Sleep and Neuromuscular Disorders

Novel Genetic and Phenotypic Expansion in Ameliorated PUF60-Related Disorders

Heterozygous variants in the Poly(U) Binding Splicing Factor 60kDa gene (PUF60) have been associated with Verheij syndrome, which has the key features of coloboma, short stature, skeletal abnormalities, developmental delay, palatal abnormalities, and congenital heart and kidney defects. Here, we report five novel patients from unrelated families with PUF60-related disorders exhibiting novel genetic and clinical findings with three truncating variants, one splice-site variant with likely reduced protein expression, and one missense variant. Protein modeling of the patient's missense variant in the PUF60 AlphaFold structure revealed a loss of polar bonds to the surrounding residues. Neurodevelopmental disorders were present in all patients, with variability in speech, motor, cognitive, social-emotional and behavioral features. Novel phenotypic expansions included movement disorders as well as immunological findings with recurrent respiratory, urinary and ear infections, atopic diseases, and skin abnormalities. We discuss the role of PUF60 in immunity with and without infection based on recent organismic and cellular studies. As our five patients showed less-severe phenotypes than classical Verheij syndrome, particularly with the absence of key features such as coloboma or palatal abnormalities, we propose a reclassification as PUF60-related neurodevelopmental disorders with multi-system involvement. These findings will aid in the genetic counseling of patients and families.

Severity of nocturnal hypoxia and daytime hypercapnia predicts CPAP failure in patients with COPD and obstructive sleep apnea overlap syndrome

BACKGROUND

Obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) are independent risk factors for cardiovascular diseases. In patients with OSA and concurrent COPD, continuous positive airway pressure (CPAP) therapy improves survival. Nevertheless, a significant proportion of such patients do not tolerate CPAP. The aim of the present study was to analyze early predictors of CPAP failure in patients with OSA and concurrent COPD, and to evaluate the effects of bilevel positive airway pressure (BiPAP) in this high-risk group of patients.

METHODS

A post hoc analysis from the database of 2100 patients diagnosed with OSA between 2012 and 2014 identified 84 subjects as having concomitant COPD and meeting inclusion criteria. Demographic data, pulmonary function tests, OSA parameters, blood gases, response to CPAP and BiPAP titration, and two months of therapy were collected. A multivariate model was generated to find determinants of CPAP failure.

RESULTS

Primary CPAP failure was found in 23% of patients who were more obese (p = 0.018), had worse lung function, lower PO₂ (p = 0.023) and higher PCO₂ while awake (p < 0.001), and more sleep time with an SpO₂ < 90% (CT90%) (p < 0.001) compared to those who responded to CPAP. In multivariate analysis, PCO₂ while awake [odds ratio (OR) 29.5, confidence interval (CI) 2.22-391, p = 0.010] and CT90% (OR 1.06, CI 1.01-1.11, p = 0.017) independently predicted CPAP failure after adjustments for covariates. The BiPAP therapy was well tolerated and effectively alleviated hypercapnia in all patients with primary CPAP failure.

CONCLUSIONS

Daytime hypercapnia and nocturnal hypoxia are independent predictors of early CPAP failure in patients with the OSA-COPD overlap syndrome.

[Sleep disorders in neurological diseases]

Sleep disorders can be diagnosed in approximately 15 % of the population and have been shown to increase with age. The relationship between sleep disorders and neurological disorders, however, is still insufficiently considered in the clinical practice. Sleep disorders can be an early symptom of the disease, such as the presence of rapid eye movement (REM) sleep behavior disorder (RBD) as an early indicator of neurodegeneration. Sleep disorders have also been shown to be a main symptom of various neurological syndromes, such as in restless legs syndrome (RLS), periodic limb movement disorder (PLMD) and narcolepsy. The international classification of sleep disorders 2nd edition (ICSD 2) describes the main diagnoses, insomnia, circadian rhythm sleep disorders, sleep-related breathing disorders and hypersomnia but all of these can also appear as symptoms in various neurological diseases. Parasomnias are largely considered a differential diagnosis to nocturnal epilepsy. In this review, the main sleep disorders are described with a particular focus on how they relate to neurological diseases; in particular, how they influence disease-related symptoms and how they affect the course of the disease.

Home sleep study for patients with myasthenia gravis

OBJECTIVES

The objective of the study was to examine predictors for sleep-disordered breathing (SDB) in patients with myasthenia gravis (MG) using Watch-PAT.

MATERIALS AND METHODS

We prospectively studied 58 consecutive patients with MG without respiratory symptoms for a full-night Watch-PAT with concomitant recording of the MG score and acetylcholine receptor antibody concentration and analyzed potential risk factors of SDB.

RESULTS

Twenty-four patients (41%) had definitive SDB, which was mild in 12 patients, moderate in six, and severe in six. Assessing risk factors with multivariate models, we found four significant predictors (BMI, age, male gender, and use of azathioprine); BMI was the most powerful predictor. The severity and prevalence of sleep-disordered breathing had no significant association with MG score, myasthenia stage, or seropositivity of acetylcholine receptor antibody.

CONCLUSIONS

The prevalence of SDB in myasthenic patients with mild and moderate weakness was high when using the Watch-PAT. Both myasthenia-specific factors (use of azathioprine) and general predictors in terms of BMI, age, and male gender predisposed the development of SDB in patients with myasthenia gravis. Careful screening of patients with myasthenia gravis at risk of SDB using Watch-PAT might improve the quality of sleep and cardiovascular health through proper treatment of underlying SDB.

Chronic widespread musculoskeletal pain in patients with obstructive sleep apnea syndrome and the relationship between sleep disorder and pain level, quality of life, and disability

[Purpose] The aim of this study was to ascertain the prevalence of chronic widespread musculoskeletal pain in patients with obstructive sleep apnea syndrome and to assess the relationship between sleep disorder and pain, quality of life, and disability. [Subjects and Methods] Seventy-four patients were included in the study and classified as having mild, moderate, or severe obstructive sleep apnea. Chronic widespread pain, quality of life, and disability were evaluated. [Results] Forty-one patients (55.4%) had chronic widespread pain. Female patients had a higher incidence of chronic pain, and female patients with chronic pain had higher body mass indexes, pain levels, and disability scores than did male patients. Physical component scores of female patients with chronic pain were lower than those of male patients. No correlation was observed between the degree of sleep disorder and severity of pain, pain duration, disability, or quality of life in obstructive sleep apnea patients with pain. [Conclusion] This study showed a 55.4% prevalence of chronic widespread pain in patients with obstructive sleep apnea and a greater risk of chronic pain in female than in male patients. Female patients with obstructive sleep apnea and chronic pain have higher pain and disability levels and a lower quality of life.

Increased orexin expression promotes sleep/wake disturbances in the SOD1-G93A mouse model of amyotrophic lateral sclerosis

BACKGROUND

Sleep/wake disturbances in patients with amyotrophic lateral sclerosis (ALS) are well-documented, however, no animal or mechanistic studies on these disturbances exist. Orexin is a crucial neurotransmitter in promoting wakefulness in sleep/wake regulation, and may play an important role in sleep disturbances in ALS. In this study, we used SOD1-G93A transgenic mice as an ALS mouse model to investigate the sleep/wake disturbances and their possible mechanisms in ALS.

METHODS

Electroencephalogram/electromyogram recordings were performed in SOD1-G93A transgenic mice and their littermate control mice at the ages of 90 and 120 days, and the samples obtained from these groups were subjected to quantitative reverse transcriptase-polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay.

RESULTS

For the first time in SOD1-G93A transgenic mice, we observed significantly increased wakefulness, reduced sleep time, and up-regulated orexins (prepro-orexin, orexin A and B) at both 90 and 120 days. Correlation analysis confirmed moderate to high correlations between sleep/wake time (total sleep time, wakefulness time, rapid eye movement [REM] sleep time, non-REM sleep time, and deep sleep time) and increase in orexins (prepro-orexin, orexin A and B).

CONCLUSION

Sleep/wake disturbances occur before disease onset in this ALS mouse model. Increased orexins may promote wakefulness and result in these disturbances before and after disease onset, thus making them potential therapeutic targets for amelioration of sleep disturbances in ALS. Further studies are required to elucidate the underlying mechanisms in the future.

Sleep disordered breathing in children with mitochondrial disease

A retrospective chart review study was performed to determine the presence of sleep disordered breathing (SDB) in children with primary mitochondrial disease (MD). The symptoms, sleep-related breathing, and movement abnormalities are described for 18 subjects (ages 1.5 to 18 years, 61% male) with MD who underwent polysomnography in our pediatric sleep center from 2007 to 2012. Of the 18 subjects with MD, the common indications for polysomnography were excessive somnolence or fatigue (61%, N = 11), snoring (44%, N = 8), and sleep movement complaints (17%, N = 3). Polysomnographic measurements showed SDB in 56% (N = 10) (obstructive sleep apnea in 60% (N = 6), hypoxemia in 40% (N = 4), and sleep hypoventilation in 20% (N = 2)). There was a significant association between decreased muscle tone and SDB (P: 0.043) as well as obese and overweight status with SDB (P = 0.036). SDB is common in subjects with MD. Early detection of SDB, utilizing polysomnography, should be considered to assist in identification of MD patients who may benefit from sleep-related interventions.

A pilot study of a wearable apnoea detection device

RATIONALE

Current techniques for monitoring patients for apnoea suffer from significant limitations. These include insufficient availability to meet diagnostic needs, cost, accuracy of results in the presence of artefacts and difficulty of use in unsupervised conditions.

OBJECTIVES

We created and clinically tested a novel miniature medical device that targets overcoming these limitations.

METHODS

We studied 20 healthy control participants and 10 patients who had been referred for sleep apnoea diagnosis. The performances of the new system and also of the Food and Drug Administration (FDA) approved SOMNO clinical system, conventionally used for sleep apnoea diagnosis were evaluated under the same conditions. Both systems were tested during a normal night of sleep in controls and patients. Their performances were quantified in terms of detection of apnoea and hypopnoea in individual 10 s epochs, which were compared with scoring of signals by a blinded clinician.

MAIN RESULTS

For spontaneous apnoeas during natural sleep and considering the clinician scorer as the gold standard, the new wearable apnoea detection device had 88.6% sensitivity and 99.6% specificity. In comparison the SOMNO system had 14.3% sensitivity and 99.3% specificity. The novel device had been specifically designed to detect apnoea, but if apnoea and hypopnoea during sleep were both considered in the assessment, the sensitivity and specificity were 77.1% and 99.7%, respectively, versus 54% and 98.5%, respectively, for the SOMNO.

CONCLUSIONS

The performance of the novel device compares very well to the scoring by an experienced clinician even in the presence of breathing artefacts, in this small pilot study. This can potentially make it a real solution for apnoea home monitoring.

A fatal case of cor pulmonale with undetected chronic hypoventilation in an infant with a known congenital myopathy

The authors of this paper wish to present a case of fatal cor pulmonale with right ventricular hypertrophy complicated by a congenital myopathy. It is our intention to demonstrate the importance of vigilant clinical assessment of children with a congenital myopathy, regardless of the exact etiology of their disease, or family history of disease severity. This case highlights the risk for fatal complications if hypoventilation and respiratory insufficiency go unrecognized in myopathic children. Consequently, we recommend respiratory and cardiac monitoring surveillance as well as appropriate referral to specialists in the management of such children.

Neuromuscular disease and the pulmonologist

PURPOSE OF REVIEW

The heterogeneous nature of neuromuscular disorders (NMDs) continues to promote slow but steady advances in diagnosis, classification, and treatment. This review focuses on the updates in the general management and treatment of NMDs, with emphasis on key updates in muscular dystrophy, myotonic dystrophy, mitochondrial myopathy, spinal muscular atrophy, and hereditary neuropathies.

RECENT FINDINGS

Current research shows that improvements in morbidity and mortality in various NMDs may be possible. Key components include advances in identification and classification of individual NMDs; attention to anesthetic and surgical risks; aggressive pulmonary care; and implementations of a proactive, multidisciplinary, standard-of-care approach. Innovative molecular and pharmaceutical therapeutic options are being investigated in many of these disorders, but unfortunately no new intervention has borne out.

SUMMARY

Important advances were made in the last year in the field of neuromuscular disease. However, because of their heterogeneous nature and rarity, diagnosis and treatment of these disorders either as a single disorder or as a group continue to be both a clinical and a research challenge. It is of utmost importance that clinicians and researchers be aware of these disorders to aid in identification and treatment.

Management of symptoms in amyotrophic lateral sclerosis

The mainstay of treatment of amyotrophic lateral sclerosis (ALS) is management of symptoms. Health care providers involved in the care of ALS patients should be armed with the most current knowledge about symptomatic management of these patients so that an aggressive approach to controlling symptoms can be undertaken at the most appropriate time. Among the important modalities is noninvasive positive pressure ventilation, which has been shown to improve not only quality of life but also survival. Similarly, clinicians should consider earlier intervention with enteral feeding. Palliative care should begin soon after ALS is diagnosed.

Nocturnal noninvasive ventilation

Nocturnal noninvasive ventilation (NNV), the provision of ventilatory assistance via a noninvasive interface mainly during sleep, has assumed an important role in the management of chronic hypoventilatory syndromes. This review focuses on recent developments related to the use of NNV to treat various forms of chronic respiratory failure or insufficiency. In the past, NNV has been used mainly to treat respiratory insufficiency in patients with neuromuscular disease (NMD) or chest wall deformity; it should be instituted when these patients have orthopnea or daytime symptoms associated with nocturnal hypoventilation. An emerging application is to treat obesity-hypoventilation syndrome, particularly in continuous positive airway pressure (CPAP) failures. Additionally, it has a role in managing some patients with obstructive sleep apnea who are hypoventilating or find the lower expiratory pressure with bilevel positive pressure ventilators more tolerable than with CPAP alone. NNV to treat severe, stable COPD remains controversial, although a subgroup of patients with hypercapnea and sleep-disordered breathing (SDB) seems most likely to respond favorably. NNV to treat central SDB in patients with congestive heart failure continues to be investigated. Recent findings from a Canadian CPAP trial were disappointing, but preliminary results on a novel adaptive NNV mode are promising.

Sleep disorders in neuromuscular diseases

PURPOSE OF REVIEW

Patients with neuromuscular disorders (NMD) are especially vulnerable to sleep-related dysfunction. Sleep-disordered breathing often precedes diurnal respiratory failure in NMD patients, requiring timely recognition and management with noninvasive ventilation (NIV). This paper reviews the mechanisms, diagnostic evaluation, and management of sleep disorders in various neuromuscular diseases.

RECENT FINDINGS

The severity, duration, and type of NMD influence the pattern of sleep disturbance. Several investigators have addressed other clinical aspects including rating scales for sleep complaints, hypocretin-1 deficiency, excessive daytime somnolence, and relation of sleep disorder with length of CTG trinucleotide repeats in myotonic dystrophy. Benefits of NIV on quality of life and survival in adults and children with chronic NMD are well established, and recently have been documented even in patients with nocturnal hypoventilation and daytime normocapnia. In contrast, the timing for investigation with polysomnography and for initiation of NIV is debated.

SUMMARY

Patients with chronic NMD should be routinely assessed for sleep-disordered breathing and sleep complaints, because these are treatable complications in an otherwise progressive disease process. Further research is needed to establish the indications for polysomnography and to determine the optimal timing for initiating NIV to treat sleep-disordered breathing in patients with neuromuscular diseases.