Percutaneous nocturnal oximetry in amyotrophic lateral sclerosis: Periodic desaturation

Automated pipeline for denoising, missing data processing, and feature extraction for signals acquired via wearable devices in multiple sclerosis and amyotrophic lateral sclerosis applications

Introduction

The incorporation of health-related sensors in wearable devices has increased their use as essential monitoring tools for a wide range of clinical applications. However, the signals obtained from these devices often present challenges such as artifacts, spikes, high-frequency noise, and data gaps, which impede their direct exploitation. Additionally, clinically relevant features are not always readily available. This problem is particularly critical within the H2020 BRAINTEASER project, funded by the European Community, which aims at developing models for the progression of Multiple Sclerosis (MS) and Amyotrophic Lateral Sclerosis (ALS) using data from wearable devices.

Methods

The objective of this study is to present the automated pipeline developed to process signals and extract features from the Garmin Vivoactive 4 smartwatch, which has been chosen as the primary wearable device in the BRAINTEASER project. The proposed pipeline includes a signal processing step, which applies retiming, gap-filling, and denoising algorithms to enhance the quality of the data. The feature extraction step, on the other hand, utilizes clinical partners' knowledge and feedback to select the most relevant variables for analysis.

Results

The performance and effectiveness of the proposed automated pipeline have been evaluated through pivotal beta testing sessions, which demonstrated the ability of the pipeline to improve the data quality and extract features from the data. Further clinical validation of the extracted features will be performed in the upcoming steps of the BRAINTEASER project.

Discussion

Developed in Python, this pipeline can be used by researchers for automated signal processing and feature extraction from wearable devices. It can also be easily adapted or modified to suit the specific requirements of different scenarios.

Impact of diabetes mellitus on the respiratory function of amyotrophic lateral sclerosis patients

BACKGROUND AND PURPOSE

Respiratory insufficiency and its complications are the main cause of death in amyotrophic lateral sclerosis (ALS). The impact of diabetes mellitus (DM) on respiratory function of ALS patients is uncertain.

METHODS

A retrospective cohort study was carried out. From the 1710 patients with motor neuron disease followed in our unit, ALS and progressive muscular atrophy patients were included. We recorded demographic characteristics, functional ALS rating scale (Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised [ALSFRS-R]) and its subscores at first visit, respiratory function tests, arterial blood gases, phrenic nerve amplitude (PhrenAmpl), and mean nocturnal oxygen saturation (SpO2 mean). We excluded patients with other relevant diseases. Two subgroups were analysed: DIAB (patients with DM) and noDIAB (patients without DM). Independent t-test, χ2 , or Fisher exact test was applied. Binomial logistic regression analyses assessed DM effects. Kaplan-Meier analysis assessed survival. p < 0.05 was considered significant.

RESULTS

We included 1639 patients (922 men, mean onset age = 62.5 ± 12.6 years, mean disease duration = 18.1 ± 22.0 months). Mean survival was 43.3 ± 40.7 months. More men had DM (p = 0.021). Disease duration was similar between groups (p = 0.063). Time to noninvasive ventilation (NIV) was shorter in DIAB (p = 0.004); total survival was similar. No differences were seen for ALSFRS-R or its decay rate. At entry, DIAB patients were older (p < 0.001), with lower forced vital capacity (p = 0.001), arterial oxygen pressure (p = 0.01), PhrenAmpl (p < 0.001), and SpO2 mean (p = 0.014).

CONCLUSIONS

ALS patients with DM had increased risk of respiratory impairment and should be closely monitored. Early NIV allowed for similar survival rate between groups.

Current challenges in primary lateral sclerosis diagnosis

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

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

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

Thoracic Excursion Is a Biomarker for Evaluating Respiratory Function in Amyotrophic Lateral Sclerosis

Objective

To evaluate the usefulness of thoracic excursion as a biomarker in patients with amyotrophic lateral sclerosis (ALS).

Methods

We measured the forced the vital capacity (FVC), thoracic excursion, baseline-to-peak diaphragmatic compound muscle action potential (DCMAP) amplitude, diaphragm thickness at full inspiration (DTfi), Medical Research Council (MRC) sum score for muscle strength, and arterial partial pressures of oxygen and carbon dioxide and administered the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) and modified Medical Research Council (mMRC) Dyspnea Scale. The test–retest reliability of thoracic excursion was determined.

Results and Conclusions

Thirty-four patients with ALS and 26 age- and sex-matched healthy participants were enrolled. Thoracic excursion measurement had excellent test–retest reliability (intraclass coefficient: 0.974). Thoracic excursion was more strongly correlated with FVC (r = 0.678, p &lt; 0.001) than DCMAP amplitude (r = 0.501, p = 0.003) and DTfi (r = 0.597, p &lt; 0.001). It was also correlated with ALSFRS-R score (r = 0.610, p &lt; 0.001), MRC sum score (r = 0.470, p = 0.005), and mMRC Dyspnea Scale score (r = −0.446, p = 0.008) and was the most sensitive parameter for assessing dyspnea and FVC. Thoracic excursion decreased as FVC declined in the early and late stages, there were no differences in DCMAP amplitude and DTfi between the early and late stages, and ALSFRS-R score and MRC sum score decreased only in the late stage. Thoracic excursion was well correlated with respiratory function and is useful for predicting respiratory and general dysfunction in patients with ALS regardless of stage.

Respiratory function tests in amyotrophic lateral sclerosis: The role of maximal voluntary ventilation

BACKGROUND

Pulmonary function tests are routinely used to measure progression in ALS. This study aimed to assess the change of various respiratory tests, in particular maximal voluntary ventilation (MVV), which evaluates respiratory endurance.

METHODS

A group of 51 patients were assessed 3 times (T1, T2, T3, separated by 5.4 months), including slow (SVC) and forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF), maximal inspiratory (MIP) and expiratory (MEP) pressures, MVV, and sniff nasal inspiratory pressure (SNIP). In addition, body mass index (BMI), ALSFRS-R and phrenic nerve responses were obtained 4 times. Patients with dementia and marked bulbar involvement were excluded.

RESULTS

Mean ALSFRS-R was high at entry (42.9) and its decline was moderately slow at 0.4/month. FVC and FEV1 declined significantly in the three time frames analysed. MVV reduced significantly only between T1-T3 and SVC between T2-T3, and MIP, MEP, PEF and SNIP did not change significantly. The amplitude and the latency of the motor response of the phrenic nerve changed significantly, and BMI declined significantly in most time periods, and ALSFRS-R changed significantly in the 4 time periods. We found a strong correlation between MVV, and FVC, SVC, FEV1, SNIP, phrenic nerve amplitude/area (p < 0.001), and markedly with PEF (rho = 0.821) and ALSFRS-R (rho = 0.713).

CONCLUSIONS

Our study of early affected patients supports the use of a set of volitional and non-volitional respiratory tests to assess disease progression, rather than any single test. We found MVV a potentially useful marker of pulmonary function in ALS.

Medical therapies for amyotrophic lateral sclerosis-related respiratory decline: an appraisal of needs, opportunities and obstacles

A roundtable convened in July 2020 examined issues concerning respiratory support in amyotrophic lateral sclerosis (ALS), with reference to the potential for an early-phase orally administered medication that might either postpone the introduction of noninvasive ventilation (NIV) and/or enhance the benefits to be gained from it. Attention was also given to the impact of the COVID-19 pandemic on usual practice in the assessment and management of ALS-related respiratory difficulties. Implementation of NIV marks a step-change in clinical status for patients and a major increase in burden for caregivers. All means to ease this transition should be explored: an oral therapy that supported respiratory function and patients' independence and sense of well-being would aid discussions to facilitate the eventual successful introduction of NIV. Assessment of a candidate oral therapy that might support respiratory function in ALS patients would be aided by the development of improved patient-reported outcome measures for robust quantification of treatment effect and quality of life. Such instruments could also be used to monitor patients' status during the COVID-19 pandemic, averting some of the risks of face-to-face assessment plus the patient burden and costs of traditional methods. Several oral candidate therapies have recently failed to meet their primary endpoints in clinical trials. However, understanding of the underlying physiology and appropriate trial design have grown and will inform future developments in this field.

Compensatory metabolic and central respiratory drive mechanisms in ALS

Introduction: Airway pressure in the first 100 ms of an occluded inspiration (P0.1) evaluates respiratory center activity. Its increase compensates for respiratory muscle weakness in amyotrophic lateral sclerosis (ALS). We aimed to evaluate if an exhaustion over disease progression emerges. Methods: Consecutive ALS patients with P0.1 at baseline (T0) above 90th percentile for the whole population were included. There were two patient categories within this population: G1 patients had respiratory function tests (RFT) at T0 and 6 months later (T1); G2 patients were immediately adapted to noninvasive ventilation at T0. Functional ALS rating scale (ALSFRS) and its subscores, RFT including maximal inspiratory pressure (MIP), P0.1 percentage (%P0.1), P0.1/MIP, blood gas analyses, phrenic nerve motor amplitude and nocturnal pulsed oximetry (NPO) were compared at T0 between groups (Mann-Whitney U test) and longitudinal progression in G1 was assessed (Wilcoxon test). p < 0.05 was taken as significant. Results: Forty-nine patients were studied: 13 men, mean disease duration 17.1 ± 19.5 months, 21 with spinal-onset; 27 bulbar-onset; one with respiratory presentation. In G1, there was a progressive deterioration in all variables but P0.1/MIP did not significantly change (p = 0.394). PCO₂ (p = 0.045) and bicarbonate ion (HCO₃^-p = 0.054) increased. In G2, the ALSFRS (p = 0.049) scores were lower, PCO₂ (p = 0.057) and HCO₃^- (p = 0.016) higher, and reduced arterial oxygen saturation (SpO₂<90%) at NPO (p = 0.007). Discussion: Patients with high central respiratory drive responses did not develop a short-term "exhaustion phenomenon". Both metabolic and central respiratory mechanisms interact to compensate for respiratory muscle weakness. The role of spasticity and the respiratory-metabolic-renal buffering system deserves further studies.

Mouth occlusion pressure at 100ms (P0.1) as a respiratory biomarker in amyotrophic lateral sclerosis

INTRODUCTION

Airway pressure in the first 100ms of an occluded inspiration (P0.1) evaluates the respiratory center activity, increasing in the presence of respiratory muscle weakness. It is uncertain if its activity can compensate for respiratory muscles weakness in amyotrophic lateral sclerosis (ALS). Methods: Consecutive ALS patients with P0.1 evaluated at first visit were included. Depending on P0.1 percentile, patients were divided in three groups: G1 (<25th percentile); G2 (25th-74th percentiles); G3 (≥75th percentile); two subgroups were further considered: SG0 (<10th percentile); SG1 (>90th percentile). Body mass index (BMI), functional ALS rating scale and its subscores, respiratory function tests, including forced vital capacity, maximal inspiratory (MIP) and expiratory pressures, percentage of P0.1 (%P0.1), blood gas analyses, phrenic nerve motor amplitude (MeanPhrenAmpl) were compared. P0.1/MIP and %P0.1 predictors were explored by linear and multinomial logistic regression analyses. p < 0.05 was considered as significant. Results: From the 497 patients included, 124 were in G1 and G3 each, 249 in G2, 49 in SG0 and SG1 each. G1 included more men, with higher BMI (p < 0.001). G3 had older women, with predominant bulbar phenotype (p < 0.001). Lower respiratory function (p < 0.05) was present in both groups. SG0 (%P0.1 < 51.73%, P0.1/MIP = 1.48 ± 1.02) had more spinal-onset men (p < 0.001) with lower MeanPhrenAmpl (p < 0.004). SG1 (P0.1 > 147.12, P0.1/MIP = 7.92 ± 4.62) predominantly included older patients (p = 0.033), women (p = 0.012), with lower MeanPhrenAmpl (p = 0.039). Discussion: ALS patients with respiratory failure can show high or low P01 values, related to phenotype. Possible central drive reactivity and exhaustion, and the role of respiratory-metabolic-renal buffering system should be further addressed.

The uses of overnight pulse oximetry

Overnight pulse oximetry (OPO) has proven to be an effective and beneficial technique to determine the cardiorespiratory status of patients in both the inpatient and outpatient settings. It is a cheap, safe, reliable, simple, and accurate method of patient monitoring as compared to the expensive and labor-intensive method of multichannel polysomnography for detecting sleep-disordered breathing. It provides accurate information about patient's oxygenation status and also helps in monitoring the response to continuous positive airway pressure and in the surgical treatment of obstructive sleep apnea (OSA). Nocturnal hypoxemia portends a poor prognosis in patients of chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD), and neuromuscular diseases. OPO can help its early detection and management.

Sleep in chronic respiratory disease: COPD and hypoventilation disorders

COPD and obstructive sleep apnoea (OSA) are highly prevalent and different clinical COPD phenotypes that influence the likelihood of comorbid OSA. The increased lung volumes and low body mass index (BMI) associated with the predominant emphysema phenotype protects against OSA whereas the peripheral oedema and higher BMI often associated with the predominant chronic bronchitis phenotype promote OSA. The diagnosis of OSA in COPD patients requires clinical awareness and screening questionnaires which may help identify patients for overnight study. Management of OSA-COPD overlap patients differs from COPD alone and the survival of overlap patients treated with nocturnal positive airway pressure is superior to those untreated. Sleep-related hypoventilation is common in neuromuscular disease and skeletal disorders because of the effects of normal sleep on ventilation and additional challenges imposed by the underlying disorders. Hypoventilation is first seen during rapid eye movement (REM) sleep before progressing to involve non-REM sleep and wakefulness. Clinical presentation is nonspecific and daytime respiratory function measures poorly predict nocturnal hypoventilation. Monitoring of respiration and carbon dioxide levels during sleep should be incorporated in the evaluation of high-risk patient populations and treatment with noninvasive ventilation improves outcomes.

Unstable control of breathing can lead to ineffective noninvasive ventilation in amyotrophic lateral sclerosis

Upper airway obstruction with decreased central drive (ODCD) is one of the causes of ineffective noninvasive ventilation (NIV) in amyotrophic lateral sclerosis (ALS). The aim of this study is to determine the mechanism responsible for ODCD in ALS patients using NIV.

This is a prospective study that included ALS patients with home NIV. Severity of bulbar dysfunction was assessed with the Norris scale bulbar subscore; data on upper or lower bulbar motor neuron predominant dysfunction on physical examination were collected. Polysomnography was performed on every patient while using NIV and the ODCD index (ODCDI: number of ODCD events/total sleep time) was calculated. To determine the possible central origin of ODCD, controller gain was measured by inducing a hypocapnic hyperventilation apnoea. Sonography of the upper airway during NIV was performed to determine the location of the ODCD.

30 patients were enrolled; three (10%) had ODCDI >5 h⁻¹. The vast majority of ODCD events were produced during non-rapid eye movement sleep stages and were a consequence of an adduction of the vocal folds. Patients with ODCDI >5 h⁻¹ had upper motor neuron predominant dysfunction at the bulbar level, and had greater controller gain (1.97±0.33 versus 0.91±0.36 L·min⁻¹·mmHg⁻¹; p<0.001) and lower carbon dioxide (CO₂) reserve (4.00±0.00 versus 10.37±5.13 mmHg; p=0.043). ODCDI was correlated with the severity of bulbar dysfunction (r= −0.37; p=0.044), controller gain (r=0.59; p=0.001) and CO₂ reserve (r= −0.35; p=0.037).

ODCD events in ALS patients using NIV have a central origin, and are associated with instability in the control of breathing and an upper motor neuron predominant dysfunction at the bulbar level.

Upper airway obstructions in ALS patients using NIV have a central origin, and are associated with instability in the control of breathing and an upper motor neuron predominant dysfunction at the bulbar levelhttp://bit.ly/2WEMt28

Clinical and research applications of neuromuscular ultrasound in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder characterized by dysfunction at multiple levels of the neuraxis. It remains a clinical diagnosis without a definitive diagnostic investigation. Electrodiagnostic testing provides supportive information and, along with imaging and biochemical markers, can help exclude mimicking conditions. Neuromuscular ultrasound has a valuable role in the diagnosis and monitoring of ALS and provides complementary information to clinical assessment and electrodiagnostic testing as well as insights into the underlying pathophysiology of this disease. This review highlights the evidence for ultrasound in the evaluation of bulbar, limb and respiratory musculature and peripheral nerves in ALS. Further research in this evolving area is required.

Diaphragmatic Neurophysiology and Respiratory Markers in ALS

The main reason for short survival in amyotrophic lateral sclerosis (ALS) is involvement of respiratory muscles. Severe compromise of diaphragmatic function due to marked loss of motor units causes poor inspiratory strength leading to symptomatic respiratory fatigue, and hypercapnia and hypoxemia, often firstly detected while sleeping supine. Weakness of expiratory muscles leads to cough weakness and poor bronchial clearance, increasing the risk of respiratory infection. Respiratory tests should therefore encompass inspiratory and expiratory function, and include measurements of blood gases during sleep. Non-volitional tests, such as phrenic nerve stimulation, are particularly convenient for investigating respiratory function in patients unable to perform standard respiratory function tests due to poor cooperation or facial weakness. However, SNIP is a sensitive test when patients with bulbar involvement are able to perform the necessary maneuvers. It is likely that central respiratory regulation is disturbed in some ALS patients, but its evaluation is more complex and not regularly implemented. Practical tests should incorporate tolerability, sensitivity, easy application for regular monitoring, and prognostic value. Impending respiratory failure can cause increased circulating inflammatory markers, but molecular assessment of respiratory distress requires further study. In future, home-monitoring of patients with accessible devices should be developed.

Breathing: Motor Control of Diaphragm Muscle

Breathing occurs without thought but is controlled by a complex neural network with a final output of phrenic motor neurons activating diaphragm muscle fibers (i.e., motor units). This review considers diaphragm motor unit organization and how they are controlled during breathing as well as during expulsive behaviors.

Definition, discrimination, diagnosis and treatment of central breathing disturbances during sleep

The complexity of central breathing disturbances during sleep has become increasingly obvious. They present as central sleep apnoeas (CSAs) and hypopnoeas, periodic breathing with apnoeas, or irregular breathing in patients with cardiovascular, other internal or neurological disorders, and can emerge under positive airway pressure treatment or opioid use, or at high altitude. As yet, there is insufficient knowledge on the clinical features, pathophysiological background and consecutive algorithms for stepped-care treatment. Most recently, it has been discussed intensively if CSA in heart failure is a “marker” of disease severity or a “mediator” of disease progression, and if and which type of positive airway pressure therapy is indicated. In addition, disturbances of respiratory drive or the translation of central impulses may result in hypoventilation, associated with cerebral or neuromuscular diseases, or severe diseases of lung or thorax. These statements report the results of an European Respiratory Society Task Force addressing actual diagnostic and therapeutic standards. The statements are based on a systematic review of the literature and a systematic two-step decision process. Although the Task Force does not make recommendations, it describes its current practice of treatment of CSA in heart failure and hypoventilation.

Ultrasound for assessment of diaphragm in ALS

OBJECTIVE

To evaluate the correlation between diaphragm thickness assessed by ultrasound (US) with respiratory function tests and the diaphragm motor responses, in patients with amyotrophic lateral sclerosis (ALS).

METHODS

42 consecutive ALS patients were studied (11 with bulbar-onset), excluding patients with marked orofacial paresis. Investigation included: revised ALS functional rating scale (ALSFRS-R), forced vital capacity (FVC), maximal voluntary ventilation (MVV), maximal inspiratory (MIP) and expiratory (MEP) pressures, nasal inspiratory pressure during sniff (SNIP); peak-to-peak amplitude of the diaphragmatic motor response to phrenic nerve stimulation (Diaphragm-CMAP), diaphragmatic thickness measured by ultrasound during maximal inspiration and during maximal expiration. Patients were analysed in bulbar or spinal subgroups. Correlations and multiple linear regression models were studied.

RESULTS

The mean age at disease onset was 58.4 ± 11.1 years and with a mean disease duration of 17.8 ± 13.6 months. Ultrasound studies of diaphragm thickness in full inspiration correlated with diaphragm CMAP in the whole population and in spinal-onset patients; and were similar in the two groups. Multiple linear modelling showed that FVC, SNIP and MVV were dependent on the change of thickness (p=0.001, 0.001 and 0.020, respectively) and that MIP and MEP were related to diaphragm CMAP p=0.003 and p=0.025, respectively).

CONCLUSION

Diaphragm thickness correlates with Diaphragm-CMAP, except in bulbar-onset patients. Respiratory tests are dependent on both diaphragm thickness and Diaphragm-CMAP.

SIGNIFICANCE

US thickness of the diaphragm correlates with the number of functional motor units as assessed by the phrenic nerve motor amplitude.

Vascular endothelial growth factor and amyotrophic lateral sclerosis: the interplay with exercise and noninvasive ventilation

INTRODUCTION

We evaluated plasma vascular endothelial growth factor (VEGF) levels in patients with amyotrophic lateral sclerosis (ALS) with reference to the effects of respiratory failure, noninvasive ventilation (NIV), and exercise.

METHODS

We studied plasma VEGF levels in 83 ALS patients, 20 healthy controls, and 10 patients with other disorders. There were 4 groups of ALS patients: G1, 27 patients without respiratory problems; G2, 14 patients stabilized on nocturnal NIV; G3, 30 patients presenting with respiratory failure; G4, 12 patients on an aerobic exercise protocol.

RESULTS

VEGF plasma levels did not differ significantly between ALS patients and controls, or between ALS groups. In G3, the mean VEGF levels increased 75% during NIV. In G4, the mean VEGF level increased by 300% during the exercise program. VEGF levels did not change during the course of the disease.

CONCLUSIONS

VEGF levels in ALS depend on changes in ventilation and exercise but are probably not affected by the disease process itself.

Breathing new life into treatment advances for respiratory failure in amyotrophic lateral sclerosis patients

SUMMARY In the last three decades, improvements in respiratory management are responsible for increasing survival and improving quality of life for amyotrophic lateral sclerosis (ALS) patients. Nowadays, ALS patients with respiratory involvement are offered a support treatment other than the traditional respiratory palliative care. Knowledge about available respiratory support potentialities is essential for appropriate, customized and effective treatment of ALS, which should probably be started sooner than the conventional approach. There is evidence supporting that respiratory support has a larger impact than riluzole on survival. Noninvasive ventilation is essential in the treatment of ALS patients with respiratory involvement. In this article methods to determine respiratory failure in ALS, mechanical invasive and noninvasive ventilation, telemetry, diaphragm pacing, cough aids and respiratory exercise are reviewed, after a brief overlook of respiratory insufficiency in ALS.

Intermittent hypoxia can aggravate motor neuronal loss and cognitive dysfunction in ALS mice

BACKGROUND

Patients with ALS may be exposed to variable degrees of chronic intermittent hypoxia. However, all previous experimental studies on the effects of hypoxia in ALS have only used a sustained hypoxia model and it is possible that chronic intermittent hypoxia exerts effects via a different molecular mechanism from that of sustained hypoxia. No study has yet shown that hypoxia (either chronic intermittent or sustained) can affect the loss of motor neurons or cognitive function in an in vivo model of ALS.

OBJECTIVE

To evaluate the effects of chronic intermittent hypoxia on motor and cognitive function in ALS mice.

METHODS

Sixteen ALS mice and 16 wild-type mice were divided into 2 groups and subjected to either chronic intermittent hypoxia or normoxia for 2 weeks. The effects of chronic intermittent hypoxia on ALS mice were evaluated using the rotarod, Y-maze, and wire-hanging tests. In addition, numbers of motor neurons in the ventral horn of the spinal cord were counted and western blot analyses were performed for markers of oxidative stress and inflammatory pathway activation.

RESULTS

Compared to ALS mice kept in normoxic conditions, ALS mice that experienced chronic intermittent hypoxia had poorer motor learning on the rotarod test, poorer spatial memory on the Y-maze test, shorter wire hanging time, and fewer motor neurons in the ventral spinal cord. Compared to ALS-normoxic and wild-type mice, ALS mice that experienced chronic intermittent hypoxia had higher levels of oxidative stress and inflammation.

CONCLUSIONS

Chronic intermittent hypoxia can aggravate motor neuronal death, neuromuscular weakness, and probably cognitive dysfunction in ALS mice. The generation of oxidative stress with activation of inflammatory pathways may be associated with this mechanism. Our study will provide insight into the association of hypoxia with disease progression, and in turn, the rationale for an early non-invasive ventilation treatment in patients with ALS.

Nocturnal hypoxia in ALS is related to cognitive dysfunction and can occur as clusters of desaturations

Background

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that leads to progressive weakness of the respiratory and limb muscles. Consequently, most patients with ALS exhibit progressive hypoventilation, which worsens during sleep. The aim of this study was to evaluate the relationship between nocturnal hypoxia and cognitive dysfunction and to assess the pattern of nocturnal hypoxia in patients with ALS.

Method

Twenty-five patients with definite or probable ALS underwent neuropsychologic testing, nocturnal pulse oximetry, and capnography. Patients were grouped according to the presence of nocturnal hypoxia (SpO₂<95% for ≥10% of the night) and their clinical characteristics and cognitive function were compared.

Results

Compared to patients without nocturnal hypoxia, those with nocturnal hypoxia (n = 10, 40%) had poor memory retention (p = 0.039) and retrieval efficiency (p = 0.045). A cluster-of-desaturation pattern was identified in 7 patients (70%) in the Hypoxia Group.

Conclusions

These results suggest that nocturnal hypoxia can be related to cognitive dysfunction in ALS. In addition, a considerable number of patients with ALS may be exposed to repeated episodes of deoxygenation–reoxygenation (a cluster-of-desaturation pattern) during sleep, which could be associated with the generation of reactive oxygen species. Further studies are required to define the exact causal relationships between these phenomena, the exact manifestations of nocturnal cluster-of-desaturation patterns, and the effect of clusters of desaturation on ALS progression.

Economic cost of home-telemonitoring care for BiPAP-assisted ALS individuals

Our objective was to measure direct (hospital and NHS) and indirect (patient/caregiver) costs of following up in-home compliance to non-invasive ventilation via wireless modem. We constructed a prospective controlled trial of 40 consecutive ALS home-ventilated patients, randomly assigned according to their residence area to G1 (nearby hospital, office-based follow-up) and G2 (outside hospital area, telemetry device-based follow-up). Total NHS direct cost encompassed costs related to outpatients' visits (office and emergency room) and hospitalizations. Hospital direct costs included transportation to/from hospital, office visit per hour cost and equipment maintenance. Non-medical costs considered days of wages lost due to absenteeism. G1 included 20 patients aged 60 ± 10 years and G2 included 19 patients aged 62 ± 13 years. Results showed that no differences were found regarding clinical/demographic characteristics at admission. NHS costs showed a 55% reduction in average total costs with a statistically significant decrease of 81% in annual costs per patient in G2. Hospital costs were found to be significantly higher in G2 with regard to total costs (64% average increase) but not annual costs (7%). No statistical difference was found with regard to expenses from absenteeism. In conclusion, at the cost of an initial financial constraint to the hospital per year (non-significant), telemonitoring is cost-effective, representing major cost savings to the NHS in the order of 700 euros/patient/year.

Sleep–wake problems in patients with amyotrophic lateral sclerosis: implications for patient management

SUMMARY Sleep–wake problems are frequent, although unrecognized, complications of amyotrophic lateral sclerosis (ALS). Sleep disorders such as insomnia, sleep-disordered breathing and restless legs syndrome have all been reported in patients with ALS, despite the limited number of studies and the small populations investigated so far. Sleep disturbances gradually worsen with disease progression, suggesting a relationship between the severity of disease and the neurodegenerative process. However, poor sleep can also be a consequence of several disturbances such as anxiety, depression, pain, choking, sialorrhea, fasciculations, cramps, nocturia and the inability to get comfortable and move freely in bed. Sleep disorders may have many reflections on patients with ALS, including excessive daytime somnolence, fatigue, impaired cognition, reduced quality of life and survival. This article reviews the recent literature on sleep–wake problems in patients with ALS, focusing on the implications for patient management.

Nocturnal home pulse oximetry: variability and clinical implications in home mechanical ventilation

BACKGROUND

Nocturnal home pulse oximetry (NHPO) provides information by measuring a series of variables: time spent with SaO(2) <90% expressed as percentage (T90) or in minutes (Tm90), mean SaO(2) (MnS), and lowest SaO(2) (LwS.) The presence of significant nocturnal desaturation has been proposed as a parameter in decision making with regard to initiating home mechanical ventilation (HMV) or monitoring HMV effectiveness. However, there is limited information on the possible variability of the test, and this could influence the interpretation of results.

OBJECTIVES

To explore the variability between 2 consecutive measurements of NHPO and to determine clinical applications in HMV.

METHODS

The patients presented diseases susceptible to HMV treatment and were enrolled in stable condition without respiratory failure. NHPO was conducted on 2 consecutive nights. The variables analyzed were: T90, Tm90, Mns, and LwS. The coefficient of variation (CV), a concordance coefficient (CC), and the Bland-Altman method were used in order to explore the variability.

RESULTS

We studied 40 cases. Two were excluded, and the remaining 38 were aged 58 ± 16 years (19 males). Eighteen were receiving HMV. CV values exceeded 100% for T90 and Tm90 and were below 5% for MnS and LwS. The CC for T90, Tm90, and LwS showed confidence intervals with lower limits below 0.5, while for MnS the value was 0.88 (0.79-0.93).

CONCLUSIONS

There is a wide variability in NHPO recordings for T90, Tm90, and LwS, so a single determination to detect nocturnal desaturation may not be valid for decision making; the parameter with the least interindividual variability and intraindividual variability was MnS.

Respiratory failure in a 70-year-old veteran

In Western countries the incidence of amyotrophic lateral sclerosis (ALS) is 1.89 per 100,000 per year and the prevalence is 5.2 per 100,000. The incidence of ALS is lower among African, Asian, and Hispanic ethnicities when compared to Caucasians. The mean age of onset for sporadic ALS is about 60 years and there is a slight male predominance (male to female ratio of 1.5 to 1). Approximately two thirds of patients with ALS have the spinal form of the disease with symptoms presenting in the extremities. Patients typically have evidence of both lower motor neuron degeneration (atrophy, weakness, and fasciculations) and upper motor neuron degeneration (spasticity, weakness, and hyperreflexia). Patients with limb onset ALS typically complain of focal muscle weakness and wasting. The symptoms may start either distally or proximally in the upper and/or lower limbs. Gradually spasticity develops in the weakened atrophic limbs, affecting manual dexterity and gait. Patients with bulbar onset ALS typically present with dysarthria and dysphagia for solid or liquids. Limb symptoms can develop simultaneously with bulbar onset. In the vast majority of patients, limb weakness will occur within 1-2 years of bulbar onset ALS symptoms. A case of bulbar and sporadic limb ALS in a 70-year-old veteran, presenting with right diaphragmatic paralysis and respiratory failure, is presented.

[Update on fundamental and clinical research in amyotrophic lateral sclerosis]

This paper from a group of French experts in amyotrophic lateral sclerosis (ALS) presents an update of recent advances in fundamental, epidemiological and clinical research in ALS. Recent development in the pathogenesis of ALS suggests that motor neuron degeneration is a multifactorial and noncell autonomous process. Research has been advanced through the identification of the TAR-DNA-binding protein (TDP-43) as a common neuropathological marker of ALS and frontotemporal lobar degeneration with ubiquitin-positive inclusions. Recently, mutations in the TDP-43 gene have been described in individuals with familial and sporadic ALS. Fundamental research in ALS is expected to lead to the disclosure of new diagnostic markers and therapeutic targets. A small trial has suggested that lithium carbonate may slow ALS progression but larger trials will be needed to confirm these results.