1st Italian SMA Family Association Consensus Meeting: Management and recommendations for respiratory involvement in spinal muscular atrophy (SMA) types I-III, Rome, Italy, 30-31 January 2015

Sleep and sleep-related breathing disorders in patients with spinal muscular atrophy: a changing perspective from novel treatments?

Spinal Muscular Atrophy (SMA) is an inherited neuromuscular disorder characterized by progressive muscle weakness and atrophy, resulting from the degeneration of motor neurons in the spinal cord. A critical aspect of SMA is its impact on respiratory function. As the disease progresses, respiratory muscles, in particular intercostal muscles, become increasingly affected, leading to breathing difficulties and respiratory failure. Without intervention, many children with SMA type 1 die from respiratory failure before their second year of life. While assisted ventilation has improved survival, it often results in ventilator dependence. The development of new SMN-augmenting therapies has renewed optimism, but their long-term impact on respiratory function is uncertain, and non-invasive respiratory support remains an important part of SMA management. Despite the importance of respiratory support in SMA, knowledge regarding sleep disorders in this population is limited. This review aims to synthesize existing literature on sleep and sleep-related breathing disorders in patients with SMA, with a focus on SMA type 1. We summarize evidence of sleep-disordered breathing and respiratory failure in SMA, as well as outcomes and survival benefits associated with non-invasive or invasive ventilation with or without pharmacological therapies. We also discuss current knowledge regarding the effects of novel disease-modifying therapies for SMA on respiratory function and sleep. In conclusion, optimal care for children with SMA requires a multidisciplinary approach that includes neurology and respiratory specialists. This review highlights the importance of monitoring sleep and respiratory function in SMA, as well as the potential benefits and challenges associated with assisted ventilation combined with new therapies.

Dysphagia and Lung Disease in Children With Spinal Muscular Atrophy Treated With Disease-Modifying Agents

OBJECTIVES

Disease-modifying agents (DMAs) for the treatment of spinal muscular atrophy (SMA) have evolved the SMA phenotype with improved survival. Ongoing oropharyngeal dysphagia and respiratory complications are reported. The extent of dysphagia and respiratory morbidity in this population, since DMAs' introduction, has not been well described.

METHODS

A whole-population study involved all children with treated SMA types 1-3 in our facility. Videofluoroscopic swallow studies (type 1 alone), chest CT scans, and clinical data were collected.

RESULTS

Thirty-six children were included (n = 9 type 1, n = 14 type 2, and n = 13 type 3; age range 0.3-15.4 years). Abnormal swallowing characteristics were demonstrated in all children with type 1 (n = 8; 100%). Bronchiectasis was found on chest CT: 3 of 9 (33.3%), 2 of 14 (14.3%), and 2 of 13 (15.4%) of type 1, 2, and 3, respectively. Atelectasis, mucus plugging, bronchial wall thickening, and parenchymal changes were common.

DISCUSSION

Swallow impairments were universal in children with type 1. Bronchiectasis was common in all pediatric SMA types, with a prevalence of 1 in 5. Routine monitoring and management of dysphagia/recurrent respiratory infection should be implemented for improvement in lung health.

Long-Term Ventilation in Children with Medical Complexity: A Challenging Issue

Children with medical complexity (CMCs) represent a subgroup of children who may have congenital or acquired multisystemic disease. CMCs are frequently predisposed to respiratory problems and often require long-term mechanical ventilation (LTMV). The indications for LTMV in CMCs are increasing, but gathering evidence about indications, titration, and monitoring is currently the most difficult challenge due to the absence of validated data. The aim of this review was to examine the clinical indications and ethical considerations for the initiation, continuation, or withdrawal of LTMV among CMCs. The decision to initiate long-term ventilation should always be based on clinical and ethical considerations and should be shared with the parents.

The effect of scoliosis surgery on pulmonary function in spinal muscular atrophy patients: review of the literature and a meta-analysis

PURPOSE

To determine the effect of surgical instrumentation on pulmonary function after surgery.

METHODS

A literature review was performed to identify articles reporting on the effect of scoliosis surgery on the pulmonary function in patients with spinal muscular atrophy (SMA). Data for each patient were extracted from included studies, and a meta-analysis was performed using the values of forced vital capacity (FVC) before and after surgery.

RESULTS

A total of 127 articles were reviewed, and ten articles were selected for data extraction according to inclusion criteria. The results of the meta-analysis showed no difference in respiratory function pre-operatively and at last follow-up. Four out of ten studies demonstrated similar results and five studies reported a decrease in pulmonary function after surgery. Only one study showed improvement in lung function.

CONCLUSION

At the moment, there is insufficient evidence in the literature to support that spinal surgery can improve respiratory function. According to our meta-analysis study, vital capacity remains either unchanged or the rate of deterioration is decreased after surgery. Nevertheless, these are both considered favorable outcomes taking into account the natural course of the disease with progressive deterioration of pulmonary function over time.

Management of Spinal Muscular Atrophy in the Adult Population

Spinal muscular atrophy (SMA) is a group of neurodegenerative disorders resulting from the loss of spinal motor neurons. 95% of patients share a pathogenic mechanism of loss of survival motor neuron (SMN) 1 protein expression due to homozygous deletions or other mutations of the SMN1 gene, with the different phenotypes influenced by variable copy numbers of the SMN2 gene. Advances in supportive care, disease modifying treatment and novel gene therapies have led to an increase in the prevalence of SMA, with a third of SMA patients now represented by adults. Despite the growing number of adult patients, consensus on the management of SMA has focused primarily on the pediatric population. As the disease burden is vastly different in adult SMA, an approach to treatment must be tailored to their unique needs. This review will focus on the management of the adult SMA patient as they age and will discuss proper transition of care from a pediatric to adult center, including the need for continued monitoring for osteoporosis, scoliosis, malnutrition, and declining mobility and functioning. As in the pediatric population, multidisciplinary care remains the best approach to the management of adult SMA. Novel and emerging therapies such as nusinersen and risdiplam provide hope for these patients, though these medications are of uncertain efficacy in this population and require additional study.

[The SMA France national registry: already encouraging results]

Spinal muscular atrophy is a debilitating neuromuscular disease due to the deletion of the SMN1 gene (SMA). The emergence of innovative targeted therapies changed the natural history of this condition. The French registry of SMA (Registre SMA France) was launched in 2020 to obtain a better knowledge of the pathology. The goal of the register was also to meet the need for real-life data regarding the arrival of these innovative therapies in order to identify the best therapeutic strategies and to improve patient care. The registry collects retrospective and prospective data of all genetically confirmed SMA, treated or not treated, in reference centers belonging to the national neuromuscular network (FILNEMUS). The estimated enrollment is 1,000 patients (50% children). On October 1^st, 666 patients have been enrolled (357 children and 309 adults) by 44 out of 51 open centers of the national network (FILNEMUS) with: 150 type 1 (22%); 278 type 2 (42%), 232 type 3 (35%) and 4 type 4 (1%) respectively.

Sleep breathing disorders in pediatric patients with spinal muscular atrophy 2

OBJECTIVES

The study is aimed to analyze both sleep architecture and prevalence of sleep-disordered breathing (SDB), in a group of patients with type 2 spinal muscular atrophy (SMA), considering motor dysfunction, and compare them with age-matched controls.

METHODS

Eighteen SMA type 2 patients (nine males median age 9.5 (4-17) years) and eighteen controls (fourteen males, median age 8,5 (1-16) years) underwent nocturnal polysomnography. SMA type 2 patients were evaluated with motor scales; Hammersmith Functional Motor Scale Expanded (HFMSE), Revised upper limb model (ULMR) and Egen Klassification Scale Version 2 (EK2). Parents/tutors completed two pediatric sleep questionnaires (respiratory subscale from Chervin Pediatric Sleep Questionnaire and Bruni's Sleep Disturbance Scale for Children).

RESULTS

When compared with controls, SMA type 2 patients showed no significant differences in age (9.72 ± 4.2 vs 8.22 ± 3.9 (p = 0.28), gender 9 (9 men (50%) vs 14 (77,8%) (p = 0.083) and nutritional status; Body Mass Index (BMI) (16.4 (12.2-34.8) vs 17.6 (4.4-24.2) (p = 0.83). Apnea Hypopnea Index (AHI) was statistically higher in SMA type 2 patients (6.7 ± 6.2 vs 0.4 ± 0.3) (p < 0.001). The SpO2 mean values in cases were (96% ± 1.4) vs (97.5% ± 1.2) (p = 0.007). TcPCO2 median value (41,5 mmHg; (range 34-47.2) in the SMA type-2 patients within normal reference values. Only one motor scale; Hammersmith Functional Motor Scale Expanded (HFMSE) showed a negative correlation with AHI (r = -0.132).

CONCLUSIONS

Patients affected by SMA type 2 presented significantly higher apnea-hypopnea indices than controls; differences in sleep architecture identified include: decreased total sleep time, increased percentage of stage N1 of NREM sleep as well as increased sleep fragmentation seen in the SMA type 2 group, due to respiratory related arousals. We would like to point out that validated pediatric sleep questionnaires in general population, may not be useful tools when screening for SDB in these patients. This should be taken into consideration in clinical practice and in the elaboration of future clinical guidelines for these patients.

Phenotypic variance in pediatric obstructive sleep apnea

It is crucial that clinicians understand what underpins the considerable phenotypic variance in pediatric obstructive sleep apnea syndrome (OSAS), if they are to implement individually tailored phenotype-based approaches to diagnosis and management. This review summarizes the current literature on how disease severity, comorbidities, genetic and environmental/lifestyle factors interact to determine the overall OSAS phenotype. The first part discusses the impact of these factors on OSAS-related morbidity in the context of otherwise healthy children, whilst the second half details children with complex conditions, particularly focusing on the anatomical and functional abnormalities predisposing to upper airway obstruction unique to each condition. One can then understand the need for a multidimensional assessment strategy for pediatric OSAS; one that incorporates the history, physical examination, sleep study results, and biomarkers to enable precise stratification, so vital for effective determination of the timing and the nature of the therapeutic interventions required.

Effect of nusinersen on respiratory function in paediatric spinal muscular atrophy types 1-3

INTRODUCTION

Nusinersen is used in spinal muscular atrophy (SMA) to improve peripheral muscle function; however, respiratory effects are largely unknown.

AIM

To assess the effects of nusinersen on respiratory function in paediatric SMA during first year of treatment.

METHODS

A prospective observational study in paediatric patients with SMA who began receiving nusinersen in Queensland, Australia, from June 2018 to December 2019. Outcomes assessed were the age-appropriate respiratory investigations: spirometry, oscillometry, sniff nasal inspiratory pressure, mean inspiratory pressure, mean expiratory pressure, lung clearance index, as well as polysomnography (PSG) and muscle function testing. Lung function was collected retrospectively for up to 2 years prior to nusinersen initiation. Change in lung function was assessed using mixed effects linear regression models, while PSG and muscle function were compared using the Wilcoxon signed-rank test.

RESULTS

Twenty-eight patients (15 male, aged 0.08-18.58 years) were enrolled: type 1 (n=7); type 2 (n=12); type 3 (n=9). The annual rate of decline in FVC z-score prior to nusinersen initiation was -0.58 (95% CI -0.75 to -0.41), and post initiation was -0.25 (95% CI -0.46 to -0.03), with a significant difference in rate of decline (0.33 (95% CI 0.02 to 0.66) (p=0.04)). Most lung function measures were largely unchanged in the year post nusinersen initiation. The total Apnoea-Hypopnoea Index (AHI) was reduced from a median of 5.5 events/hour (IQR 2.1-10.1) at initiation to 2.7 events/hour (IQR 0.7-5.3) after 1 year (p=0.02). All SMA type 1% and 75% of SMA types 2 and 3 had pre-defined peripheral muscle response to nusinersen.

CONCLUSION

The first year of nusinersen treatment saw reduced lung function decline (especially in type 2) and improvement in AHI.

The effects of non-invasive mechanical ventilation on cardiac autonomic dysfunction in spinal muscular atrophy

In patients with spinal muscular atrophy (SMA), obstructive sleep apnea syndrome (OSAS) constitutes an important cause of cardiovascular morbidity and mortality. We investigated heart rate variability (HRV) to evaluate the effects of non-invasive mechanical ventilation on cardiac autonomic dysfunction in patients with SMA and OSAS. Six patients with SMA (type 1 and 2) and six age- and sex-matched healthy children were consecutively enrolled. A whole-night diagnostic polysomnography was performed, and SMA patients with OSAS were given non-invasive mechanical ventilation therapy. HRV analysis was performed on the basis of whole-night electrocardiography recordings via a computer-base program. Apnea-hypopnea index (AHI) was 9.2 ± 6.2/hr in SMA patients, while it was 0.4 ± 0.5/hr in controls (p = 0.036). All SMA patients had OSAS, while none of the controls had OSAS (p = 0.012). Mean percentage of successive R wave of QRS complex (R-R) intervals>50 ms was significantly lower in SMA patients than those in controls (p = 0.031). Significant correlations were found between AHI and high-frequency power, low/high-frequency ratio in wakefulness and in sleep (p<0.05). Repeated HRV analysis in SMA patients following OSAS therapy showed significant reductions in average R-R duration (p = 0.028) and percentage of successive R-R intervals>50 ms (p = 0.043). Our study demonstrates the beneficial effects of non-invasive mechanical ventilation on cardiac autonomic dysfunction in SMA patients with OSAS.

Ultrasound assessment of diaphragmatic function in type 1 spinal muscular atrophy

OBJECTIVE

To investigate ultrasound features of diaphragm motion and function in type 1 spinal muscular atrophy (SMA-1) patients.

DESIGN

Prospective study.

PATIENTS

The study cohort included SMA-1 children younger than 18-year-old. Control subjects included type 2 and type 3 SMA and other neuromuscular disorders younger than 18-year-old.

METHODOLOGY

Diaphragm ultrasound evaluating diaphragmatic excursion, speed of diaphragmatic contraction, duration of the respiratory cycle, inspiratory/expiratory relationship, end-inspiratory and -expiratory thickness, thickening fraction, and pattern of contractility. The interrater reliability for each variable was established by calculation of Cohen's k coefficient.

RESULTS

Twenty-three SMA-1 patients and 12 controls were evaluated. Diaphragm ultrasound values were within normal ranges in all study cohort patients and no difference was found with controls. There was a gradient of diaphragm function with SMA 1.9 subgroup having the best and SMA 1.1 having the worst parameters, particularly in end-inspiratory thickness and diaphragmatic excursion (P = .031 and P = .041, respectively). Seventy-four percent of SMA-1 patients had a dysmotility pattern of diaphragm contraction, mostly represented in SMA 1.9 subgroup (P = .001). This pattern was observed in 92.8% of children on noninvasive ventilation (NIV) for less than 16 hours/d of and in 20% patients with invasive ventilation or NIV for more than 16 hours/d (P = .027). The dysmotility pattern was never observed in the control group. The levels of interobserver agreement were high for "diaphragm irregularities," "inspiratory/expiratory relationship," and "diaphragm thickness," and good for the other variables.

CONCLUSIONS

Ultrasound can be used to evaluate diaphragm function and contractility in SMA-1 children, providing additional information to the clinical examination and functional respiratory tests, describing a characteristic contractility pattern in these patients. Longitudinal studies are needed to understand the impact of diaphragm dysmotility and other parameters on long-term outcome in SMA-1 patients.

Relative hyperventilation in non-ventilated patients with spinal muscular atrophy

Spinal muscular atrophy (SMA) is a relatively common autosomal recessive neuromuscular disorder, characterised by progressive degeneration of spinal cord and bulbar motor neurons. It is caused by survival motor neuron (SMN) protein deficiency, due to homozygous loss of function of the SMN1 gene. Due to the effects of genetic modifiers, SMA displays a broad range in severity. The current clinical classification system distinguishes four types, based on age at onset and acquired motor milestones, i.e. infantile onset without achieving the ability to sit (type 1), childhood onset with the ability to sit but not to walk (type 2), childhood onset with the ability to walk for at least a short period of time (type 3) and adult onset with mild symptoms (type 4) [1, 2]. Disease course is progressive, irrespective of type [3] and patients with SMA type 1, 2 and 3 are at high or moderate risk of developing respiratory insufficiency, which may necessitate initiating mechanical ventilation [4, 5].

Lower ranges of carbon dioxide levels are normal in non-ventilated SMA patients. Physicians should be aware of pending respiratory insufficiency if carbon dioxide levels increase to normal levels in patients with pre-existing low carbon dioxide levelshttps://bit.ly/2Ag7jQ5

New and Developing Therapies in Spinal Muscular Atrophy: From Genotype to Phenotype to Treatment and Where Do We Stand?

Spinal muscular atrophy (SMA) is a congenital neuromuscular disorder characterized by motor neuron loss, resulting in progressive weakness. SMA is notable in the health care community because it accounts for the most common cause of infant death resulting from a genetic defect. SMA is caused by low levels of the survival motor neuron protein (SMN) resulting from SMN1 gene mutations or deletions. However, patients always harbor various copies of SMN2, an almost identical but functionally deficient copy of the gene. A genotype–phenotype correlation suggests that SMN2 is a potent disease modifier for SMA, which also represents the primary target for potential therapies. Increasing comprehension of SMA pathophysiology, including the characterization of SMN1 and SMN2 genes and SMN protein functions, has led to the development of multiple therapeutic approaches. Until the end of 2016, no cure was available for SMA, and management consisted of supportive measures. Two breakthrough SMN-targeted treatments, either using antisense oligonucleotides (ASOs) or virus-mediated gene therapy, have recently been approved. These two novel therapeutics have a common objective: to increase the production of SMN protein in MNs and thereby improve motor function and survival. However, neither therapy currently provides a complete cure. Treating patients with SMA brings new responsibilities and unique dilemmas. As SMA is such a devastating disease, it is reasonable to assume that a unique therapeutic solution may not be sufficient. Current approaches under clinical investigation differ in administration routes, frequency of dosing, intrathecal versus systemic delivery, and mechanisms of action. Besides, emerging clinical trials evaluating the efficacy of either SMN-dependent or SMN-independent approaches are ongoing. This review aims to address the different knowledge gaps between genotype, phenotypes, and potential therapeutics.

Respiratory Needs in Patients with Type 1 Spinal Muscular Atrophy Treated with Nusinersen

OBJECTIVE

To evaluate the effects of nusinersen on respiratory function of patients with type 1 spinal muscular atrophy.

STUDY DESIGN

Observational, longitudinal cohort study. We collected respiratory data from 118 children with type 1 spinal muscular atrophy and differing pulmonary requirements and conducted a semistructured qualitative interview among a subsample of caregivers at baseline, 6 months, and 10 months after the first nusinersen treatment. Patients were stratified according to ventilation modalities and age at study entry.

RESULTS

Most patients in our cohort remained stable (84/109 = 77%). More than 80% of the children treated before age 2 years survived, in contrast to the lower survival reported in natural history studies, and did so without tracheostomy or noninvasive ventilation (NIV) ≥16 hours. In those less than 2 years old, only 3 patients shifted from NIV ≤10 hours to NIV >10 hours, and the other 3 reduced the hours of NIV required. Most of the older patients remained stable; this included not only those on tracheostomy or NIV >10 hours but also 75% of those on NIV ≤10 hours.

CONCLUSIONS

Our results suggest that nusinersen may produce some improvement in the progression of respiratory impairment, both in terms of survival and need for respiratory support ≥16 hours, especially before the age of 2 years.

Health, wellbeing and lived experiences of adults with SMA: a scoping systematic review

BACKGROUND

Spinal muscular atrophy (SMA) is a neurodegenerative disease that has a substantial and multifaceted burden on affected adults. While advances in supportive care and therapies are rapidly reshaping the therapeutic environment, these efforts have largely centered on pediatric populations. Understanding the natural history, care pathways, and patient-reported outcomes associated with SMA in adulthood is critical to advancing health policy, practice and research across the disease spectrum. The aim of this study was to systematically review research investigating the healthcare, well-being and lived experiences of adults with SMA.

METHODS

In accordance with the Preferred Reported Items for Systematic Reviews and Meta-Analysis guidelines, seven electronic databases were systematically searched until January 2020 for studies examining clinical (physical health, natural history, treatment) and patient-reported (symptoms, physical function, mental health, quality of life, lived experiences) outcomes in adults with SMA. Study risk of bias and the level of evidence were assessed using validated tools.

RESULTS

Ninety-five articles met eligibility criteria with clinical and methodological diversity observed across studies. A heterogeneous clinical spectrum with variability in natural history was evident in adults, yet slow declines in motor function were reported when observational periods extended beyond 2 years. There remains no high quality evidence of an efficacious drug treatment for adults. Limitations in mobility and daily activities associated with deteriorating physical health were commonly reported, alongside emotional difficulties, fatigue and a perceived lack of societal support, however there was no evidence regarding effective interventions.

CONCLUSIONS

This systematic review identifies the many uncertainties regarding best clinical practice, treatment response, and long-term outcomes for adults with SMA. This comprehensive identification of the current gaps in knowledge is essential to guide future clinical research, best practice care, and advance health policy with the ultimate aim of reducing the burden associated with adult SMA.

Effect of mechanical insufflation-exsufflation in children with neuromuscular weakness

INTRODUCTION

Children with neuromuscular diseases develop cough impairment. Airway clearance techniques (ACTs) may help to prevent recurrent respiratory tract infections (RTIs). A commonly used ACT is mechanical insufflation-exsufflation (MI-E), but evidence for efficacy is limited. We hypothesize that MI-E has beneficial effect on RTI related hospital admission rate.

METHODS

In this single-center retrospective study, we reviewed all children who used daily MI-E between 2005 till June 2019. Primary outcome studied was the number of RTIs requiring hospital admission. Patient satisfaction and burden experienced by MI-E use were explored by questionnaires using a Likert scale. The relative number of RTIs requiring admission and the number of admission days per eligible period before and after the introduction of MI-E were compared using the Friedman test and the Wilcoxon signed-rank test.

RESULTS

Thirty-seven children were included. The median number of RTI related hospital admissions per 1000 eligible days after the introduction of MI-E was 0.9 (interquartile range [IQR] 0.0-3.1) compared to the 3 preceding years (median 3.7; IQR 1.4-5.9; P = .006). The median number of RTI related admission days per 1000 eligible days after the introduction of MI-E was significantly lower with a median of 2.7 (IQR 0.0-17.4) compared to the 3 preceding years (median 33.6; IQR 15.0-51.1; P = .001). Patient satisfaction was high with low burden, even in patients who discontinued treatment.

CONCLUSION

A significantly lower number of RTIs requiring hospital admission and shorter admission duration after the introduction of MI-E was found, with high patient satisfaction and low burden.

Practical approach to respiratory emergencies in neurological diseases

Many neurological diseases may cause acute respiratory failure (ARF) due to involvement of bulbar respiratory center, spinal cord, motoneurons, peripheral nerves, neuromuscular junction, or skeletal muscles. In this context, respiratory emergencies are often a challenge at home, in a neurology ward, or even in an intensive care unit, influencing morbidity and mortality. More commonly, patients develop primarily ventilatory impairment causing hypercapnia. Moreover, inadequate bulbar and expiratory muscle function may cause retained secretions, frequently complicated by pneumonia, atelectasis, and, ultimately, hypoxemic ARF. On the basis of the clinical onset, two main categories of ARF can be identified: (i) acute exacerbation of chronic respiratory failure, which is common in slowly progressive neurological diseases, such as movement disorders and most neuromuscular diseases, and (ii) sudden-onset respiratory failure which may develop in rapidly progressive neurological disorders including stroke, convulsive status epilepticus, traumatic brain injury, spinal cord injury, phrenic neuropathy, myasthenia gravis, and Guillain-Barré syndrome. A tailored assistance may include manual and mechanical cough assistance, noninvasive ventilation, endotracheal intubation, invasive mechanical ventilation, or tracheotomy. This review provides practical recommendations for prevention, recognition, management, and treatment of respiratory emergencies in neurological diseases, mostly in teenagers and adults, according to type and severity of baseline disease.

Effects of long-term non-invasive ventilation on sleep structure in children with Spinal Muscular Atrophy type 2

OBJECTIVE

Changes of sleep architecture have been reported in children with Spinal Muscular Atrophy type 2 (SMA2), mainly represented by a decrease of arousability. No studies have evaluated the effect of long-term ventilation on sleep parameters in these children. The aim of this study was to evaluate the effects of long-term non-invasive positive pressure ventilation (LTNPPV) on sleep architecture and to assess the residual differences from normal controls.

METHODS

Nine consecutive children with SMA2 underwent two distinct polysomnographic (PSG) studies, one in spontaneous breathing, and subsequently after LTNPPV. The results were then compared to 15 age-matched controls.

RESULTS

SMA2 patients showed only slightly modified sleep architecture on LTNPPV: increased stage N2% and decreased number of awakenings, while several significant differences persisted between SMA2 patients on LTNPPV and controls (decreased total sleep time, number of awakenings, sleep efficiency, and percentage of REM sleep). Sleep microstructure, evaluated by means of the Cyclic alternating pattern (CAP) showed only marginal changes on LTNPPV (small shortening of CAP A1 subtype duration and small increase in CAP A3 index). Conversely, CAP parameters on LTNPPV showed significant differences between SMA2 patients vs. controls, with increased A1 subtype percentage and decreased percentage of A2 and A3 subtypes.

CONCLUSIONS

This is the first study in children affected by SMA2 reporting data on sleep microstructure and their changes after LTNPPV. We found persisting, small but important changes in sleep microstructure during LTNPPV in these children, suggesting that this treatment only partially improves their arousability.

The Italian neuromuscular registry: a coordinated platform where patient organizations and clinicians collaborate for data collection and multiple usage

BACKGROUND

The worldwide landscape of patient registries in the neuromuscular disease (NMD) field has significantly changed in the last 10 years, with the international TREAT-NMD network acting as strong driver. At the same time, the European Medicines Agency and the large federations of rare disease patient organizations (POs), such as EURORDIS, contributed to a great cultural change, by promoting a paradigm shift from product-registries to patient-centred registries. In Italy, several NMD POs and Fondazione Telethon undertook the development of a TREAT-NMD linked patient registry in 2009, with the referring clinical network providing input and support to this initiative through the years. This article describes the outcome of this joint effort and shares the experience gained.

METHODS

The Italian NMD registry is based on an informatics technology platform, structured according to the most rigorous legal national and European requirements for management of patient sensitive data. A user-friendly web interface allows both direct patients and clinicians' participation. The platform's design permits expansion to incorporate new modules and new registries, and is suitable of interoperability with other international efforts.

RESULTS

When the Italian NMD Registry was initiated, an ad hoc legal entity (NMD Registry Association) was devised to manage registries' data. Currently, several disease-specific databases are hosted on the platform. They collect molecular and clinical details of individuals affected by Duchenne or Becker muscular dystrophy, Charcot-Marie-Tooth disease, transthyretin type-familial amyloidotic polyneuropathy, muscle glycogen storage disorders, spinal and bulbar muscular atrophy, and spinal muscular atrophy. These disease-specific registries are at different stage of development, and the NMD Registry itself has gone through several implementation steps to fulfil different technical and governance needs. The new governance model is based on the agreement between the NMD Registry Association and the professional societies representing the Italian NMD clinical network. Overall, up to now the NMD registry has collected data on more than 2000 individuals living with a NMD condition.

CONCLUSIONS

The Italian NMD Registry is a flexible platform that manages several condition-specific databases and is suitable to upgrade. All stakeholders participate in its management, with clear roles and responsibilities. This governance model has been key to its success. In fact, it favored patient empowerment and their direct participation in research, while also engaging the expert clinicians of the Italian network in the collection of accurate clinical data according to the best clinical practices.

A New Method for Measuring Bell-Shaped Chest Induced by Impaired Ribcage Muscles in Spinal Muscular Atrophy Children

The involvement of the respiratory muscular pump makes SMA children prone to frequent hospitalization and morbidity, particularly in type 1. Progressive weakness affects ribcage muscles resulting in bell-shaped chest that was never quantified. The aims of the present work were: (1) to quantify the presence of bell-shaped chest in SMA infants and children and to correlate it with the action of ribcage muscles, assessed by the contribution of pulmonary ribcage to tidal volume (ΔV_{RC, p}); (2) to verify if and how the structure of the ribcage and ΔV_{RC, p} change after 1-year in SMA type 2. 91 SMA children were studied in supine position during awake spontaneous breathing: 32 with type 1 (SMA1, median age: 0.8 years), 51 with type 2 (SMA2, 3.7 years), 8 with type 3 (SMA3, 5.4 years) and 20 healthy children (HC, 5.2 years). 14 SMA2 showed negative ΔV_{RC, p} (SMA2px), index of paradoxical inspiratory inward motion. The bell-shaped chest index was defined as the ratio between the distance of the two anterior axillary lines at sternal angle and the distance between the right and left 10th costal cartilage. If this index was < < 1, it indicated bell shape, if ~1 it indicated rectangular shape, while if >> 1 an inverted triangle shape was identified. While the bell-shaped index was similar between HC (0.92) and SMA3 (0.91), it was significantly (p < 0.05) reduced in SMA2 (0.81), SMA2px (0.74) and SMA1 (0.73), being similar between the last two. There was a good correlation (Spearman's rank correlation coefficient, ρ = 0.635, p < 0.001) between ribcage geometry and ΔV_{RC, p}. After 1 year, ΔV_{RC, p} reduced while bell-shaped chest index did not change being significantly lower than HC. The shape of the ribcage was quantified and correlated with the action of ribcage muscles in SMA children. The impaired ribcage muscles function alters the ribcage structure. HC and SMA3 show an almost rectangular ribcage shape, whereas SMA2, SMA2px and SMA1 are characterized by bell-shaped chest. In SMA, therefore, a vicious cycle starts since infancy: the disease progressively affects ribcage muscles resulting in reduced expansion of lung and ribcage that ultimately alters ribcage shape. This puts the respiratory muscles at mechanical disadvantage.

The role of sleep diagnostics and non-invasive ventilation in children with spinal muscular atrophy

Spinal muscular atrophy (SMA) is a degenerative motor neurone disorder causing progressive muscular weakness. Without assisted ventilation or novel therapies, most children with SMA type 1 die before the second year of life due to respiratory failure as the respiratory muscles and bulbar function are severely affected. Active respiratory treatment (mechanically assisted cough, invasive or non-invasive ventilation) has improved survival significantly in recent decades, but often at the cost of becoming ventilator dependent. The advent of a new oligonucleotide based therapy (Nusinersen) has created new optimism for improving motor function. However, the long-term effect on respiratory function is unclear and non-invasive respiratory support will remain an important part of medical management in patients with SMA. This review summarises the existing knowledge about sleep-disordered breathing and respiratory failure in patients with SMA, especially type 1, as well as the evidence of improved outcome and survival in patients treated with non-invasive or invasive ventilation. Practical considerations and ethical concerns are delineated with discussion on how these may be affected by the advent of new therapies such as Nusinersen.

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.

Diagnosis and management of spinal muscular atrophy: Part 2: Pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics

This is the second half of a two-part document updating the standard of care recommendations for spinal muscular atrophy published in 2007. This part includes updated recommendations on pulmonary management and acute care issues, and topics that have emerged in the last few years such as other organ involvement in the severe forms of spinal muscular atrophy and the role of medications. Ethical issues and the choice of palliative versus supportive care are also addressed. These recommendations are becoming increasingly relevant given recent clinical trials and the prospect that commercially available therapies will likely change the survival and natural history of this disease.

Spontaneous Breathing Pattern as Respiratory Functional Outcome in Children with Spinal Muscular Atrophy (SMA)

Introduction

SMA is characterised by progressive motor and respiratory muscle weakness. We aimed to verify if in SMA children 1)each form is characterized by specific ventilatory and thoraco-abdominal pattern(VTAp) during quiet breathing(QB); 2)VTAp is affected by salbutamol therapy, currently suggested as standard treatment, or by the natural history(NH) of SMA; 3)the severity of global motor impairment linearly correlates with VTAp.

Materials and methods

VTAp was analysed on 32 SMA type I (SMA1,the most severe form), 51 type II (SMA2,the moderate), 8 type III (SMA3,the mildest) and 20 healthy (HC) using opto-electronic plethysmography. Spirometry, cough and motor function were measured in a subgroup of patients.

Results

In SMA1, a normal ventilation is obtained in supine position by rapid and shallow breathing with paradoxical ribcage motion. In SMA2, ventilation is within a normal range in seated position due to an increased respiratory rate(p<0.05) with reduced tidal volume(p<0.05) secondary to a poor contribution of pulmonary ribcage(%ΔV_RC,P, p<0.001). Salbutamol therapy had no effect on VTAp during QB(p>0.05) while tachypnea occurred in type I NH. A linear correlation(p<0.001) was found between motor function scales and VTAp.

Conclusion

A negative or reduced %ΔV_RC,P, indicative of ribcage muscle weakness, is a distinctive feature of SMA1 and SMA2 since infancy. Its quantitative assessment represents a non-invasive, non-volitional index that can be obtained in all children, even uncollaborative, and provides useful information on the action of ribcage muscles that are known to be affected by the disease.Low values of motor function scales indicate impairment of motor but also of respiratory function.