Sleep-disordered breathing in Duchenne muscular dystrophy: a preliminary study of the role of portable monitoring

Breathing in Duchenne muscular dystrophy: Translation to therapy

Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular disease caused by a deficiency in dystrophin - a structural protein which stabilizes muscle during contraction. Dystrophin deficiency adversely affects the respiratory system leading to sleep-disordered breathing, hypoventilation, and weakness of the expiratory and inspiratory musculature, which culminate in severe respiratory dysfunction. Muscle degeneration associated respiratory impairment in neuromuscular disease is a result of disruptions at multiple sites of the respiratory control network, including sensory and motor pathways. As a result of this pathology, respiratory failure is a leading cause of premature death in DMD patients. Currently available treatments for DMD respiratory insufficiency attenuate respiratory symptoms without completely reversing the underlying pathophysiology. This underscores the need to develop curative therapies to improve quality of life and longevity of DMD patients. This review summarises research findings on the pathophysiology of respiratory insufficiencies in DMD disease in humans and animal models, the clinical interventions available to ameliorate symptoms, and gene-based therapeutic strategies uncovered by preclinical animal studies. Abstract figure legend: Summary of the therapeutic strategies for respiratory insufficiency in DMD (Duchenne muscular dystrophy). Treatment options currently in clinical use only attenuate respiratory symptoms without reversing the underlying pathology of DMD-associated respiratory insufficiencies. Ongoing preclinical and clinical research is aimed at developing curative therapies that both improve quality of life and longevity of DMD patients. AAV - adeno-associated virus, PPMO - Peptide-conjugated phosphorodiamidate morpholino oligomer This article is protected by copyright. All rights reserved.

Comparison of home ambulatory type 2 polysomnography with a portable monitoring device and in-laboratory type 1 polysomnography for the diagnosis of obstructive sleep apnea in children

STUDY OBJECTIVES

To compare type 2 polysomnography (T2PSG) to the gold standard type 1 in-laboratory polysomnography (T1PSG) for diagnosing obstructive sleep apnea (OSA) in children; validate home T2PSG in children with suspected OSA.

METHODS

Eighty-one participants (ages 6-18) with suspected OSA had simultaneous T1PSG and T2PSG in the sleep laboratory, 47 participants (ages 5-16) had T1PSG in the sleep laboratory and T2PSG performed at home. Sleep scientists staged and scored polysomnography data, and pediatric sleep physicians assigned a diagnosis of normal or OSA. Participant demographics, polysomnography variables, and diagnoses were compared using chi-square and Fisher's exact tests for nominal variables, t test for continuous variables and Cohen's kappa to assess concordance.

RESULTS

Acceptable recordings were obtained for every home T2PSG. When T1PSG and T2PSG were simultaneous, correlation between the number of arousals, respiratory disturbance index, and sleep stages was excellent. T2PSG at home demonstrated less stage 2 sleep, more rapid eye movement sleep, and higher sleep efficiency. Comparison of home T2PSG to T1PSG for diagnosing OSA showed a false-positive rate of 6.6% and false-negative rate of 3% for those performed at home.

CONCLUSIONS

T2PSG in the home is feasible with excellent concordance with T1PSG for the purposes of diagnosing OSA in children aged 5-18 years. Home T2PSG may be more representative of a "normal" night for children and could benefit those suspected of having OSA by reducing waiting times for laboratory PSG, improving access to PSG and possibly reducing costs of investigating and treating OSA.

CITATION

Withers A, Maul J, Rosenheim E, O'Donnell A, Wilson A, Stick S. Comparison of home ambulatory type 2 polysomnography with a portable monitoring device and in-laboratory type 1 polysomnography for the diagnosis of obstructive sleep apnea in children. J Clin Sleep Med. 2022;18(2):393-402.

Clinical application of home sleep apnea testing in children: a prospective pilot study

STUDY OBJECTIVES

(1) To determine the sensitivity and specificity of the home sleep apnea test (HSAT) performed in typically developing children who were diagnosed with moderate to severe obstructive sleep apnea during overnight attended laboratory polysomnography (LPSG). (2) To determine the utility of a screening questionnaire to identify children at increased risk for obstructive sleep apnea.

METHODS

Participants completed 2 consecutive study nights, the first night with the HSAT followed by LPSG on the second night. The SHOOTS questionnaire, composed of 6 questions (snoring, hyperactivity, obesity, observed apnea, tonsillar hypertrophy, and sleepiness) concerning sleep-disordered breathing, was administered by the clinician before the first study night.

RESULTS

Thirty-eight participants completed both studies. The mean age was 13.8 ± 3.0 years. Twenty (53%) were male. Most participants were obese. The mean LPSG total sleep time was 7.34 ± 1.19 hours; the mean HSAT total recording time was 8.86 ± 1.73 hours (P < .001). The median obstructive apnea-hypopnea index for LPSG and HSAT was 6.6 and 0.8 events/h, respectively. For an obstructive apnea-hypopnea index ≥ 3.1 events/h by HSAT, the sensitivity was 71.43% (95% confidence interval, 41.9-91.6) and the specificity was 95.83% (95% confidence interval, 78.9-99.9) for identifying those with an LPSG obstructive apnea-hypopnea index of ≥ 10 events/h. For a SHOOTS score with ≥ 4 "yes" responses, the sensitivity and specificity were 85.7% (95% confidence interval, 57.2-98.2) and 54.2% (95% confidence interval, 32.8-74.4), respectively, for identifying those with an LPSG obstructive apnea-hypopnea index ≥ 10 events/h.

CONCLUSIONS

Using HSAT, we clinically applied cutoff values to identify moderate to severe obstructive sleep apnea in typically developing children. The SHOOTS questionnaire may aid in identifying children at risk for obstructive sleep apnea and who are candidates for HSAT.

CITATION

Revana A, Vecchio J, Guffey D, Minard CG, Glaze DG. Clinical application of home sleep apnea testing in children: a prospective pilot study. J Clin Sleep Med. 2022;18(2):533-540.

Validation of home portable monitoring for the diagnosis of sleep-disordered breathing in adolescents and adults with neuromuscular disorders

STUDY OBJECTIVES

Sleep-disordered breathing (SDB) is common in patients with neuromuscular disorders (NMD), developing before chronic hypercapnia appears. Polysomnography (PSG) is the diagnostic gold standard but is often impractical and poorly accessible for individuals with NMD. We sought to determine the diagnostic accuracy, feasibility, and patient preference of home sleep apnea testing (HSAT) compared with PSG for the detection of SDB in NMD.

METHODS

Participants with NMD at risk for SDB aged ≥ 13 years underwent HSAT followed by overnight PSG with concomitant laboratory sleep apnea testing (same device as HSAT). Sensitivity and specificity were calculated for standard apnea-hypopnea index cutoffs for mild (≥ 5 events/h), moderate (≥ 15 events/h), and severe SDB (≥ 30 events/h) and for an oxygen desaturation index ≥ 5 events/h. Receiver operating characteristic curves were built. A questionnaire assessed patient preference.

RESULTS

Of 38 participants, 73% had moderate to severe SDB and 79% had technically acceptable HSAT. For an apnea-hypopnea index ≥ 15 events/h, HSAT sensitivity and specificity were 50% and 88%, respectively. For an oxygen desaturation index ≥ 5 events/h, HSAT sensitivity and specificity were 95% and 78%, respectively. The area under the receiver operating characteristic curve for an apnea-hypopnea index ≥ 15 events/h was 0.88 (95% confidence interval, 0.69-1.00) for HSAT. The HSAT underestimated the apnea-hypopnea index from PSG (bias, -10.7 ± 15.9 events/h). HSAT was preferred to PSG by 61% of participants.

CONCLUSIONS

HSAT is feasible, preferred by patients, and reliable for detecting SDB in most patients, although it cannot definitively rule out SDB. Therefore, HSAT is a viable diagnostic approach for SDB in NMD when PSG is not feasible, recognizing that it does not accurately distinguish between upper-airway obstruction and hypoventilation. Additional work is needed to further optimize home sleep testing in NMD.

CITATION

Westenberg JN, Petrof BJ, Noel F, et al. Validation of home portable monitoring for the diagnosis of sleep-disordered breathing in adolescents and adults with neuromuscular disorders. J Clin Sleep Med. 2021;17(8):1579-1590.

Validity and Cost-Effectiveness of Pediatric Home Respiratory Polygraphy for the Diagnosis of Obstructive Sleep Apnea in Children: Rationale, Study Design, and Methodology

Obstructive sleep apnea (OSA) in children is a prevalent, albeit largely undiagnosed disease associated with a large spectrum of morbidities. Overnight in-lab polysomnography remains the gold standard diagnostic approach, but is time-consuming, inconvenient, and expensive, and not readily available in many places. Simplified Home Respiratory Polygraphy (HRP) approaches have been proposed to reduce costs and facilitate the diagnostic process. However, evidence supporting the validity of HRP is still scarce, hampering its implementation in routine clinical use. The objectives were: Primary; to establish the diagnostic and therapeutic decision validity of a simplified HRP approach compared to PSG among children at risk of OSA. Secondary: (a) Analyze the cost-effectiveness of the HRP versus in-lab PSG in evaluation and treatment of pediatric OSA; (b) Evaluate the impact of therapeutic interventions based on HRP versus PSG findings six months after treatment using sleep and health parameters and quality of life instruments; (c) Discovery and validity of the urine biomarkers to establish the diagnosis of OSA and changes after treatment.

Noninvasive Ventilation and Spinal Cord Injury

Individuals with spinal cord injury (SCI) are at increased risk of respiratory complications during wake and sleep. Sleep-disordered breathing (SDB) is commonly associated with SCI and requires an individualized approach to its management. Respiratory control plays a key role in the pathogenesis of SDB in cervical SCI. Noninvasive ventilation plays an important role in the management of respiratory complications in individuals with SCI acutely and in chronic phases. Positive airway pressure treatment may be effective in eliminating SDB and improving sleepiness symptoms, but adherence to treatment is poor and effect on long-term outcomes is questionable.

N-acetylcysteine Decreases Fibrosis and Increases Force-Generating Capacity of mdx Diaphragm

Respiratory muscle weakness occurs due to dystrophin deficiency in Duchenne muscular dystrophy (DMD). The mdx mouse model of DMD shows evidence of impaired respiratory muscle performance with attendant inflammation and oxidative stress. We examined the effects of N-acetylcysteine (NAC) supplementation on respiratory system performance in mdx mice. Eight-week-old male wild type (n = 10) and mdx (n = 20) mice were studied; a subset of mdx (n = 10) received 1% NAC in the drinking water for 14 days. We assessed breathing, diaphragm, and external intercostal electromyogram (EMG) activities and inspiratory pressure during ventilatory and non-ventilatory behaviours. Diaphragm muscle structure and function, cytokine concentrations, glutathione status, and mRNA expression were determined. Diaphragm force-generating capacity was impaired in mdx compared with wild type. Diaphragm muscle remodelling was observed in mdx, characterized by increased muscle fibrosis, immune cell infiltration, and central myonucleation. NAC supplementation rescued mdx diaphragm function. Collagen content and immune cell infiltration were decreased in mdx + NAC compared with mdx diaphragms. The cytokines IL-1β, IL-6 and KC/GRO were increased in mdx plasma and diaphragm compared with wild type; NAC decreased systemic IL-1β and KC/GRO concentrations in mdx mice. We reveal that NAC treatment improved mdx diaphragm force-generating capacity associated with beneficial anti-inflammatory and anti-fibrotic effects. These data support the potential use of NAC as an adjunctive therapy in human dystrophinopathies.

Pathophysiology of Neuromuscular Respiratory Diseases

Gas exchange between the atmosphere and the human body depends on the lungs and the function of the respiratory pump. The respiratory pump consists of the respiratory control center located in the brain, bony rib cage, diaphragm, and intercostal, accessory, and abdominal muscles. A variety of muscles serve to fine-tune adjustments of ventilation to metabolic demands. Appropriate evaluation and interventions can prevent respiratory complications and prolong life in individuals with neuromuscular diseases. This article discusses normal function of the respiratory pump, general pathophysiologic issues, and abnormalities in more common neuromuscular diseases.

Sleep-Disordered Breathing in Neuromuscular and Chest Wall Diseases

Neuromuscular and chest wall diseases include a diverse group of conditions that share common risk factors for sleep-disordered breathing, including respiratory muscle weakness and/or thoracic restriction. Sleep-disordered breathing results from both the effects of normal sleep on ventilation and the additional challenges imposed by the underlying disorders. Patterns of sleep- disordered breathing vary with the specific diagnosis and stage of disease. Sleep hypoventilation precedes diurnal respiratory failure and may be difficult to recognize clinically because symptoms are nonspecific. Polysomnography has a role in both the diagnosis of sleep-disordered breathing and in the titration of effective noninvasive positive-pressure ventilation.

Assessment and treatment of pediatric obstructive sleep apnea in Canada: history and current state of affairs

AIM

To highlight Canada's contributions to the assessment and treatment of pediatric obstructive sleep apnea as well as outline the current state of pediatric obstructive sleep apnea in Canada.

METHODS

A search was conducted in MEDLINE (Ovid) using Medical Subject Headings (MeSH) and free-text terms for 'child' and 'obstructive sleep apnea' with subsequent 'human' limit. The results were reviewed to identify publications where any author's listed a Canadian institution.

RESULTS

Canadian contributions to the field of pediatric obstructive sleep apnea have grown over the last 30 years with an increase in number of contributors and centres. Much of the early work stemmed from McGill University with important contributions in examining alternatives to polysomnography and post-adenotonsillectomy respiratory compromise. Today, contributors from centres across the country are engaged in the field and come from a greater diversity of disciplines. With continued challenges and opportunities, Canada will continue to help advance the field of pediatric OSA.

CONCLUSION

Canada has a strong community of people invested in continuing to work to improve the lives of Canadian children with pediatric OSA.

The Accuracy of an Ambulatory Level III Sleep Study Compared to a Level I Sleep Study for the Diagnosis of Sleep-Disordered Breathing in Children With Neuromuscular Disease

STUDY OBJECTIVES

Polysomnography (PSG) surveillance recommendations are not being met for children with neuromuscular disease (NMD) because of limited diagnostic facilities. We evaluated the diagnostic accuracy of an ambulatory level III device as compared to a level I PSG.

METHODS

A cross-sectional study was conducted at a tertiary pediatric institution. Eligibility criteria included: (1) children with NMD; (2) age 6 to 18 years; (3) booked for a clinically indicated overnight level I PSG. Participants were randomized to an overnight level I PSG followed by an ambulatory level III study with end tidal carbon dioxide (etCO₂) or vice versa. Sensitivity and specificity of the ambulatory level III device to diagnose sleep-disordered breathing (SDB) at an apnea-hypopnea index (AHI) cutoff of > 1.0 events/h was the primary outcome.

RESULTS

Moderate to severe SDB was found in 46% of participants (13/28). The device's sensitivity and specificity to detect SDB was 61.5% and 86.7%, respectively. The positive predictive value of the level III study was 80.0% and the negative predictive value was 72.0%. Fifty percent of the cohort were either missing or had incomplete or falsely low ambulatory etCO₂ data.

CONCLUSIONS

A level III device with etCO₂ is not yet able to be implemented in clinical practice as a diagnostic tool for SDB in pediatric patients with NMD.

COMMENTARY

A commentary on this article appears in this issue on page 1973.

Sleep Disorders in Childhood Neurological Diseases

Sleep problems are frequently addressed as a primary or secondary concern during the visit to the pediatric neurology clinic. Sleep disorders can mimic other neurologic diseases (e.g., epilepsy and movement disorders), and this adds challenges to the diagnostic process. Sleep disorders can significantly affect the quality of life and functionality of children in general and those with comorbid neurological diseases in particular. Understanding the pathophysiology of sleep disorders, recognizing the implications of sleep disorder in children with neurologic diseases and behavioral difficulties, and early intervention continue to evolve resulting in better neurocognitive outcomes.

Sleep Disorders in Childhood Neurogenetic Disorders

enetic advances in the past three decades have transformed our understanding and treatment of many human diseases including neurogenetic disorders. Most neurogenetic disorders can be classified as "rare disease," but collectively neurogenetic disorders are not rare and are commonly encountered in general pediatric practice. The authors decided to select eight relatively well-known neurogenetic disorders including Down syndrome, Angelman syndrome, Prader-Willi syndrome, Smith-Magenis syndrome, congenital central hypoventilation syndrome, achondroplasia, mucopolysaccharidoses, and Duchenne muscular dystrophy. Each disorder is presented in the following format: overview, clinical characteristics, developmental aspects, associated sleep disorders, management and research/future directions.

Sleep Disordered Breathing in Duchenne Muscular Dystrophy

This review aims to explain the inevitable imbalance between respiratory load, drive, and muscular force that occurs in the natural aging of Duchenne muscular dystrophy and that predisposes these patients to sleep disordered breathing (SDB). In DMD, SDB is characterized by oxygen desaturation, apneas, hypercapnia, and hypoventilation during sleep and ultimately develops into respiratory failure during wakefulness. It can be present in all age groups. Young patients risk obstructive apneas because of weight gain, secondary to progressive physical inactivity and prolonged corticosteroid therapy; older patients hypoventilate and desaturate because of respiratory muscle weakness, in particular the diaphragm. These conditions are further exacerbated during REM sleep, the phase of maximal muscle hypotonia during which the diaphragm has to provide most of the ventilation. Evidence is given to the daytime predictors of early symptoms of SDB, important indicators for the proper time to initiate mechanical ventilation.

Sleep-Disordered Breathing in Duchenne Muscular Dystrophy: An Assessment of the Literature

STUDY OBJECTIVES

The aim of this review is to review the literature on sleep-disordered breathing in Duchenne muscular dystrophy (DMD).

METHODS

PubMed was searched with an array of search terms, including "OSA," "obstructive sleep apnea," "sleep-disordered breathing," "muscular dystrophy," "neuromuscular," "Duchenne muscular dystrophy," "polysomnography," and "portable monitoring." All relevant articles were discussed.

RESULTS

Eighteen research articles and 1 consensus statement were reviewed, and assessed with relevant data presented. Three early studies prior to 1990 assessed DMD associated obstructive sleep apnea. Five studies assessed positive airway pressure (PAP) ventilation and/or sleep in varying neuromuscular disorders, including a cohort with DMD. Six studies since 2000 include PSG data in exclusively DMD cohorts. Three studies involved portable monitoring (PM).

CONCLUSIONS

PSG with transcutaneous CO2 capnography is an important part of the clinical care for those with DMD. The utility of PM in DMD is unclear with only 1 study to date comparing PSG to PM data. Initiation of PAP therapy using bilevel modality may prevent the need for device switching as the disease progresses.

Louis EK. Neuromuscular disorders and sleep in critically ill patients

Sleep-disordered breathing (SDB) is a frequent presenting manifestation of neuromuscular disorders and can lead to significant morbidity and mortality. If not recognized and addressed early in the clinical course, SDB can lead to clinical deterioration with respiratory failure. The pathophysiologic basis of SDB in neuromuscular disorders, clinical features encountered in specific neuromuscular diseases, and diagnostic and management strategies for SDB in neuromuscular patients in the critical care setting are reviewed. Noninvasive positive pressure ventilation has been a crucial advance in critical care management, improving sleep quality and often preventing or delaying mechanical ventilation and improving survival in neuromuscular patients.

Reliability of home respiratory polygraphy for the diagnosis of sleep apnea in children

OBJECTIVE

The objective of this study was to evaluate the diagnostic reliability of home respiratory polygraphy (HRP) in children with a clinical suspicion of OSA-hypopnea syndrome (OSAS).

METHODS

A prospective blind evaluation was performed. Children between the ages of 2 to 14 years with clinical suspicion of OSAS who were referred to the Sleep Unit were included. An initial HRP followed by a later date, same night, in-laboratory overnight respiratory polygraphy and polysomnography (PSG) in the sleep laboratory were performed. The apnea-hypopnea index (AHI)-HRP was compared with AHI-PSG, and therapeutic decisions based on AHI-HRP and AHI-PSG were analyzed using intraclass correlation coefficients, Bland-Altman plots, and receiver operator curves (ROCs).

RESULTS

Twenty-seven boys and 23 girls, with a mean age of 5.3 ± 2.5 years, were studied, and 66% were diagnosed with OSAS based on a PSG-defined obstructive respiratory disturbance index ≥ 3/h total sleep time. Based on the availability of concurrent HRP-PSG recordings, the optimal AHI-HRP corresponding to the PSG-defined OSAS criterion was established as ≥ 5.6/h The latter exhibited a sensitivity of 90.9% (95% CI, 79.6%-100%) and a specificity of 94.1% (95% CI, 80%-100%).

CONCLUSIONS

HRP recordings emerge as a potentially useful and reliable approach for the diagnosis of OSAS in children. However, more research is required for the diagnosis of mild OSAS using HRP in children.

Respiratory Control in the mdx Mouse Model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a genetic disease caused by defects in the dystrophin gene resulting in loss of the structural protein dystrophin. Patients have reduced diaphragm functional capacity due to progressive muscle weakness. Respiratory morbidity in DMD is further characterised by hypoxaemic periods due to hypoventilation. DMD patients die prematurely due to respiratory and cardiac failure. In this study, we examined respiratory function in young adult male mdx (dystrophin deficient) mice (C57BL/10ScSn-Dmd(mdx)/J; n = 10) and in wild-type controls (WT; C57BL/10ScSnJ; n = 11). Breathing was assessed in unrestrained, unanaesthetised animals by whole-body plethysmography. Ventilatory parameters were recorded during air breathing and during exposure to acute hypoxia (F(i)O(2) = 0.1, 20 min). Data for the two groups of animals were compared using Student's t tests. During normoxic breathing, mdx mice had reduced breathing frequency (p = 0.011), tidal volume (p = 0.093) and minute ventilation (p = 0.033) compared to WT. Hypoxia increased minute ventilation in WT and mdx animals. Mdx mice had a significantly increased ventilatory response to hypoxia which manifest as an elevated % change from baseline for minute ventilation (p = 0.0015) compared to WT. We conclude that mdx mice have impaired normoxic ventilation suggestive of hypoventilation. Furthermore, mdx mice have an enhanced hypoxic ventilatory response compared to WT animals which we speculate may be secondary to chronic hypoxaemia. Our results indicate that a significant respiratory phenotype is evident as early as 8 weeks in the mdx mouse model of DMD.

Pulmonary issues in patients with chronic neuromuscular disease

Patients with chronic neuromuscular diseases such as spinal cord injury, amyotrophic lateral sclerosis, and muscular dystrophies experience respiratory complications that are cared for by the respiratory practitioner. An organized anatomical approach for evaluation and treatment is helpful to provide appropriate clinical care. Effective noninvasive strategies for management of hypoventilation, sleep-disordered breathing, and cough insufficiency are available for these patients.

Prevalence and profile of sleep disturbances in Guillain-Barre Syndrome: a prospective questionnaire-based study during 10 days of hospitalization

INTRODUCTION

Sleep disturbances in Guillain-Barre Syndrome (GBS), though common, have not received focused attention.

OBJECTIVES

To study frequency and nature of sleep disturbances in patients with GBS, using validated questionnaires, and analyze the contributing factors.

MATERIALS AND METHODS

This prospective study included 60 patients fulfilling National Institute of Neurological and Communicative Diseases and Stroke (NINCDS) criteria for GBS (mean age: 32.7 ± 12.9 years; median: 30 years; M:F = 46:14), evaluated from 2008 to 2010. Data regarding sleep were collected on 10 consecutive days following admission using Richard Campbell Sleep score, St Mary's Hospital Sleep Questionnaire, and Pittsburgh Sleep Quality Index (PSQI) and correlated with various possible contributing factors like pain, paresthesia, anxiety, depression, autonomic dysfunctions, severity of disease, and therapeutic interventions among others.

OBSERVATIONS

Qualitative and quantitative sleep disturbances were rather frequent and involved over 50% patients: abnormal PSQI - 13.3%, abnormal score on Richard scale - 51.6%, abnormal sleep onset latency - 35%, sleep fragmentation - 40%, and reduced sleep duration - 46.6%. The symptoms were severe during the first week of hospitalization and reduced thereafter. Sleep disturbances as scored on Richard scale significantly correlated with anxiety, pain, paresthesia, and severity of immobility (P < 0.05) but not with depression and use of analgesics or antineuritic drugs.

CONCLUSIONS

This study first of its kind suggests that sleep disturbance in GBS is frequent, multi-factorial, often disturbing, and varies during the course of illness. Routine enquiry into the sleep disturbances and timely intervention may reduce morbidity and improve their quality of life.

Sleep, sleep disordered breathing, and nocturnal hypoventilation in children with neuromuscular diseases

Sleep disordered breathing (SDB) is now well recognized in children with neuromuscular diseases (NMD) and may lead to significant morbidity and increased mortality. Predisposing factors to SDB in children with NMD include reduced ventilatory responses, reduced activity of respiratory muscles during sleep and poor lung mechanics due to the underlying neuro-muscular disorder. SDB may present long before signs of respiratory failure emerge. When untreated, SDB may contribute to significant cardiovascular morbidities, neuro-cognitive deficits and premature death. One of the problems in detecting SDB in patients with NMD is the lack of correlation between lung function testing and daytime gas exchange. Polysomnography is the preferred method to evaluate for SDB in children with NMD. When the diagnosis of SDB is confirmed, treatment by non-invasive ventilation (NIV) is usually recommended. However, other modalities of mechanical ventilation do exist and may be indicated in combination with or without other supportive measures.

Assessment of sleep-disordered breathing in pediatric neuromuscular diseases

This is a summary of the presentation on the assessment of sleep-disordered breathing in pediatric neuromuscular diseases, presented as part of the program on pulmonary management of pediatric patients with neuromuscular disorders at the 30th annual Carrell-Krusen Neuromuscular Symposium on February 20, 2008.

[Reliability of respiratory polygraphy for the diagnosis of sleep apnea-hypopnea syndrome in children]

OBJECTIVE

Overnight polysomnography (PSG) is the gold standard diagnostic tool for sleep apnea-hypopnea syndrome (SAHS) in children. The aim of the present study was to evaluate the usefulness of diagnostic respiratory polygraphy in children with clinically suspected SAHS referred to our sleep-disordered breathing clinic.

PATIENTS AND METHODS

We studied 53 children referred with clinical suspicion of SAHS; 29 (54.7%) were boys and the mean (SD) age was 6.4 (2.9) years. After a medical history was taken and a physical examination performed, patients underwent respiratory polygraphy (Edentec) simultaneously with overnight PSG in the sleep laboratory. The 2 diagnostic tools were compared using statistical analysis.

RESULTS

SAHS was defined by an obstructive apnea-hypopnea index (OAHI) of 3 or more in overnight PSG and a respiratory disturbance index (RDI) of 3 or more in respiratory polygraphy. The rate of diagnostic agreement was 84.9%. The difference between the mean OAHI and RDI values was not significant (0.7 +/- 5.4; P=.34). The intraclass correlation coefficient between the OAHI and RDI was 89.4 (95% confidence interval, 82.4-93.7; P< .001). When receiver operating characteristic curves were calculated for the OAHI cutoff points used for the diagnosis of SAHS (> or =1, > or =3, and > or =5), the best RDI cutoff for all 3 OAHI values considered was found to be 4.6. When age strata were considered, in children 6 years or older the best RDI cutoff for the 3 OAHI values was 2.1. In children younger than 6 years the best RDI cutoff was 3.35 for OAHI > or =1 and 5.85 for OAHI > or =3 and > or =5.

CONCLUSIONS

Respiratory polygraphy in the sleep laboratory is a valid method for the diagnosis of SAHS in children.

Neuromuscular disorders and sleep

Neuromuscular disorders are caused by the primary involvement of the motor unit. In these patients, sleep-disordered breathing (SDB) due to respiratory muscle weakness is often encountered during sleep. Because there is a tendency to overlook this disorder, all patients with neuromuscular disorders should be questioned about SDB. Overnight polysomnography is the best investigation for SDB and nocturnal desaturations. In the management of these patients, noninvasive intermittent positive pressure ventilation results in improvement of SDB and breathing.

Sleep disorders in children with neurologic diseases

Pediatric neurologic diseases are often associated with different kinds of sleep disruption (mainly insomnia, less frequently hypersomnia or parasomnias). Due to the key-role of sleep for development, the effort to ameliorate sleep patterns in these children could have important prognostic benefits. Study of sleep architecture and organization in neurologic disorders could lead to a better comprehension of the pathogenesis and a better treatment of the disorders. This article focuses on the following specific neurologic diseases: nocturnal frontal lobe epilepsy and abnormal motor behaviors of epileptic origin, evaluating differential diagnosis with parasomnias; achondroplasia, confirming the crucial role of craniofacial deformity in determining sleep-disordered breathing; neuromuscular diseases, mainly Duchenne's muscular dystrophy and myotonic dystrophy; cerebral palsy, evaluating either the features of sleep architecture and the importance of the respiratory problems associated; headaches, confirming the strict relationships with sleep in terms of neurochemical and neurobehavioral substrates; and finally a review on the effectiveness of melatonin for sleep problems in children with neurologic syndromes and mental retardation, blindness, and epilepsy.