Respiratory aspects of neurological disease

Neuroanatomical frameworks for volitional control of breathing and orofacial behaviors

Breathing is the only vital function that can be volitionally controlled. However, a detailed understanding how volitional (cortical) motor commands can transform vital breathing activity into adaptive breathing patterns that accommodate orofacial behaviors such as swallowing, vocalization or sniffing remains to be developed. Recent neuroanatomical tract tracing studies have identified patterns and origins of descending forebrain projections that target brain nuclei involved in laryngeal adductor function which is critically involved in orofacial behavior. These nuclei include the midbrain periaqueductal gray and nuclei of the respiratory rhythm and pattern generating network in the brainstem, specifically including the pontine Kölliker-Fuse nucleus and the pre-Bötzinger complex in the medulla oblongata. This review discusses the functional implications of the forebrain-brainstem anatomical connectivity that could underlie the volitional control and coordination of orofacial behaviors with breathing.

Schwann cells in the normal and pathological lung microenvironment

The lungs are a key organ in the respiratory system. They are regulated by a complex network of nerves that control their development, structure, function, and response to various pathological stimuli. Accumulating evidence suggests the involvement of a neural mechanism in different pathophysiological conditions in the lungs and the development and progression of common respiratory diseases. Lung diseases are the chief source of death globally. For instance, lung cancer is the second most commonly diagnosed malignancy, after prostate cancer in men and breast cancer in women, and is the most lethal cancer worldwide. However, although airway nerves are accepted as a mechanistically and therapeutically important feature that demands appropriate emphasizing in the context of many respiratory diseases, significantly less is known about the role of the neuroglial cells in lung physiology and pathophysiology, including lung cancer. New data have uncovered some cellular and molecular mechanisms of how Schwann cells, as fundamental components of the peripheral nervous system, may regulate lung cancer cells' survival, spreading, and invasiveness in vitro and in vivo. Schwann cells control the formation and maintenance of the lung cancer microenvironment and support metastasis formation. It was also reported that the number of lung cancer-associated Schwann cells correlates with patients' survival. Different factors secreted by Schwann cells, including microRNA, are known to sharpen the lung cancer environment by regulating the tumor-neuro-immune axis. Further clinical and experimental studies are required to elucidate the detailed role of Schwann cells in creating and maintaining pulmonary tumor-neuro-immune axis, which will advance our understanding of the pathogenesis of lung cancer and may inform therapeutic hypotheses aiming neoplasms and metastases in the lung.

Researches of calcium-activated chloride channel ANO1 intervening amyotrophic lateral sclerosis progression by activating EGFR and CaMKII signaling

BACKGROUND

ANO1 is closely correlated with the activation of EGFR and CaMKII, while EGFR and CaMKII show low activation in amyotrophic lateral sclerosis (ALS) models. Therefore, we designed experiments to verify that ANO1 may play a protective role on motor neurons in ALS by activating EGFR and CaMKII.

METHODS

The expression changes of ANO1, EGFR, CaMKII, pEGFR, and pCaMKII, cell survival status, and apoptosis were studied by western blot, real-time quantitative PCR, immunofluorescence, immunohistochemistry, CCK-8, and flow cytometry. The role of ANO1 in the ALS model by activating EGFR and CaMKII was studied by applying corresponding activators, inhibitors, gene silencing, and overexpression.

RESULTS

In hSOD1G93A transgenic animals and cell lines, low expression of ANO1 and low activation of EGFR and CaMKII were identified. ANO1 expression decreased gradually with the progression of ALS. Overexpression of ANO1 in the hSOD1G93A cell line and primary neurons of hSOD1G93A transgenic mice increased cell viability and decreased cell apoptosis. After the application of ANO1 inhibitor CaCC-inhA01 in hSOD1G93A cell line and primary neurons of hSOD1G93A transgenic mice, EGFR activator EGF and CaMKII activator Carbachol, increased cell viability and reduced cell apoptosis. After ANO1 was overexpressed in the hSOD1G93A cell line and primary neurons of hSOD1G93A transgenic mice, EGFR inhibitor AEE788 and CaMKII inhibitor KN93 decreased cell viability and increased cell apoptosis.

CONCLUSIONS

Our results suggest that ANO1 plays an important role in the survival of ALS motor neurons. ANO1 can increase cell activity and reduce apoptosis by activating EGFR and CaMKII signals.

Phenome-wide genetic-correlation analysis and genetically informed causal inference of amyotrophic lateral sclerosis

Leveraging genome-wide association statistics generated from a large study of amyotrophic lateral sclerosis (ALS; 29,612 cases and 122,656 controls) and UK Biobank (UKB; 4,024 phenotypes, up to 361,194 participants), we conducted a phenome-wide analysis of ALS genetic liability and identified 46 genetically correlated traits, such as fluid intelligence score (rg = - 0.21, p = 1.74 × 10-6), "spending time in pub or social club" (rg = 0.24, p = 2.77 × 10-6), non-work related walking (rg = - 0.25, p = 1.95 × 10-6), college education (rg = - 0.15, p = 7.08 × 10-5), "ever diagnosed with panic attacks (rg = 0.39, p = 4.24 × 10-5), and "self-reported other gastritis including duodenitis" (rg = 0.28, p = 1.4 × 10-3). To assess the putative directionality of these genetic correlations, we conducted a latent causal variable analysis, identifying significant genetic causality proportions (gĉp) linking ALS genetic liability to seven traits. While the genetic component of "self-reported other gastritis including duodenitis" showed a causal effect on ALS (gĉp = 0.50, p = 1.26 × 10-29), the genetic liability to ALS is potentially causal for multiple traits, also including an effect on "ever being diagnosed with panic attacks" (gĉp = 0.79, p = 5.011 × 10-15) and inverse effects on "other leisure/social group activities" (gĉp = 0.66, p = 1 × 10-4) and prospective memory result (gĉp = 0.35, p = 0.005). Our subsequent Mendelian randomization analysis indicated that some of these associations may be due to bidirectional effects. In conclusion, this phenome-wide investigation of ALS polygenic architecture highlights the widespread pleiotropy linking this disorder with several health domains.

Insights into the promising prospect of medicinal chemistry studies against neurodegenerative disorders

Medicinal chemistry is an interdisciplinary field that incorporates organic chemistry, biochemistry, physical chemistry, pharmacology, informatics, molecular biology, structural biology, cell biology, and other disciplines. Additionally, it considers molecular factors such as the mode of action of the drugs, their chemical structure-activity relationship (SAR), and pharmacokinetic aspects like absorption, distribution, metabolism, elimination, and toxicity. Neurodegenerative disorders (NDs), which are defined by the breakdown of neurons over time, are affecting an increasing number of people. Oxidative stress, particularly the increased production of Reactive Oxygen Species (ROS), plays a crucial role in the growth of various disorders, as indicated by the identification of protein, lipid, and Deoxyribonucleic acid (DNA) oxidation products in vivo. Because of their inherent nature, most biological molecules are vulnerable to ROS, even if they play a role in metabolic parameters and cell signaling. Due to their high polyunsaturated fatty acid content, low antioxidant barrier, and high oxygen uptake, neurons are particularly vulnerable to oxidation by nature. As a result, excessive ROS generation in neurons looks especially harmful, and the mechanisms associated with biomolecule oxidative destruction are several and complex. This review focuses on the formation and management of ROS, as well as their chemical characteristics (both thermodynamic and kinetic), interactions, and implications in NDs.

Initiation and Withdrawal of Invasive Ventilation for Patients with Amyotrophic Lateral Sclerosis: A Narrative Literature Review

Decisions regarding invasive ventilation with tracheostomy (TIV) in patients with amyotrophic lateral sclerosis (ALS) involve serious ethical issues. Cultural differences in the attitudes of patients, caregivers, and physicians toward TIV initiation and withdrawal decisions have been analyzed based on a narrative review approach, comparing the situation between Japan and the U.S. Three main issues were identified regarding the implementation of TIV. The first is the lack of Advance Care Planning. Second, some patients may choose TIV based on the wishes of their physicians or caregivers, even if the patients themselves do not want TIV in the Japanese context. Third is the influence of patient associations, which advocate for the protection of patients’ rights. Next, this study identifies the following issues related to TIV discontinuation. The main concern here is cultural differences in legislation and ethical intuitions regarding the discontinuation of TIV. The treatment guidelines for patients with ALS advise physicians to reassure patients that TIV can be withdrawn at any point. However, TIV withdrawal is not explicitly discussed in Japan. Moreover, Japanese ALS treatment guidelines state that ventilation withdrawal is currently impossible, due to a lack of legal support. Most Japanese physicians have told patients that they are not allowed to stop ventilation via such a request. Unlike in the U.S., withholding and withdrawing ventilators are not ethically equivalent in Japan. In conclusion, the decision-making process regarding TIV is difficult, not only for the patients and caregivers, but also for physicians. Even if patients are legally entitled to refuse unwanted treatment, there have been cases in which Japanese physicians have felt an ethical dilemma in stopping TIV for patients with ALS. However, few studies have investigated in detail why physicians oppose the patient’s right to discontinue TIV in Japan.

Phrenic nerve paralysis and phrenic nerve reconstruction surgery

Phrenic nerve injury results in paralysis of the diaphragm muscle, the primary generator of an inspiratory effort, as well as a stabilizing muscle involved in postural control and spinal alignment. Unilateral deficits often result in exertional dyspnea, orthopnea, and sleep-disordered breathing, whereas oxygen or ventilator dependency can occur with bilateral paralysis. Common etiologies of phrenic injuries include cervical trauma, iatrogenic injury in the neck or chest, and neuralgic amyotrophy. Many patients have no identifiable etiology and are considered to have idiopathic paralysis. Diagnostic evaluation requires radiographic and pulmonary function testing, as well as electrodiagnostic assessment to quantitate the nerve deficit and determine the extent of denervation atrophy. Treatment for symptomatic diaphragm paralysis has traditionally been limited. Medical therapies and nocturnal positive airway pressure may provide some benefit. Surgical repair of the nerve injury to restore functional diaphragmatic activity, termed phrenic nerve reconstruction, is a safe and effective alternative to static repositioning of the diaphragm (diaphragm plication), in properly selected patients. Phrenic nerve reconstruction has increasingly become a standard surgical treatment for diaphragm paralysis due to phrenic nerve injury. A multidisciplinary approach at specialty referral centers combining diagnostic evaluation, surgical treatment, and rehabilitation is required to achieve optimal long-term outcomes.

A retrospective cohort study of idiopathic diaphragmatic palsy: a diagnostic triad, natural history and prognosis

Background

Isolated diaphragmatic palsy in the absence of progressive neuromuscular disease is uncommon. It poses diagnostic challenges and limited data are available regarding prognosis. We present retrospective cohort data from two large teaching hospitals in the United Kingdom.

Method

60 patients who were assessed either as inpatients or outpatients were included in this study. Patients with progressive neuromuscular disease were excluded. Clinical presentation, tests of respiratory muscle function (sitting/supine vital capacity, maximal expiratory pressure (MEP), maximal inspiratory pressure (MIP) and sniff nasal inspiratory pressure (SNIP)) and outcomes were recorded.

Results

For patients with diaphragmatic palsy, mean±sd seated and supine vital capacity pre-noninvasive ventilation (NIV) were reduced at 1.7±1.2 L and 1.1±0.9 L, respectively, with a mean±sd postural fall in vital capacity of 42±0.16%. The mean MEP/MIP and MEP/SNIP ratios for diaphragmatic palsy were 3 and 3.5, respectively. After a year of treatment with NIV, mean±sd upright and supine vital capacity had increased to 2.1±0.9 L and 1.8±1 L, respectively, and the mean±sd fall in vital capacity from sitting to supine reduced to 29±0.17%. MEP/MIP and MEP/SNIP ratios reduced to 2.6 and 2.9, respectively, from the pre-NIV values. The values of postural fall in vital capacity correlated (p<0.05) with MEP/MIP and MEP/SNIP ratio (r²=0.86 and r²=0.7, respectively).

Conclusion

Tests of respiratory muscle strength are valuable in the diagnostic workup of patients with unexplained dyspnoea. A triad of 1) orthopnoea, with 2) normal lung imaging and 3) MEP/MIP and/or MEP/SNIP ratio ≥2.7 points towards isolated diaphragmatic palsy. This needs to be confirmed by prospective studies.

Tests of respiratory muscle strength are valuable in the diagnostic workup of patients with unexplained dyspnoea. A triad of 1) orthopnoea with 2) normal lung imaging and 3) MEP/MIP and/or MEP/SNIP ratios ≥2.7 points towards isolated diaphragmatic palsy.https://bit.ly/2SpOXW2

Minor Allele Frequencies and Molecular Pathways Differences for SNPs Associated with Amyotrophic Lateral Sclerosis in Subjects Participating in the UKBB and 1000 Genomes Project

Amyotrophic lateral sclerosis (ALS) is a complex disease with a late onset and is characterized by the progressive loss of muscular and respiratory functions. Although recent studies have partially elucidated ALS's mechanisms, many questions remain such as what the most important molecular pathways involved in ALS are and why there is such a large difference in ALS onset among different populations. In this study, we addressed this issue with a bioinformatics approach, using the United Kingdom Biobank (UKBB) and the European 1000 Genomes Project (1KG) in order to analyze the most ALS-representative single nucleotide polymorphisms (SNPs) that differ for minor allele frequency (MAF) between the United Kingdom population and some European populations including Finnish in Finland, Iberian population in Spain, and Tuscans in Italy. We found 84 SNPs associated with 46 genes that are involved in different pathways including: "Ca²⁺ activated K⁺ channels", "cGMP effects", "Nitric oxide stimulates guanylate cyclase", "Proton/oligopeptide cotransporters", and "Signaling by MAPK mutants". In addition, we revealed that 83% of the 84 SNPs can alter transcription factor-motives binding sites of 224 genes implicated in "Regulation of beta-cell development", "Transcription-al regulation by RUNX3", "Transcriptional regulation of pluripotent stem cells", and "FOXO-mediated transcription of cell death genes". In conclusion, the genes and pathways analyzed could explain the cause of the difference of ALS onset.

A Case Report of Acute Flaccid Paralysis Caused by Enterovirus D68 Infection: The Beginning of a Polio-Like Epidemic?

Enterovirus D68 (EV-D68) is a non-polio enterovirus that occasionally causes respiratory illnesses. EV-D68 infections have occurred over the last couple of years and have a high prevalence worldwide. This virus has recently been linked to acute flaccid paralysis and particularly affects children. We report the case of a young adult who presented with acute neurological manifestations along with respiratory involvement. EV-D68 was detected in the patient’s broncho-alveolar lavage and was followed by a prolonged recovery period. Clinicians should consider EV-D68 infection in the differential diagnosis of acute flaccid paralysis (AFP) and respiratory failure.

Glucose Metabolic Dysfunction in Neurodegenerative Diseases-New Mechanistic Insights and the Potential of Hypoxia as a Prospective Therapy Targeting Metabolic Reprogramming

Glucose is the main circulating energy substrate for the adult brain. Owing to the high energy demand of nerve cells, glucose is actively oxidized to produce ATP and has a synergistic effect with mitochondria in metabolic pathways. The dysfunction of glucose metabolism inevitably disturbs the normal functioning of neurons, which is widely observed in neurodegenerative disease. Understanding the mechanisms of metabolic adaptation during disease progression has become a major focus of research, and interventions in these processes may relieve the neurons from degenerative stress. In this review, we highlight evidence of mitochondrial dysfunction, decreased glucose uptake, and diminished glucose metabolism in different neurodegeneration models such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). We also discuss how hypoxia, a metabolic reprogramming strategy linked to glucose metabolism in tumor cells and normal brain cells, and summarize the evidence for hypoxia as a putative therapy for general neurodegenerative disease.

Impacts of the COVID-19 Pandemic on the Mental Health and Motor Deficits in Cuban Patients with Cerebellar Ataxias

Although there are no convincing evidences of detrimental effect of SARS-CoV2 infection on the cerebellum, the COVID-19 pandemic could impact the life quality of patients with cerebellar ataxias, but few studies have addressed this concern. To assess the motor and mental health changes caused by the COVID-19 pandemics in Cuban patients with cerebellar ataxias, three hundred four patients with cerebellar ataxias and 167 healthy controls were interviewed for risks of exposure to COVID-19, and the self-perception of the pandemics’ impact on the disease progression and on the mental health. All subjects underwent the Hospital Anxiety and Depression Scale. The patients reported low exposition to SARS-CoV2 infection, but one case was confirmed with a mild COVID-19. Overall, depressive and anxiety symptoms were significantly and marginally increased in patients, respectively, with higher scores in cases with severe and moderate ataxia. Positive patient’s impression of psychopathological changes was associated to increased age, age at onset, and anxiety. Sixty-seven patients had a positive self-perception of ataxia progression, which was mainly influenced by higher anxiety scores but not by the adherence to at-home exercise programs. However, the practice of physical exercise was related with lower depression and anxiety scores, but this therapeutical effect was not significantly influenced by the disease stage. We demonstrated the negative effect of the COVID-19 pandemic on the mental and motor deficits in Cuban patients with cerebellar ataxias and the positive effect of the at-home physical exercise programs on their mental well-being. These findings give rationales to develop tele-medicine approaches to minimize these health impacts and to study the long-term effects of such sequelae and accordingly define their treatments.

Cardiorespiratory and skeletal muscle damage due to COVID-19: making the urgent case for rehabilitation

INTRODUCTION

It has become increasingly evident that COVID-19 contributes to multiorgan pathophysiology. The systemic inflammatory response increases both pro-inflammatory cytokine and chemokine levels, leading to immune dysregulation and increasing the likelihood of incurring cardiac and pulmonary injuries.

AREAS COVERED

Longer periods of hospitalization (~20 days) increase susceptibility to ICU-acquired muscle weakness and deconditioning, which decreases muscle function and functional capacity. These conditions affect the quality of life in the post-COVID-19 period and require multi-disciplinary approaches to rehabilitate the cardiopulmonary and musculoskeletal systems of these patients. In this context, this narrative review, which included articles published in the Embase, PEDro and PubMed databases up to December 2020, is focused on discussing the essential role of exercise and rehabilitation health professionals in the COVID-19 recovery process, from hospitalization to hospital discharge, addressing strategies for professionals to mitigate the cardiac and pulmonary impairments associated with hospitalization to home or ambulatory rehabilitation, purposing ways to conduct rehabilitation programs to restore their functional status and quality of life after the infection.

EXPERT OPINION

In the current environment, these findings further point to the vital role of rehabilitation health professionals in the coming years and the urgent need to develop strategies to assist COVID-19 survivors.

Posterior circulation stroke presenting as a new continuous cough: not always COVID-19

A 19-year-old man was admitted with a 2-week history of continuous cough along with a day history of acute onset unsteadiness and hiccups. Given the current pandemic, he was initially suspected to have COVID-19, however he tested negative on two occasions. Subsequent brain magnetic resonance imaging (MRI)confirmed a small left acute and subacute lateral medullary infarction with chest X-ray suggesting aspiration pneumonia with right lower lobe collapse. This is a distinctive case of posterior circulation stroke presenting with a new continuous cough in this era of COVID-19 pandemic. We anticipate based on MRI findings that his persistent cough was likely due to silent aspiration from dysphagia because of the subacute medullary infarction. It is therefore imperative that healthcare workers evaluate people who present with new continuous cough thoroughly to exclude any other sinister pathology. We should also be familiar with the possible presentations of posterior circulation stroke in this pandemic era.

Nonpharmacological interventions for respiratory health in Parkinson's disease: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Respiratory dysfunction in Parkinson's disease (PD) is often an underdiagnosed and untreated impairment associated with the disease. Clinically, a reactive approach to respiratory morbidity is taken, rather than preventative approaches that address underlying impairment/s. This systematic review identifies the current evidence to support nonpharmacological interventions to improve respiratory impairments in individuals with PD.

METHODS

The relevant literature was searched using a customised and systematic strategy. Randomised and nonrandomised control trials of nonpharmacological interventions targeting respiratory outcome measures in PD were included. Outcomes of interest were respiratory morbidity and mortality, respiratory muscle strength, spirometry measures, lung volumes, peak cough flow, and perception of dyspnoea.

RESULTS

Nonpharmacological interventions included: functional training, generalised strength training, respiratory muscle strength training, aerobic exercise, qigong, yoga, breath stacking, incentive spirometry and singing. Methodological quality of included studies varied. Meta-analyses of nonpharmacological interventions demonstrated significant effects for inspiratory muscle strength (mean difference [MD] 19.68; confidence interval [CI] 8.49, 30.87; z = 3.45; p = 0.0006; I²  = 2%), expiratory muscle strength (MD 18.97; CI 7.79, 30.14; z = 3.33; p = 0.0009; I²  = 23%) and peak expiratory flow (MD 72.21; CI 31.19, 113.24; z = 3.45; p = 0.0006; I²  = 0%). Best-evidence synthesis identified level 1 evidence supporting nonpharmacological interventions for improving peak cough flow and perceived dyspnoea. No studies were identified reporting outcomes of respiratory rate, inspiration:expiration ratio or respiratory morbidity or mortality in PD.

CONCLUSIONS

Nonpharmacological interventions improved respiratory muscle strength and peak expiratory flow in PD. Additional trials targeting respiratory dysfunction and longitudinal studies examining the relationship between respiratory dysfunction and morbidity and mortality rates in PD are required.

Chameleons, red herrings, and false localizing signs in neurocritical care

False localizing signs (FLS) and other misleading neurological signs have long been an intractable aspect of neurocritical care. Because they suggest an incorrect location or etiology of the pathological lesion, they have often led to misdiagnosis and mismanagement of the patient. Here, we reviewed the existing literature to provide an updated, comprehensive descriptive review of these difficult to diagnose signs in neurocritical care. For each sign presented, we discuss the non-false localizing presentation of symptoms, the common FLS or misleading presentation, etiology/pathogenesis of the sign, and diagnosis, as well as any other clinically relevant considerations. Within cranial neuropathies, we cover cranial nerves III, IV, V, VI, VII, VIII, as well as multiple cranial nerve involvement of IX, X, and XII. FLS ophthalmologic symptoms indicate diagnostically challenging neurological deficits, and here we discuss downbeat nystagmus, ping-pong-gaze, one-and-a-half syndrome, and wall-eyed bilateral nuclear ophthalmoplegia (WEBINO). Cranial herniation syndromes are integral to any discussion of FLS and here we cover Kernohan's notch phenomenon, pseudo-Dandy Walker malformation, and uncal herniation. FLS in the spinal cord have also been relatively well documented, but in addition to compressive lesions, we also discuss newer findings in radiculopathy and disc herniation. Finally, pulmonary syndromes may sometimes be overlooked in discussions of neurological signs but are critically important to recognize and manage in neurocritical care, and here we discuss Cheyne-Stokes respiration, cluster breathing, central neurogenic hyperventilation, ataxic breathing, Ondine's curse, and hypercapnia. Though some of these signs may be rare, the framework for diagnosing and treating them must continue to evolve with our growing understanding of their etiology and varied presentations.

Correlation between dysphonia and dysphagia evolution in amyotrophic lateral sclerosis patients

MATERIALS AND METHODS

Between March 2017 and February 2018, 27 newly diagnoses patients (about 2 months) were examined in the ENT Clinic of our University Hospital. The bulbar-onset of ALS was diagnosed by neurologists.

RESULTS

According to the endoscopic and clinical results, patients were classified in 4 classes of dysphagia. Laryngology and speech pathology assessment with spectroacuostic analysis of speech using Praat software are fundamental for the proper evaluation of dysphonia of these patients. This study was the first attempt to find a vocal indicator of advancement in swallowing dysfunction in the patient population of ALS. Preliminary findings indicate that the reduction in the maximum fundamental frequency is associated with advancement of dysphagia.

CONCLUSIONS

Monitoring the vocal parameters could be useful in order to give an early rehabilitation aid to these patients improving their quality of life and reducing aspiration risks.

Canine Models of Inherited Musculoskeletal and Neurodegenerative Diseases

Mouse models of human disease remain the bread and butter of modern biology and therapeutic discovery. Nonetheless, more often than not mouse models do not reproduce the pathophysiology of the human conditions they are designed to mimic. Naturally occurring large animal models have predominantly been found in companion animals or livestock because of their emotional or economic value to modern society and, unlike mice, often recapitulate the human disease state. In particular, numerous models have been discovered in dogs and have a fundamental role in bridging proof of concept studies in mice to human clinical trials. The present article is a review that highlights current canine models of human diseases, including Alzheimer's disease, degenerative myelopathy, neuronal ceroid lipofuscinosis, globoid cell leukodystrophy, Duchenne muscular dystrophy, mucopolysaccharidosis, and fucosidosis. The goal of the review is to discuss canine and human neurodegenerative pathophysiologic similarities, introduce the animal models, and shed light on the ability of canine models to facilitate current and future treatment trials.

Therapeutic alternative of the ketogenic Mediterranean diet to improve mitochondrial activity in Amyotrophic Lateral Sclerosis (ALS): A Comprehensive Review

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease which is pathogenically based on the mitochondrial alteration of motor neurons, causing progressive neuron death. While ALS is characterized by enormous oxidative stress, the Mediterranean diet has been seen to have high antioxidant power. Therefore, the aim of this study is to determine how the Mediterranean diet can improve mitochondrial activity, establishing the specific nutrients and, in addition, observing the pathogenic mechanisms related to the disease that would achieve this improvement. To this end, a comprehensive review of the literature was performed using PubMed. KBs have been observed to have a neuroprotective effect to improve energy balance, increasing survival and the number of motor neurons. This ketogenesis can be achieved after following a Mediterranean diet which is associated with great benefits in other neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and ALS. These benefits are due to the high antioxidant power especially based on polyphenols contained mainly in olive oil, wine, nuts, or berries. In short, KBs could be considered as a promising option to treat ALS, representing an alternative source to glucose in motor neurons by providing neuroprotection. In addition, treatment results can be improved as ketogenesis can be achieved (increase in KBs) by following a Mediterranean diet, thanks to the high antioxidant properties which, at the same time, would improve the high oxidative stress that characterizes the disease.

Respiratory repercussions of neurological diseases and how best to manage them

Introduction: The high incidence of respiratory impairments in patients with neurological diseases is recognized, but the design, dosage, and effectiveness of interventions to manage them are seen as an ongoing challenge.Areas covered: This article summarizes the evidence regarding the respiratory impairments in major neurological diseases, and how to best manage them.Expert opinion: On the balance of available evidence, respiratory impairments are part of the clinical profile of neurological diseases including Multiple Sclerosis, Stroke, and Parkinson's Disease, acquiring more importance as the pathologies progress. It is recognized that knowledge gaps remain in some areas of relevance related to respiratory function and further research is required. When considering the therapeutic options, the respiratory training emerges as the approach with most evidence. However, important questions remain unsolved: what kind, how much, and how to best include respiratory interventions is uncertain. At present, respiratory programs also fail to include clinically relevant factors such as ambulation and trunk stability.

Comparison of arterial and venous blood gases in patients with obesity hypoventilation syndrome and neuromuscular disease

OBJECTIVES:

Obesity hypoventilation syndrome (OHS) and some neuromuscular diseases (NMD) present with hypercapnic respiratory failure. Arterial blood gas (ABG) analysis is important in the diagnosis, follow-up, and treatment response of these diseases. However, ABG sampling is difficult in these patients because of excessive subcutaneous fat tissue, muscle atrophy, or contracture. The aim of this study is to investigate the value of venous blood gas (VBG), which is an easier and less complicated method, among stable patients with OHS and NMD.

METHODS:

The study included stable OHS and NMD patients who had been previously diagnosed and followed up between March 2017 and May 2017 in the outpatient clinic. ABG was taken from all patients in room air, and peripheral VBG was taken within 5 min after ABG sampling.

RESULTS:

Thirty-six patients with OHS and 46 patients with NMD were included in the study. There was a moderate positive correlation between arterial and venous pH values for all patients (r_s = 0.590, P < 0.001). There were a strong and very strong positive correlations between arterial and venous pCO₂ and HCO₃ values (r_s = 0.725 and r_s = 0.934, respectively) (P < 0.001). There was no correlation between arterial and venous pO₂ and saturation values. There was an agreement in Bland–Altman method for the values of ABG and VBG (pH, pCO₂, and HCO₃).

CONCLUSIONS:

There was a correlation between ABG and VBG values (pH, pCO₂, and HCO₃). VBG parameters (pH, pCO₂, and HCO₃) can be used safely instead of ABG parameters which have many risks, during treatment and follow-up of patients with OHS and NMD.

Phenotypical Variation with Same Genetic Mutation in Familial Hypokalemic Periodic Paralysis

Hypokalemic periodic paralysis is a genetic neuromuscular disorder characterized by episodes of painless muscle paralysis associated with low serum potassium, exclusively, during the attack. This may be precipitated by heavy exercise, fasting, or high-carbohydrate meals. We report two siblings, presenting at different ages with varying symptomatology—older sibling with episodic weakness in the morning associated with reduced physical exercise and consumption of large carbohydrate meal, whereas younger sibling complained of muscle stiffness following large carbohydrate meal and at the end of physical exercise. Molecular genetic study showed both siblings and their father were positive for calcium channel alpha-1S subunit (CACNA1S) C3716G>A; p.Arg1239His mutation. It is important to check serum potassium in a child presenting with muscle stiffness or weakness after a carbohydrate meal or vigorous exercise. This condition responds with potassium supplement. Often relevant family history and trigger factors with clinical correlation and blood results can lead to its diagnosis.

Evaluation of Respiratory Muscle Strength in the Acute Phase of Stroke: The Role of Aging and Anthropometric Variables

BACKGROUND

During hospitalization, stroke patients are bedridden due to neurologic impairment, leading to loss of muscle mass, weakness, and functional limitation. There have been few studies examining respiratory muscle strength (RMS) in the acute phase of stroke.

OBJECTIVE

This study aimed to evaluate the RMS of patients with acute stroke compared with predicted values and to relate this to anthropometric variables, risk factors, and neurologic severity.

METHODS

This is a cross-sectional study in the acute phase of stroke. After admission, RMS was evaluated by maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP); anthropometric data were collected; and neurologic severity was evaluated by the National Institutes of Health Stroke Scale. The analysis of MIP and MEP with predicted values was performed by chi-square test, and the relationship between anthropometric variables, risk factors, and neurologic severity was determined through multiple linear regression followed by residue analysis by the Shapiro-Wilk test; P < .05 was considered statistically significant.

RESULTS

In the 32 patients studied, MIP and MEP were reduced when compared with the predicted values. MIP declined significantly by 4.39 points for each 1 kg/m² increase in body mass index (BMI), and MEP declined significantly by an average of 3.89 points for each 1 kg/m² increase in BMI. There was no statistically significant relationship between MIP or MEP and risk factors, and between MIP or MIP and neurologic severity in acute phase of stroke.

CONCLUSION

There is a reduction of RMS in the acute phase of stroke, and RMS was lower in individuals with increased age and BMI.

Guillain-Barré syndrome: causes, immunopathogenic mechanisms and treatment

INTRODUCTION

Guillain-Barré syndrome is a rare disease representing the most frequent cause of acute flaccid symmetrical weakness of the limbs and areflexia usually reaching its peak within a month. The etiology and pathogenesis remain largely enigmatic and the syndrome results in death or severe disability in 9-17% of cases despite immunotherapy. Areas covered: In terms of etiology, Guillain-Barré syndrome is linked to Campylobacter infection but less than 0.1% of infections result in the syndrome. In terms of pathogenesis, activated macrophages and T cells and serum antibodies against gangliosides are observed but their significance is unclear. Expert commentary: Guillain-Barré syndrome is a heterogeneous condition with numerous subtypes and recent data point towards the role of ganglioside epitopes by immunohistochemical methods. Ultimately, the syndrome results from a permissive genetic background on which environmental factors, including infections, vaccination and the influence of aging, lead to disease.

Management of bronchial secretions with Free Aspire in children with cerebral palsy: impact on clinical outcomes and healthcare resources

Background

Management of secretions in children with cerebral palsy is often problematic due to severe deformation of the rib cage, impaired cough, and patients’inability to collaborate with chest physiotherapy. Assessing the effectiveness of different methods and techniques of secretion clearance is hampered by the lack of direct outcome measures and by limited patient cooperation.

This observational study was planned to evaluate the efficacy of Free Aspire, a device that utilizes a special method to remove secretions from the bronchial tree in hypersecretive patients.

Case presentation

Cerebral palsy patients were selected who had experienced more than 3 episodes of respiratory exacerbations in the latest year despite therapeutic optimization (including bronchial clearance techniques) and who had received at least one antibiotic course or underwent at least one access to the Emergency Room (ER) or admission to hospital in the 6 months prior to the study. Patients with congestive heart failure or contraindications for Free Aspire were excluded. We prospectively enrolled 8 patients (mean age 8.25 ± 6.11 years) who had been using in the past techniques for clearance secretions different from Free Aspire.

The treatment with Free Aspire consisted of at least two 20-min sessions per day. The observational study period was 18 months.

In the 6 months prior to start the treatment (T0), patients had a mean number of 4.0 ± 2.23 visits from the primary care pediatrician (PCP), spent 14 ± 20 days in hospital, and received antibiotics for 35 ± 17 days. After the first 6 months of treatment (T1), they had 1.7 ± 0.73 PCP visits, no days spent in hospital, and 9.75 ± 10.4 days of antibiotic therapy. At 12 months of treatment (T2), PCP visits were 1.7 ± 0.70, days in hospital 1.12 ± 0.3, and days of antibiotics 10.25 ± 10. At 18 months of treatment (T3) no hospitalizations had occurred, PCP visits were 0.25 ± 0.70, and days of antibiotic therapy 4.8 ± 12.62. The technique proved to be safe and well tolerated.

Conclusion

Our findings show that Free Aspire for bronchial secretion clearance in cerebral palsy patients with limited capacity to collaborate is safe and effective in reducing the impact of respiratory exacerbations in terms of number of PCP visits, days spent in hospital, and days of antibiotic therapy; its regular use maintains this effect in time.

A comprehensive review of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a late-onset fatal neurodegenerative disease affecting motor neurons with an incidence of about 1/100,000. Most ALS cases are sporadic, but 5–10% of the cases are familial ALS. Both sporadic and familial ALS (FALS) are associated with degeneration of cortical and spinal motor neurons. The etiology of ALS remains unknown. However, mutations of superoxide dismutase 1 have been known as the most common cause of FALS. In this study, we provide a comprehensive review of ALS. We cover all aspects of the disease including epidemiology, comorbidities, environmental risk factor, molecular mechanism, genetic factors, symptoms, diagnostic, treatment, and even the available supplement and management of ALS. This will provide the reader with an advantage of receiving a broad range of information about the disease.

Nocturnal hypoventilation in neuromuscular disease: prevalence according to different definitions issued from the literature

PURPOSE

Restrictive respiratory failure is a major cause of morbidity and mortality in neuromuscular diseases (NMD). Home mechanical ventilation (HMV) is used to treat hypoventilation, identified by daytime hypercapnia or nocturnal desaturation. Recently, transcutaneous measure of CO2 (TcCO2) has been increasingly used to detect hypoventilation, using different cut-offs. We aimed to compare the prevalence of hypoventilation in an unselected adult NMD population according to different definitions issued from the literature.

METHODS

All consecutive nocturnal capno-oximetries performed between 2010 and 2014 in unventilated adult NMD patients were analysed retrospectively. Concomitant blood gas analysis and lung function data were collected. Patients on oxygen therapy were excluded. Hypoventilation was defined according to eight criteria, based on daytime PaCO2, daytime base excess, nocturnal SpO2 or TcCO2.

RESULTS

Data from 232 patients were analysed (mean age 43.1 ± 15.4 years; 50.0 % women; vital capacity 59.2 ± 24.2 % of predicted). The hypoventilation prevalence was 10.3 to 61.2 %, depending on the used definition. The different definitions showed 49.1 to 94.8 % concordance (Cohen's kappa for agreement 0.115 to 0.763). Overall agreement between the eight definitions was poor (Light's kappa 0.267), and agreement between definitions based on nocturnal SpO2 and those based on TcCO2 was even lower (Light's kappa 0.204).

CONCLUSIONS

We found large differences in hypoventilation prevalence according to the used definition. This has practical consequences, as HMV indication relies upon hypoventilation detection. We believe that capno-oximetry should be included in the diagnostic tools used to detect hypoventilation but this requires an update of consensus guidelines to agree upon the best definition.

Breathing and the nervous system

Breathing requires complex interactions of the central and peripheral nervous systems with the respiratory system. It involves cortical (volitional) as well as subcortical (automatic) output. Cortical output is mainly through the corticospinal tract, whereas the brainstem sends signals via the reticulospinal tract. Groups of nuclei in the brainstem (pneumotaxic center, dorsal and ventral respiratory group), situated in the pons and medulla, function as rhythm generators. Some of these nuclei have intrinsic pacemaker activity; however, their output is affected extensively by various chemical (through aortic and carotid bodies), mechanical (stretch reflexes), and neural feedbacks from the peripheral nervous system involving cranial nerves V, VII, IX, X, and XI. Brainstem nuclei also have central chemoreceptors that detect changes in serum carbon dioxide and pH. Various neurologic disorders such as stroke or neurodegenerative diseases (Parkinson's disease, multiple system atrophy) can adversely affect respiration and may even be the first sign of disease onset. Clinicians should have a better understanding of this complex but important physiological process to better appreciate pathologies affecting it. Future research is needed to enhance our understanding of this intricate process.

Effects of respiratory muscle training on pulmonary functions in patients with slowly progressive neuromuscular disease: a randomized controlled trial

Objective:

To investigate the effects of inspiratory and expiratory muscle training on pulmonary functions in patients with slowly progressive neuromuscular disease.

Design:

Prospective randomized controlled double-blinded study.

Setting:

Chest diseases clinic of university hospital.

Subjects:

Twenty-six patients with slowly progressive neuromuscular disease followed for respiratory problems were included in the study. Patients were randomly divided into two groups; experimental ( n = 14; age 31.6 ±12.3 years) and sham ( n = 12; age 26.5 ±8.6 years) groups.

Methods:

Spirometry, peak cough flow, maximal inspiratory pressure, maximal expiratory pressure, and sniff nasal inspiratory pressure were measured before the eighth week of study, and subsequently at end of it. Respiratory muscle training was performed by inspiratory (Threshold Inspiratory Muscle Trainer) and expiratory (Threshold Positive Expiratory Pressure) threshold loading methods. Training intensities were increased according to maximal inspiratory and expiratory pressures in the experimental group, while the lowest loads were used for training in the sham group. Patients performed 15 minutes inspiratory muscle training and 15 minutes expiratory muscle training, twice a day, five days/week, for a total of eight weeks at home. Training intensity was adjusted in the training group once a week.

Results:

Maximal inspiratory and expiratory pressures (cmH2O, % predicted) (respectively p = 0.002, p = 0.003, p = 0.04, p = 0.03) and sniff nasal inspiratory pressure ( p = 0.04) were improved in the experimental group when compared with the sham group. However, there was no improvement in spirometric measurements when groups were compared ( p > 0.05).

Conclusions:

As a conclusion of our study, we found that respiratory muscle strength improved by inspiratory and expiratory muscle training in patients with slowly progressive neuromuscular disease.

Persistent hyperlactacidaemia: about a clinical case

Lactate is the endogenous end product of the anaerobic glycolysis, whose production is favoured in situations of hypoperfusion or mitochondrial dysfunction. Leigh syndrome is a rare, progressive encephalomyopathy that represents a spectrum of mitochondrial genetic diseases phenotypically distinct, but with neuroradiological and pathological uniform presentation. We present the case of a 7-month-old infant, with a history of prematurity, psychomotor retardation and epilepsy, admitted to the paediatric intensive care unit (PICU) due to cardio-respiratory arrest because of respiratory infection. Hyperlactacidaemia was detected and was persistent. The study of redox potential was normal but MRI with spectroscopy identified bilateral and symmetrical lesions involving thalamic and basal ganglia, with small lactate peaks at T2 flair, findings that were suggestive of Leigh syndrome. Subsequent enzymatic study identified lack of pyruvate dehydrogenase. Persistent hyperlactacidaemia, in the appropriate clinical context, should lead to the screening of mitochondrial diseases.

A case of motor neuron disease presenting as dyspnea in the emergency department

Motor neuron disease encompasses a group of progressive neurologic disorders that destroy cells responsible for the control of essential muscles. The disorders are characterized by progressive weakness, muscle atrophy and fasciculation, spasticity, dysarthria, dysphagia, and respiratory compromise. A 66-year-old male presented to the emergency department with progressive dyspnea and, ultimately, respiratory failure. In spite of extensive cardiopulmonary evaluation, a cause could not be identified except aging. After complete history taking, physical and neurologic examination, motor neuron disease was suspected at last. Thus, elderly patients with dyspnea in the emergency department could have hidden diseases beyond the normal aging process.

Hypoventilation syndromes

A wide variety of mechanisms can lead to the hypoventilation associated with various medical disorders, including derangements in central ventilatory control, mechanical impediments to breathing, and abnormalities in gas exchange leading to increased dead space ventilation. The pathogenesis of hypercapnia in obesity hypoventilation syndrome remains somewhat obscure, although in many patients comorbid obstructive sleep apnea appears to play an important role. Hypoventilation in neurologic or neuromuscular disorders is primarily explained by weakness of respiratory muscles, although some central nervous system diseases may affect control of breathing. In other chest wall disorders, obstructive airways disease, and cystic fibrosis, much of the pathogenesis is explained by mechanical impediments to breathing, but an element of increased dead space ventilation also often occurs. Central alveolar hypoventilation syndrome involves a genetically determined defect in central respiratory control. Treatment in all of these disorders involves coordinated management of the primary disorder (when possible) and, increasingly, the use of noninvasive positive pressure ventilation.

Dysarthria in amyotrophic lateral sclerosis: A review

Dysarthria is a motor disorder of speech characterized by abnormalities of the articulation and intelligibility of speech. Phonation and the rate of facial movements may also be affected. Understanding the nature and course of dysarthria in amyotrophic lateral sclerosis (ALS) is important because loss of communication prevents patients from participating in many activities, may lead to social isolation, and reduces the quality of life. The goal of management of dysarthria in ALS patients is to optimize communication effectiveness for as long as possible. The information about dysarthria in ALS is dispersed in physiological, pathological, speech therapy, otorhinolaringological and neurological publications. This review summarizes the current state of knowledge on the clinical features, differential diagnosis, pathophysiology, investigations and management of dysarthria in ALS patients. There is a need to compare the different methods used to assess dysarthria and for controlled clinical trials to assess therapeutic strategies.

Safety, tolerability, and efficacy of high-frequency chest wall oscillation in pediatric patients with cerebral palsy and neuromuscular diseases: an exploratory randomized controlled trial

Airway secretions and infections are common in cerebral palsy and neuromuscular diseases. Chest physiotherapy is standard therapy but effort is substantial. High-frequency chest wall oscillation is used in cystic fibrosis but tolerability and safety data in cerebral palsy and neuromuscular disease are limited. A prospective, randomized, controlled trial of high-frequency chest wall oscillation and standard chest physiotherapy was performed in participants with neuromuscular disease or cerebral palsy. Outcome measures included respiratory-related hospitalizations, antibiotic therapy, chest radiographs, and polysomnography. Care-givers were questioned regarding therapy adherence. A total of 28 participants enrolled, 23 completed (12 chest physiotherapy, mean study period 5 months). No adverse outcomes were reported. Adherence to prescribed regimen was higher with high-frequency chest wall oscillation (P = .036). Our data suggest safety, tolerability, and better compliance with high-frequency chest wall oscillation. Improvement in airway clearance may help prevent hospitalizations. Larger controlled trials are required to confirm these results.

Spirometer‐dependence of vital capacity in ALS: Validation of a portable device in 52 patients

Since the evaluation of vital capacity (VC) needs to be carried out every three months in patients with amyotrophic lateral sclerosis (ALS), a portable spirometer would be of value in clinical practice. Over the follow-up of 52 ALS patients, we compared the values of slow vital capacity measured by two spirometers: a reference flow-metered spirometer based on a Hans-Rudolph pneumotachograph and a portable Venturi spirometer. The objectives were to analyse the overall concordance of the measurements from the two devices and determine a discordance cut-off. The correlation between measurements was high (r = 0.936) and significant (p<10(-20)). Bland and Altman analysis showed that the measurements were concordant at a statistical risk of 5%; nevertheless, on examination of the raw differences between the measurements, two sub-populations could be identified on either side of the 56% cut-off where the means of the differences were significantly different (p<0.0001). The 56% cut-off was also statistically significant in plotting differences against the coefficient of variations of the data pairs expressed as (100 x s/mean). The differences observed between the two spirometers could be explained by technical differences between the devices as well as by an increase in variability with progression of the disease. In conclusion, this study demonstrates that a portable spirometer can be used reliably at the bedside. For values of vital capacity below the discordance cut-off of 56%, vital capacity should be determined by operators trained in pulmonary function examinations.

Airway clearance in Duchenne muscular dystrophy

This is a summary of the presentation on airway clearance in neuromuscular disorders presented as part of the program on airway clearance in Duchenne muscular dystrophy at the 30th annual Carrell-Krusen Neuromuscular Symposium on February 20, 2008.

Abnormalities of respiratory control and the respiratory motor unit

BACKGROUND

Control of ventilation depends on a brainstem neuronal network that controls activity of the motor neurons innervating the respiratory muscles. This network includes the pontine respiratory group and the dorsal and ventral respiratory groups in the medulla. Neurologic disorders affecting these areas or the respiratory motor unit may lead to abnormal breathing.

REVIEW SUMMARY

The brainstem respiratory network contains neurons critical for respiratory rhythmogenesis; this network receives inputs from peripheral and central chemoreceptors sensitive to levels of carbon dioxide (PaCO2) and oxygen (PaO2) and from forebrain structures that control respiration as part of integrated behaviors such as speech or exercise. Manifestations associated with disorders of this network include sleep apnea and dysrhythmic breathing frequently associated with disturbances of cardiovagal and sympathetic vasomotor control. Common disorders associated with impaired cardiorespiratory control include brainstem stroke or compression, syringobulbia, Chiari malformation, high cervical spinal cord injuries, and multiple system atrophy. By far, neuromuscular disorders are the more common neurologic conditions leading to respiratory failure.

CONCLUSIONS

Respiratory dysfunction constitute an early and relatively major manifestation of several neurologic disorders and may be due to an abnormal breathing pattern generation due to involvement of the cardiorespiratory network or more frequently to respiratory muscle weakness.

Positive inotropic effects of Tityus cambridgei and T. serrulatus scorpion venoms on skeletal muscle

Toxins that block voltage-dependent K+ channels and those that modify Na+ channel gating exhibit positive inotropic effect on skeletal muscle. We compared the effect of the venom of Tityus cambridgei (Tc) and Tityus serrulatus (Ts) scorpions on mouse diaphragm force, in vitro. In indirect and direct (using D-tubocurarine 7.3 microM) stimulation, Tc, 10microg/mL, increased the contractile force, an effect prevented by tetrodotoxin (TTX) while Ts, 0.5 microg/mL, potentiated only indirectly stimulated diaphragm, thus indicating its activity is mainly mediated through acetylcholine release from nerve terminal. This effect is prevented by TTX and attenuated by the K+ channel opener cromakalim. In conclusion, our data show that while the positive inotropic effect of both venoms appears associated to the activity of Na+ and K+ channels, only Tc venom acts also directly on skeletal muscle. This finding call for further studies on Tc venom to identify the toxin responsible for its direct inotropic activity as it may have clinical applications.

Mushroom-cage gastrostomy tube placement in patients with amyotrophic lateral sclerosis: a 5-year experience in 104 patients in a single institution

To review our experience of placement of a mushroom-cage gastrostomy tube (Entristar, Tyco Healthcare, Mansfield, MA), using radiological guidance, in patients with amyotrophic lateral sclerosis (ALS). All procedures were performed under local anaesthesia without sedation. Complications were recorded as peri-procedural, early (<24 h), late (>24 h), major or minor. Deaths were recorded as related to the underlying ALS or secondary to radiological-inserted gastrostomy (RIG) placement. Replacement RIG tube rate was recorded. Over a 5-year period RIG tubes were placed in 104 patients with ALS (male n = 52, female n = 52), with a median age of 62 years (range 34-86 years). All procedures were technically successful. Of the RIG procedures, 21/104 (20.2%) were performed with respiratory support. The 30-day mortality rate was 7/104 (6.7%); no patient died as a result of the procedure. There were 23/104 (22.1%) complications overall; 20/104 (19.2%) were minor and 3/104 (2.9%) major, requiring surgery (n = 2) and radiological-guided abscess drainage (n = 1). A median interval between replacement RIG procedures in 20/104 (19.2%) patients was 141.5 days (range 43-537 days). A mushroom-cage RIG tube may be safely and effectively inserted in a 'one-step' radiological procedure and may replace endoscopic-inserted gastrostomy tubes in the nutritional management of ALS.

Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterised by progressive muscular paralysis reflecting degeneration of motor neurones in the primary motor cortex, corticospinal tracts, brainstem and spinal cord. Incidence (average 1.89 per 100,000/year) and prevalence (average 5.2 per 100,000) are relatively uniform in Western countries, although foci of higher frequency occur in the Western Pacific. The mean age of onset for sporadic ALS is about 60 years. Overall, there is a slight male prevalence (M:F ratio approximately 1.5:1). Approximately two thirds of patients with typical ALS have a spinal form of the disease (limb onset) and present with symptoms related to focal muscle weakness and wasting, where the symptoms may start either distally or proximally in the upper and lower limbs. Gradually, spasticity may develop in the weakened atrophic limbs, affecting manual dexterity and gait. Patients with bulbar onset ALS usually present with dysarthria and dysphagia for solid or liquids, and limbs symptoms can develop almost simultaneously with bulbar symptoms, and in the vast majority of cases will occur within 1-2 years. Paralysis is progressive and leads to death due to respiratory failure within 2-3 years for bulbar onset cases and 3-5 years for limb onset ALS cases. Most ALS cases are sporadic but 5-10% of cases are familial, and of these 20% have a mutation of the SOD1 gene and about 2-5% have mutations of the TARDBP (TDP-43) gene. Two percent of apparently sporadic patients have SOD1 mutations, and TARDBP mutations also occur in sporadic cases. The diagnosis is based on clinical history, examination, electromyography, and exclusion of 'ALS-mimics' (e.g. cervical spondylotic myelopathies, multifocal motor neuropathy, Kennedy's disease) by appropriate investigations. The pathological hallmarks comprise loss of motor neurones with intraneuronal ubiquitin-immunoreactive inclusions in upper motor neurones and TDP-43 immunoreactive inclusions in degenerating lower motor neurones. Signs of upper motor neurone and lower motor neurone damage not explained by any other disease process are suggestive of ALS. The management of ALS is supportive, palliative, and multidisciplinary. Non-invasive ventilation prolongs survival and improves quality of life. Riluzole is the only drug that has been shown to extend survival.

[A nationwide survey of ALS patients on trachoestomy positive pressure ventilation (TPPV) who developed a totally locked-in state (TLS) in Japan]

We conducted a nationwide survey of ALS patients on tracheostomy positive pressure ventilation (TPPV) who had developed a totally locked-in state (TLS) during the period from August to November 2006, in Japan. TLS occurred in 89 of 709 (13%) ALS patients on TPPV. On the second investigation, 29 of 41 patients with TLS showed complete palsy of more than two voluntary motor systems out of 4 motor systems [respiratory, pontine and medullar (bulbar), limb and external ocular motor systems] successively during a certain six months. The conventional classification of ALS based on the initial symptoms (bulbar, upper limb and lower limb type) was not found to be useful for predicting the onset of TLS. Seventy percent the patients developed TLS within 5 years after the start of TPPV. Thirty-seven (90%) patients finally developed total ophthalmoplegia at the onset of TLS, while one patient eventually developed complete bulbar palsy. One of 11 ALS patients with TLS, whom we experienced at Tokyo Metropolitan Neurological Hospital, also eventually showed complete palsy of the pontine (bulbar) motor system (inability to pull back the jaw). Due to the fact that TLS is a state of complete palsy of the voluntary motor systems for communication, which may occur during the course of ALS in around 15% of patients, further clinical investigation of TLS including cognition is thus considered to be essential for improving the palliative care of ALS patients on TPPV.

Phrenic nerve stimulation

Weakness of the limbs and respiratory muscles has increasingly been found to be a frequent event that complicates the medical history of patients in Intensive Care. The problem normally affects more serious cases and presents as muscular weakness leading to flaccid paralysis and difficulty in weaning patients off mechanical ventilation. This latter sign leads the intensivist to suspect possible involvement of the neuromuscular respiratory system. Unfortunately, in-depth clinical assessment of the neuromuscular respiratory system is difficult with critically ill patients, and electrophysiological studies have been used instead to overcome this problem. Of these latter, electric and electromagnetic stimulation of the phrenic nerve have been successful (along with needle electromyography of the diaphragm) in identifying the causes of neuromuscular respiratory insufficiency, especially in Intensive Care. In this brief chapter, we will be discussing the technique of electric stimulation of the phrenic nerve and neuromuscular respiratory insufficiency within the field of critical illness polyneuropathy.