Primary lateral sclerosis: diagnosis and management

Enhancing ALS disease management: exploring integrated user value through online communities evidence

Introduction

Assistive technologies (ATs) offer significant potential to improve the quality of life for individuals with Amyotrophic Lateral Sclerosis (ALS). This study explores the concept of integrated user value (IUV), focusing on five key aspects: quality, user experience, cost-effectiveness, safety, and accessibility. Understanding IUV is crucial for enhancing the development and deployment of ATs in ALS disease management.

Methods

A systematic search approach was utilized to collect data from Facebook ALS support groups, comprising posts from individuals with ALS and their caregivers. Using a predefined set of keywords, 416 posts were analyzed. The posts were categorized based on the five aspects of IUV, and an in-depth content analysis was conducted to explore patterns, challenges, and experiences associated with AT usage.

Results

The analysis revealed significant challenges across all aspects of IUV. Quality and user experience were interlinked, with users frequently citing inadequate designs and unmet customization needs. Cost-effectiveness was a key concern, with high costs and limited insurance coverage contributing to financial strain. Accessibility issues, including delays in acquiring devices and insufficient public facilities, further highlighted systemic challenges. Safety concerns emphasized the need for personalized and intuitive AT designs.

Discussion

The findings underscore the importance of a holistic approach to AT development, integrating all five aspects of IUV. Recommendations include enhancing product quality, ensuring affordability, prioritizing user-centered design, and addressing accessibility gaps. Collaboration between AT designers, healthcare providers, and policymakers is essential to optimize AT value and improve the quality of life for individuals with ALS and their caregivers.

Upper motor neuron-predominant motor neuron disease presenting as atypical parkinsonism: A clinicopathological study

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by upper and lower motor neuron signs. There are, however, cases where upper motor neurons (UMNs) are predominantly affected, leading to clinical presentations of UMN-dominant ALS or primary lateral sclerosis. Furthermore, cases exhibiting an UMN-predominant pattern of motor neuron disease (MND) presenting with corticobasal syndrome (CBS) have been sparsely reported. This study aims to clarify the clinicopathological features of patients with UMN-predominant MND. We reviewed 24 patients with UMN-predominant MND with TDP-43 pathology in the presence or absence of frontotemporal lobar degeneration. Additionally, we reviewed the medical records of patients with pathologically-confirmed corticobasal degeneration (CBD) who received a final clinical diagnosis of CBS (n = 10) and patients with pathologically-confirmed progressive supranuclear palsy (PSP) who received a final clinical diagnosis of PSP syndrome (n = 10). Of 24 UMN-predominant MND patients, 20 had a clinical diagnosis of an atypical parkinsonian disorder, including CBS (n = 11) and PSP syndrome (n = 8). Only two patients had antemortem diagnoses of motor neuron disease. UMN-predominant MND patients with CBS less frequently exhibited apraxia than those with CBD, and they were less likely to meet clinical criteria for possible or probable CBS. Similarly, UMN-predominant MND patients with PSP syndrome less often met clinical criteria for probable PSP than PSP patients with PSP syndrome. Our findings suggest that UMN-predominant MND can mimic atypical parkinsonism, and should be considered in the differential diagnosis of CBS and PSP syndrome, in particular when criteria are not met.

Could PLS represent a UMN-predominant ALS syndrome?

Primary lateral sclerosis (PLS) is a motor neuron condition marked by pure upper motor neuron (UMN) degeneration. PLS represents around 3% of all motor neuron diseases. Classically the prognosis of PLS is less severe than those of amyotrophic lateral sclerosis (ALS). This explains the necessity to distinguish both conditions as early as possible. The key hallmark between the two diseases is the involvement of the lower motor neuron (LMN) system which is classically considered spared in PLS contrary to ALS. Although it seemed clinically easy to distinguish PLS from ALS with the aid of clinical and complementary examinations, there is a large body of evidence highlighting that the LMN system might be impaired in PLS. This led us to suggest that PLS might be considered as an almost pure UMN ALS phenotype.

Diagnosing primary lateral sclerosis: a clinico-pathological study

BACKGROUND

 Primary lateral sclerosis (PLS) is a rare motor neuron disease characterized by upper motor neuron degeneration, diagnosed clinically due to the absence of a (neuropathological) gold standard. Post-mortem studies, particularly TDP-43 pathology analysis, are limited.

METHODS

This study reports on 5 cases in which the diagnostic criteria for PLS were met, but in which neuropathology findings showed (partially) conflicting results. These discrepancies prompted us to perform a clinico-pathology study focussing on diagnostic challenges and accuracy in PLS. To this end, all cases were reviewed by an international panel of 11 experts using an e-module and structured questionnaires.

RESULTS

Autopsy exhibited neuropathological findings consistent with amyotrophic lateral sclerosis (ALS) in one case, while two cases exhibited similar, but more limited lower motor neuron involvement, hinting at PLS or ALS overlap. Another case displayed tau-pathology indicative of progressive supranuclear palsy. The final case displayed extensive myelin loss without a proteinopathy or a clear diagnosis. The expert panel identified 24 different ancillary investigations lacking across cases (e.g. genetic testing, DAT scans, neuropsychological evaluation), listed 28 differential diagnoses, and identified 13 different conditions as the most likely diagnosis. Autopsy results led panel members to change their final diagnosis in 42% of the cases.

CONCLUSIONS

This study underscores the diagnostic challenges posed by diverse underlying pathologies resulting in upper motor neuron phenotypes. Despite adhering to the same diagnostic criteria, consensus amongst experts was limited. Ensuring the diagnostic consistency is crucial for advancing understanding and treatment of PLS. Explicit guidelines for excluding potential mimics along with a neuropathological gold standard are imperative.

Instrumented assessment of lower and upper motor neuron signs in amyotrophic lateral sclerosis using robotic manipulation: an explorative study

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a lethal progressive neurodegenerative disease characterized by upper motor neuron (UMN) and lower motor neuron (LMN) involvement. Their varying degree of involvement results in a clinical heterogenous picture, making clinical assessments of UMN signs in patients with ALS often challenging. We therefore explored whether instrumented assessment using robotic manipulation could potentially be a valuable tool to study signs of UMN involvement.

METHODS

We examined the dynamics of the wrist joint of 15 patients with ALS and 15 healthy controls using a Wristalyzer single-axis robotic manipulator and electromyography (EMG) recordings in the flexor and extensor muscles in the forearm. Multi-sinusoidal torque perturbations were applied, during which participants were asked to either relax, comply or resist. A neuromuscular model was used to study muscle viscoelasticity, e.g. stiffness (k) and viscosity (b), and reflexive properties, such as velocity, position and force feedback gains (kv, kp and kf, respectively) that dominated the responses. We further obtained clinical signs of LMN (muscle strength) and UMN (e.g. reflexes, spasticity) dysfunction, and evaluated their relation with the estimated neuromuscular model parameters.

RESULTS

Only force feedback gains (kf) were elevated in patients (p = 0.033) compared to controls. Higher kf, as well as the resulting reflexive torque (Tref), were both associated with more severe UMN dysfunction in the examined arm (p = 0.040 and p < 0.001). Patients with UMN symptoms in the examined arm had increased kf and Tref compared to controls (both p = 0.037). Neither of these measures was related to muscle strength, but muscle stiffness (k) was lower in weaker patients (p = 0.012). All these findings were obtained from the relaxed test. No differences were observed during the instructions comply and resist.

CONCLUSIONS

This findings are proof-of-concept that instrumented assessment using robotic manipulation is a feasible technique in ALS, which may provide quantitative, operator-independent measures relating to UMN symptoms. Elevated force feedback gains, driving larger reflexive muscle torques, appear to be particularly indicative of clinically established levels of UMN dysfunction in the examined arm.

Amyotrophic lateral sclerosis; clinical features, differential diagnosis and pathology

Amyotrophic lateral sclerosis (ALS) is a late-onset syndrome characterized by the progressive degeneration of both upper motor neurons (UMN) and lower motor neurons (LMN). ALS forms a clinical continuum with frontotemporal dementia (FTD), in which there are progressive language deficits or behavioral changes. The genetics and pathology underlying both ALS and FTD overlap as well, with cytoplasmatic misvocalization of TDP-43 as the hallmark. ALS is diagnosed by exclusion. Over the years several diagnostic criteria have been proposed, which in essence all require a history of slowly progressive motor symptoms, with UMN and LMN signs on neurological examination, clear spread of symptoms through the body, the exclusion of other disorder that cause similar symptoms and an EMG that it is compatible with LMN loss. ALS is heterogeneous disorder that may present in multitude ways, which makes the diagnosis challenging. Therefore, a systematic approach in the diagnostic process is required in line with the most common presentations. Subsequently, assessing whether there are cognitive and/or behavioral changes within the spectrum of FTD and lastly determining the cause is genetic. This chapter, an outline on how to navigate this 3 step process.

Familial motor neuron disease: co-occurrence of PLS and ALS (-FTD)

OBJECTIVE

To report the frequency and characteristics of patients diagnosed with primary lateral sclerosis (PLS) with a positive family history for motor neuron diseases (MND) in the Netherlands and to compare our findings to the literature.

METHODS

Patients were identified through our ongoing, prospective population-based study on MND in The Netherlands, which also includes a standardized collection of patient characteristics, genetic testing, and family history. Only patients meeting the latest consensus criteria for definite PLS were included. The family history was considered positive for MND if any family members had been diagnosed with PLS, amyotrophic lateral sclerosis (ALS)(-FTD), or progressive muscular atrophy (PMA). Additionally, the literature was reviewed on PLS cases in which MND co-occurred within the same family.

RESULTS

We identified 392 definite PLS cases, resulting in 9 families with a PLS patient and a positive family history for MND (2.3%). In only one of these pedigrees, a pathogenic variant (C9orf72 repeat expansion) was found. Our literature review revealed 23 families with a co-occurrence of PLS and MND, with 12 of them having a potentially pathogenic genetic variant.

CONCLUSIONS

The consistent observation of PLS patients with a positive family history for MND, evident in both our study and the literature, implies the presence of shared underlying genetic factors between PLS and ALS. However, these factors are yet to be elucidated.

Primary Lateral Sclerosis: An Overview

Primary lateral sclerosis (PLS) is a rare neurodegenerative disorder which causes the selective deterioration of the upper motor neurons (UMNs), sparing the lower motor neuron (LMN) system. The clinical course is defined by a progressive motor disability due to muscle spasticity which typically involves lower extremities and bulbar muscles. Although classically considered a sporadic disease, some familiar cases and possible causative genes have been reported. Despite it having been recognized as a rare but distinct entity, whether it actually represents an extreme end of the motor neuron diseases continuum is still an open issue. The main knowledge gap is the lack of specific biomarkers to improve the clinical diagnostic accuracy. Indeed, the diagnostic imprecision, together with some uncertainty about overlap with UMN-predominant ALS and Hereditary Spastic Paraplegia (HSP), has become an obstacle to the development of specific therapeutic trials. In this study, we provided a comprehensive analysis of the existing literature, including neuropathological, clinical, neuroimaging, and neurophysiological features of the disease, and highlighting the controversies still unsolved in the differential diagnoses and the current diagnostic criteria. We also discussed the current knowledge gaps still present in both diagnostic and therapeutic fields when approaching this rare condition.

Current challenges in primary lateral sclerosis diagnosis

INTRODUCTION

Primary lateral sclerosis (PLS) is a rare, adult-onset and slowly progressive motor neuron disorder whose clinical core is characterized by upper motor neuron (UMN) dysfunction. Its formal diagnosis is clinically based and disease duration-dependent. Differentiating PLS from other disorders involving UMN can be challenging, particularly in the early stages.

AREAS COVERED

Our review covers and discusses different aspects of the PLS field, including the diagnostic criteria and its limitations, its differential diagnosis and their major pitfalls, and the actual role of neurophysiology, neuroimaging, genetics, and molecular biomarkers. Symptomatic treatment of the different manifestations is also addressed. The authors searched MEDLINE and Scopus. They also searched the reference lists of articles identified by our search strategy and reviewed and selected those deemed relevant. They selected papers and studies based on the quality of the report, significance of the findings, and on the author's critical appraise and expertise.

EXPERT OPINION

It is important to investigate novel molecular biomarkers and plan multicenter clinical trials for PLS. However, this will require a large international project to recruit enough patients, particularly given the diagnostic uncertainty of the current clinical criteria. A better understanding of PLS pathophysiology is crucial for designing disease-targeted therapies.

Guideline "Motor neuron diseases" of the German Society of Neurology (Deutsche Gesellschaft für Neurologie)

INTRODUCTION

In 2021, the Deutsche Gesellschaft für Neurology published a new guideline on diagnosis and therapy of motor neuron disorders. Motor neuron disorders affect upper motor neurons in the primary motor cortex and/or lower motor neurons in the brain stem and spinal cord. The most frequent motor neuron disease amyotrophic lateral sclerosis (ALS) is a rapidly progressive disease with an average life expectancy of 2-4 years with a yearly incidence of 3.1/100,000 in Central Europe (Rosenbohm et al. in J Neurol 264(4):749-757, 2017. https://doi.org/10.1007/s00415-017-8413-3 ). It is considered a rare disease mainly due to its low prevalence as a consequence of short disease duration.

RECOMMENDATIONS

These guidelines comprise recommendations regarding differential diagnosis, neuroprotective therapies and multidisciplinary palliative care including management of respiration and nutrition as well as provision of assistive devices and end-of-life situations.

CONCLUSION

Diagnostic and therapeutic guidelines are necessary due the comparatively high number of cases and the aggressive disease course. Given the low prevalence and the severe impairment of patients, it is often impossible to generate evidence-based data so that ALS guidelines are partially dependent on expert opinion.

Differenzialdiagnose der Amyotrophen Lateralsklerose in der klinischen Praxis

Die Diagnose der Amyotrophen Lateralsklerose (ALS) beruht vorwiegend auf klinischen Kriterien und kann aufgrund des heterogenen Erscheinungsbildes gerade in frühen Krankheitsstadien mitunter schwierig sein. Wegweisend sind der Nachweis einer kombinierten Pathologie des oberen und unteren Motoneurons, der fokale Onset, das Ausbreitungsmuster (Spreading), das typische Verteilungsmuster der Paresen, das Vorhandensein oder Fehlen nicht-motorischer Zusatzsymptome sowie Art und Geschwindigkeit der Krankheitsprogredienz. Dieser Review stellt Charakteristika der ALS sowohl im Hinblick auf die klinische Untersuchung als auch apparativer Zusatzdiagnostik in Abgrenzung zu den wichtigsten Differenzialdiagnosen in Form von Einschlusskörperchenmyositis, Chronisch Inflammatorischer Demyelinisierender Polyneuropathie (CIDP), Mulifokaler Motorischer Neuropathie (MMN), adulter Form der Spinalen Muskelatrophie (SMA), Kennedy-Syndrom und Hereditärer Spastischer Paralyse (HSP) dar.

Primary lateral sclerosis

Like motor neuron diseases (MNDs) refer to a constellation of primarily sporadic neurodegenerative diseases characterized by a progressive loss of upper and/or lower motor neurons. Primary lateral sclerosis (PLS) is considered a neurodegenerative disorder that is characterized by a gradually progressive course affecting the central motor systems, designated by the phrase "upper motor neurons." Despite significant development in neuroimaging, neurophysiology, and molecular biology, there is a growing consensus that PLS is of unknown etiology. Currently there is no disease-modifying treatment for PLS, or prospective randomized trials being carried out, partly due to the rarity of the disease and lack of significant understanding of the underlying pathophysiology. Consequently, the approach to treatment remains largely symptomatic. In this chapter we provide an overview of primary lateral sclerosis including clinical and electrodiagnostic considerations, differential diagnosis, updates in genetics and pathophysiology, and future directions for research.

Primary lateral sclerosis natural history study - planning, designing, and early enrollment

Introduction/Aims. Primary lateral sclerosis (PLS) is exceedingly rare and has been an enigmatic disease. Recent progress has drastically changed this perception, with early biomarkers being investigated and potential medications for PLS emerging at the preclinical stage. The aim of this paper is to describe a study of PLS natural history and discuss the limitations and proposed solutions to the study of a rare and slowly progressive disease. Methods. The PLS Natural History Study is a 30-site, 24-month, prospective study that is supported by multiple funding sources. The study aims to enroll 50 early PLS (disease duration ≤4 years) and 50 definite PLS (disease duration 4 to 15 years) participants using modified PLS Diagnostic Criteria. Smartphone-based assessments including semi-quantitative and quantitative measures and patient-reported outcomes are utilized. In-person quantitative measures are also completed during site visits. The change in the PLS Functional Rating Scale score is the primary outcome. The study utilizes the NeuroBANK^® patient-centric data capture and management platform. The biostatistical analysis plan has been developed. Results. In one year, 28 participants have been recruited. Enrollment has been much slower than anticipated due to the COVID-19 pandemic, the rarity of PLS, and potential study competition for internal resources from ALS clinical trials. Discussion. We discuss the need for more innovative methods to enroll and study individuals with such rare diseases and propose a number of mechanisms by which more efficient enrollment could be facilitated.

Primary progressive aphasia and motor neuron disease: A review

Background

This study aims at reviewing, within the framework of motor neuron disease-frontotemporal degeneration (MND-FTD)-spectrum disorders, evidence on the co-occurrence between primary progressive aphasia (PPA) and MND in order to profile such a complex at pathological, genetic and clinical levels.

Methods

This review was pre-registered (osf.io/ds8m4) and performed in accordance with the 2020 PRISMA guidelines. Case reports/series and group studies were included if addressing (1) progressive non-fluent aphasia (PNFA) or semantic dementia (SD) with MND or (2) MND patients with co-morbid PNFA/SD.

Results

Out of 546 initial records, 56 studies were included. As to case reports/series (N = 35), which included 61 PPA-MND patients, the following findings yielded: (1) PNFA is more frequent than SD in PPA-MND; (2) in PPA-MND, the most prevalent motor phenotypes are amyotrophic lateral sclerosis and predominant-upper MND, with bulbar involvement being ubiquitous; (3) extrapyramidal features are moderately frequent in PPA-MND; (4) PPA-MND patients usually display frontotemporal, left-greater-than-right involvement; (5) TDP-43-B is the typical pathological substrate of PPA-MND; (6) TBK1 mutations represent the most frequent genetic risk factors for PPA-MND.

As to group studies, including 121 patients, proportional meta-analytic procedures revealed that: (1) the lifetime prevalence of MND in PPA is 6%; (2) PPA occurs in 19% of patients with co-morbid MND and FTD; (3) MND is more frequent in PNFA (10%) than in SD patients (3%).

Discussion

Insights herewith delivered into the clinical, neuropathological and genetic features of PPA-MND patients prompt further investigations aimed at improving clinical practice within the MND-FTD spectrum.

Presenilin-1 Mutations Are a Cause of Primary Lateral Sclerosis-Like Syndrome

Background and Purpose

Primary lateral sclerosis (PLS) is a progressive upper motor neuron (UMN) disorder. It is debated whether PLS is part of the amyotrophic lateral sclerosis (ALS) spectrum, or a syndrome encompassing different neurodegenerative diseases. Recently, new diagnostic criteria for PLS have been proposed. We describe four patients of two pedigrees, meeting definite PLS criteria and harboring two different mutations in presenilin 1 (PSEN1).

Methods

Patients underwent neurological and neuropsychological examination, MRI, 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), amyloid-related biomarkers, and next-generation sequencing (NGS) testing.

Results

Four patients, aged 25–45 years old, presented with a progressive UMN syndrome meeting clinical criteria of definite PLS. Cognitive symptoms and signs were mild or absent during the first year of the disease but appeared or progressed later in the disease course. Brain MRI showed microbleeds in two siblings, but iron-related hypointensities in the motor cortex were absent. Brain FDG-PET showed variable areas of hypometabolism, including the motor cortex and frontotemporal lobes. Amyloid deposition was confirmed with either cerebrospinal fluid (CSF) or imaging biomarkers. Two heterozygous likely pathogenic mutations in PSEN1 (p.Pro88Leu and p.Leu166Pro) were found in the NGS testing.

Conclusion

Clinically defined PLS is a syndrome encompassing different neurodegenerative diseases. The NGS testing should be part of the diagnostic workup in patients with PLS, at least in those with red flags, such as early-onset, cognitive impairment, and/or family history of neurodegenerative diseases.

Familial clustering of primary lateral sclerosis and amyotrophic lateral sclerosis: Supplementary evidence for a continuum

BACKGROUND AND PURPOSE

Primary lateral sclerosis (PLS) is a motor neuron disorder characterized by a pure upper motor neuron degeneration in the bulbar and spinal regions. The key difference with amyotrophic lateral sclerosis (ALS) is the lower motor neuron system integrity. Despite important literature on this disease, the pathophysiology of PLS remains unknown, and the link with ALS still balances between a continuum and a separate entity from ALS.

METHODS

We report nine families in which both PLS and ALS cases occurred, in general among first-degree relatives.

RESULTS

The patients with PLS and ALS had a typical disease presentation. Genetic studies revealed mutations in SQSMT1, TBK1, and TREM2 genes in two PLS patients and one ALS patient.

CONCLUSIONS

These results strongly support a phenotypic continuum between PLS and ALS.

Upper Motor Neuron Disorders: Primary Lateral Sclerosis, Upper Motor Neuron Dominant Amyotrophic Lateral Sclerosis, and Hereditary Spastic Paraplegia

Following the exclusion of potentially reversible causes, the differential for those patients presenting with a predominant upper motor neuron syndrome includes primary lateral sclerosis (PLS), hereditary spastic paraplegia (HSP), or upper motor neuron dominant ALS (UMNdALS). Differentiation of these disorders in the early phases of disease remains challenging. While no single clinical or diagnostic tests is specific, there are several developing biomarkers and neuroimaging technologies which may help distinguish PLS from HSP and UMNdALS. Recent consensus diagnostic criteria and use of evolving technologies will allow more precise delineation of PLS from other upper motor neuron disorders and aid in the targeting of potentially disease-modifying therapeutics.

Amyotrophic lateral sclerosis: update on clinical management

PURPOSE OF REVIEW

The current review will provide recent updates in the clinical management of amyotrophic lateral sclerosis (ALS).

RECENT FINDINGS

Although there is no cure for ALS, there are new treatments, growing knowledge of genetics, development of clinical staging systems, and the recent coronavirus disease 2019 pandemic that have recently impacted the clinical management of ALS. Increased understanding of genetics has helped provide insights into pathophysiology, the staging systems and clinical measures help to provide tools for monitoring disease clinically, and the recent coronavirus disease 2019 pandemic has provided opportunities to develop telemedicine and remote monitoring of disease thereby increasing accessibility to care and reducing burden of travel to centers for people living with the disease and their caregivers.

SUMMARY

ALS is a progressive neurodegenerative disease that causes degeneration of the motor neurons which leads to paralysis and respiratory failure. Despite the lack of a cure, multidisciplinary care, proactive respiratory management, nutritional care and management of symptoms as well as pharmacological interventions that can improve quality of life and survival.