Spreading of amyotrophic lateral sclerosis lesions--multifocal hits and local propagation?

The burden of upper motor neuron involvement is correlated with the bilateral limb involvement interval in patients with amyotrophic lateral sclerosis: a retrospective observational study

JOURNAL/nrgr/04.03/01300535-202505000-00032/figure1/v/2024-07-28T173839Z/r/image-tiff Amyotrophic lateral sclerosis is a rare neurodegenerative disease characterized by the involvement of both upper and lower motor neurons. Early bilateral limb involvement significantly affects patients' daily lives and may lead them to be confined to bed. However, the effect of upper and lower motor neuron impairment and other risk factors on bilateral limb involvement is unclear. To address this issue, we retrospectively collected data from 586 amyotrophic lateral sclerosis patients with limb onset diagnosed at Peking University Third Hospital between January 2020 and May 2022. A univariate analysis revealed no significant differences in the time intervals of spread in different directions between individuals with upper motor neuron-dominant amyotrophic lateral sclerosis and those with classic amyotrophic lateral sclerosis. We used causal directed acyclic graphs for risk factor determination and Cox proportional hazards models to investigate the association between the duration of bilateral limb involvement and clinical baseline characteristics in amyotrophic lateral sclerosis patients. Multiple factor analyses revealed that higher upper motor neuron scores (hazard ratio [HR] = 1.05, 95% confidence interval [CI] = 1.01-1.09, P = 0.018), onset in the left limb (HR = 0.72, 95% CI = 0.58-0.89, P = 0.002), and a horizontal pattern of progression (HR = 0.46, 95% CI = 0.37-0.58, P < 0.001) were risk factors for a shorter interval until bilateral limb involvement. The results demonstrated that a greater degree of upper motor neuron involvement might cause contralateral limb involvement to progress more quickly in limb-onset amyotrophic lateral sclerosis patients. These findings may improve the management of amyotrophic lateral sclerosis patients with limb onset and the prediction of patient prognosis.

Evaluation of the applicability of weak shoulder and arm sparing signs in amyotrophic lateral sclerosis by multiple neurologists and neurology residents: A single-center study

INTRODUCTION/AIMS

Amyotrophic lateral sclerosis (ALS) exhibits selective muscle weakness. The weak shoulder and arm sparing signs, assessed by a single experienced neurologist, have been reported to be superior to previous signs in sensitivity and specificity. However, it is unknown whether the same results are observed when assessed by multiple neurologists.

METHODS

Subjects were retrospectively identified from our department's inpatient database from 2014 to 2023. Medical Research Council (MRC) scores of the deltoid (Del), biceps brachii (BB), triceps brachii (TB), and first dorsal interosseous (FDI) muscles were evaluated. The weak shoulder sign was defined as positive when Del was weaker than BB and TB. The arm sparing sign was defined as positive when both Del and FDI were weaker than BB and TB. Sensitivity was analyzed in all ALS patients and in subgroups based on the region of symptom onset, presence or absence of upper motor neuron (UMN) signs, and the Japanese ALS Severity Classification.

RESULTS

Seventy-one patients with ALS were identified. Eight neurologists and three neurology residents evaluated each patient's MRC scores. The weak shoulder and arm sparing signs were observed in 72% and 48% of patients, respectively, with no significant difference in sensitivity across patient subgroups.

DISCUSSION

The weak shoulder and arm sparing signs showed high and moderate sensitivity, respectively, consistent with a previous report, even when evaluated by multiple examiners. This expands the clinical utility and increases the reliability of these signs, potentially contributing to accurate ALS diagnosis when combined with other clinical features and objective assessments.

Cervical and thoracic spinal cord gray matter atrophy is associated with disability in patients with amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

In amyotrophic lateral sclerosis (ALS), there is an unmet need for more precise patient characterization through quantitative, ideally operator-independent, assessments of disease extent and severity. Radially sampled averaged magnetization inversion recovery acquisitions (rAMIRA) magnetic resonance imaging enables gray matter (GM) and white matter (WM) area quantitation in the cervical and thoracic spinal cord (SC) with optimized contrast. We aimed to investigate rAMIRA-derived SC GM and SC WM areas and their association with clinical phenotype and disability in ALS.

METHODS

A total of 36 patients with ALS (mean [SD] age 61.7 [12.6] years, 14 women) and 36 healthy, age- and sex-matched controls (HCs; mean [SD] age 63.1 [12.1] years, 14 women) underwent two-dimensional axial rAMIRA imaging at the inter-vertebral disc levels C2/3-C5/C6 and the lumbar enlargement level Tmax. ALS Functional Rating Scale-revised (ALSFRS-R) score, muscle strength, and sniff nasal inspiratory pressure (SNIP) were assessed.

RESULTS

Compared to HCs, GM and WM areas were reduced in patients at all cervical levels (p < 0.0001). GM area (p = 0.0001), but not WM area, was reduced at Tmax. Patients with King's Stage 3 showed significant GM atrophy at all levels, while patients with King's Stage 1 showed significant GM atrophy selectively at Tmax. SC GM area was significantly associated with muscle force at corresponding myotomes. GM area at C3/C4 was associated with ALSFRS-R (p < 0.001) and SNIP (p = 0.0016).

CONCLUSION

Patients with ALS assessed by rAMIRA imaging show significant cervical and thoracic SC GM and SC WM atrophy. SC GM area correlates with muscle strength and clinical disability. GM area reduction at Tmax may be an early disease sign. Longitudinal studies are warranted.

Multimodal layer modelling reveals in vivo pathology in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing neurodegenerative disease characterized by the loss of motor control. Current understanding of ALS pathology is largely based on post-mortem investigations at advanced disease stages. A systematic in vivo description of the microstructural changes that characterize early stage ALS, and their subsequent development, is so far lacking. Recent advances in ultra-high field (7 T) MRI data modelling allow us to investigate cortical layers in vivo. Given the layer-specific and topographic signature of ALS pathology, we combined submillimetre structural 7 T MRI data (qT1, QSM), functional localizers of body parts (upper limb, lower limb, face) and layer modelling to systematically describe pathology in the primary motor cortex (M1), in 12 living ALS patients with reference to 12 matched controls. Longitudinal sampling was performed for a subset of patients. We calculated multimodal pathology maps for each layer (superficial layer, layer 5a, layer 5b, layer 6) of M1 to identify hot spots of demyelination, iron and calcium accumulation in different cortical fields. We show preserved mean cortical thickness and layer architecture of M1, despite significantly increased iron in layer 6 and significantly increased calcium in layer 5a and superficial layer, in patients compared to controls. The behaviourally first-affected cortical field shows significantly increased iron in L6 compared to other fields, while calcium accumulation is atopographic and significantly increased in the low myelin borders between cortical fields compared to the fields themselves. A subset of patients with longitudinal data shows that the low myelin borders are particularly disrupted and that calcium hot spots, but to a lesser extent iron hot spots, precede demyelination. Finally, we highlight that a very slow progressing patient (Patient P4) shows a distinct pathology profile compared to the other patients. Our data show that layer-specific markers of in vivo pathology can be identified in ALS patients with a single 7 T MRI measurement after first diagnosis, and that such data provide critical insights into the individual disease state. Our data highlight the non-topographic architecture of ALS disease spread and the role of calcium, rather than iron accumulation, in predicting future demyelination. We also highlight a potentially important role of low myelin borders, that are known to connect to multiple areas within the M1 architecture, in disease spread. Finally, the distinct pathology profile of a very-slow progressing patient (Patient P4) highlights a distinction between disease duration and progression. Our findings demonstrate the importance of in vivo histology imaging for the diagnosis and prognosis of neurodegenerative diseases such as ALS.

Regional spreading pattern is associated with clinical phenotype in amyotrophic lateral sclerosis

Increasing evidence shows that disease spreading in amyotrophic lateral sclerosis (ALS) follows a preferential pattern with more frequent involvement of contiguous regions from the site of symptom onset. The aim of our study was to assess if: (i) the burden of upper (UMN) and lower motor neuron (LMN) involvement influences directionality of disease spreading; (ii) specific patterns of disease progression are associated with motor and neuropsychological features of different ALS subtypes (classic, bulbar, primary lateral sclerosis, UMN-predominant, progressive muscular atrophy, flail arm, flail leg); and (iii) specific clinical features may help identify ALS subtypes, which remain localized to the site of onset for a prolonged time (regionally entrenching ALS). A single-centre, retrospective cohort of 913 Italian ALS patients was evaluated to assess correlations between directionality of the disease process after symptom onset and motor/neuropsychological phenotype. All patients underwent an extensive evaluation including the following clinical scales: Penn Upper Motor Neuron Score (PUMNS), MRC Scale for Muscle Strength and the Edinburgh Cognitive and Behavioural ALS Screen (ECAS). The most frequent initial spreading pattern was that towards adjacent horizontal regions (77.3%), which occurred preferentially in patients with lower MRC scores (P = 0.038), while vertical diffusion (21.1%) was associated with higher PUMNS (P < 0.001) and with reduced survival (P < 0.001). Non-contiguous disease spreading was associated with more severe UMN impairment (P = 0.003), while contiguous disease pattern with lower MRC scores. Furthermore, non-contiguous disease spreading was associated with more severe cognitive impairment in both executive and visuospatial ECAS domains. Individuals with regionally entrenching ALS were more frequently female (45.6% versus 36.9%; P = 0.028) and had higher frequencies of symmetric disease onset (40.3% versus 19.7%; P < 0.001) and bulbar phenotype (38.5% versus 16.4%; P < 0.001). Our study suggests that motor phenotypes characterized by a predominant UMN involvement are associated with a vertical pattern of disease progression reflecting ipsilateral spreading within the motor cortex, while those with predominant LMN involvement display more frequently a horizontal spreading from one side of the spinal cord to the other. These observations raise the hypothesis that one of the mechanisms underlying disease spreading in ALS pathology is represented by diffusion of toxic factors in the neuron microenvironment. Finally, it is possible that in our cohort, regionally entrenching ALS forms are mainly observed in patients with atypical bulbar phenotypes, characterized by a slowly progressive course and relatively benign prognosis.

Intercellular transmission of pathogenic proteins in ALS: Exploring the pathogenic wave

In patients with amyotrophic lateral sclerosis (ALS), disease symptoms and pathology typically spread in a predictable spatiotemporal pattern beginning at a focal site of onset and progressing along defined neuroanatomical tracts. Like other neurodegenerative diseases, ALS is characterized by the presence of protein aggregates in postmortem patient tissue. Cytoplasmic, ubiquitin-positive aggregates of TDP-43 are observed in approximately 97% of sporadic and familial ALS patients, while SOD1 inclusions are likely specific to cases of SOD1-ALS. Additionally, the most common subtype of familial ALS, caused by a hexanucleotide repeat expansion in the first intron of the C9orf72 gene (C9-ALS), is further characterized by the presence of aggregated dipeptide repeat proteins (DPRs). As we will describe, cell-to-cell propagation of these pathological proteins tightly correlates with the contiguous spread of disease. While TDP-43 and SOD1 are capable of seeding protein misfolding and aggregation in a prion-like manner, C9orf72 DPRs appear to induce (and transmit) a 'disease state' more generally. Multiple mechanisms of intercellular transport have been described for all of these proteins, including anterograde and retrograde axonal transport, extracellular vesicle secretion, and macropinocytosis. In addition to neuron-to-neuron transmission, transmission of pathological proteins occurs between neurons and glia. Given that the spread of ALS disease pathology corresponds with the spread of symptoms in patients, the various mechanisms by which ALS-associated protein aggregates propagate through the central nervous system should be closely examined.

Verification of propagation hypothesis in patients with sporadic hand onset amyotrophic lateral sclerosis

OBJECTIVE

If lesions in sporadic amyotrophic lateral sclerosis (ALS) originate from a single focal onset site and spread contiguously by prion-like cell-to-cell propagation at a constant speed, the lesion spread time should be proportional to the anatomical distance. We verify this model in the patients.

METHODS

In 29 sporadic ALS patients with hand onset followed by spread to shoulder and leg, we retrospectively evaluated the inter/intra-regional spread time ratio: time interval of symptoms from hand-to-leg divided by that from hand-to-shoulder. We also obtained the corresponding inter-/intra-regional distance ratios of spinal cord from magnetic resonance imaging of 12 patients, and those of primary motor cortex from coordinates using neuroimaging software.

RESULTS

Inter-/intra-regional spread time ratios ranged from 0.29 to 6.00 (median 1.20). Distance ratios ranged from 1.85 to 2.86 in primary motor cortex and from 5.79 to 8.67 in spinal cord. Taken together with clinical manifestations, of 27 patients with the requisite information available, lesion spreading was consistent with the model in primary motor cortex in 4 (14.8%) patients, and in spinal cord in only 1 (3.7%) patient. However, in more patients (12 of 29 patients: 41.4%), the inter-regional spread times in a long anatomical distance of hand-to-leg were shorter than or equal to the intra-regional spread times in a short anatomical distance of hand-to-shoulder.

CONCLUSION

Contiguous cell-to-cell propagation at a constant speed might not play a major role at least in distant lesion spreading of ALS. Several mechanisms can be responsible for progression in ALS.

Clinical Profiles and Patterns of Neurodegeneration in Amyotrophic Lateral Sclerosis: A Cluster-Based Approach Based on MR Imaging Metrics

BACKGROUND AND PURPOSE

The previous studies described phenotype-associated imaging findings in amyotrophic lateral sclerosis (ALS) with a prior categorization of patients based on clinical characteristics. We investigated the natural segregation of patients through a radiologic cluster-based approach without a priori patient categorization using 3 well-known prognostic MR imaging biomarkers in ALS, namely bilateral precentral and paracentral gyrus cortical thickness and medulla oblongata volume. We aimed to identify clinical/prognostic features that are cluster-associated.

MATERIALS AND METHODS

Bilateral precentral and paracentral gyri and medulla oblongata volume were calculated using FreeSurfer in 90 patients with amyotrophic lateral sclerosis and 25 healthy controls. A 2-step cluster analysis was performed using precentral and paracentral gyri (averaged pair-wise) and medulla oblongata volume.

RESULTS

We identified 3 radiologic clusters: 28 (31%) patients belonged to "cluster-1"; 51 (57%), to "cluster 2"; and 11 (12%), to "cluster 3." Patients in cluster 1 showed statistically significant cortical thinning of the analyzed cortical areas and lower medulla oblongata volume compared with subjects in cluster 2 and cluster 3, respectively. Patients in cluster 3 exhibited significant cortical thinning of both paracentral and precentral gyri versus those in cluster 2, and this latter cluster showed lower medulla oblongata volume than cluster 3. Patients in cluster 1 were characterized by older age, higher female prevalence, greater disease severity, higher progression rate, and lower survival compared with patients in clusters 2 and 3.

CONCLUSIONS

Patients with amyotrophic lateral sclerosis spontaneously segregate according to age and sex-specific patterns of neurodegeneration. Some patients with amyotrophic lateral sclerosis showed an early higher impairment of cortical motor neurons with relative sparing of bulbar motor neurons (cluster 3), while others expressed an opposite pattern (cluster 2). Moreover, 31% of patients showed an early simultaneous impairment of cortical and bulbar motor neurons (cluster 1), and they were characterized by higher disease severity and lower survival.

Respiratory onset in amyotrophic lateral sclerosis: clinical features and spreading pattern

Objective To describe the clinical features and progression of patients with respiratory onset amyotrophic lateral sclerosis (ALS). Methods: We analyzed the clinical features, including respiratory tests, functional score, noninvasive ventilation (NIV) time and survival of ALS patients with respiratory-onset in our database consisting of 1688 patients. In a subset of 625 ALS patients we analyzed the spreading pattern to other bodily regions. Results: We included 1579 patients with ALS. Sixty-three patients (4%) presented respiratory-onset (79.4% men, mean onset-age 67.7 ± 8.9yrs). All had predominant LMN involvement, and significant weight loss (>10%) was identified in 38.9%. The respiratory tests were abnormal in these respiratory-onset patients (p < 0.001). ALSFRS-R respiratory subscore was lower in this population (p < 0.001). NIV was adapted in 84.1%, sooner than in the larger group of ALS patients (p < 0.001), and survival from disease onset was shorter (p < 0.001). Respiratory-onset was a predictor of time to NIV (X²=42.0, p < 0.001) and of survival (X²=7.1, p = 0.008). The spreading pattern was studied in 18 patients with isolated respiratory-onset. The progression interval to the 2nd region was 4.7 ± 5.7mo and to a 3rd region 6.1 ± 8.7mo. Different patterns of spread had no impact on survival. Conclusions: This phenotype is typically seen in emaciated older men with predominant lower motor neuron involvement, and is associated with diaphragm paresis and central respiratory involvement. NIV adaptation is rapid but total survival is shorter than in the other patients. Spreading pattern did not affect time to NIV adaptation or total survival, as NIV support is a modifying treatment in the course of ALS.

Spatial-temporal pattern of propagation in amyotrophic lateral sclerosis and effect on survival: a cohort study

BACKGROUND

Clarification of propagation patterns in amyotrophic lateral sclerosis (ALS) is challenging, but implicational for individual prognostication and clinical trials design. However, systematic knowledge lacks. Therefore, we aim to characterize the spatial and temporal features of propagation patterns in ALS, and to evaluate the association between propagation patterns and survival.

METHODS

A cohort of 833 patients with ALS were diagnosed between January 2018 and December 2019, and followed to August 2021. Spatial and temporal features of propagation patterns were determined based on the involved functional regions (bulbar, cervical, thoracic/respiratory and lumbar) in time order. The final propagation pattern was identified in patients with at least 3 functional regions involved. Kaplan-Meier analysis and Cox regression analysis were performed.

RESULTS

During a median follow-up of 21.2 months, 19 final propagation patterns were identified in 657 (78.9%) patients. In survival analysis, we found that the more forward of respiratory involved, the higher the risk of death (1st: hazard ratio [HR], 3.35; 95% CI, 1.23-9.15; 2nd: HR, 2.45; 95% CI, 1.55-3.87; 3rd: HR, 1.94; 95% CI, 1.52-2.49), adjusting for age, sex, diagnostic delay, the revised ALS Functional Rating Scale score, cognitive impairment and riluzole. Shorter interval time between involved regions was an independent adverse prognostic factor.

CONCLUSIONS

The propagation patterns of ALS are varied. The position of respiratory involved and interval time between involved functional regions are predictors for prognosis.

A machine-learning based objective measure for ALS disease severity

Amyotrophic Lateral Sclerosis (ALS) disease severity is usually measured using the subjective, questionnaire-based revised ALS Functional Rating Scale (ALSFRS-R). Objective measures of disease severity would be powerful tools for evaluating real-world drug effectiveness, efficacy in clinical trials, and for identifying participants for cohort studies. We developed a machine learning (ML) based objective measure for ALS disease severity based on voice samples and accelerometer measurements from a four-year longitudinal dataset. 584 people living with ALS consented and carried out prescribed speaking and limb-based tasks. 542 participants contributed 5814 voice recordings, and 350 contributed 13,009 accelerometer samples, while simultaneously measuring ALSFRS-R scores. Using these data, we trained ML models to predict bulbar-related and limb-related ALSFRS-R scores. On the test set (n = 109 participants) the voice models achieved a multiclass AUC of 0.86 (95% CI, 0.85–0.88) on speech ALSFRS-R prediction, whereas the accelerometer models achieved a median multiclass AUC of 0.73 on 6 limb-related functions. The correlations across functions observed in self-reported ALSFRS-R scores were preserved in ML-derived scores. We used these models and self-reported ALSFRS-R scores to evaluate the real-world effects of edaravone, a drug approved for use in ALS. In the cohort of 54 test participants who received edaravone as part of their usual care, the ML-derived scores were consistent with the self-reported ALSFRS-R scores. At the individual level, the continuous ML-derived score can capture gradual changes that are absent in the integer ALSFRS-R scores. This demonstrates the value of these tools for assessing disease severity and, potentially, drug effects.

Motor cortical patterns of upper motor neuron pathology in amyotrophic lateral sclerosis: A 3 T MRI study with iron-sensitive sequences

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M1 regions associated with the body site of onset are frequently affected at MRI.

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The simultaneous involvement of both homologous M1 regions is frequent.

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The T2* hypointensity in non-contiguous M1 regions seems rare.

Background

Patterns of initiation and propagation of disease in Amyotrophic Lateral Sclerosis (ALS) are still partly unknown. Single or multiple foci of neurodegeneration followed by disease diffusion to contiguous or connected regions have been proposed as mechanisms underlying symptom occurrence. Here, we investigated cortical patterns of upper motor neuron (UMN) pathology in ALS using iron-sensitive MR imaging.

Methods

Signal intensity and magnetic susceptibility of the primary motor cortex (M1), which are associated with clinical UMN burden and neuroinflammation, were assessed in 78 ALS patients using respectively T2*-weighted images and Quantitative Susceptibility Maps. The signal intensity of the whole M1 and each of its functional regions was rated as normal or reduced, and the magnetic susceptibility of each M1 region was measured.

Results

The highest frequencies of T2* hypointensity were found in M1 regions associated with the body sites of symptom onset. Homologous M1 regions were both hypointense in 80–93 % of patients with cortical abnormalities, and magnetic susceptibility values measured in homologous M1 regions were strongly correlated with each other (ρ = 0.88; p < 0.0001). In some cases, the T2* hypointensity was detectable in two non-contiguous M1 regions but spared the cortex in between.

Conclusions

M1 regions associated with the body site of onset are frequently affected at imaging. The simultaneous involvement of both homologous M1 regions is frequent, followed by that of adjacent regions; the affection of non-contiguous regions, instead, seems rare. This type of cortical involvement suggests the interhemispheric connections as one of the preferential paths for the UMN pathology diffusion in ALS.

Weak shoulder and arm sparing signs in amyotrophic lateral sclerosis

INTRODUCTION/AIMS

A number of signs of selective involvement have been reported in amyotrophic lateral sclerosis (ALS). In this study, we describe two new ones, "weak shoulder" and "arm sparing" signs.

METHODS

Subjects were retrospectively identified from our electrodiagnosis database. Medical Research Council scores of relevant muscles were evaluated. Weak shoulder was defined as the deltoid (Del) muscle being weaker than the biceps brachii (BB)/ triceps brachii (TB) muscles, i.e. Del was weaker than either or both of the two muscles and no stronger than either. Arm sparing was defined as both Del and the first dorsal interosseous (FDI) being weaker than BB/TB. Sensitivities of these signs were compared with other signs of selective involvement. The specificities of these signs were investigated in patients with cervical spondylotic amyotrophy (CSA) and multifocal motor neuropathy (MMN).

RESULTS

We reviewed 130 patients with ALS, 64 patients with CSA, and 16 patients with MMN. The weak shoulder and the arm sparing signs were observed in 73% and 55% of patients with ALS, 44% and 2% of patients with CSA (93% and 0% of patients with proximal CSA), respectively, and no patients with MMN. The sensitivity of the weak shoulder was higher than conventional signs, whereas that of the arm sparing sign was no different from them.

DISCUSSION

The weak shoulder sign was highly sensitive in ALS, and was specific in comparison with MMN. The arm sparing sign was highly specific for ALS. The two new signs are promising as clinical clues to diagnosing ALS.

Role of neuro-sonography of peripheral nerves as a diagnostic and a differentiation tool of amyotrophic lateral sclerosis

Background

Motor neuron disease is a heterogeneous group of progressive neurodegenerative disorders, most common of which is amyotrophic lateral sclerosis (ALS). There are many clinical and radiological criteria to diagnose amyotrophic lateral sclerosis and to differentiate it from other motor neuron disease and neurodegenerative disorders. Neuro-sonography is one of the easily applied tools to diagnose and differentiate ALS. ALS diagnosis is delayed up to 3 years according to some authors due to the wide differential diagnosis, with cervical degeneration being a common misdiagnosis. The objective of this study was to evaluate the role of neuro-sonography in diagnosis and differentiation of amyotrophic lateral sclerosis from other causes of progressive mixed upper and lower motor neuron lesion.

Results

A total neuro-sonography score at a cut-off point (≤ 127) predicted patients with ALS, with good (85%) accuracy, sensitivity = 73% and specificity = 83% (p < 0.01) and Lt median arm score at a cut-off point (≤ 6) predicted patients with ALS, with good (88%) accuracy, sensitivity = 86% and specificity = 86% (p < 0.01) and the median nerve at the arm level was the most sensitive and specific nerve to predict patients with ALS.

Conclusion

Neuro-sonography of peripheral nerves is a recent, noninvasive, accessible technique that can be used in early diagnosis of ALS.

Time of symptoms beyond the bulbar region predicts survival in bulbar onset amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. Spreading pattern and time interval of spreading are getting more and more attention. The aim of present study was to investigate spreading pattern in bulbar onset ALS patients and to explore the relationship between time interval of spreading and survival.

METHODS

ALS patients with bulbar onset diagnosed at Chinese PLA General Hospital from January 2015 to December 2018 were recruited. Clinical features including gender, onset age, diagnostic delay, the second involved region (SIR), time of symptoms beyond the bulbar region, forced vital capacity (FVC), ALSFRS-R score, electromyography results, and survival time were retrospectively collected.

RESULTS

A total of 96 bulbar onset ALS patients were collected. Overall patients showed female predominance. Median age at onset was 56 years. Median diagnostic delay was 8.5 months. Median time of symptoms beyond the bulbar region (TBBR) was 7 months. Median ALSFRS-R score at baseline was 40. Fifty-six (58.3%) patients' SIR were upper limb, 6 (6.3%) patients' SIR were lower limb, 3 (3.1%) patients' SIR were upper and lower limbs, and 5 (5.2%) patients' SIR were thoracic region. Twenty-six (27.1%) patients did not report SIR. The median survival time of patients with TBBR ≥ 7 months was significantly longer than that with TBBR < 7 month. Multivariate Cox regression showed that onset age and TBBR were prognostic factors.

CONCLUSIONS

In bulbar onset ALS patients, cervical region is the second most common SIR. TBBR is an independent prognostic factor.

Higher incidence of cervical spinal cord compression in amyotrophic lateral sclerosis: a single-institute cohort study

BACKGROUND

Although the relationship between amyotrophic lateral sclerosis (ALS) and cervical spondylotic myelopathy (CSM) is important, data relating to CSM complications in ALS remain lacking.

PURPOSE

We aimed to investigate and validate the spinal cord conditions of ALS patients.

MATERIALS AND METHODS

We recruited all patients diagnosed with ALS, Parkinson's disease (PD), or chronic inflammatory demyelinating polyneuropathy (CIDP) who were admitted to our department from April 1, 2017, to March 31, 2020. We analyzed the cervical or thoracolumbar magnetic resonance imaging (MRI) scans of these 128 patients. Data relating to spondylosis, cord compression, spinal canal diameter, spinal cord diameter, and the closest distance between the cervical spinal canal and cord were validated using MRI.

RESULTS

Of the 128 patients, 52 had ALS, 48 had PD, and 28 had CIDP. The proportions of both cervical spondylosis and cervical cord compression were highest in the ALS group compared with the other patient groups (p < 0.05). The proportion of cervical spondylosis in ALS patients reached 38.3%, and that of cervical cord compression reached 53.2%. The closest distance between the cervical spinal canal and cord was also significantly smaller in ALS patients compared with CIDP patients (p < 0.05). In contrast to the cervical cord findings, there were no significant differences in the thoracolumbar cord between ALS patients and the other patient groups.

CONCLUSIONS

Of the three disease groups, the proportion of CSM was highest in ALS patients. Furthermore, cervical cord conditions were significantly more crowded in the ALS patients than in the other patient groups.

The rostral to caudal gradient of clinical and electrophysiological features in sporadic amyotrophic lateral sclerosis with bulbar-onset

Objective

Amyotrophic lateral sclerosis (ALS) with bulbar-onset (BO-ALS) tends to propagate to the adjacent anatomical regions symptomatically. However, the spreading pattern of clinical and electrophysiological features is not well documented.

Methods

This retrospective study enrolled consecutive patients with sporadic BO-ALS. The clinical progression and electrophysiological data by electromyography examination were retrospectively analysed based on information from the medical records.

Results

The study enrolled 57 patients: 43 presented with contiguous (37 of 57) or non-contiguous (6 of 57) progression clinically; and 14 patients did not present with symptomatic propagation to other spinal segments. Lower motor neuron dysfunction was more frequently involved in the bulbar and cervical segments and less in the thoracic and lumbosacral segments. As a result, a small proportion of patients had intact thoracic paraspinal or leg muscles or both by electromyography examination. Furthermore, the patients with diagnostic latency ≤6 months showed a significantly lower incidence of neurogenic changes in the lumbosacral spinal cord compared with those with diagnostic latency > 6 months.

Conclusion

This current study demonstrated a relative rostral–caudal descending gradient of lower motor neuron dysfunction in patients with BO-ALS. These results suggest that follow-up EMG might be necessary for a proportion of patients.

Phenotypic variability in amyotrophic lateral sclerosis

Clinically, ALS phenotypes depend on the areas of the body that are affected, the different degrees of involvement of upper and lower motor neurons, the degrees of involvement of other systems, particularly cognition and behavior, and rates of progression. Phenotypic variability of ALS is characteristic and can be declined on the distribution of motor manifestations but also on the presence of extra-motor signs present in a variable manner in ALS patients. Neuropathologically, ALS is defined by the loss of UMN and LMN and the presence of two representative motor neuronal cytoplasmic inclusions, Bunina bodies and 43kDa Transactivation Response DNA Binding Protein (TDP-43) - positive cytoplasmic inclusions. The distribution of cytopathology and neuronal loss in patients is variable and this variability is directly related to phenotypic variability. Key regulators of phenotypic variability in ALS have not been determined. The functional decrement of TDP-43, and region-specific neuronal susceptibility to ALS, may be involved. Due to the selective vulnerability among different neuronal systems, lesions are multicentric, region-oriented, and progress at different rates. They may vary from patient to patient, which may be linked to the clinicopathological variability across patients.

Progressive supranuclear palsy: Neuropathology of patients with a short disease duration due to unexpected death

Progressive supranuclear palsy (PSP) presents with a wide variety of signs/symptoms, making early initial diagnosis difficult. We investigated the clinical and neuropathological features of five patients with autopsy-proven PSP of short duration, ranging from 11 to 41 months (average, 26.2 months) due to unexpected death, focusing particularly on the distribution and severity of neuronal loss as well as neuronal and glial tau pathology in the affected brain. Clinical features were studied retrospectively through careful review of the medical records, and neuropathological examinations were carried out, along with tau immunohistochemistry using a monoclonal antibody AT8. These patients were diagnosed as having probable PSP (n = 4) and suggestive PSP (n = 1), respectively. In all cases, neuronal loss was evident in the substantia nigra, subthalamic nucleus, globus pallidus, and locus ceruleus. AT8-identified tau lesions, that is, pretangles/neurofibrillary tangles (PTs/NFTs), tufted astrocytes (TAs), and coiled bodies/neuropil threads (CBs/NTs), were distributed widely in the brain regions, especially in patients with longer disease duration. All cases showed variation in the regional tau burden among PTs/NFTs, TAs, and CBs/NTs. There was also a tendency for tau deposition to be more predominant in neuronal cells in the brainstem and cerebellum and in glial cells in the cerebral cortex and subcortical gray matter. These findings suggest that in PSP, the initial signs/symptoms are associated with degeneration and subsequent death of neurons with pathological tau deposition, and that the tau deposition in neuronal cells is independent of that in glial cells.

Defining novel functions for cerebrospinal fluid in ALS pathophysiology

Despite the considerable progress made towards understanding ALS pathophysiology, several key features of ALS remain unexplained, from its aetiology to its epidemiological aspects. The glymphatic system, which has recently been recognised as a major clearance pathway for the brain, has received considerable attention in several neurological conditions, particularly Alzheimer's disease. Its significance in ALS has, however, been little addressed. This perspective article therefore aims to assess the possibility of CSF contribution in ALS by considering various lines of evidence, including the abnormal composition of ALS-CSF, its toxicity and the evidence for impaired CSF dynamics in ALS patients. We also describe a potential role for CSF circulation in determining disease spread as well as the importance of CSF dynamics in ALS neurotherapeutics. We propose that a CSF model could potentially offer additional avenues to explore currently unexplained features of ALS, ultimately leading to new treatment options for people with ALS.

Cerebrospinal fluid cytotoxicity in amyotrophic lateral sclerosis: a systematic review of in vitro studies

Various studies have suggested that a neurotoxic cerebrospinal fluid profile could be implicated in amyotrophic lateral sclerosis. Here, we systematically review the evidence for cerebrospinal fluid cytotoxicity in amyotrophic lateral sclerosis and explore its clinical correlates. We searched the following databases with no restrictions on publication date: PubMed, Embase and Web of Science. All studies that investigated cytotoxicity in vitro following exposure to cerebrospinal fluid from amyotrophic lateral sclerosis patients were considered for inclusion. Meta-analysis could not be performed, and findings were instead narratively summarized. Twenty-eight studies were included in our analysis. Both participant characteristics and study conditions including cerebrospinal fluid concentration, exposure time and culture model varied considerably across studies. Of 22 studies assessing cell viability relative to controls, 19 studies reported a significant decrease following exposure to cerebrospinal fluid from patients with amyotrophic lateral sclerosis, while three early studies failed to observe any difference. Seven of eight studies evaluating apoptosis observed significant increases in the levels of apoptotic markers following exposure to cerebrospinal fluid from patients with amyotrophic lateral sclerosis, with the remaining study reporting a qualitative difference. Although five studies investigated the possible relationship between cerebrospinal fluid cytotoxicity and patient characteristics, such as age, gender and disease duration, none demonstrated an association with any of the factors. In conclusion, our analysis suggests that cerebrospinal fluid cytotoxicity is a feature of sporadic and possibly also of familial forms of amyotrophic lateral sclerosis. Further research is, however, required to better characterize its underlying mechanisms and to establish its possible contribution to amyotrophic lateral sclerosis pathophysiology.

Spreading in ALS: The relative impact of upper and lower motor neuron involvement

Objective

To investigate disease spread in amyotrophic lateral sclerosis (ALS), and determine the influence of lower (LMN) and upper motor neuron (UMN) involvement.

Methods

We assessed disease spread in ALS in 1376 consecutively studied patients, from five European centers, applying an agreed proforma to assess LMN and UMN signs. We defined the pattern of disease onset and progression from predominant UMN or lower motor neuron (LMN) dysfunction in bulbar, upper limbs, lower limbs, and thoracic regions Non‐linear regression analysis was applied to fit the data to a model that described the relation between two random variables, graphically represented by an inverse exponential curve. We analyzed the probability, rate of spread, and both combined (area under the curve).

Results

We found that progression was more likely and quicker to or from the region of onset to close spinal regions. When the disease had a limb onset, bulbar motor neurons were more resistant. Furthermore, in the same time frame more patients progressed from bulbar to lower limbs than vice‐versa, whether predominantly UMN or LMN involvement. Patients with initial thoracic involvement had a higher probability for rapid change. The presence of predominant UMN signs was associated with a faster caudal progression.

Interpretation

Contiguous progression was leading pattern, and predominant UMN involvement is important in shortening the time for cranial‐caudal spread. Our results can best be fitted to a model of independent LMN and UMN degeneration, with regional progression of LMN degeneration mostly by contiguity. UMN lesion causes an acceleration of rostral‐caudal LMN loss.

ALS phenotype is influenced by age, sex, and genetics: A population-based study

OBJECTIVE

To assess the determinants of amyotrophic lateral sclerosis (ALS) phenotypes in a population-based cohort.

METHODS

The study population included 2,839 patients with ALS diagnosed in Piemonte, Italy (1995-2015). Patients were classified according to motor (classic, bulbar, flail arm, flail leg, predominantly upper motor neuron [PUMN], respiratory) and cognitive phenotypes (normal, ALS with cognitive impairment [ALSci], ALS with behavioral impairment [ALSbi], ALSci and ALSbi combined [ALScbi], ALS-frontotemporal dementia [FTD]). Binary logistic regression analysis was adjusted for sex, age, and genetics.

RESULTS

Bulbar phenotype correlated with older age (p < 0.0001), women were more affected than men at increasing age (p < 0.0001), classic with younger age (p = 0.029), men were more affected than women at increasing age (p < 0.0001), PUMN with younger age (p < 0.0001), flail arm with male sex (p < 0.0001) and younger age (p = 0.04), flail leg with male sex with increasing age (p = 0.008), and respiratory with male sex (p < 0.0001). C9orf72 expansions correlated with bulbar phenotype (p < 0.0001), and were less frequent in PUMN (p = 0.041); SOD1 mutations correlated with flail leg phenotype (p < 0.0001), and were less frequent in bulbar (p < 0.0001). ALS-FTD correlated with C9orf72 (p < 0.0001) and bulbar phenotype (p = 0.008), ALScbi with PUMN (p = 0.014), and ALSci with older age (p = 0.008).

CONCLUSIONS

Our data suggest that the spatial-temporal combination of motor and cognitive events leading to the onset and progression of ALS is characterized by a differential susceptibility to the pathologic process of motor and prefrontal cortices and lower motor neurons, and is influenced by age, sex, and gene variants. The identification of those factors that regulate ALS phenotype will allow us to reclassify patients into pathologically homogenous subgroups, responsive to targeted personalized therapies.

Phenotypic variability and its pathological basis in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is characterized by its inherent clinicopathological variability. The concurrence of upper and lower motor neuron signs is a common feature in the majority of patients with ALS. However, some patients manifest an atypical clinical course, with only upper or lower motor neuron signs, or various extra-motor symptoms including cognitive dysfunction, parkinsonism, autonomic dysfunction, or ophthalmoparesis. This variability indicates different manifestations of ALS and is reflected by ALS pathology spreading into the central nervous system. The presence of cytoplasmic inclusions positive for transactivation response DNA-binding protein 43 kDa (TDP-43) is a key feature in ALS. Loss of TDP-43 from the nucleus and its subsequent aggregation in the cytoplasm may occur in susceptible regions and may be associated with neuronal loss. However, in some regions, there is no apparent neuronal loss while TDP-43 accumulation is evident; in contrast, in other regions, neuronal loss is apparent without any evidence of TDP-43 accumulation. Therefore, in addition to TDP-43 dysfunction, underlying region-specific cellular vulnerability may exist in the upper and lower motor neurons and frontotemporal system in patients with ALS. The microscopic discrepancy and selective vulnerability may be linked to the macroscopic propensities of the sites of onset, and may also determine the direction and rate of progression of the lesions. Thus, there may be multicentric sites of onset, region-oriented disease development, and different speeds of disease progression across patients with ALS. ALS lesions occur in motor-related areas but may spread to neighboring areas. However, since lesions may spread in a discontinuous manner, and the dynamics of disease propagation have not been able to be identified, it remains controversial whether the stepwise appearance of TDP-43-positive inclusions is based on direct cell-to-cell protein propagation. Further understanding of the phenotypic variability of ALS and its pathological basis may serve as a guide for investigating the underlying pathogenesis of ALS.

Discontiguous or Contiguous Spread Patterns Affect the Functional Staging in Patients With Sporadic Amyotrophic Lateral Sclerosis

Objective: This study aimed to investigate whether the spread pattern affects functional staging in amyotrophic lateral sclerosis (ALS). We examined the spreading patterns of disease following symptom onset and the affected regions in ALS using electromyography. Methods: This study reviewed the medical records of 103 patients with sporadic ALS in the Second Hospital of Hebei Medical University from 2012 to 2017. According to the clinical manifestation and the distribution of the affected regions on electromyography, spread patterns were classified as discontiguous or contiguous. The patients were graded according to the ALS-Milano-Torino staging (MITOS) system. Results: The clinical spread patterns were contiguous in 91.5% of patients and discontiguous in 8.5% of patients. The electrophysiological spread patterns were contiguous in 87.4% of patients and discontiguous in 12.6% of patients. Sex, age, or delay in diagnosis did not affect the clinical or electrophysiological spread patterns. No significant correlation was observed between the clinical classification and the ALS-MITOS grade, but the electrophysiological spread was significantly correlated with the ALS-MITOS. Conclusion: This study provides evidence that not all ALS patients show contiguous clinical or electrophysiological spread patterns. The electrophysiological spread pattern can affect the functional staging in ALS patients.

A hyperthermophilic protein G variant engineered via directed evolution prevents the formation of toxic SOD1 oligomers

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by selective death of motor neurons in the brainstem, motor cortex, and spinal cord, leading to muscle atrophy and eventually to death. It is currently held that various oligomerization-inducing mutations in superoxide dismutase 1 (SOD1), an amyloid-forming protein, may be implicated in the familial form of this fast-progressing highly lethal neurodegenerative disease. A possible therapeutic approach could therefore lie in developing inhibitors to SOD1 mutants. By screening a focused mutagenesis library, mutated randomly in specific "stability patch" positions of the B1 domain of protein G (HTB1), we previously identified low affinity inhibitors of aggregation of SOD1_G93A and SOD1_G85R mutants. Herein, with the aim to generate a more potent inhibitor with higher affinity to SOD1 mutants, we employed an unbiased, random mutagenesis approach covering the entire sequence space of HTB1 to optimize as yet undefined positions for improved interactions with SOD1. Using affinity maturation screens in yeast, we identified a variant, which we designated HTB1_M3 , that bound strongly to SOD1 misfolded mutants but not to wild-type SOD1. In-vitro aggregation assays indicated that in the presence of HTB1_M3 misfolded SOD1 assembled into oligomeric species that were not toxic to NSC-34 neuronal cells. In addition, when NSC-34 cells were exposed to misfolded SOD1 mutants, either soluble or preaggregated, in the presence of HTB1_M3 , this inhibitor prevented the prion-like propagation of SOD1 from one neuronal cell to another by blocking the penetration of SOD1 into the neuronal cells.

The role of liquid-liquid phase separation in aggregation of the TDP-43 low-complexity domain

Pathological aggregation of the transactive response DNA-binding protein of 43 kDa (TDP-43) is associated with several neurodegenerative disorders, including ALS, frontotemporal dementia, chronic traumatic encephalopathy, and Alzheimer's disease. TDP-43 aggregation appears to be largely driven by its low-complexity domain (LCD), which also has a high propensity to undergo liquid-liquid phase separation (LLPS). However, the mechanism of TDP-43 LCD pathological aggregation and, most importantly, the relationship between the aggregation process and LLPS remains largely unknown. Here, we show that amyloid formation by the LCD is controlled by electrostatic repulsion. We also demonstrate that the liquid droplet environment strongly accelerates LCD fibrillation and that its aggregation under LLPS conditions involves several distinct events, culminating in rapid assembly of fibrillar aggregates that emanate from within mature liquid droplets. These combined results strongly suggest that LLPS may play a major role in pathological TDP-43 aggregation, contributing to pathogenesis in neurodegenerative diseases.

Biomarkers in Neurodegenerative Diseases

The past decade has seen tremendous efforts in biomarker discovery and validation for neurodegenerative diseases. The source and type of biomarkers has continued to grow for central nervous system diseases, from biofluid-based biomarkers (blood or cerebrospinal fluid (CSF)), to nucleic acids, tissue, and imaging. While DNA remains a predominant biomarker used to identify familial forms of neurodegenerative diseases, various types of RNA have more recently been linked to familial and sporadic forms of neurodegenerative diseases during the past few years. Imaging approaches continue to evolve and are making major contributions to target engagement and early diagnostic biomarkers. Incorporation of biomarkers into drug development and clinical trials for neurodegenerative diseases promises to aid in the development and demonstration of target engagement and drug efficacy for neurologic disorders. This review will focus on recent advancements in developing biomarkers for clinical utility in Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS).

Patterns of symptom development in patients with motor neuron disease

OBJECTIVE

To investigate whether symptom development in motor neuron disease (MND) is a random or organized process.

METHODS

Six hundred patients with amyotrophic lateral sclerosis (ALS), upper motor neuron (UMN) or lower motor neuron (LMN) phenotypes were invited for a questionnaire concerning symptom development. A binomial test was used to examine distribution of symptoms from site of onset. Development of symptoms over time was evaluated by Kaplan-Meier analysis.

RESULTS

There were 470 respondents (ALS = 254; LMN = 100; UMN = 116). Subsequent symptoms were more often in the contralateral limb following unilateral limb onset (ALS: arms p = 1.05 × 10^-8, legs p < 2.86 × 10^-15; LMN phenotype: arms p = 6.74 × 10^-9, legs p = 6.26 × 10^-6; UMN phenotype: legs p = 4.07 × 10^-14). In patients with limb onset, symptoms occurred significantly faster in the contralateral limb, followed by the other limbs and lastly by the bulbar region. Patterns of non-contiguous symptom development were also reported: leg symptoms followed bulbar onset in 30%, and bulbar symptoms followed leg onset in 11% of ALS patients.

CONCLUSIONS

Preferred spread of symptoms from one limb to the contralateral limb, and to adjacent sites appears to be a characteristic of MND phenotypes, suggesting that symptom spread is organized, possibly involving axonal connectivity. Non-contiguous symptom development, however, is not uncommon, and may involve other factors.

Possible concurrence of TDP-43, tau and other proteins in amyotrophic lateral sclerosis/frontotemporal lobar degeneration

Transactivation response DNA-binding protein 43 kDa (TDP-43) has been regarded as a major component of ubiquitin-positive/tau-negative inclusions of motor neurons and the frontotemporal cortices in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Neurofibrillary tangles (NFT), an example of tau-positive inclusions, are biochemically and morphologically distinguished from TDP-43-positive inclusions, and are one of the pathological core features of Alzheimer disease (AD). Although ALS/FTLD and AD are distinct clinical entities, they can coexist in an individual patient. Whether concurrence of ALS/FTLD-TDP-43 and AD-tau is incidental is still controversial, because aging is a common risk factor for ALS/FTLD and AD development. Indeed, it remains unclear whether the pathogenesis of ALS/FTLD is a direct causal link to tau accumulation. Recent studies suggested that AD pathogenesis could cause the accumulation of TDP-43, while abnormal TDP-43 accumulation could also lead to abnormal tau expression. Overlapping presence of TDP-43 and tau, when observed in a brain during autopsy, should attract attention, and should initiate the search for the pathological substrate for this abnormal protein accumulation. In addition to tau, other proteins including α-synuclein and amyloid β should be also taken into account as candidates for an interaction with TDP-43. Awareness of a possible comorbidity between TDP-43, tau and other proteins in patients with ALS/FTLD will be useful for our understanding of the influence of these proteins on the disease development and its clinical manifestation.

Spinal cord homogenates from SOD1 familial amyotrophic lateral sclerosis induce SOD1 aggregation in living cells

Mutant Cu/Zn superoxide dismutase (SOD1) can confer its misfolding on wild-type SOD1 in living cells; the propagation of misfolding can also be transmitted between cells in vitro. Recent studies identified fluorescently-tagged SOD1^G85R as a promiscuous substrate that is highly prone to aggregate by a variety of templates, in vitro and in vivo. Here, we utilized several SOD1-GFP reporter proteins with G37R, G85R, or G93A mutations in SOD1. We observed that human spinal cord homogenates prepared from SOD1 familial ALS (FALS) can induce significantly more intracellular reporter protein aggregation than spinal cord homogenates from sporadic ALS, Alzheimer’s disease, multiple system atrophy or healthy control individuals. We also determined that the induction of reporter protein aggregation by SOD1-FALS tissue homogenates can be attenuated by incubating the cells with the SOD1 misfolding-specific antibody 3H1, or the small molecule 5-fluorouridine. Our study further implicates SOD1 as the seeding particle responsible for the spread of SOD1-FALS neurodegeneration from its initial onset site(s), and demonstrates two potential therapeutic strategies for SOD1-mediated disease. This work also comprises a medium-throughput cell-based platform of screening potential therapeutics to attenuate propagated aggregation of SOD1.

Clinical Spectrum of Amyotrophic Lateral Sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is primarily characterized by progressive loss of motor neurons, although there is marked phenotypic heterogeneity between cases. Typical, or "classical," ALS is associated with simultaneous upper motor neuron (UMN) and lower motor neuron (LMN) involvement at disease onset, whereas atypical forms, such as primary lateral sclerosis and progressive muscular atrophy, have early and predominant involvement in the UMN and LMN, respectively. The varying phenotypes can be so distinctive that they would seem to have differing biology. Because the same phenotypes can have multiple causes, including different gene mutations, there may be multiple molecular mechanisms causing ALS, implying that the disease is a syndrome. Conversely, multiple phenotypes can be caused by a single gene mutation; thus, a single molecular mechanism could be compatible with clinical heterogeneity. The pathogenic mechanism(s) in ALS remain unknown, but active propagation of the pathology neuroanatomically is likely a primary component.

Regional glucose hypometabolic spread within the primary motor cortex is associated with amyotrophic lateral sclerosis disease progression: A fluoro-deoxyglucose positron emission tomography study

Objective

Here we investigate the process of neurodegeneration in amyotrophic lateral sclerosis (ALS). The relationship between the cortical field spreading of glucose metabolic decreases in the primary motor cortex (PMC) and the progression of corresponding extremity dysfunction was evaluated using [¹⁸F] fluoro-deoxyglucose (FDG)-positron emission tomography (PET).

Methods

Patients with ALS underwent [¹⁸F] FDG-PET and the resulting datasets were individually contrasted against healthy controls using the NEUROSTAT software. The extent ratio was defined as the proportion of pixels with a significant Z-score decrease within regions of the primary motor cortex (precentral gyrus or paracentral lobule) opposite to the impaired upper extremities (UEs) or lower extremities (LEs), respectively. Clinical symptoms in all extremities were assessed using an upper motor neuron (UMN) score and the MRC (Medical Research Council) sum score upon physical examination. Cross-sectional correlations were analysed between clinical symptoms, the duration of these symptoms, and the extent ratio.

Results

Nineteen regions of the primary motor cortex corresponding to symptomatic limb in 10 participants were evaluated. In the corresponding region of the primary motor cortex, the extent ratio increased (same meaning as hypometabolic area spread) in association with symptom duration (r_s = 0.5, p = 0.03). Neither UMN nor lower motor neuron (LMN) scores were correlated with symptom duration. Three out of 19 impaired regions did not show upper motor neuron (UMN) signs upon physical examination. The extent ratio and UMN score-controlled symptom duration were partially correlated (r_s = 0.5, p = 0.05).

Conclusions

In patients with ALS, glucose metabolism decreased in the impaired side of the primary motor cortex depending on the clinical symptom progression in the corresponding extremities, regardless of the presence of clinical UMN signs. A decrement in glucose metabolism on FDG-PET corresponding to symptoms in the primary motor cortex might be an indicator of the time-dependent course of ALS neurodegeneration.

Intercellular Prion-Like Conversion and Transmission of Cu/Zn Superoxide Dismutase (SOD1) in Cell Culture

The prion hypothesis has extended to the fatal motor neuron disease, amyotrophic lateral sclerosis (ALS), as a means to explain the spatiotemporal spread of pathology from one or more focal points through the neuroaxis. About 20% of inheritable cases of ALS are due to mutation in the gene encoding the Cu/Zn superoxide dismutase (SOD1), causing the protein to misfold and form neurotoxic aggregates. Mutant SOD1 has been shown to impart its misfold onto natively folded wild-type SOD1 in living cells. Furthermore, misfolded wild-type SOD1 can itself induce further rounds of propagated SOD1 misfolding. Finally, this prion-like mechanism of propagated SOD1 misfolding can be transmitted from cell to cell in human cell culture. Here, we describe a protocol for the induction of wild-type SOD1 misfolding inside living cells and its subsequent transmission from cell to cell in a prion-like fashion.

Association Between Rectus Abdominis Denervation and Ventilation Dysfunction in Patients with Amyotrophic Lateral Sclerosis

Background:

Spontaneous potentials in electromyography (EMG) of paraspinal muscles are associated with diaphragm denervation and, therefore, poor respiratory function in amyotrophic lateral sclerosis (ALS) is understandable. EMG changes in the rectus abdominis (RA) display an effect similar to those in paraspinal muscles with respect to the function of lower motor neurons in the thoracic spinal cord. The RA denervation was examined to determine its association with ventilation dysfunction in ALS.

Methods:

We collected the clinical data of 128 patients with sporadic ALS in Department of Neurology of Peking University Third Hospital from 2009 to 2013. EMG, Revised ALS Functional Rating Scale (ALSFRS-R) and forced vital capacity (FVC) were performed in all patients and the differences in the EMG changes in RA between those with and without FVC ≥ 80% were analysed.

Results:

The mean FVC value was 83.4% ± 17.1% (range: 45%–131%) of the predicted value. A total of 79 patients displayed FVC ≥80%, and 49 patients displayed FVC <80%. Compared with the patients displaying a normal FVC (60/79, 75.9%), spontaneous activity in RA was significantly different among those patients displaying an FVC <80% (47/49, 95.9%). In addition, spontaneous potentials in RA were more frequently detected in patients exhibiting dyspnea (32/33, 97.0%) than in patients without dyspnea (75/95, 78.9%).

Conclusion:

Spontaneous potentials in RA are associated with ventilation dysfunction and dyspnea in ALS patients.

Pathogenesis of amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) or motor neuron disease is a rapidly progressive neurodegenerative disorder. The primary involvement is of motor neurons in the brain, spinal cord and peripherally. There is secondary weakness of muscles and primary involvement of other brain regions, especially involving cognition.

SOURCES OF DATA

Peer-reviewed journal articles and reviews. PubMed.gov

AREAS OF AGREEMENT

The pathogenesis of ALS remains largely unknown. There are a wide range of potential mechanisms related to neurodegeneration. An increasing number of genetic factors are recognized.

AREAS OF CONTROVERSY

There remains controversy, or lack of knowledge, in explaining how cellular events manifest as the complex human disease. There is controversy as to how well cellular and animal models of disease relate to the human disease.

GROWING POINTS

Large-scale international collaborative genetic epidemiological studies are replacing local studies. Therapies related to pathogenesis remain elusive, with the greatest advances to date relating to provision of care (including multidisciplinary management) and supportive care (nutrition and respiratory support).

AREAS TIMELY FOR DEVELOPING RESEARCH

The identification of C9orf72 hexanucleotide repeats as the most frequent genetic background to ALS, and the association with frontotemporal dementia, gives the potential of a genetic background against which to study other risk factors, triggers and pathogenic mechanisms, and to develop potential therapies.

Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis

Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p < 0.05), greater threshold changes in depolarizing threshold electrotonus (p < 0.05) and depolarizing current threshold relationship (i.e. less accommodation; (p < 0.05), greater superexcitability (a measure of fast potassium current; p < 0.05) and reduced late subexcitability (a measure of slow potassium current; p < 0.05), suggesting increased persistent sodium currents and decreased potassium currents. The reduced potassium currents were found even in the patient subgroups with normal CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS.

TDP-43 or FUS-induced misfolded human wild-type SOD1 can propagate intercellularly in a prion-like fashion

Amyotrophic lateral sclerosis (ALS), which appears to spread through the neuroaxis in a spatiotemporally restricted manner, is linked to heritable mutations in genes encoding SOD1, TDP-43, FUS, C9ORF72, or can occur sporadically without recognized genetic mutations. Misfolded human wild-type (HuWt) SOD1 has been detected in both familial and sporadic ALS patients, despite mutations in SOD1 accounting for only 2% of total cases. We previously showed that accumulation of pathological TDP-43 or FUS coexist with misfolded HuWtSOD1 in patient motor neurons, and can trigger its misfolding in cultured cells. Here, we used immunocytochemistry and immunoprecipitation to demonstrate that TDP-43 or FUS-induced misfolded HuWtSOD1 can propagate from cell-to-cell via conditioned media, and seed cytotoxic misfolding of endogenous HuWtSOD1 in the recipient cells in a prion-like fashion. Knockdown of SOD1 using siRNA in recipient cells, or incubation of conditioned media with misfolded SOD1-specific antibodies, inhibits intercellular transmission, indicating that HuWtSOD1 is an obligate seed and substrate of propagated misfolding. In this system, intercellular spread of SOD1 misfolding is not accompanied by transmission of TDP-43 or FUS pathology. Our findings argue that pathological TDP-43 and FUS may exert motor neuron pathology in ALS through the initiation of propagated misfolding of SOD1.