Respiratory phenotypes of neuromuscular diseases: A challenging issue for pediatricians

Systematic literature review of the impact of spinal muscular atrophy therapies on bulbar function

BACKGROUND

Improvement and maintenance of bulbar function are important goals of disease-modifying treatments (DMTs) for spinal muscular atrophy (SMA), but standardized and validated measures for assessing bulbar function do not exist, nor does a widely accepted definition of bulbar function in SMA. As such, the impact of DMTs on bulbar function has not yet been comprehensively evaluated.

OBJECTIVE

We conducted a systematic literature review (SLR) to identify evidence about the impact of DMTs for SMA on bulbar function.

METHODS

We used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines to conduct this review. Embase® and MEDLINE® databases were searched through August 10, 2023. Eligible studies included patients with SMA who were treated with any DMT and reported bulbar function outcomes. Non-English studies were excluded.

RESULTS

We identified 51 studies (across 83 publications) that evaluated SMA DMTs and bulbar function for more than 1600 patients. The ability to feed orally, the ability to tolerate liquids, and the need for nutrition support were commonly reported. Most infants treated with any DMT before SMA symptom onset preserved bulbar function. Infants, children, and adults treated after SMA symptom onset experienced variable results in terms of bulbar function outcomes.

CONCLUSIONS

The definition and assessment of bulbar function are not standardized. Therefore, the tools, scales, methods, and timing used for bulbar function assessments varied among studies. Larger prospective studies using standardized and age-based assessments with longer follow-up periods are needed to assess the clinical stability of bulbar function for patients with SMA who receive DMTs.

Multicentric Study on the Diagnostic of Neuromuscular Diseases in Children with High Creatinine Phosphokinase Levels

BACKGROUND

Neuromuscular diseases (NMDs) are rare, predominantly hereditary, with progressive course disorders. Furthermore, diagnosis can be delayed by years after symptoms emerge, resulting in missed opportunities for modifying disease progression, specific therapeutic approaches, and counseling. Some NMDs have high levels of creatine phosphokinase (CK). Thus, its measurement can indicate an NMD associated with muscle involvement.

OBJECTIVES

We aimed to identify myopathies and muscular dystrophies through elevated CK levels for early detection of these disorders.

METHODS

A prospective, observational, and analytical study of children and teenagers showing high levels of CK, showing mild symptoms, or who were asymptomatic with elevation of transaminases from all pediatric units in the north of Portugal was performed. All diagnosed patients were referred to our Center for Neuromuscular Diseases. Additionally, CK level confirmation, clinical examination, and investigation were performed according to best-practice clinical guidelines.

RESULTS

We found 33 patients from 8/12 pediatric units. A diagnosis with implications for care measures and treatment was performed in half of the patients. A total of 30% presented an NMD diagnosis. Dystrophinopathies represented the largest group (21%).

CONCLUSIONS

Therefore, NMDs should be considered in children and teenagers with high CK levels, even those with mild symptoms. Screening for CK elevation should be used to promote an earlier diagnosis of many NMDs.

Paediatric sleep diagnostics in the 21st century: the era of "sleep-omics"?

Paediatric sleep diagnostics is performed using complex multichannel tests in specialised centres, limiting access and availability and resulting in delayed diagnosis and management. Such investigations are often challenging due to patient size (prematurity), tolerability, and compliance with "gold standard" equipment. Children with sensory/behavioural issues, at increased risk of sleep disordered breathing (SDB), often find standard diagnostic equipment difficult.SDB can have implications for a child both in terms of physical health and neurocognitive development. Potential sequelae of untreated SDB includes failure to thrive, cardiopulmonary disease, impaired learning and behavioural issues. Prompt and accurate diagnosis of SDB is important to facilitate early intervention and improve outcomes.The current gold-standard diagnostic test for SDB is polysomnography (PSG), which is expensive, requiring the interpretation of a highly specialised physiologist. PSG is not feasible in low-income countries or outwith specialist sleep centres. During the coronavirus disease 2019 pandemic, efforts were made to improve remote monitoring and diagnostics in paediatric sleep medicine, resulting in a paradigm shift in SDB technology with a focus on automated diagnosis harnessing artificial intelligence (AI). AI enables interrogation of large datasets, setting the scene for an era of "sleep-omics", characterising the endotypic and phenotypic bedrock of SDB by drawing on genetic, lifestyle and demographic information. The National Institute for Health and Care Excellence recently announced a programme for the development of automated home-testing devices for SDB. Scorer-independent scalable diagnostic approaches for paediatric SDB have potential to improve diagnostic accuracy, accessibility and patient tolerability; reduce health inequalities; and yield downstream economic and environmental benefits.

Sleep disordered breathing assessment in patient with slowly progressive neuromuscular disease

BACKGROUND

Sleep-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.

METHODS

This 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.

RESULTS

Among 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.

CONCLUSION

The 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.

The role of sleep in neuromuscular disorders

Sleep represents a major frontier both in clinical myology and as a new possibility for delivering treatment to neuromuscular patients since various neuromuscular cases present a variable degree of disordered sleep and such conditions should be diagnosed and prevented, i.e., sleep apnea and hypoxemia. These sleep disorders are present in dystrophinopathies and in various types of limb-girdle muscular dystrophies (LGMD). Excessive daytime sleepiness (EDS) is found in patients affected by spastic paraparesis or cerebellar ataxia but is rather common in both myotonic dystrophy type 1 and 2, and the correction of sleep disorders is therefore important to improve their daily quality of life (QoL) and consequent daily functioning. Other types of sleep dysfunction such as insomnia, a reduction in rapid eye movement (REM) sleep, loss of normal REM, or sleep-disordered breathing are found in other disorders including myasthenia, ataxias, spastic paraparesis, Charcot-Marie-Tooth disease, and neurogenic disorders, including polyneuropathies, and need appropriate treatment. Research done on this topic aims to incorporate a variety of nuances in metabolic disorders such as those in late-onset Pompe disease and are such as those in late-onset Pompe disease who are susceptible to enzyme replacement therapy (ERT). The overarching goal is to explore both the diagnosis and methodology of sleep-related problems in both genetic and acquired neuromuscular disorders. We also review the type of available treatment opportunities utilized to improve neuromuscular patients' QoL.

Pediatric Sleep Respiratory Disorders: A Narrative Review of Epidemiology and Risk Factors

Sleep is a fundamental biological necessity, the lack of which has severe repercussions on the mental and physical well-being in individuals of all ages. The phrase "sleep-disordered breathing (SDB)" indicates a wide array of conditions characterized by snoring and/or respiratory distress due to increased upper airway resistance and pharyngeal collapsibility; these range from primary snoring to obstructive sleep apnea (OSA) and occur in all age groups. In the general pediatric population, the prevalence of OSA varies between 2% and 5%, but in some particular clinical conditions, it can be much higher. While adenotonsillar hypertrophy ("classic phenotype") is the main cause of OSA in preschool age (3-5 years), obesity ("adult phenotype") is the most common cause in adolescence. There is also a "congenital-structural" phenotype that is characterized by a high prevalence of OSA, appearing from the earliest ages of life, supported by morpho-structural abnormalities or craniofacial changes and associated with genetic syndromes such as Pierre Robin syndrome, Prader-Willi, achondroplasia, and Down syndrome. Neuromuscular disorders and lysosomal storage disorders are also frequently accompanied by a high prevalence of OSA in all life ages. Early recognition and proper treatment are crucial to avoid major neuro-cognitive, cardiovascular, and metabolic morbidities.