and cognitive scores. Characteristic patterned changes of cortical function in ALS signify widespread disease-associated network disruption, pointing to extensive dysfunction of both motor and cognitive networks. These statistically robust findings, that correlate with clinical scores, provide a strong rationale for further development as biomarkers of network disruption for future clinical trials.

The Fåhræus-Lindqvist effect in small blood vessels: how does it help the heart?

The Fåhræus-Lindqvist effect is usually explained from a physical point of view with the so-called Haynes' marginal zone theory, i.e., migration of red blood cells (RBCs) to a core layer surrounded by an annular RBCs-free plasma layer. In this paper we show that the marginal layer, though causing a substantial reduction in flow resistance and increasing discharge, does not reduce the rate of energy dissipation. This fact is not surprising if one considers the electric analog of the flow in a vessel: a resistance reduction increases both the current intensity (i.e., the discharge) and the energy dissipation. This result is obtained by considering six rheological models that relate the blood viscosity to hematocrit (volume fraction occupied by erythrocytes). Some physiological implications are discussed.

Cerebrospinal Fluid Neurofilaments May Discriminate Upper Motor Neuron Syndromes: A Pilot Study.

BACKGROUND: Patients presenting with upper motor neuron (UMN) signs may widely diverge in prognosis, ranging from amyotrophic lateral sclerosis (ALS) to primary lateral sclerosis (PLS) and hereditary spastic paraplegia (hSP). Neurofilaments are emerging as potential diagnostic and prognostic biomarkers for ALS, but the diagnosis of UMN syndromes still relies mostly on clinical long-term observation and on familiarity or genetic confirmation. OBJECTIVES: To test whether phosphorylated neurofilament heavy chain (pNfH) may discriminate different UMN syndromes at diagnosis and to test their prognostic role among these diseases. METHODS: We measured the cerebrospinal fluid (CSF) and serum pNfH of 30 patients presenting with UMN signs and diagnosed with ALS, hSP, and PLS, plus 9 healthy controls (HC). RESULTS: ALS patients had higher levels of pNfH in CSF and serum compared to HC (p < 0.001 and p < 0.001 in CSF and serum, respectively) and PLS (p = 0.015 and p = 0.038) and hSP (p = 0.003 and p = 0.001) patients. PLS and hSP patients had similar CSF and serum pNfH concentrations, but a higher CSF pNfH concentration, compared to HC (p = 0.002 and p = 0.003 for PLS and hSP, respectively). Receiver operating characteristic curves for discriminating ALS from PLS and hSP showed an area under the curve of 0.79 for CSF and 0.81 for serum. In multivariable survival analysis including relevant clinical factors CSF pNfH represented the strongest variable predicting survival (HR 40.43; 95% CI 3.49-467.79, p = 0.003) independently of clinical group. CONCLUSIONS: Despite some statistical instability of the results due to limitations in sample size, our study supports the role of CSF pNfH as a prognostic biomarker for motor neuron diseases presenting with UMN signs. A potential power to discriminate between ALS and other UMN syndromes at presentation, and between all of the examined MND and HC, has been detected for both CSF and serum pNfH.

Pesticides, polychlorinated biphenyls and polycyclic aromatic hydrocarbons in cerebrospinal fluid of amyotrophic lateral sclerosis patients: a case-control study.

Neurotoxic chemicals including several pesticides have been suggested to play a role in the etiology of amyotrophic lateral sclerosis (ALS). We investigated the relation between organochlorine pesticides and their metabolites (OCPs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in the etiology of sporadic ALS, determining for the first time their levels in cerebrospinal fluid as indicator of antecedent exposure. We recruited 38 ALS patients and 38 controls referred to an Italian clinical center for ALS care, who underwent a lumbar puncture for diagnostic purposes between 1994-2013, and had 1mL of cerebrospinal fluid available for the determination of OCPs, PCBs and PAHs. Many chemicals were undetectable in both case and control CSF samples, and we found little evidence of any increased disease risk according to higher levels of exposure. Among males >60 years, we found a slight but statistically very unstable increased ALS risk with higher levels of the congener PCB 28 and the OCP metabolite p,p'-DDE. Overall, these results do not suggest an involvement of the neurotoxic chemicals investigated in this study in disease etiology, although small numbers limited the precision of our results.

Changes in routine laboratory tests and survival in amyotrophic lateral sclerosis.

The aim of this study is to evaluate the association between changes in routinely prescribed laboratory tests and tracheostomy-free survival in amyotrophic lateral sclerosis (ALS). Two hundred seventy-five ALS patients were retrospectively studied. BMI, forced vital capacity, hemoglobin, hematocrit, lymphocytes, cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, proteins, albumin, creatine-phosphokinase, iron, ferritin, transferrin, glucose, urea, uric acid, and creatinine were measured every 6 months from baseline to 24 months, death or study end, together with the probability of death or tracheostomy. Missing data were handled using multiple imputation chained equations. Hemoglobin (OR = 1.71, 95%CI 1.24-2.36 for IQR increase), hematocrit (OR = 1.87, 95%CI 1.34-2.63 for IQR increase), urea (OR = 1.51, 95%CI 1.21-1.89 for IQR increase), and uric acid (OR = 1.98, 95%CI 1.23-3.20 for IQR increase) were directly associated, while triglycerides (OR = 0.69, 0.51 to 0.93 for IQR increase) were inversely associated with the odds of death or tracheostomy. In our cohort, an increase of hemoglobin, hematocrit, urea, and uric acid was directly associated, and an increase of triglycerides was inversely associated with the odds of death or tracheostomy. Should these findings be replicated in an external cohort, they might help to discriminate ALS progression and patients' decisions about procedures and end of life.

Amyotrophic lateral sclerosis and myasthenia gravis: association or chance occurrence?

Very few cases of patients with myasthenia gravis (MG) who later developed amyotrophic lateral sclerosis (ALS) have been described, although some studies showed that significantly more cases than expected have ALS associated with a prior diagnosis of autoimmune diseases. Our aim was to investigate whether the association of ALS and MG was higher than expected in a population-based study and to describe the clinical features characterizing these patients. In Emilia Romagna Region of Italy, a prospective registry has been collecting all incident ALS cases since 1.1.2009. For each patient, detailed clinical information is collected by caring physicians, including comorbidities. From 1.1.2009 to 31.12.2014, 671 patients were diagnosed with ALS; five patients (0.75%) were also affected by MG. Considering Western Countries incidence rates the occurrence of both the diseases should be a really exceptional event (7.5/109), compared to our findings (1.87/107) (p < 0.01). Patients with ALS and MG had more frequently a bulbar onset and a fast progressive course. These cases of ALS after MG raise the possibility of potential shared immunological dysfunctions, which may be expression of common pathogenic mechanisms, as well as of shared disease-course modulating events.

Heterogeneity in ALSFRS-R decline and survival: a population-based study in Italy.

Very few studies examined trend over time of the revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) and factors influencing it; previous studies, then, included only patients attending tertiary ALS Centres. We studied ALSFRS-R decline, factors influencing this trend and survival in a population-based setting. From 2009 onwards, a prospective registry records all incident ALS cases among residents in Emilia Romagna (population: 4.4 million). For each patient, demographic and clinical details (including ALSFRS-R) are collected by caring physicians at each follow-up. Analysis was performed on 402 incident cases (1279 ALSFRS-R assessments). The average decline of the ALSFRS-R was 0.60 points/month during the first year after diagnosis and 0.34 points/month in the second year. ALSFRS-R decline was heterogeneous among subgroups. Repeated measures mixed model showed that ALSFRS-R score decline was influenced by age at onset (p < 0.01), phenotype (p = 0.01), body mass index (BMI) (p < 0.01), progression rate at diagnosis (ΔFS) (p < 0.01), El Escorial Criteria-Revised (p < 0.01), and FVC% at diagnosis (p < 0.01). Among these factors, at multivariate analysis, only age, site of onset and ΔFS independently influenced survival. In this first population-based study on ALSFRS-R trend, we confirm that ALSFRS-R decline is not homogeneous among ALS patients and during the disease. Factors influencing ALSFRS-R decline may not match with those affecting survival. These disease modifiers should be taken into consideration for trials design and in clinical practice during discussions with patients on prognosis.