Adult Neuromuscular Disease Research Articles

Sleep disordered breathing assessment in patient with slowly progressive neuromuscular disease

BackgroundSleep-disordered breathing (SDB) is common in patients with neuromuscular diseases (NMD). Focusing on hypercapnia may lead to the neglect of other SDB such as obstructive and/or central sleep apnea syndrome (SAS). Our objectives were to assess the risk of inappropriate SDB management according to different screening strategies and to evaluate the prevalence and determinants of isolated and overlapping sleep apnea in patients with slowly progressive NMD. MethodsThis monocentric, cross-sectional, retrospective study analyzed medical records of adult NMD patients referred to a sleep department. Diagnostic strategies, including respiratory polygraphy (RP), nocturnal transcutaneous capnography (tcCO2), and blood gases (BG), were assessed for their performance in diagnosing SDB. Demographics and pulmonary function test results were compared between patients with or without SDB to identify predictors. ResultsAmong the 149 patients who underwent a full diagnostic panel (RP + tcCO2 + BG), 109 were diagnosed with SDB. Of these, 33% had isolated SAS, and central apneas were predominant. Using single diagnostic strategies would lead to inappropriate SDB management in two thirds of patients. A combination of 2 diagnostic tools resulted respectively in 21.1, 22.9 and 42.2 % of inappropriate SDB management for RP + tcCO2, RP + BG and tcCO2 + BG. ConclusionThe significant prevalence of sleep apnea syndrome in patients with slowly progressive NMD highlights the need for increased awareness among clinicians. Improved diagnostics involve a systematic approach addressing both sleep apnea and diurnal and nocturnal alveolar hypoventilation to avoid inappropriate management and limit the consequences of SDB.

Evaluation of bone health in terms of osteoporosis in adult patients with neuromuscular disease.

There are no current guidelines to help clinicians decide whether patients with adult neuromuscular disease (NMD) should be screened or treated for osteoporosis (OP). This study was undertaken to investigate the presence of OP in patients with various types of NMD and to examine the relationship between OP evaluation parameters and functional status, daily living activities, balance, and ambulation levels. This cross-sectional study included 45 patients with NMDs. The patients were divided into 3 groups, depending on the affected component of the motor unit (neuronopathy group, neuropathy group, and myopathy group). The laboratory and demographic data were recorded from patient files. Functional level, pain, muscular strength, balance, and daily living activity scores were evaluated. The presence of OP was quantified using bone densitometry, fracture history, and biochemical parameters. Clinical findings were correlated with laboratory and dual-energy X-ray absorptiometry (DEXA) findings. The mean hip T-score was -1.20, and the mean lumbar spine (L1-L4) T-score was -0.95 in all groups. Six patients with T-score values of -2.5 or below were detected. Vitamin D level was found to be low in all patient groups, especially in the myopathy group, but there was no significant difference (p > 0.05). There was a negative correlation between hip T-score and the frequency of falling (r = -0.604, p = 0.022), while a positive correlation was found between hip T-score and the age at which independent walking was no longer possible (r = 0.900, p = 0.037). OP is often overlooked in NMD patients with neurological problems and a high risk of falling. These patients should be screened for bone health and fragility.

The role of lung volume recruitment therapy in neuromuscular disease: a narrative review.

Respiratory muscle weakness results in substantial discomfort, disability, and ultimately death in many neuromuscular diseases. Respiratory system impairment manifests as shallow breathing, poor cough and associated difficulty clearing mucus, respiratory tract infections, hypoventilation, sleep-disordered breathing, and chronic ventilatory failure. Ventilatory support (i.e., non-invasive ventilation) is an established and key treatment for the latter. As survival outcomes improve for people living with many neuromuscular diseases, there is a shift towards more proactive and preventative chronic disease multidisciplinary care models that aim to manage symptoms, improve morbidity, and reduce mortality. Clinical care guidelines typically recommend therapies to improve cough effectiveness and mobilise mucus, with the aim of averting acute respiratory compromise or respiratory tract infections. Moreover, preventing recurrent infective episodes may prevent secondary parenchymal pathology and further lung function decline. Regular use of techniques that augment lung volume has similarly been recommended (volume recruitment). It has been speculated that enhancing lung inflation in people with respiratory muscle weakness when well may improve respiratory system "flexibility", mitigate restrictive chest wall disease, and slow lung volume decline. Unfortunately, clinical care guidelines are based largely on clinical rationale and consensus opinion rather than level A evidence. This narrative review outlines the physiological changes that occur in people with neuromuscular disease and how these changes impact on breathing, cough, and respiratory tract infections. The biological rationale for lung volume recruitment is provided, and the clinical trials that examine the immediate, short-term, and longer-term outcomes of lung volume recruitment in paediatric and adult neuromuscular diseases are presented and the results synthesised.

Subclinical cardiac involvement present as electrocardiographic abnormalities in various neuromuscular diseases

BackgroundCardiac involvement is commonly present in various neuromuscular diseases which may develop life-threatening consequences. The early manifestation is often asymptomatic which however has been insufficiently studied. ObjectivesWe aim to characterize electrocardiographic (ECG) changes in neuromuscular diseases without cardiac symptoms. MethodsAdults having genetically and/or pathologically confirmed type 1 myotonic dystrophy (DM1), Becker muscular dystrophy (BMD), limb girdle muscular dystrophies (LGMDs) and mitochondrial diseases (MtDs) but without history of heart diseases and cardiovascular symptoms were enrolled. The 12-lead ECG characteristics and other test results at diagnosis were retrieved and analyzed. Results196 patients with neuromuscular diseases (44 DM1, 25 BMD, 82 LGMDs, 45 MtDs) were consecutively enrolled. ECG abnormalities were identified in 107 (54.6%) patients with a prevalence of 59.1% in DM1, 76.0% in BMD, 40.2% in LGMDs and 64.4% in MtDs. Conduction block was more commonly present in DM1 than the other groups (P < 0.01), which had a longest PR interval and QRS duration of 186.1 ± 38.3 ms and 104.2 [90.0–108.0]ms, respectively. QT prolongation was most frequently seen in DM1 (P < 0.001). Left ventricular hypertrophy features were found in BMD, LGMDs and MtDs (P < 0.05) without intergroup difference, while a significantly higher right ventricular amplitude is observed in BMD than in other groups (P < 0.001). ConclusionsSubclinical cardiac involvement is commonly present as ECG abnormalities in multiple adult neuromuscular diseases before associated symptoms occur and show diversity in different groups.

Screening for oropharyngeal dysphagia in adult patients with neuromuscular diseases using the Sydney Swallow Questionnaire.

Oropharyngeal dysphagia is common in patients with neuromuscular diseases (NMDs). Its early recognition is vital for proper management. We tested a large cohort of adult NMD patients for oropharyngeal dysphagia using the Sydney Swallow Questionnaire (SSQ). We also looked for possible differences in characteristics of oropharyngeal dysphagia in various NMD groups and diseases. Finally, we compared results of this screening with those from their corresponding medical records for eventual "clinical history" of dysphagia. We asked patients to fill in the SSQ during follow-up outpatient visits at our neuromuscular reference center. A total score above the cutoff score of 118.5 out of 1700 was indicative of oropharyngeal dysphagia. Of the 304 adult patients assessed for eligibility, 201 NMD patients (96 women and 105 men, aged 49.0 ± 16.2 years) were included and tested in this study. Oropharyngeal dysphagia was detected in 45% of all the NMD patients when using the SSQ, whereas only 12% had a positive medical record for dysphagia. The median SSQ scores for patients with myotonic syndromes (including myotonic dystrophy type 1), with amyotrophic lateral sclerosis, and with facioscapulohumeral dystrophy were above the cutoff score. The SSQ scores obtained revealed distinct oropharyngeal dysphagia characteristics in the different NMD groups and diseases. The SSQ tests positively for oropharyngeal dysphagia in a higher proportion of NMD patients compared with their medical records. The distinct oropharyngeal dysphagia characteristics we revealed in different NMD groups and diseases may help to elaborate adapted clinical approaches in the management of oropharyngeal dysphagia.

Determinants of usage and nonadherence to noninvasive ventilation in children and adults with Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a neuromuscular disorder that leads to chronic respiratory insufficiency and failure. Use of home noninvasive ventilation (NIV) has been linked to improved outcomes including reduced mortality. Despite the importance of NIV, factors promoting optimal NIV usage and determinants of nonadherence have not been rigorously examined. Moreover, given that respiratory issues in DMD span between childhood and adulthood, examination across a broad age group is needed. The objectives of this study were to (1) evaluate NIV usage across a broad spectrum of patients with DMD, including both children and adults, and (2) identify biological and socioeconomic determinants of NIV usage and NIV nonadherence. We performed a retrospective review of all patients with DMD from February 2016 to February 2020 who underwent evaluation at associated pediatric and adult neuromuscular disease clinics. NIV use was determined objectively from device downloads. A priori, we defined nonadherence as < 4 hours use per night, quantified as the percentage of nights below this threshold across a 30-day period within 6 months of a clinic visit. We also assessed the average hours of NIV usage over this time period. Predictors examined included demographics, social determinants, and pulmonary function. 33 patients with DMD were identified, 29 (87%) of whom were using NIV (13 age < 21 years). Mean age was 22.9 ± 6.6 years (range 13-39 years), body mass index was 23.4 ± 10.4 kg/m2, and seated forced vital capacity was 23% ± 18% predicted. Mean nightly NIV usage was 7.4 ± 3.8 hours and mean percentage of nonadherent nights was 13% ± 30%. In univariable analysis, age did not predict use. Those with lower forced vital capacity had higher NIV usage hours (P = .01) and a trend toward less nonadherence (P = .06). Higher estimated household income demonstrated a trend toward increased usage hours and less nonadherence (both P = .08). Multivariable analysis found increased usage hours were predicted best by higher income, higher inspiratory positive airway pressure, and higher bicarbonate. Nonadherence was higher in those with lower income or higher forced vital capacity. In this cohort of adult and pediatric patients with DMD, most individuals were using NIV. While usage hours were higher with lower lung function, substantial variability remains unexplained by examined factors. Nonadherence was observed in some individuals, including those with advanced disease. Further investigations should focus on evaluating patient-oriented outcomes to define optimal NIV usage across the spectrum of disease and determine strategies to counteract issues with nonadherence. Hurvitz MS, Bhattacharjee R, Lesser DJ, Skalsky AJ, Orr JE. Determinants of usage and nonadherence to noninvasive ventilation in children and adults with Duchenne muscular dystrophy. J Clin Sleep Med. 2021;17(10):1973-1980.

Prognostic value of nocturnal hypoventilation in neuromuscular patients

In neuromuscular disease (NMD) patients, current guidelines recommend the initiation of home mechanical ventilation (HMV) in case of daytime hypercapnia or nocturnal desaturation as an indirect sign of hypoventilation. Transcutaneous capno-oximetry (TcCO2) enables the direct assessment of nocturnal hypercapnia; however the best cut-off value remains to be defined. We aimed to compare the prognostic value of several published definitions of nocturnal hypercapnia in a cohort of NMD patients. All consecutive TcCO2 recordings performed between 2010 and 2014 in unventilated adult NMD patients in a tertiary reference centre were retrospectively collected. Initiation of HMV and mortality were collected as outcomes of interest. 124 patients with normal daytime blood gazes were analysed (median age 39 [IQR 31–55] years; vital capacity 61% [43–82] of predicted). The prevalence of nocturnal hypercapnia ranged from 3% to 44%, depending on the definition. Over a median follow-up duration of 2.5 years [IQR 1.6–4.1], HMV was initiated for 51 patients, whilst 4 patients died. Nocturnal peak TcCO2 ≥49 mmHg was the best predictor of HMV initiation in the follow-up, being associated with a hazard ratio of 2.6 [95% CI 1.4–4.6] in a multivariate analysis adjusting for lung function parameters. Nocturnal TcCO2 identifies NMD patients at risk for subsequent need for HMV in the following few years, who were not identified by daytime blood gases or nocturnal oximetry. As a consequence, peak nocturnal TcCO2 ≥49 mmHg should be considered as one of the criteria to start HMV in patients with NMDs, along with symptoms of hypoventilation, daytime hypercapnia, abnormal nocturnal oximetry results, and a diminished level of forced vital capacity.

A population-based epidemiologic study of adult neuromuscular disease in the Republic of Ireland.

To estimate the prevalence rates (PRs) of acquired and inherited neuromuscular diseases (NMD) in the adult Irish population, reflecting the burden of these conditions in a single country. This population-based study was performed in the Republic of Ireland (RoI), with a PR estimated for December 2013. Multiple case ascertainment sources were utilized. Demographic and clinical information and relevant diagnostic results were registered. A total of 2,641 adults were identified, giving a PR of 62.6/100,000 (95% confidence interval [CI] 59.95-65.24) for all NMD in RoI. Disease-specific PR include chronic inflammatory demyelinating polyradiculoneuropathy 5.87/100,000 (95% CI 5.06-6.68), Charcot-Marie-Tooth 10.52/100,000 (95% CI 9.44-11.61), hereditary neuropathy with liability to pressure palsies 0.84/100,000 (95% CI 0.54-1.15), myotonic dystrophy type I 6.75/100,000 (95% CI 5.88-7.61), Duchenne muscular dystrophy 3.0/100,000 (95% CI 2.33-3.70), Becker muscular dystrophy 2.2/100,000 (95% CI 1.64-2.88), facioscapulohumeral dystrophy 2.59/100,000 (95% CI 2.05-3.13), limb-girdle muscular dystrophy 2.88/100,000 (95% CI 2.31-3.45), periodic paralysis 1.72/100,000 (95% CI 1.28-2.15), myotonia congenita 0.32/100,000 (95% CI 0.18-0.56), paramyotonia congenita 0.15/100,000 (95% CI 0.06-0.34), Kennedy disease 0.83/100,000 (95% CI 0.40-1.27), Lambert-Eaton myasthenic syndrome 0.29/100,000 (95% CI 0.11-0.47), myasthenia gravis 15.12/100,000 (95% CI 13.82-16.42), and sporadic inclusion body myositis 11.7/100,000 (95% CI 9.82-13.58). PR for amyotrophic lateral sclerosis was established from an existing Register as 7.20/100,000 (95% CI 6.34-8.15). The PR of all adult NMD in RoI is relatively high when compared with other chronic neurologic disorders, although some figures may be an underestimate of the true prevalence. The data provide a framework for international comparison and service planning.

Prognostic Value of Initial Assessment of Residual Hypoventilation Using Nocturnal Capnography in Mechanically Ventilated Neuromuscular Patients: A 5-Year Follow-up Study.

Restrictive respiratory failure is a major cause of morbidity and mortality in neuromuscular diseases (NMD). Home mechanical ventilation (HMV) is used to treat hypoventilation, and its efficiency is mostly assessed by daytime blood gases or nocturnal oxygen saturation monitoring (SpO2). Non-invasive transcutaneous measure of CO2 (TcCO2) allows to directly assess nocturnal hypercapnia and to detect residual hypoventilation with a higher sensitivity than SpO2. We aimed to compare the prognostic value of nocturnal SpO2 and TcCO2 in ventilated adult NMD patients. All consecutive capno-oximetries performed between 2010 and 2011 in ventilated adult NMD patients were analyzed retrospectively. Concomitant blood gas analysis and lung function data were collected. Patients on oxygen therapy were excluded. Nocturnal hypoxemia and hypercapnia (using four different definitions) at baseline were compared in their ability to predict mortality and respiratory events requiring ICU admission during follow-up. Data from 55 patients were analyzed (median age 28 [interquartile range: 25-36.5] years; 71% Duchenne muscular dystrophy; vital capacity 12 [7-27]% of predicted; 51% tracheostomy). Capno-oxymetry showed hypoxemia in 14.5% and hypercapnia in 12.7-41.8%, according to the used definition. Over a follow-up lasting up to 5 years (median 4.0 [3.6-4.5] years), we observed 12 deaths and 20 respiratory events requiring ICU admission. Hypercapnia was significantly associated with the study outcomes, with TcCO2 > 49 mmHg during ≥10% of the time being the best definition, while hypoxemia was not. Our data show for the first time that residual hypoventilation, assessed by capnometry, is significantly associated with negative outcomes in adult ventilated NMD patients, while oximetry is not. Accordingly, we suggest capnometry to be included in the systematic assessment of HMV efficiency in NMD patients. NCT02551406.

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

Restrictive respiratory failure is a major cause of morbidity and mortality in neuromuscular diseases (NMD). Home mechanical ventilation (HMV) is used to treat hypoventilation, identified by daytime hypercapnia or nocturnal desaturation. Recently, transcutaneous measure of CO2 (TcCO2) has been increasingly used to detect hypoventilation, using different cut-offs. We aimed to compare the prevalence of hypoventilation in an unselected adult NMD population according to different definitions issued from the literature. All consecutive nocturnal capno-oximetries performed between 2010 and 2014 in unventilated adult NMD patients were analysed retrospectively. Concomitant blood gas analysis and lung function data were collected. Patients on oxygen therapy were excluded. Hypoventilation was defined according to eight criteria, based on daytime PaCO2, daytime base excess, nocturnal SpO2 or TcCO2. Data from 232 patients were analysed (mean age 43.1 ± 15.4years; 50.0% women; vital capacity 59.2 ± 24.2% of predicted). The hypoventilation prevalence was 10.3 to 61.2%, depending on the used definition. The different definitions showed 49.1 to 94.8% concordance (Cohen's kappa for agreement 0.115 to 0.763). Overall agreement between the eight definitions was poor (Light's kappa 0.267), and agreement between definitions based on nocturnal SpO2 and those based on TcCO2 was even lower (Light's kappa 0.204). We found large differences in hypoventilation prevalence according to the used definition. This has practical consequences, as HMV indication relies upon hypoventilation detection. We believe that capno-oximetry should be included in the diagnostic tools used to detect hypoventilation but this requires an update of consensus guidelines to agree upon the best definition.

Methodology and Design of a National Epidemiological Study on Adult Neuromuscular Disease

Background: There have been no previous population-based studies of adult neuromuscular disease (NMD) in the Republic of Ireland (RoI). This article describes methods and case-ascertainment strategies used to identify patients with inherited and acquired NMD for the purpose of obtaining the prevalence of these disorders in the RoI. Methods: This epidemiological study was conducted between January 2012 and January 2014. Prospective and retrospective (until 1990) case identification of adults with inherited and acquired NMD have been carried out. Multiple countrywide patient identification sources including neuromuscular clinics, hospital neurology databases, the hospital in-patient enquiry (HIPE) system of each hospital and the records of Muscular Dystrophy Ireland, a nonprofit organisation, were used. Results: In total, 3,724 potential cases were identified. Of these, 1,083 were excluded because 869 cases represented duplicates or triplicates, 133 were coded incorrectly in HIPE, 74 patients were deceased and 7 patients had moved out of the country. The highest number of cases was identified in neurology databases and HIPE (1,724 and 884, respectively). A total of 2,641 individuals fulfilled the inclusion criteria and were included in the study. Conclusion: Detailed epidemiological data of this nature is difficult to acquire in the current structure of the Irish health service, requiring multiple sources including input from voluntary patient organisations. The development of a national patient registry for some or all of these conditions would greatly facilitate standardised data recording, giving a true picture of the burden of neuromuscular diseases in a population.

P.10.6 Reliability and validity of trunk assessment methods in neuromuscular disease

The aim of the study was to investigate the reliability and validity of trunk control test (TCT) and trunk impairment scale (TIS) in people with adult neuromuscular diseases (NMD). 66patients participated to the study. TCT, TIS, Manual Muscle Test (trunk, upper and lower extremities), Motor Function Measurement (MFM), Functional Independency Measurement (FIM) and Rivermead Mobility Index (RMI) were applied to the participants. Test–retest and item total reliability, construct validity and concurrent validity were assessed both of TIS and TCT. Both TIS and TCT Intraclass correlation and test re-test agreement were high (0.96 and 0.98 for TIS and 0.97 and 0.98 for TCT). Correlation between TIS and FIM, MFM, hip and trunk muscle strength scores were significant (<i>r</i>=0.30, <i>p</i><0.05), (<i>r</i>=0.29, <i>p</i><0.01), (<i>r</i>=0.34, <i>p</i><0.05), (<i>r</i>=0.59, <i>p</i><0.01) respectively. Also the TCT scores were correlated with MFM score (<i>r</i>=0.57) and trunk muscle strength scores (<i>r</i>=0.61). The cronbachalfa coefficients for TIS was 0.82, for TCT is 0.74. Item total test scores of both TCT and TIS were significant (<i>p</i><0,01). AlthoughTCT and TIS were found to be a valid and reliable methods, we suggest that TIS provide more detailed information about trunk impairment in NMD patients.

Trinucleotide repeat expansion at the myotonic dystrophy locus reduces expression of DMAHP.

Myotonic dystrophy, or dystrophia myotonica (DM), is an autosomal dominant multisystem disorder caused by the expansion of a CTG trinucleotide repeat in the 3' untranslated region of the DMPK protein kinase gene on chromosome 19q13.3 (refs 1-3). Although the DM mutation was identified more than five years ago, the pathogenic mechanisms underlying this most prevalent form of hereditary adult neuromuscular disease remain elusive. Previous work from our laboratory demonstrated that a DNase l-hypersensitive site located adjacent to the repeats on the wild-type allele is eliminated by repeat expansion, indicating that large CTG-repeat arrays may be associated with a local chromatin environment that represses gene expression. Here we report that the hypersensitive site contains an enhancer element that regulates transcription of the adjacent DMAHP homeobox gene. Analysis of DMAHP expression in the cells of DM patients with loss of the hypersensitive site revealed a two- to fourfold reduction in steady-state DMAHP transcript levels relative to wild-type controls. Allele-specific analysis of DMAHP expression showed that steady-state transcript levels from the expanded allele were greatly reduced in comparison to those from the wild-type allele. Together, these results demonstrate that CTG-repeat expansions can suppress local gene expression and implicate DMAHP in DM pathogenesis.