Phrenic nerve studies predict survival in amyotrophic lateral sclerosis

Neurophysiological and imaging biomarkers of lower motor neuron dysfunction in motor neuron diseases/amyotrophic lateral sclerosis: IFCN handbook chapter

This chapter discusses comprehensive neurophysiological biomarkers utilised in motor neuron disease (MND) and, in particular, its commonest form, amyotrophic lateral sclerosis (ALS). These encompass the conventional techniques including nerve conduction studies (NCS), needle and high-density surface electromyography (EMG) and H-reflex studies as well as novel techniques. In the last two decades, new methods of assessing the loss of motor units in a muscle have been developed, that are more convenient than earlier methods of motor unit number estimation (MUNE),and may use either electrical stimulation (e.g. MScanFit MUNE) or voluntary activation (MUNIX). Electrical impedance myography (EIM) is another novel approach for the evaluation that relies upon the application and measurement of high-frequency, low-intensity electrical current. Nerve excitability techniques (NET) also provide insights into the function of an axon and reflect the changes in resting membrane potential, ion channel dysfunction and the structural integrity of the axon and myelin sheath. Furthermore, imaging ultrasound techniques as well as magnetic resonance imaging are capable of detecting the constituents of morphological changes in the nerve and muscle. The chapter provides a critical description of the ability of each technique to provide neurophysiological insight into the complex pathophysiology of MND/ALS. However, it is important to recognise the strengths and limitations of each approach in order to clarify utility. These neurophysiological biomarkers have demonstrated reliability, specificity and provide additional information to validate and assess lower motor neuron dysfunction. Their use has expanded the knowledge about MND/ALS and enhanced our understanding of the relationship between motor units, axons, reflexes and other neural circuits in relation to clinical features of patients with MND/ALS at different stages of the disease. Taken together, the ultimate goal is to aid early diagnosis, distinguish potential disease mimics, monitor and stage disease progression, quantify response to treatment and develop potential therapeutic interventions.

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.

The impact of upper and lower motor neuron burden on diagnostic certainty, and clinical course of spinal-onset amyotrophic lateral sclerosis: a cluster-based approach

BACKGROUND

Upper motor neuron (UMN) and lower motor neuron (LMN) involvement represent the core clinical features of amyotrophic lateral sclerosis (ALS). Several studies divided patients into prevalent UMN and LMN impairment phenotypes to investigate the association between motor systems impairments and ALS clinical course. However, this distinction was somehow heterogeneous and significantly affected the comparability across studies.

AIMS

This study aimed to investigate whether patients spontaneously segregate based on the extent of UMN and LMN involvement without a-priori categorization and to identify potential clinical and prognostic features of different clusters.

METHODS

Eighty-eight consecutive spinal-onset ALS patients were referred to an ALS tertiary center between 2015 and 2022. UMN and LMN burden was assessed with the Penn Upper Motor Neuron scale (PUMNS) and the Devine score, respectively. PUMNS and LMN scores were normalized into 0-1 and analyzed using a two-step cluster analysis and the Euclidean distance measure. The Bayesian Information Criterion was used to determine the cluster number. Demographic and clinical variables were tested for differences among the clusters.

RESULTS

Three distinct clusters emerged at cluster analysis. Patients in "cluster-1" showed moderate UMN and severe LMN involvement, corresponding to the typical ALS phenotype. Patients in "cluster-2" showed mild LMN and severe UMN damage, corresponding to a predominant UMN phenotype, while "cluster-3" patients showed mild UMN and moderate LMN damage, corresponding to a predominant LMN phenotype. Patients in "cluster-1" and "cluster-2" showed a higher prevalence of definite ALS than those in "cluster-3" (61% and 46 vs 9%, p < 0.001). "Cluster-1" patients had a lower median ALSFRS-r score compared to both "cluster-2" and 3 patients (27 vs 40 and 35, < 0.001). "Cluster-1" (HR: 8.5; 95% CI 2.1-35.1 and p = 0.003) and 3 (HR: 3.2; 95% CI 1.1-9.1; p = 0.03) were associated with shorter survival than those in "cluster-2".

CONCLUSIONS

Spinal-onset ALS can be categorized into three groups according to LMN and UMN burden. The UMN burden is related to higher diagnostic certainty and broader disease spread, while LMN involvement is associated with higher disease severity and shorter survival.

Sonographic Phrenic Nerve Changes in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects both the upper and lower motor neurons in the nervous system, causing muscle weakness and severe disability. The progressive course of the disease reduces the functional capacity of the affected patients, limits daily activities, and leads to complete dependence on caregivers, ultimately resulting in a fatal outcome. Respiratory dysfunction mostly occurs later in the disease and is associated with a worse prognosis. Forty-six participants were included in our study, with 23 patients in the ALS group and 23 individuals in the control group. The ultrasound examination of the phrenic nerve (PN) was performed by two authors using a high-resolution "Philips EPIQ 7" ultrasound machine with a linear 4-18 MHz transducer. Our study revealed that the phrenic nerve is significantly smaller on both sides in ALS patients compared to the control group (p < 0.001). Only one significant study on PN ultrasound in ALS, conducted in Japan, also showed significant results (p < 0.00001). These small studies are particularly promising, as they suggest that ultrasound findings could serve as an additional diagnostic tool for 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.

Utility of phrenic nerve conduction studies for identification of patients with neuromuscular diseases requiring invasive mechanical ventilation

INTRODUCTION/AIMS

Predicting when a patient will require invasive mechanical ventilation (IMV) is a major challenge in routine care for some neuromuscular diseases. In this study, we prospectively investigated whether phrenic nerve conduction studies (PNCS) can predict when IMV will be required in patients with amyotrophic lateral sclerosis (ALS), Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), and myotonic dystrophy (DM).

METHODS

PNCS amplitude (avAMP) and latency (avLAT) were compared between patients who required IMV (IMV group) and those who did not (non-IMV group). PNCS were performed in 62 healthy controls and in patients with four different diseases that may require IMV: ALS (n = 56), GBS (n = 72), CIDP (n = 38), and DM (n = 24).

RESULTS

The IMV group consisted of 12 patients with ALS, 14 with GBS, 2 with CIDP, and 4 with DM. avAMP was significantly lower in the IMV group with ALS than in the non-IMV group (P < .05), but no significant difference was observed in avLAT. avAMP was significantly lower and avLAT was significantly longer in the IMV group with GBS than in the non-IMV group (both P < .05). Receiver operating characteristic analysis showed that the avAMP cutoff between the IMV and non-IMV groups was 184.3 μV (area under the curve = 0.921; sensitivity, 84.6%; specificity, 88.2%) for ALS and GBS.

DISCUSSION

PNCSs may aid in determining whether a patient with ALS or GBS requires IMV.

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.

Phrenic nerve study as outcome in clinical trials for amyotrophic lateral sclerosis

Introduction: Respiratory tests are fundamental for monitoring respiratory function in ALS, and essential in clinical trials. Slow vital capacity (SVC) was canceled in some countries to prevent COVID-19 transmission. We aimed to test phrenic nerve motor responses as an option to SVC in clinical trials. Methodology: Patients followed-up in our unit were selected respecting inclusion criteria used elsewhere: possible/probable/definite disease; onset-age 18-80years; disease duration from disease duration ≤24months; body mass index (BMI)>20kg/m²; respiratory subscore of the revised ALS functional rating scale (ALSFRS-R)≥11; upright SVC ≥ 70%. We added normal phrenic responses (meanPhrenAmpl, ≥0.4mV). All patients were on riluzole. SVC and meanPhrenAmpl were recorded at study entry (T0) and 24 weeks later (T1). Decays were determined. Sample size was calculated for a treatment effect of 30% on the decay rate. Results: We included 317 ALS patients (191 males, 225 spinal-onset), mean onset-age 59.9 ± 10.7 (31-80)years, mean onset BMI 25.48 ± 3.2 (20.1-35)kg/m², mean disease duration 10.5 ± 5.6 (1-24)months, mean ALSFRS-R 41.54 ± 4.3 (22-47) and respiratory subscore 11.83 ± 0.38 (11-12). MeanPhrenAmpl and SVC were weakly but significantly correlated at T0 and T1. At T1, MeanPhrenAmpl decayed 16.94 ± 16.45% and SVC 13.5 ± 16.86%. For the proposed drug effect, 174 and 272 patients would be needed to recruit using respectively meanPhrenAmpl and SVC decline as the primary outcome measurement (accepting no dropouts). Discussion: Contrary to SVC, meanPhrenAmpl is non-volitional and not associated with aerosolization risk. Lower recruitment number (98 patients less) would be needed, translating shorter inclusion period, trial length and costs, and probable lower missed data rate. MeanPhrenAmp is an alternative test in ALS clinical trials.

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.

Utility of phrenic nerve ultrasound in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder affecting the upper and lower motor neurons causing progressive weakness. It eventually involves the diaphragm which leads to respiratory paralysis and subsequently death. Phrenic nerve (PN) conduction studies and diaphragm ultrasound has been studied and correlated with pulmonary function tests in ALS patients. However, PN ultrasonography has not been employed in ALS. This study aims to sonographically evaluate the morphologic appearance of the PN of ALS patients. Thirty-eight ALS patients and 28 normal controls referred to the neurophysiology laboratory of two institutions were retrospectively included in the study. Baseline demographic and clinical variables such as disease duration, ALS Functional Rating Scale-Revised score, and ALS region of onset were collected. Ultrasound was used to evaluate the PN cross-sectional area (CSA) of ALS and control subjects. The mean PN CSA of ALS patients were 1.08 ± 0.39 mm on the right and 1.02 ± 0.34 mm on the left. The PN CSA of ALS patients were significantly decreased compared to controls (p value < 0.00001). The PN CSA of ALS patients was not correlated to any of the demographic and clinical parameters tested. This study demonstrates that ALS patients have a smaller PN size compared to controls using ultrasonography.

Whole-mount staining of neuromuscular junctions in adult mouse diaphragms with a sandwich-like apparatus

BACKGROUND

Investigation of neuromuscular junction (NMJ) morphology by immunochemistry can provide important insights into the physiological and pathological status of neuromuscular disorders. Sectioning and muscle fiber tearing are commonly required to prepare experimentally accessible samples, while muscles that are flat and thin can be investigated with whole-mount immunohistochemistry for a comprehensive overview of the entire innervation pattern. The diaphragm is important for respiratory function and one of the flat muscles frequently used for studying neuromuscular development as well as neuromuscular pathology. Nevertheless, techniques for reliable whole-mount immunolabeling of adult diaphragms are lacking, mainly due to the poor tissue permeability of labeling reagents. An effective approach for researchers to be able to comprehensively visualize and characterize NMJ defects of the adult diaphragm in mouse models is therefore of clear importance.

NEW METHOD

This protocol demonstrates that the diaphragm can be thinned and spread out under even pressure using two Perspex boards for better whole-mount immunostaining.

RESULTS

The expanded mouse diaphragm allows the comprehensive assessment of a number of NMJ phenotypes.

COMPARISON WITH EXISTING METHODS

Most peer-reviewed and online protocols can be applied to the embryonic diaphragm but fail to show the entire innervation pattern in the adult diaphragm. Our method provides a convenient approach and present a clear innervation pattern that increases the reliability of the assessment of NMJ phenotypes in the diaphragm.

CONCLUSIONS

This simple method for whole-mount immunostaining of the adult diaphragm will allow researchers to perform a detailed analysis of the neuromuscular system in mouse models.

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.

Diaphragmatic CMAP amplitude from phrenic nerve stimulation predicts functional decline in ALS

OBJECTIVE

To evaluate phrenic nerve motor amplitude (PhrenicAmp) as an independent predictor of functional decline in amyotrophic lateral sclerosis (ALS). We also assessed both PhrenicAmp and forced vital capacity (FVC) as predictors of functional loss in patients with bulbar dysfunction.

METHODS

We included consecutive ALS patients with PhrenicAmp and FVC at baseline. Participants were evaluated with the revised ALS Functional Rating Scale (ALSFRS-R) at inclusion and at, at least, one subsequent follow-up visit. The outcome measure of functional decline was the percentage reduction in ALSFRS-R from baseline. Bulbar dysfunction was defined by the presence of any relevant symptom on the ALSFRS-R bulbar sub-score. Correlations and mixed-effects regressions were used to study the relationship between functional decline and both PhrenicAmp and FVC baseline evaluations.

RESULTS

A total of 249 ALS patients were included; 64.2% of these had bulbar dysfunction. At inclusion, significant correlations were found between PhrenicAmp and FVC (p < 0.001), as well as between each respiratory measure and ALSFRS-R (all p < 0.001). The functional decline at first (median 3 months) and second (median 6 months) follow-up visits was significantly correlated with baseline values of both respiratory evaluations (all p < 0.01) in the entire ALS population, but only with baseline PhrenicAmp (all p < 0.05) in bulbar dysfunction cases. Regression analysis revealed that PhrenicAmp (all p < 0.05), but not FVC, was a significant independent predictor of functional decline in ALS patients and in those with bulbar dysfunction.

CONCLUSION

Baseline PhrenicAmp is an independent predictor of functional decline in ALS, whether or not bulbar dysfunction is present.

Noninvasive Prediction of Twitch Transdiaphragmatic Pressure: Insights from Spirometry, Diaphragm Ultrasound, and Phrenic Nerve Stimulation Studies

BACKGROUND

Twitch transdiaphragmatic pressure (twPdi) following magnetic stimulation (MS) of the phrenic nerves is the gold standard for non-volitional assessment of diaphragm strength. Expiratory muscle function can be investigated using MS of the abdominal muscles and measurement of twitch gastric pressure (twPgas).

OBJECTIVES

To investigate whether twitch pressures following MS of the phrenic and lower thoracic nerve roots can be predicted noninvasively by diaphragm ultrasound parameters and volitional tests of respiratory muscle strength.

METHODS

Sixty-three healthy subjects underwent standard spirometry, measurement of maximum inspiratory (PImax) and expiratory pressure (PEmax), and diaphragm ultrasound. TwPdi following cervical MS of the phrenic nerve roots and twPgas after lower thoracic MS (twPgas-Thor) were measured using esophageal and gastric balloon catheters inserted transnasally. Using surface electrodes, compound muscle action potentials (CMAP) were simultaneously recorded from the diaphragm or obliquus abdominis muscles, respectively.

RESULTS

Forced expiratory flow (FEF25-75) was significantly correlated with twPdi (r = 0.37; p = 0.003) and its components (twPgas and twitch esophageal pressure, twPes). Diaphragm excursion velocity during tidal breathing was correlated to twPes (r = 0.44; p = 0.02). No prediction of twitch pressures was possible from CMAP amplitude, forced vital capacity (FVC), or PImax. TwPgas-Thor was correlated with FEF25-75 (r = 0.46; p = 0.05) and diaphragm thickness at total lung capacity (r = 0.38; p = 0.04) but could not be predicted from CMAP amplitude, FVC, or PEmax.

CONCLUSIONS

TwPdi and twPgas-Thor cannot be predicted from volitional measures of respiratory muscle strength, diaphragm and abdominal CMAP, or diaphragm ultrasound. Invasive recording of esophageal and gastric pressures following MS remains indispensable for objective assessment of respiratory muscle strength.

Electrophysiological Properties of the Human Diaphragm Assessed by Magnetic Phrenic Nerve Stimulation: Normal Values and Theoretical Considerations in Healthy Adults

PURPOSE

This study determined normal values for motor evoked potentials (MEPs) and compound muscle action potentials (CMAPs) of the diaphragm following cortical and cervical magnetic stimulation (COMS and CEMS) of the phrenic nerves in healthy adults.

METHODS

Using surface electrodes, diaphragmatic MEP and CMAP were recorded in 70 subjects (34 ± 13 years, 25 men) following supramaximal cortical magnetic stimulation and CEMS at functional residual capacity and using a standardized inspiratory pressure trigger (-0.5 kPa). All healthy volunteers underwent standard spirometry and measurement of maximum inspiratory and expiratory pressure.

RESULTS

At functional residual capacity, upper limit of normal for MEP latency was 25 ms in men and 23 ms in women (p < 0.05), and upper limit of normal for CMAP latency was 6 ms. In contrast to MEP and CMAP amplitude, corresponding latencies showed little interindividual and intraindividual variability. Use of an inspiratory pressure trigger enhanced reproducibility and amplitude of diaphragm MEP. Diaphragm responses to both cortical and cervical magnetic stimulation were symmetrical and independent of age (in our cohort), with higher values for latency and amplitude in men (each p < 0.05). Diaphragm CMAP amplitude showed weak-moderate correlations with forced vital capacity (r = 0.47; p < 0.01), maximum inspiratory pressure (r = 0.39; p < 0.01), and maximum expiratory pressure (r = 0.32; p < 0.01).

CONCLUSIONS

Combination of cortical magnetic stimulation and CEMS of the phrenic nerves is feasible and allows noninvasive assessment of both central and peripheral conductivity of the diaphragm and the inspiratory pathway.

Tracking a Fast-Moving Disease: Longitudinal Markers, Monitoring, and Clinical Trial Endpoints in ALS

Amyotrophic lateral sclerosis (ALS) encompasses a heterogeneous group of phenotypes with different progression rates, varying degree of extra-motor involvement and divergent progression patterns. The natural history of ALS is increasingly evaluated by large, multi-time point longitudinal studies, many of which now incorporate presymptomatic and post-mortem assessments. These studies not only have the potential to characterize patterns of anatomical propagation, molecular mechanisms of disease spread, but also to identify pragmatic monitoring markers. Sensitive markers of progressive neurodegenerative change are indispensable for clinical trials and individualized patient care. Biofluid markers, neuroimaging indices, electrophysiological markers, rating scales, questionnaires, and other disease-specific instruments have divergent sensitivity profiles. The discussion of candidate monitoring markers in ALS has a dual academic and clinical relevance, and is particularly timely given the increasing number of pharmacological trials. The objective of this paper is to provide a comprehensive and critical review of longitudinal studies in ALS, focusing on the sensitivity profile of established and emerging monitoring markers.

SVC Is a Marker of Respiratory Decline Function, Similar to FVC, in Patients With ALS

Introduction: Respiratory function is a critical predictor of survival in amyotrophic lateral sclerosis (ALS). We aimed to determine if slow vital capacity (SVC) is a predictor of functional loss in ALS as compared to forced vital capacity (FVC).

Methods: Consecutive ALS patients in whom respiratory tests were performed at baseline and 6 months later were included. All patients were evaluated with revised ALS functional rating scale (ALSFRS-R) and the respiratory tests, SVC, and FVC. Significant independent variables of functional decay were assessed by univariate Kaplan-Meier log-rank test and multivariate Cox proportional hazards model. A monthly decay not exceeding 0.92 in ALSFRS was considered as the time event.

Results: We included 232 patients (134 men; mean onset-age 59.1 ± 11.23 years; mean disease duration from first symptoms to first visit: 14.5 ± 12.9 months; 166 spinal and 66 bulbar onset). All variables studied declined significantly between the two evaluations (p < 0.001). FVC and SVC were strongly correlated at study entry (r² = 0.98, p < 0.001) and FVC and SVC decays between first evaluation and 6 months after were the only significant prognostic variables of functional decay (p < 0.001).

Conclusion: FVC and SVC decay are inter-changeable in predicting functional decay in ALS. Pharmacological interventions reducing the decline rate of FVC and SVC can have a positive impact on the global functional impairment, with relevant implications for clinical trials' design and interpretation.

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.

Phrenic Nerve Conduction in Healthy Subjects

INTRODUCTION

Assessment of diaphragm compound muscle action potential by noninvasive phrenic nerve stimulation at the neck is well described. However, normal values in a large cohort of healthy subjects are lacking. Our objective was to determine reference values of phrenic nerve conduction in healthy subjects.

METHODS

We recruited 155 healthy subjects (25-79 years old) and measured mean amplitude (PhrenAmp) and latency (PhrenLat) of motor responses according to Bolton's method.

RESULTS

The lower limit for PhrenAmp was 0.28 and 0.25 mV and the upper limit for PhrenLat was 8.41 and 8.56 ms for right and left side, respectively. PhrenLat was correlated with age. PhrenAmp, PhrenLat and area were significantly higher in men. Tolerance to phrenic nerve stimulation was excellent.

CONCLUSIONS

Our study provides normative values of phrenic nerve motor responses in a large cohort of healthy subjects and identifies age and sex as factors of variation. Muscle Nerve 59:451-456, 2019.

The clinical assessment of amyotrophic lateral sclerosis patients' prognosis by ZNF512B gene, neck flexor muscle power score and body mass index (BMI)

BACKGROUND

Assessment on the prognosis of amyotrophic lateral sclerosis (ALS) is becoming a focus of research in recent years since there is no effective treatment. The aim of the research is to explore the major factors involving in prognosis of ALS patients through long-term follow-up.

METHODS

ALS patients' DNA extracted from peripheral blood white cells were detected for the risk allele by single nucleotide polymorphism (SNP) analysis. Neck flexor muscle score and body mass index (BMI) were recorded during Medical Research Council follow-up using manual muscle testing method.

RESULTS

ALS patients with risk alleles (C) deteriorated rapidly with poor clinical outcome. It seemed that the higher neck flexor muscle strength score in ALS patients with the longer survival time but without significant correlation (p > 0.05). The lower the basal body mass index, the shorter the survival time and the faster deterioration (p < 0.05). The patients with body mass index less than 22.04 seemed to have short survival time than those with BMI more than 22.04 (p < 0.05), however, the speed of deterioration in two groups of patients had no significant difference (p > 0.05).

CONCLUSION

The risk (C) allele of the SNP (rs2275294) in the ZNF512B gene, cervical flexor muscle power and body weight index might have clinical potential for ALS prognostication, since these indicators is so simple to perform that they might be very suitable for primary clinics and even community medical institutions to carry out.

Diaphragm: Pathophysiology and Ultrasound Imaging in Neuromuscular Disorders

Respiratory muscles are classically involved in neuromuscular disorders, leading to a restrictive respiratory pattern. The diaphragm is the main respiratory muscle involved during inspiration. Ultrasound imaging is a noninvasive, radiation-free, accurate and safe technique allowing assessment of diaphragm anatomy and function. The authors review the pathophysiology of diaphragm in neuromuscular disorders, the methodology and indications of diaphragm ultrasound imaging as well as possible pitfalls in the interpretation of results.

Respiratory involvement in neuromuscular disorders

PURPOSE OF REVIEW

In numerous neuromuscular disorders (NMDs), respiratory muscle weakness is present, and acute or chronic respiratory failure may evolve. Very often, respiratory involvement substantially adds to the burden of disease, impairs quality of life, or reduces life expectancy. This article summarizes new aspects of both diagnosis and management of respiratory muscle weakness in patients with NMDs.

RECENT FINDINGS

Drugs like deflazacort, ataluren, eteplirsen, and nusinersen are now approved treatments for Duchenne Muscular Dystrophy and Spinal Muscular Atrophy, and others are on their way in NMDs. Although observing how innovative drugs will change the natural history of these diseases, including respiratory function over time, adequate symptomatic treatment remains meaningful and is strongly recommended. Physicians should systematically take respiratory involvement into account to improve patients' quality of life and prognosis.

SUMMARY

First, it is outlined in which subtypes of NMD respiratory muscle dysfunction is particularly relevant. Second, new developments regarding diagnostic procedures, including respiratory muscle strength testing, spirometry, and sleep studies, are covered. Third, this article gives an overview on current concepts of ventilatory support and management of secretions in patients with NMD.

Respiratory measures in amyotrophic lateral sclerosis

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disease that causes skeletal muscle weakness, including muscles involved with respiration. Death often results from respiratory failure within 3-5 years. Monitoring respiratory status is therefore critical to ALS management, as respiratory/pulmonary function tests (PFTs) are used to make decisions including when to initiate noninvasive ventilation. Understanding the different respiratory and PFTs as they relate to disease progression and survival may help determine which tests are most suitable.

METHODS

This review describes the tests used to assess respiratory muscle and pulmonary function in patients with ALS and the correlations between different respiratory measures and clinical outcomes measures.

RESULTS

The most commonly used measurement, forced vital capacity (VC), has been shown to correlate with clinical milestones including survival, but also requires good motor coordination and facial strength to form a tight seal around a mouthpiece. Other tests such as slow VC, sniff inspiratory pressure, or transdiaphragmatic pressure with magnetic stimulation are also associated with distinct advantages and disadvantages.

CONCLUSIONS

Therefore, how and when to use different tests remains unclear. Understanding how each test relates to disease progression and survival may help determine which is best suited for specific clinical decisions.

Plasma level of club-cell (CC-16) predicts outcome in amyotrophic lateral sclerosis

OBJECTIVES

The club cell protein (CC-16) is a biomarker associated with respiratory distress and pulmonary inflammation. We evaluated CC-16 as a candidate biomarker for respiratory failure in amyotrophic lateral sclerosis (ALS).

MATERIALS AND METHODS

We studied 81 ALS patients and 30 matched controls. We used an ALS-related measure of functional capacity, and tested forced vital capacity (FVC) and the amplitude of the diaphragmatic response by phrenic nerve stimulation (PhrenAmpl). Plasma CC-16 levels were measured in venous blood. Kaplan-Meier survival curves were plotted to evaluate risk to non-invasive ventilation and death in patients with abnormal CC-16 levels.

RESULTS

CC-16 levels were significantly raised in ALS patients (10.56 ng/mL ± 6.84 vs 8.34 ng/mL ± 3.10, P = .02), and in 17% of them, CC-16 level was above the upper cutoff value (mean + 2.5SD). CC-16 levels did not correlate with age, onset region, disease duration, functional status, FVC, and PhrenAmpl. In patients with increased CC-16 level, the risk of non-invasive was greater in the following 6 months (P = .01) and tended to have higher mortality in the following 30 months (P = .07).

CONCLUSIONS

We propose that increased CC-16 levels is a marker of lung inflammatory response that associated with ventilatory insufficiency are related to impending respiratory failure, not fully predicted by conventional respiratory tests. The latter are limited by the moment of testing.

Comparison of slow and forced vital capacities on ability to predict survival in ALS

INTRODUCTION

Slow (SVC) and forced (FVC) vital capacities are the most used pulmonary function tests in amyotrophic lateral sclerosis (ALS). It is unknown if they equally predict survival in ALS. The aim of the present study was to compare both measures in predicting survival in this disease.

METHODS

Consecutive definite/probable ALS patients (2000-2014) in whom respiratory tests were performed at baseline and four months later were included. All patients were evaluated with the revised ALS functional rating scale (ALSFRS-R), respiratory (RofALSFRS-R), bulbar (ALSFRSb), upper and lower limb subscores, SVC, FVC, maximal inspiratory (MIP) and expiratory (MEP) pressures. King's functional staging system was applied retrospectively. Survival analysis was carried out by univariate Kaplan-Meier log-rank test. Multivariate Cox proportional hazards model determined significant independent variables.

RESULTS

We included 469 patients (270 males; mean onset age 61.0 ± 11.5 years; mean disease duration from first symptoms to first visit: 15.8 ± 16.1months; 329 spinal and 140 bulbar onset). FVC and SVC were strongly correlated (r² = 0.981, p < 0.001). Significant survival prognostic variables (Kaplan-Meier analyses) were onset region, age, disease duration, ALSFRS-R, ALSFRSb, RofALSFRS-R, ALSFRS-R decay, SVC, FVC, MIP, MEP and King's staging (p ≤ 0.01). Final Cox model including the significant variables showed similar results for FVC and SVC (p < 0.001). Moreover, 1% decrease in either predicted values increased death probability by 1.02.

CONCLUSION

FVC and SVC are inter-changeable in predicting survival in ALS.

Respiratory Muscle Strength as a Predictive Biomarker for Survival in Amyotrophic Lateral Sclerosis

RATIONALE

Biomarkers for survival in amyotrophic lateral sclerosis (ALS) would facilitate the development of novel drugs. Although respiratory muscle weakness is a known predictor of poor prognosis, a comprehensive comparison of different tests is lacking.

OBJECTIVES

To compare the predictive power of invasive and noninvasive respiratory muscle strength assessments for survival or ventilator-free survival, up to 3 years.

METHODS

From a previously published report respiratory muscle strength measurements were available for 78 patients with ALS. Time to death and/or ventilation were ascertained. Receiver operating characteristic analysis was used to determine the cutoff point of each parameter.

MEASUREMENTS AND MAIN RESULTS

Each respiratory muscle strength assessment individually achieved statistical significance for prediction of survival or ventilator-free survival. In multivariate analysis sniff trans-diaphragmatic and esophageal pressure, twitch trans-diaphragmatic pressure (Tw Pdi), age, and maximal static expiratory mouth pressure were significant predictors of ventilation-free survival and Tw Pdi and maximal static expiratory mouth pressure for absolute survival. Although all measures had good specificity, there were differing sensitivities. All cutoff points for the VC were greater than 80% of normal, except for prediction of 3-month outcomes. Sequential data showed a linear decline for direct measures of respiratory muscle strength, whereas VC showed little to no decline until 12 months before death/ventilation.

CONCLUSIONS

The most powerful biomarker for mortality stratification was Tw Pdi, but the predictive power of sniff nasal inspiratory pressure was also excellent. A VC within normal range suggested a good prognosis at 3 months but was of little other value.

Toward a Framework for Benefit-Risk Assessment in Diagnostic Imaging: Identifying Scenario-specific Criteria

RATIONALE AND OBJECTIVES

Diagnostic imaging has many effects and there is no common definition of value in diagnostic radiology. As benefit-risk trade-offs are rarely made explicit, it is not clear which framework is used in clinical guideline development. We describe initial steps toward the creation of a benefit-risk framework for diagnostic radiology.

MATERIALS AND METHODS

We performed a literature search and an online survey of physicians to identify and collect benefit-risk criteria (BRC) relevant to diagnostic imaging tests. We operationalized a process for selection of BRC with the use of four clinical use case scenarios that vary by diagnostic alternatives and clinical indication. Respondent BRC selections were compared across clinical scenarios and between radiologists and nonradiologists.

RESULTS

Thirty-six BRC were identified and organized into three domains: (1) those that account for differences attributable only to the test or device (n = 17); (2) those that account for clinical management and provider experiences (n = 12); and (3) those that capture patient experience (n = 7). Forty-eight survey participants selected 22 criteria from the initial list in the survey (9-11 per case). Engaging ordering physicians increased the number of criteria selected in each of the four clinical scenarios presented. We developed a process for standardizing selection of BRC in guideline development.

CONCLUSION

These results suggest that a process relying on elements of comparative effectiveness and the use of standardized BRC may ensure consistent examination of differences among alternatives by way of making explicit implicit trade-offs that otherwise enter the decision-making space and detract from consistency and transparency. These findings also highlight the need for multidisciplinary teams that include input from ordering physicians.

A clinical tool for predicting survival in ALS

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a progressive and usually fatal neurodegenerative disease. Survival from diagnosis varies considerably. Several prognostic factors are known, including site of onset (bulbar or limb), age at symptom onset, delay from onset to diagnosis and the use of riluzole and non-invasive ventilation (NIV). Clinicians and patients would benefit from a practical way of using these factors to provide an individualised prognosis.

METHODS

575 consecutive patients with incident ALS from a population-based registry in South-East England register for ALS (SEALS) were studied. Their survival was modelled as a two-step process: the time from diagnosis to respiratory muscle involvement, followed by the time from respiratory involvement to death. The effects of predictor variables were assessed separately for each time interval.

FINDINGS

Younger age at symptom onset, longer delay from onset to diagnosis and riluzole use were associated with slower progression to respiratory involvement, and NIV use was associated with lower mortality after respiratory involvement, each with a clinically significant effect size. Riluzole may have a greater effect in younger patients and those with longer delay to diagnosis. A patient's survival time has a roughly 50% chance of falling between half and twice the predicted median.

INTERPRETATION

A simple and clinically applicable graphical method of predicting an individual patient's survival from diagnosis is presented. The model should be validated in an independent cohort, and extended to include other important prognostic factors.

Pattern of Respiratory Deterioration in Sporadic Amyotrophic Lateral Sclerosis According to Onset Lesion by Using Respiratory Function Tests

Most amyotrophic lateral sclerosis (ALS) patients show focal onset of upper and lower motor neuron signs and spread of symptoms to other regions or the other side clinically. Progression patterns of sporadic ALS are unclear. The aim of this study was to evaluate the pattern of respiratory deterioration in sporadic ALS according to the onset site by using respiratory function tests. Study participants included 63 (42 cervical-onset [C-ALS] and 21 lumbosacral-onset [L-ALS]) ALS patients and 31 healthy controls. We compared respiratory function test parameters among the 3 groups. Age was 57.4±9.6 (mean±SD), 60.8±9, and 60.5±7 years, and there were 28, 15, and 20 male participants, in the C-ALS, L-ALS, and control groups, respectively. Disease duration did not differ between C-ALS and L-ALS patients. Sniff nasal inspiratory pressure (SNIP) was significantly low in C-ALS patients compared with controls. Maximal expiratory pressure (MEP) and forced vital capacity percent predicted (FVC% predicted) were significantly low in C-ALS and L-ALS patients compared with controls. Maximal inspiratory pressure to maximal expiratory pressure (MIP:MEP) ratio did not differ among the 3 groups. Eighteen C-ALS and 5 L-ALS patients were followed up. ΔMIP, ΔMEP, ΔSNIP, ΔPEF, and ΔFVC% predicted were higher in C-ALS than L-ALS patients without statistical significance. Fourteen C-ALS (77.8%) and 3 L-ALS (60%) patients showed a constant MIP:MEP ratio above or below 1 from the first to the last evaluation. Our results suggest that vulnerability of motor neurons in sporadic ALS might follow a topographic gradient.

Integrative biomarker discovery in neurodegenerative diseases

Data mining has been widely applied in biomarker discovery resulting in significant findings of different clinical and biological biomarkers. With developments in technology, from genomics to proteomics analysis, a deluge of data has become available, as well as standardized data repositories. Nonetheless, researchers are still facing important challenges in analyzing the data, especially when considering the complexity of pathways involved in biological processes and diseases. Data from single sources appear unable to explain complex processes, such as those involved in brain-related disorders, including Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis, thus raising the need for a more comprehensive perspective. A possible solution relies on data and model integration, where several data types are combined to provide complementary views. This in turn can result in the discovery of previously unknown biomarkers by unraveling otherwise hidden relationships between data from different sources, and/or validate such composite biomarkers in more powerful predictive models.

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.

Usefulness of phrenic latency and forced vital capacity in patients with ALS with latent respiratory dysfunction

OBJECTIVES

The pulmonary function test (PFT) is a non-invasive and easily available technique to assess respiratory function in patients with amyotrophic lateral sclerosis (ALS); however, patients with dyspnea sometimes show normal PFT findings. Herein, we investigated whether phrenic nerve conduction study (NCS) and PFT are useful to evaluate respiratory function of patients with ALS with normal value ranges in the PFT.

METHODS

We prospectively enrolled 34 patients with definite or probable ALS, who showed FVC (%) ⩾80 of predicted and 78 healthy subjects. PFT and phrenic NCS were performed with the measurement of forced vital capacity (FVC, %), forced expiratory volumes in 1s (FEV1, %), FEV1/FCV ratio (%), and phrenic compound muscle action potential amplitude, and latency.

RESULTS

Compared to healthy controls, ALS patients showed delayed phrenic nerve latency and the decrease of FVC (%) (p=0.006 and p<0.0001, respectively). ROC curve analysis demonstrated that phrenic latency (AUC=0.7655) and FVC (%) (AUC=0.8239) discriminated ALS patients from healthy subjects.

CONCLUSION

We demonstrated that ALS patients had early respiratory dysfunction, despite normal PFT findings.

SIGNIFICANCE

Phrenic latency and FVC (%) can be helpful to discriminate ALS patients with latent respiratory dysfunction from healthy subjects.

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.

Neck weakness is a potent prognostic factor in sporadic amyotrophic lateral sclerosis patients

OBJECTIVE

To clarify the emergence of muscle weakness in regions of the body that affect survival, and deterioration in activities of daily living (ADL) in amyotrophic lateral sclerosis (ALS) patients.

METHODS

We conducted a multicentre-based prospective cohort study of patients with ALS. We enrolled 401 sporadic patients with ALS. Death or the introduction of invasive ventilation was defined as the primary endpoint, and the time to five clinical markers of ADL deterioration associated with bulbar paralysis or limb weakness were defined as ADL milestones. Muscle weakness was assessed in the neck flexor muscles; the bilateral abductors of the shoulders; the bilateral wrist extensor muscles; the bilateral flexor muscles of the hips; and the bilateral ankle dorsiflexion muscles. We performed Cox proportional hazards regression analyses for the primary endpoint and the five ADL milestones, adjusting for known covariate prognostic factors for ALS.

RESULTS

The Medical Research Council (MRC) score for the neck flexors was the most significant prognostic factor for the primary endpoint (HR 0.74, p<0.001), loss of speech (HR 0.66, p<0.001), and loss of swallowing function (HR 0.73, p<0.001), and was one of the significant prognostic factors for loss of upper limb function, difficulty turning in bed, and loss of walking ability (p=0.001, 0.002, and 0.008, respectively). The MRC score for the neck flexors was also a significant prognostic factor for covariates of the previously reported prognostic factors.

CONCLUSIONS

Neck weakness is an independent prognostic factor for survival and deterioration in ADL in Patients with ALS.

Multidisciplinary clinics: optimizing treatment for patients with amyotrophic lateral sclerosis

SUMMARY Amyotrophic lateral sclerosis is an incurable, lethal neurodegenerative disease. The majority of patients die from respiratory failure within 2–5 years after symptom onset. Recent studies show a paradigm shift in the method of delivering a number of effective treatments through an emerging network of multidisciplinary clinics. This article focuses on the role played by these clinics in raising the standard-of-care for patients with amyotrophic lateral sclerosis. Although newly developed treatments are still underutilized, substantial progress is being made by multidisciplinary clinics, which play a pivotal role in coordinating access to effective therapeutics.