Assessment of disease progression in motor neuron disease

Distinct neuronal circuits mediate cortical hyperexcitability in amyotrophic lateral sclerosis

Cortical hyperexcitability is an important pathophysiological mechanism in amyotrophic lateral sclerosis (ALS), reflecting a complex interaction of inhibitory and facilitatory interneuronal processes that evolves in the degenerating brain. The advances in physiological techniques have made it possible to interrogate progressive changes in the motor cortex. Specifically, the direction of transcranial magnetic stimulation (TMS) stimulus within the primary motor cortex can be utilized to influence descending corticospinal volleys and to thereby provide information about distinct interneuronal circuits. Cortical motor function and cognition was assessed in 29 ALS patients with results compared to healthy volunteers. Cortical dysfunction was assessed using threshold-tracking TMS to explore alterations in short interval intracortical inhibition (SICI), short interval intracortical facilitation (SICF), the index of excitation and stimulus response curves using a figure-of-eight coil with the coil oriented relative to the primary motor cortex in a posterior-anterior, lateral-medial and anterior-posterior direction. Mean SICI, between interstimulus interval of 1-7 ms, was significantly reduced in ALS patients compared to healthy controls when assessed with the coil oriented in posterior-anterior (P = 0.044) and lateral-medial (P = 0.005) but not the anterior-posterior (P = 0.08) directions. A significant correlation between mean SICI oriented in a posterior-anterior direction and the total Edinburgh Cognitive and Behavioural ALS Screen score (Rho = 0.389, P = 0.037) was evident. In addition, the mean SICF, between interstimulus interval 1-5 ms, was significantly increased in ALS patients when recorded with TMS coil oriented in posterior-anterior (P = 0.035) and lateral-medial (P < 0.001) directions. In contrast, SICF recorded with TMS coil oriented in the anterior-posterior direction was comparable between ALS and controls (P = 0.482). The index of excitation was significantly increased in ALS patients when recorded with the TMS coil oriented in posterior-anterior (P = 0.041) and lateral-medial (P = 0.003) directions. In ALS patients, a significant increase in the stimulus response curve gradient was evident compared to controls when recorded with TMS coil oriented in posterior-anterior (P < 0.001), lateral-medial (P < 0.001) and anterior-posterior (P = 0.002) directions. The present study has established that dysfunction of distinct interneuronal circuits mediates the development of cortical hyperexcitability in ALS. Specifically, complex interplay between inhibitory circuits and facilitatory interneuronal populations, that are preferentially activated by stimulation in posterior-to-anterior or lateral-to-medial directions, promotes cortical hyperexcitability in ALS. Mechanisms that underlie dysfunction of these specific cortical neuronal circuits will enhance understanding of the pathophysiological processes in ALS, with the potential to uncover focussed therapeutic targets.

Biomagnetic signals recorded during transcranial magnetic stimulation (TMS)-evoked peripheral muscular activity

Transcranial magnetic stimulation (TMS) has widespread clinical applications from diagnosis to treatment. We combined TMS with non-contact magnetic detection of TMS-evoked muscle activity in peripheral limbs to explore a new diagnostic modality that enhances the utility of TMS as a clinical tool by leveraging technological advances in magnetometry. We recorded measurements in a regular hospital room using an array of optically pumped magnetometers (OPMs) inside a portable shield that encloses only the forearm and hand of the subject. We present magnetomyograms (MMG)s of TMS-evoked movement in a human hand, together with a simultaneous surface electromyograph (EMG) data. The biomagnetic signals recorded in the MMG provides detailed spatial and temporal information that is complementary to that of the electric signal channels. Moreover, we identify features in the magnetic recording beyond that of the EMG. This system demonstrates the value of biomagnetic signals in TMS-based clinical approaches and widens its availability and practical potential.

Alterations of Microstructure and Sodium Homeostasis in Fast Amyotrophic Lateral Sclerosis Progressors: A Brain DTI and Sodium MRI Study

BACKGROUND AND PURPOSE

While conventional MR imaging has limited value in amyotrophic lateral sclerosis, nonconventional MR imaging has shown alterations of microstructure using diffusion MR imaging and recently sodium homeostasis with sodium MR imaging. We aimed to investigate the topography of brain regions showing combined microstructural and sodium homeostasis alterations in amyotrophic lateral sclerosis subgroups according to their disease-progression rates.

MATERIALS AND METHODS

Twenty-nine patients with amyotrophic lateral sclerosis and 24 age-matched healthy controls were recruited. Clinical assessments included disease duration and the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale. Patients were clinically differentiated into fast (n = 13) and slow (n = 16) progressors according to the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale progression rate. 3T MR imaging brain protocol included ¹H T1-weighted and diffusion sequences and a ²³Na density-adapted radial sequence. Quantitative maps of diffusion with fractional anisotropy, mean diffusivity, and total sodium concentration were measured. The topography of diffusion and sodium abnormalities was assessed by voxelwise analyses.

RESULTS

Patients with amyotrophic lateral sclerosis showed significantly higher sodium concentrations and lower fractional anisotropy, along with higher sodium concentrations and higher mean diffusivity compared with healthy controls, primarily within the corticospinal tracts, corona radiata, and body and genu of the corpus callosum. Fast progressors showed wider-spread abnormalities mainly in the frontal areas. In slow progressors, only fractional anisotropy measures showed abnormalities compared with healthy controls, localized in focal regions of the corticospinal tracts, the body of corpus callosum, corona radiata, and thalamic radiation.

CONCLUSIONS

The present study evidenced widespread combined microstructural and sodium homeostasis brain alterations in fast amyotrophic lateral sclerosis progressors.

Demographics, clinical characteristics, and prognostic factors of amyotrophic lateral sclerosis in Midwest

INTRODUCTION/AIMS

The Midwest has the highest regional prevalence of self-reported amyotrophic lateral sclerosis (ALS) in the United States, but with limited epidemiological studies. We aimed to explore the characteristics of patients with ALS in the Midwest.

METHODS

This was a retrospective cohort study of participants with ALS deceased between January, 2010, and September, 2020, registered with the ALS Association Mid-America Chapter. Demographics and clinical variables included gender, race/ethnicity, military status, site of onset, interventions (gastrostomy, non-invasive ventilation, tracheostomy), and visits to ALS Association-registered clinics. Disease characteristics were compared to the National ALS Registry, and survival analysis was performed followed by sample augmentation with historical data to estimate survival with hypothetical censoring.

RESULTS

The database included 1447 participants with a mean age at diagnosis of 65.7 ± 11.9 y (>60 y at diagnosis: 72%). The median survival from symptom onset was 28.0 mo (95% confidence limit: 26.3, 29.7); sample augmentation increased this to 41.0 mo (38.5, 43.5). Bulbar onset disease and older age at diagnosis were associated with shorter survival. Participants not followed in ALS-Association registered clinics were more frequently male, had familial onset and tracheostomy. Veterans (N = 298) were older at diagnosis but had similar survival after adjustment for age.

DISCUSSIONS

Our cohort had an older age at onset and more frequent bulbar onset than the National ALS Registry, perhaps reflecting ascertainment biases in each registry. Prospective cohort studies with more clinical and functional data are needed to better characterize ALS in Midwest, veterans, and non-clinic populations, and to optimize care.

Neurologists' current practice and perspectives on communicating the diagnosis of a motor neurodegenerative condition: a UK survey

BACKGROUND

The communication of a life-changing diagnosis can be a difficult task for doctors with potential long-term effects on patient outcomes. Although several studies have addressed the experiences of individuals with motor neurodegenerative diseases in receiving this diagnosis, a significant research gap exists regarding professionals' perspectives, especially in the UK. This study aimed to assess UK neurologists' current practice and perspectives on delivering the diagnosis of a motor neurodegenerative disease, explore different aspects of the process and detail the potential challenges professionals might face.

METHODS

We conducted an anonymised online survey with 44 questions, grouped into four sections; basic demographic information, current practice, the experience of breaking bad news and education and training needs.

RESULTS

Forty-nine professionals completed the survey. Overall, participants seemed to meet the setting-related standards of good practice; however, they also acknowledged the difficulty of this aspect of their clinical work, with about half of participants (46.5%) reporting moderate levels of stress while breaking bad news. Patients' relatives were not always included in diagnostic consultations and participants were more reluctant to promote a sense of optimism to patients with poorer prognosis. Although professionals reported spending a mean of around 30-40 min for the communication of these diagnoses, a significant proportion of participants (21-39%) reported significantly shorter consultation times, highlighting organisational issues related to lack of capacity. Finally, the majority of participants (75.5%) reported not following any specific guidelines or protocols but indicated their interest in receiving further training in breaking bad news (78.5%).

CONCLUSIONS

This was the first UK survey to address neurologists' practice and experiences in communicating these diagnoses. Although meeting basic standards of good practice was reported by most professionals, we identified several areas of improvement. These included spending enough time to deliver the diagnosis appropriately, including patients' relatives as a standard, promoting a sense of hope and responding to professionals' training needs regarding breaking bad news.

Considerations on the concept, definition, and diagnosis of amyotrophic lateral sclerosis

The concept, definition, and diagnosis of amyotrophic lateral sclerosis (ALS) currently present some problems. This article systematically reviews the literature on the history, current concepts, definition, and diagnosis of ALS, and discloses the present problems based on the retrieved literature and the authors’ clinical experience. The current concepts and definitions of ALS have not yet been unified or standardized in clinical practice, and are sometimes vague or inaccurate, which can cause difficulties for neurologists in the clinical treatment of ALS. The concept and definition of ALS need to be further ascertained, and the current diagnostic criteria for ALS require further development. The identification of effective and objective biomarkers may be a feasible method for the early and accurate diagnosis of ALS. Therefore, future research should focus on the identification of reliable biomarkers—especially neuroimaging biomarkers—through autopsy. Standardizing the concept and definition of ALS and formulating clear diagnostic criteria will largely avoid many uncertainties in the future clinical research and treatment of ALS, which will greatly benefit patients.

Experience of telehealth in people with motor neurone disease using noninvasive ventilation

INTRODUCTION

Evidence is emerging that telehealth provides timely and cost-effective support for individuals with motor neurone disease (MND). However, little is known about the subjective experience of using telehealth. This study was designed to examine the experiences of using telemonitoring in patients with MND on noninvasive ventilation (NIV).

METHODS

Semi-structured interviews were conducted with seven patients (five males; mean age = 63 yrs; median illness duration = 14 m), who used a telemonitoring device for 24 weeks. Caregivers were present at five of the interviews; they supported communications and provided their feedback. Interviews were audio recorded and transcribed verbatim. Thematic analysis was conducted to find overarching themes.

RESULTS

Five themes were identified: Benefits of Timely Intervention, Reducing the Unnecessary, Increased Self-Awareness, Taking Initiative, and Technical Challenges. Overall, timely interventions were observed as a result of regular monitoring, contributing to both physical and psychological well-being of the participants. The patient-caregiver dyads suggested that telemonitoring could reduce costs, save time and ameliorate hassles associated with attending hospital appointments. Participants articulated that telemonitoring enabled symptom awareness and interpretation; the device also enabled the participants to raise concerns and/or requests to the healthcare professionals via the messaging system. Participants confirmed that the telemonitoring device was easy to use, despite some technical issues.

CONCLUSIONS

Telemonitoring was positively experienced. The findings suggest this approach is empowering and effective in promoting patients' well-being, while potentially reducing unnecessary clinical contact.Implications for RehabilitationCare for people with MND demands a flexible approach to accommodate the diversity of clinical needs and relentless physical deterioration.Telehealth allows clinicians to provide person-centred care for everyone with MND through frequent monitoring.Holistic and rehabilitative service facilitated by telehealth is generally acceptable and preferred to routine appointments among MND NIV patients.Telehealth promotes time efficient engagement with professionals that leads to symptom awareness and interpretation, while benefiting physical and psychological well-being of MND NIV patients.

Impairment of triad conditioned facilitation in amyotrophic lateral sclerosis

OBJECTIVES

The triad conditioned facilitation (TCF) technique has been shown to detect motor cortical intrinsic rhythms depending on the functioning of specific cortical layers by measuring motor evoked potential (MEP) enhancement after a triad of conditioning TMS pulses at a certain interval. However, the influence of cortical degeneration on TCF is still undetermined. We therefore studied TCF in patients with amyotrophic lateral sclerosis (ALS), a neurodegenerative disorder characterised by degeneration of the motor cortex.

METHODS

Thirteen patients with ALS and 11 age-matched disease control patients with cervical myelopathy (CM) or radiculopathy (CR) participated in the study. We studied short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and TCF using the paired-pulse and triad conditioned TMS paradigm.

RESULTS

TCF was significantly reduced in ALS patients compared to CM/CR patients, who had normal TCF. SICI and ICF did not differ between groups.

CONCLUSION

The absence of TCF with preserved SICI and ICF suggests changes in the intrinsic rhythm generation within the motor cortex due to cortical neurodegeneration in ALS patients. In contrast, TCF was normal in patents with CM/CR in whom the motor cortical intrinsic circuits are not involved. This technique may be valuable to differentiate patients with ALS from those with CM/CR.

The rights of persons with disability bill, 2014: Implications for neurological disability

India ratified the United Nations Convention on the Rights of Persons with Disabilities (UNCRPD) in 2007. This is a welcome step toward realizing the rights of the persons with disability. The UNCRPD proclaims that disability results from interaction of impairments with attitudinal and environmental barriers, which hinders full and active participation in society on an equal basis with others. Further, the convention also mandates the signatory governments to make suitable changes in the existing laws of the country, to identify and eliminate obstacles and barriers, and to comply with the terms of the UNCRPD in order to protect the rights of the person with disabilities, hence the amendments of the national laws. Hence, the Government of India drafted the Right of Persons with Disabilities Bill (RPWD Bill), 2014. It is evident that neurological disorders are emerging as priority health problems worldwide. They not only contribute to mortality but also contribute to huge morbidity. Further, shortage of neurologists, huge treatment gap, and stigma add to the burden. The situation becomes worse with regard to providing quality care, comprehensive rehabilitation, and social welfare measures to persons with neurological disability. There is no doubt that persons with neurological disability do not get adequate representation, stigmatized and discriminated across the civil societies, which hinders full and active participation in society. Hence, this article is a critique of the RPWD Bill, 2014 from the perspective of persons with neurological and neurosurgical disability. Further, this article also discusses challenges in quantifying and certifying disability in neurological disability.

Challenges in the Understanding and Treatment of Amyotrophic Lateral Sclerosis/Motor Neuron Disease

With the acceleration in our understanding of ALS and the related motor neuron disease has come even greater challenges in reconciling all of the proposed pathogenic mechanisms and how this will translate into impactful treatments. Fundamental issues such as diagnostic definition(s) of the disease spectrum, relevant biomarkers, the impact of multiple novel genetic mutations and the significant effect of symptomatic treatments on disease progression are all areas of active investigation. In this review, we will focus on these key issues and highlight the challenges that confront both clinicians and basic science researchers.

Neuroimaging as a New Diagnostic Modality in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is characterized by progressive degeneration of upper and lower motor neurons, with variable involvement of extramotor brain regions. Currently, there are no established objective markers of upper motor neuron and extramotor involvement in ALS. Here, we review the potential diagnostic value of advanced neuroimaging techniques that are increasingly being used to study the brain in ALS. First, we discuss the role of different imaging modalities in our increasing understanding of ALS pathogenesis, and their potential to contribute to objective upper motor neuron biomarkers for the disease. Second, we discuss the challenges to be overcome and the required phases of diagnostic test development to translate imaging technology to clinical care. We also present examples of multidimensional imaging approaches to achieve high levels of diagnostic accuracy. Last, we address the role of neuroimaging in clinical therapeutic trials. Advanced neuroimaging techniques will continue to develop and offer significant opportunities to facilitate the development of new effective treatments for ALS.

Tauroursodeoxycholic acid in the treatment of patients with amyotrophic lateral sclerosis

Background and purpose

Tauroursodeoxycholic acid (TUDCA) is a hydrophilic bile acid that is produced in the liver and used for treatment of chronic cholestatic liver diseases. Experimental studies suggest that TUDCA may have cytoprotective and anti‐apoptotic action, with potential neuroprotective activity. A proof of principle approach was adopted to provide preliminary data regarding the efficacy and tolerability of TUDCA in a series of patients with amyotrophic lateral sclerosis (ALS).

Methods

As a proof of principle, using a double‐blind placebo controlled design, 34 ALS patients under treatment with riluzole who were randomized to placebo or TUDCA (1 g twice daily for 54 weeks) were evaluated after a lead‐in period of 3 months. The patients were examined every 6 weeks. The primary outcome was the proportion of responders [those subjects with improvement of at least 15% in the Amyotrophic Lateral Sclerosis Functional Rating Scale Revised (ALSFRS‐R) slope during the treatment period compared to the lead‐in phase]. Secondary outcomes included between‐treatment comparison of ALSFRS‐R at study end, comparison of the linear regression slopes for ALSFFRS‐R mean scores and the occurrence of adverse events.

Results

Tauroursodeoxycholic acid was well tolerated; there were no between‐group differences for adverse events. The proportion of responders was higher under TUDCA (87%) than under placebo (P = 0.021; 43%). At study end baseline‐adjusted ALSFRS‐R was significantly higher (P = 0.007) in TUDCA than in placebo groups. Comparison of the slopes of regression analysis showed slower progression in the TUDCA than in the placebo group (P < 0.01).

Conclusions

This pilot study provides preliminary clinical data indicating that TUDCA is safe and may be effective in ALS.

Click here to view the accompanying paper in this issue.

Quantifying disease progression in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) exhibits characteristic variability of onset and rate of disease progression, with inherent clinical heterogeneity making disease quantitation difficult. Recent advances in understanding pathogenic mechanisms linked to the development of ALS impose an increasing need to develop strategies to predict and more objectively measure disease progression. This review explores phenotypic and genetic determinants of disease progression in ALS, and examines established and evolving biomarkers that may contribute to robust measurement in longitudinal clinical studies. With targeted neuroprotective strategies on the horizon, developing efficiencies in clinical trial design may facilitate timely entry of novel treatments into the clinic.

A longer diagnostic interval is a risk for depression in amyotrophic lateral sclerosis

Objective:

Recognizing depressive symptoms in patients with amyotrophic lateral sclerosis (ALS) remains problematic given the potential overlap with the normal psychological responses to a terminal illness. Understanding mental health and disease-related risk factors for depression is key to identifying psychological morbidity. The present study aimed to determine the prevalence of depressive symptoms in ALS and to explore mental health and disease-related risk factors for depression.

Method:

Structured medical and psychiatric history questionnaires and a validated depression scale (Depression, Anxiety, Stress Scale–21) were completed by 27 ALS patients (60% female; 59% limb onset; age 65.11 ± SE 2.21) prior to their initial review at a multidisciplinary clinic. Physical function was assessed with the Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS–R).

Results:

At the time of initial assessment, 44% of patients had a previous psychiatric history, although the majority (62%) reported no symptoms of depression. The mean ALSFRS–R score was 37.78 ± SE 1.22, with an average diagnostic interval of 16.04 ± SE 2.39 months. Logistic regression analysis revealed that the length of the diagnostic interval alone predicted depressive symptoms (χ2(3, n = 26) = 9.21, Odds Ratio (OR) = 1.12, p < 0.05.

Significance of Results:

The illness experiences of ALS patients rather than established mental health risk factors influence the manifestation of depressive symptoms in the early stages of the disease, with clinical implications for the assessment and treatment of psychological morbidity. Patients with lengthy diagnostic intervals may be prime targets for psychological assessment and intervention, especially in the absence of ALS-specific tests and biomarkers.

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in amyotrophic lateral sclerosis (ALS)

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases, responsible for the integrity of the basement membrane (BM) via degradation of extracellular matrix and BM components. These enzymes are presented in central and peripheral nervous system. They are considered to be involved in the pathogenesis of several neurological diseases, including amyotrophic lateral sclerosis (ALS). ALS is a motor neuron disease, leading to muscle atrophy, paralysis and death within 3–5 years from diagnosis. Currently, there is no treatment that can substantially prolong life of ALS patients. Despite the fact that MMPs are not specific for ALS, there is also strong evidence that these enzymes are involved in the pathology of ALS. MMPs are able to exert direct neurotoxic effects, or may cause cell death by degrading matrix proteins. The objective of this paper is to provide an updated and comprehensive review concerning the role of MMPs and their tissue inhibitors (TIMPs) in the pathology of ALS with an emphasis on the significance of MMP-2 and MMP-9 as well as their tissue inhibitors as potential biomarkers of ALS. Numerous hypotheses have been proposed regarding the role of selected MMPs and TIMPs in ALS pathogenesis. Moreover, selective MMPs’ inhibitors might be potential targets for therapeutic strategies for patients with ALS. However, future investigations are necessary before some of those non-specific for ALS enzymes could finally be used as biomarkers of this disease.

Why don't they accept non-invasive ventilation?: insight into the interpersonal perspectives of patients with motor neurone disease

OBJECTIVES

Although non-invasive ventilation (NIV) can benefit survival and quality of life, it is rejected by a substantial proportion of people with motor neurone disease (MND). The aim of this study was to understand why some MND patients decline or withdraw from NIV.

METHOD

Nine patients with MND (male = 7, mean age = 67 years) participated in this study. These patients, from a cohort of 35 patients who were offered NIV treatment to support respiratory muscle weakness, did not participate in NIV treatment when it was clinically appropriate. Semi-structured interviews and interpretative phenomenological analysis (IPA) were employed to explore these patient's experience of MND and their thoughts and understanding of NIV treatment.

RESULTS

Using IPA, four themes were identified: preservation of the self, negative perceptions of NIV, negative experience with health care services, and not needing NIV. Further analysis identified the fundamental issue to be the maintenance of perceived self, which was interpreted to consist of the sense of autonomy, dignity, and quality of life.

CONCLUSIONS

The findings indicate psychological reasons for disengagement with NIV. The threat to the self, the sense of loss of control, and negative views of NIV resulting from anxiety were more important to these patients than prolonging life in its current form. These findings suggest the importance of understanding the psychological dimension involved in decision-making regarding uptake of NIV and a need for sensitive holistic evaluation if NIV is declined. Statement of contribution What is already known on this subject? Non-invasive ventilation is widely used as an effective symptomatic therapy in MND, yet about a third of patients decline the treatment. Psychological disturbance generated by NIV use leads to negative experiences of the treatment. Decision-making about treatment potentials is complex and unique to each individual affected by perceived impact of disease. What does this study add? A decision concerning NIV uptake was influenced by perceived impact on individuals' sense of self. Sense of self was influenced by the maintenance of autonomy, dignity, and quality of life. Individuals' sense of self was identified to have been challenged by the disease, NIV, and their experience of health care service.

Neuroimaging to investigate multisystem involvement and provide biomarkers in amyotrophic lateral sclerosis

Neuroimaging allows investigating the extent of neurological systems degeneration in amyotrophic lateral sclerosis (ALS). Advanced MRI methods can detect changes related to the degeneration of upper motor neurons but have also demonstrated the participation of other systems such as the sensory system or basal ganglia, demonstrating in vivo that ALS is a multisystem disorder. Structural and functional imaging also allows studying dysfunction of brain areas associated with cognitive signs. From a biomarker perspective, numerous studies using diffusion tensor imaging showed a decrease of fractional anisotropy in the intracranial portion of the corticospinal tract but its diagnostic value at the individual level remains limited. A multiparametric approach will be required to use MRI in the diagnostic workup of ALS. A promising avenue is the new methodological developments of spinal cord imaging that has the advantage to investigate the two motor system components that are involved in ALS, that is, the lower and upper motor neuron. For all neuroimaging modalities, due to the intrinsic heterogeneity of ALS, larger pooled banks of images with standardized image acquisition and analysis procedures are needed. In this paper, we will review the main findings obtained with MRI, PET, SPECT, and nuclear magnetic resonance spectroscopy in ALS.

Transcranial magnetic stimulation and amyotrophic lateral sclerosis: pathophysiological insights

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder of the motor neurons in the motor cortex, brainstem and spinal cord. A combination of upper and lower motor neuron dysfunction comprises the clinical ALS phenotype. Although the ALS phenotype was first observed by Charcot over 100 years ago, the site of ALS onset and the pathophysiological mechanisms underlying the development of motor neuron degeneration remain to be elucidated. Transcranial magnetic stimulation (TMS) enables non-invasive assessment of the functional integrity of the motor cortex and its corticomotoneuronal projections. To date, TMS studies have established motor cortical and corticospinal dysfunction in ALS, with cortical hyperexcitability being an early feature in sporadic forms of ALS and preceding the clinical onset of familial ALS. Taken together, a central origin of ALS is supported by TMS studies, with an anterograde transsynaptic mechanism implicated in ALS pathogenesis. Of further relevance, TMS techniques reliably distinguish ALS from mimic disorders, despite a compatible peripheral disease burden, thereby suggesting a potential diagnostic utility of TMS in ALS. This review will focus on the mechanisms underlying the generation of TMS measures used in assessment of cortical excitability, the contribution of TMS in enhancing the understanding of ALS pathophysiology and the potential diagnostic utility of TMS techniques in ALS.

Biological and neuroimaging biomarkers for amyotrophic lateral sclerosis: 2013 and beyond

SUMMARY Amyotrophic lateral sclerosis is an idiopathic, incurable neurodegenerative disease that is fatal for most patients in less than 3 years from the time weakness first appears. Alongside identification of etiologies and stronger neuroprotective agents, the development of biomarkers is a main research priority. Since the original description, diagnosis and progression measurement in amyotrophic lateral sclerosis has been clinical. The time from symptom onset to diagnosis is usually more than a year, and clinical research studies utilize clinical end points that have low sensitivity. Few eligible patients and inefficient trials mean that just one or a few new therapies can be tested each year. Biological markers are needed not only to improve the sensitivity of clinical assessments, but also to better examine disease pathophysiology in vivo.

Exploring the transitional process from receiving a diagnosis to living with motor neurone disease

Motor neurone disease (MND) is a rapidly progressing neurodegenerative condition that results in a marked reduction in life expectancy. Currently, little is known about the experiences of people after they have received this diagnosis and the effect of this on their sense of self and identity. In this study, interpretative phenomenological analysis was used to explore both the personal and lived experiences of people with MND. Seven people diagnosed with MND within the previous six months were recruited. The three themes constructed from the participants' accounts were 'Then they dropped the bomb shell'; Receiving a diagnosis of MND; 'Getting on with it'; Learning to live with MND; and 'A lot of normal life is lost'; Experiencing progressive loss. Participants described receiving a diagnosis as a devastating experience but most participants were able to accept their diagnosis and employ adaptive strategies to cope with increasing levels of functional decline. However, in spite of this, the participants experienced functional changes that affected their identity, social status and social relationships.

Utility of transcranial magnetic stimulation in delineating amyotrophic lateral sclerosis pathophysiology

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder of the motor neurons in the motor cortex, brainstem, and spinal cord. The clinical phenotype of ALS is underscored by a combination of upper and lower motor neuron dysfunction. Although this phenotype was observed over 100 years ago, the site of ALS onset and the pathophysiological mechanisms underlying the development of motor neuron degeneration remain to be elucidated. Transcranial magnetic stimulation (TMS) enables noninvasive assessment of the functional integrity of the motor cortex and its corticomotoneuronal projections. To date, TMS studies have established cortical dysfunction in ALS, with cortical hyperexcitability being an early feature in sporadic forms of ALS and preceding the clinical onset of familial ALS. Taken together, a central origin of ALS is supported by TMS studies, with an anterograde dying-forward mechanism implicated in ALS pathogenesis. Of further relevance, TMS techniques reliably distinguish ALS from mimic disorders, despite a compatible peripheral disease burden, thereby suggesting a potential diagnostic utility of TMS in ALS. This chapter reviews the mechanisms underlying the generation of TMS parameters utilized in assessment of cortical excitability, the contribution of TMS in enhancing the understanding of ALS pathophysiology, and the potential diagnostic utility of TMS techniques in ALS.

Plasma neurofilament heavy chain levels correlate to markers of late stage disease progression and treatment response in SOD1(G93A) mice that model ALS

Background

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disorder characterised by progressive degeneration of motor neurons leading to death, typically within 3–5 years of symptom onset. The diagnosis of ALS is largely reliant on clinical assessment and electrophysiological findings. Neither specific investigative tools nor reliable biomarkers are currently available to enable an early diagnosis or monitoring of disease progression, hindering the design of treatment trials.

Methodology/Principal Findings

In this study, using the well-established SOD1^G93A mouse model of ALS and a new in-house ELISA method, we have validated that plasma neurofilament heavy chain protein (NfH) levels correlate with both functional markers of late stage disease progression and treatment response. We detected a significant increase in plasma levels of phosphorylated NfH during disease progression in SOD1^G93A mice from 105 days onwards. Moreover, increased plasma NfH levels correlated with the decline in muscle force, motor unit survival and, more significantly, with the loss of spinal motor neurons in SOD1 mice during this critical period of decline. Importantly, mice treated with the disease modifying compound arimoclomol had lower plasma NfH levels, suggesting plasma NfH levels could be validated as an outcome measure for treatment trials.

Conclusions/Significance

These results show that plasma NfH levels closely reflect later stages of disease progression and therapeutic response in the SOD1^G93A mouse model of ALS and may potentially be a valuable biomarker of later disease progression in ALS.

Is there a case for diaphragm pacing for amyotrophic lateral sclerosis patients?

Respiratory pacing has advanced the long-term management of respiratory failure secondary to neurological disorders. It has an established role in curtailing invasive mechanical ventilation after upper motor neuron lesions such as spinal cord injury. There is increasing interest to expand the application of intramuscular diaphragm pacing to amyotrophic lateral sclerosis (ALS), a progressive and fatal neurodegenerative disease. Although diaphragm pacing has been offered to ALS patients, evidence-based data to determine its benefits remain lacking. The limited current literature indicates progression of respiratory dysfunction in ALS patients despite diaphragm pacing. The data from clinical trials are inadequate to substantiate its survival and sleep benefits. Its advantages over non-invasive mechanical ventilation have not been directly investigated. Furthermore, there are cautions for ALS patients to consider when opting for diaphragm pacing. Progressive degeneration of the phrenic motor neurons in classic ALS will interrupt the transmission of pacer signals to sustain diaphragm contractions. Pacing protocols that are safe for other neurological conditions may be detrimental for ALS, at least as suggested by transgenic animal models. Issues inherent to the device warrant expert intervention in implanted patients. At present, clinical effectiveness and long-term safety concerns about diaphragm pacing in ALS remain to be addressed.

Soluble beta-amyloid precursor protein is related to disease progression in amyotrophic lateral sclerosis

Background

Biomarkers of disease progression in amyotrophic lateral sclerosis (ALS) could support the identification of beneficial drugs in clinical trials. We aimed to test whether soluble fragments of beta-amyloid precursor protein (sAPPα and sAPPß) correlated with clinical subtypes of ALS and were of prognostic value.

Methodology/Principal Findings

In a cross-sectional study including patients with ALS (N = 68) with clinical follow-up data over 6 months, Parkinson's disease (PD, N = 20), and age-matched controls (N = 40), cerebrospinal fluid (CSF) levels of sAPPα a, sAPPß and neurofilaments (NfH^SMI35) were measured by multiplex assay, Progranulin by ELISA. CSF sAPPα and sAPPß levels were lower in ALS with a rapidly-progressive disease course (p = 0.03, and p = 0.02) and with longer disease duration (p = 0.01 and p = 0.01, respectively). CSF NfH^SMI35 was elevated in ALS compared to PD and controls, with highest concentrations found in patients with rapid disease progression (p<0.01). High CSF NfH^SMI3 was linked to low CSF sAPPα and sAPPß (p = 0.001, and p = 0.007, respectively). The ratios CSF NfH^SMI35/CSF sAPPα,-ß were elevated in patients with fast progression of disease (p = 0.002 each). CSF Progranulin decreased with ongoing disease (p = 0.04).

Conclusions

This study provides new CSF candidate markers associated with progression of disease in ALS. The data suggest that a deficiency of cellular neuroprotective mechanisms (decrease of sAPP) is linked to progressive neuro-axonal damage (increase of NfH^SMI35) and to progression of disease.

Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an idiopathic, fatal neurodegenerative disease of the human motor system. In this Seminar, we summarise current concepts about the origin of the disease, what predisposes patients to develop the disorder, and discuss why all cases of ALS are not the same. In the 150 years since Charcot originally described ALS, painfully slow progress has been made towards answering these questions. We focus on what is known about ALS and where research is heading-from the small steps of extending longevity, improving therapies, undertaking clinical trials, and compiling population registries to the overarching goals of establishing the measures that guard against onset and finding the triggers for this neurodegenerative disorder.

Cortical excitability distinguishes ALS from mimic disorders

OBJECTIVE

The diagnosis of amyotrophic lateral sclerosis (ALS) relies on stringent clinical criteria, resulting in diagnostic delay and inevitably the institution of appropriate therapy. Cortical hyperexcitability, as assessed by the novel threshold tracking transcranial magnetic stimulation (TTTMS) technique, appears as an early feature of ALS. Consequently, the present study assessed the diagnostic utility of threshold tracking TMS and developed algorithms to aid the diagnosis of ALS.

METHODS

Prospective studies were undertaken on a cohort of 156 consecutive patients with neuromuscular symptoms (104 ALS and 52 lower motor neuron syndrome, non-ALS syndrome, NALS) and 62 healthy controls.

RESULTS

Short-interval intracortical inhibition (SICI) was significantly reduced in ALS patients (2.4 ± 0.9%) compared to NALS (8.7 ± 0.8%, P<0.0001) and controls (10.6 ± 0.8%, P < 0.0001). The MEP amplitude and intracortical facilitation were increased, while the cortical silent period duration was reduced in ALS, all indicative of cortical hyperexcitability. Analysis of receiver operating characteristic curves suggested that threshold tracking TMS distinguished ALS from NALS, with averaged (area under curve 0.76, P < 0.0001) and peak SICI 3 ms (area under curve 0.73, P<0.0001) being the most robust diagnostic markers.

CONCLUSIONS

The presence of cortical hyperexcitability distinguishes ALS from mimic disorders.

SIGNIFICANCE

The threshold tracking TMS techniques may prove useful as a diagnostic investigation for ALS.

Dissecting the mechanisms underlying short-interval intracortical inhibition using exercise

Recently, 2 physiologically distinct phases of short-interval intracortical inhibition (SICI) have been identified, a larger phase at interstimulus interval (ISI) 3 ms and a smaller phase at ISI 1 ms. While the former is mediated by synaptic processes, the mechanisms underlying the first phase of SICI remain a matter of debate. Separately, it is known that fatiguing hand exercise reduces SICI, a measure of cortical excitability. Consequently, the present study assessed effects of fatiguing hand exercise on the 2 SICI phases, using threshold tracking transcranial magnetic stimulation techniques, to yield further information on underlying mechanisms. Studies were undertaken on 22 subjects, with SICI assessed at baseline, after each voluntary contraction (VC) period of 120 s and 5, 10, and 20 min after last VC, with responses recorded over abductor pollicis brevis. Exercise resulted in significant reduction of SICI at ISI 1 ms (SICI_baseline 9.5 ± 2.7%; SICI_{MAXIMUM REDUCTION} 2.5 ± 2.5%, P < 0.05) and 3 ms (SICI_baseline 16.8 ± 1.7%; SICI_{MAXIMUM REDUCTION} 11.6 ± 2.1%, P < 0.05), with the time course of reduction being different for the 2 phases. Taken together, findings from the present study suggest that synaptic processes were the predominant mechanism underlying the different phases of SICI.

Well-being in patients with amyotrophic lateral sclerosis and their next of kin over time

OBJECTIVES

The well-being and physical function among patients with ALS and their next of kin was studied over time.

MATERIALS AND METHODS

Thirty-five patients with ALS and their next of kin were studied with respect to physical, general and psychological well-being by the visual analogue scale (VAS) every 4-6 months. Physical function in patients was rated by the ALSFRS-R and the Norris scale. Patients and next of kin rated the well-being of themselves and their counterpart.

RESULTS

The well-being was stable and there was a relation between the well-being of patients and next of kin throughout the time studied. Next of kin rated the well-being of the patients worse than patients rated themselves, while patients rated the well-being of their next of kin at the same level as their counterpart.

CONCLUSIONS

The basic state of well-being as well as the interaction between patient and next of kin seem to be factors that influence the well-being of both patients and their next of kin.

Differences in quality of life modalities give rise to needs of individual support in patients with ALS and their next of kin

OBJECTIVE

The aim of this study was to examine health-related quality of life (HRQoL), individual QoL, anxiety and depression in patients with amyotrophic lateral sclerosis (ALS) and their next of kin in relation to patients' physical function over time.

METHODS

35 patients and their next of kin were studied using the Short Form-36 Health Survey (SF-36), Schedule for Evaluation of Individual Quality of Life-Direct Weighting (SEIQoL-DW), and Hospital Anxiety and Depression Scale (HADS) and patients also by the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised and the Norris scale every fourth to sixth month, one to four times.

RESULTS

Changes were found over time in both patients and their next of kin in the SF-36 but not in the SEIQoL-DW or HADS. Patients rated worse than their next of kin in the SF-36 physical subscales and next of kin rated worse than the patients in the global QoL score in SEIQoL-DW. Health, hobbies, and total relations were important areas in the SEIQoL-DW among all participants, but some important areas also differed between the patients and their next of kin. In most important areas among the pairs, the next of kin estimated their functioning/satisfaction worse than patients estimated their functioning/satisfaction.

SIGNIFICANCE OF RESULTS

There were few changes over time in the QoL among the participants. Although most of the estimates in patients and their next of kin were equal, there were also some differences. These results emphasize the importance of support for both patients and their next of kin and that support ought to be given on both individual bases and together in pairs. The SEIQoL-DW might give signposts in the care through the course of the disease about what should be focused on to increase satisfaction of the important areas of life and might help the person to find coping strategies to handle his or her life situation.

INSPIRATIonAL--INSPIRAtory muscle training in amyotrophic lateral sclerosis

Respiratory impairment, due to respiratory muscle weakness, is a major cause of morbidity and mortality in patients with amyotrophic lateral sclerosis/motor neuron disease (ALS/MND). Threshold loading may strengthen the inspiratory muscles and thereby improve patient prognosis. A phase II, double-blind, randomized-controlled trial was undertaken to determine whether a 12-week inspiratory muscle training programme attenuated the decline in respiratory function and inspiratory muscle strength in patients with ALS/MND. Nine patients were randomized to inspiratory muscle training and 10 to sham training. Primary endpoints were respiratory function (forced vital capacity, vital capacity), lung volumes and inspiratory muscle strength. Patients were assessed before, during and immediately after a 12-week training period, and at eight weeks follow-up. While improvements in inspiratory muscle strength were observed in both treatment arms, there was a non-significant increase in maximum inspiratory pressure of 6.1% in the experimental group compared to controls (standard error of mean, 6.93%; 95% confidence interval -8.58 -20.79; p=0.39). The gains in inspiratory muscle strength were partially reversed during a period of training cessation. In conclusion, inspiratory muscle training may potentially strengthen the inspiratory muscles and slow the decline in respiratory function in patients with ALS/MND.

Proteome analysis reveals candidate markers of disease progression in amyotrophic lateral sclerosis (ALS)

OBJECTIVES

In amyotrophic lateral sclerosis (ALS) the pathological determinants of disease progression remain poorly understood. We aimed to identify a characteristic CSF protein pattern that could provide new candidate biomarkers of disease progression in ALS.

METHODS

Using the two-dimensional difference in gel electrophoresis (2-D-DIGE), we compared CSF samples from patients with ALS that showed a rapid progression of disease (ALS-rp, n=9) over a follow-up time of 2 years and from patients with ALS that showed a slow progression of disease over follow-up (ALS-sl, n=9) over the same period. Protein spots that showed significant differences between patients and controls were selected for further analysis by MALDI-TOF mass spectrometry. For validation of identified spots ELISA and nephelometry were performed for two candidate proteins on a second cohort of patients (n=40).

RESULTS

We identified 6 different proteins and their isoforms which were all upregulated in ALS-rp as compared to ALS-sl (heat shock protein1, alpha-1 antitrypsin, fetuin-A precursor, transferrin, transthyretin (TTR), nebulin-related anchoring protein). For Fetuin-A and TTR, our findings could be confirmed by quantitative assay.

CONCLUSIONS

Fetuin-A and TTR are promising candidate markers for disease progression in ALS that warrant further evaluation on a larger cohort of patients.