Disruption of sleep-wake continuum in myotonic dystrophy type 1: Beyond conventional sleep staging

Excessive daytime sleepiness in myotonic dystrophy: a narrative review

Introduction

Excessive daytime sleepiness (EDS) is a common and debilitating symptom in both forms of myotonic dystrophy (DM), significantly impacting patients' quality of life. The review focuses on the purpose of examining the current understanding of EDS in these conditions, the difficulty in correctly accessing it, the recent findings related to its etiology and prevalence, and a summary of potential therapeutic implications.

Methods

We conducted a comprehensive search through PubMed, selecting studies that provided significant insights into the mechanisms, prevalence, and management of EDS in DM1 and DM2.

Results and discussion

EDS is highly prevalent in both DM1 and DM2. Polysomnographic studies have revealed prominent dysregulation of REM sleep in DM1, suggesting a possible narcoleptic-like phenotype and alterations in NREM sleep that contributes to daytime sleepiness. Other factors have been proposed to explain EDS in DM1, including dysregulation of the sleep-wake circadian rhythm through nocturnal actigraphy analysis. The central origin of EDS is increasingly delineated supported by serotonin and orexin pathways dysfunction, and recent neuroradiological findings showing that in DM1 hippocampus volume was positively correlated with self-reported fatigue and somnolence. Sleep-disordered breathing and respiratory dysfunctions are prevalent in DM, their direct correlation with EDS remains complex and inconclusive, but respiratory evaluation should be recommended if obstructive sleep apneas or respiratory muscle dysfunctions are suspected. Drug interventions, such as modafinil and mexiletine, have shown promise in managing excessive daytime sleepiness and reducing myotonia without significant cardiac conduction effects. Enhancing EDS management in myotonic dystrophy is key to improving overall patient well-being.

Polysomnographic findings of myotonic dystrophy type 1/type 2: evidence from case-control studies

STUDY OBJECTIVES

This study explores polysomnographic and multiple sleep latency test (MSLT) differences between myotonic dystrophy type 1/type 2 (DM1/DM2) patients and controls.

METHODS

An electronic literature search was conducted in MEDLINE, EMBASE, All EBM databases, and Web of Science from inception to Aug 2023.

RESULTS

Meta-analyses revealed significant reductions in sleep efficiency, N2 percentage, mean SpO2, and MSLT measured mean sleep latency, and increases in N3 sleep, wake time after sleep onset, apnea hypopnea index, and periodic limb movement index in DM1 patients compared with controls. However, any differences of polysomnographic sleep change between DM2 patients and controls could not be established due to limited available studies.

CONCLUSIONS

Multiple significant polysomnographic abnormalities are present in DM1. More case-control studies evaluating polysomnographic changes in DM2 compared with controls are needed.

Assessment of self-reported and objective daytime sleepiness in adult-onset myotonic dystrophy type 1

STUDY OBJECTIVES

Excessive daytime sleepiness (EDS) in myotonic dystrophy type 1 (DM1) is mostly of central origin but it may coexist with sleep-related breathing disorders. However, there is no consensus on the sleep protocols to be used, assessments vary and only a minority of patients are regularly tested or are on treatment for EDS. Our study presents data on self-reported and objective EDS in adult-onset DM1.

METHODS

63 adult-onset DM1 patients were subjected to EDS-sleep assessments (polysomnography, PSG; Multiple Sleep Latency Test, MSLT; Epworth Sleepiness Scale, ESS. Correlation coefficients were computed to assess the relationship between sleep and sleepiness test results, fatigue, quality of life.

RESULTS

33% and 48% of patients had EDS based respectively on the ESS and the MSLT with a low concordance between these tests (k = 0.19). Thirteen patients (20%) displayed 2 or more sleep-onset REM periods on MSLT. Patients having EDS by MSLT had a shorter disease duration (p<0.05), higher total sleep time, sleep efficiency and lower WASO (Wake After Sleep Onset) on PSG. Patients with self-reported EDS reported significantly higher fatigue score compared to patients without EDS (p<0.05). No other difference was found in demographic, clinical and respiratory features.

CONCLUSIONS

EDS test results are contradictory making treatment options difficult. Combining quantitative tests and self-reported scales may facilitate physicians in planning EDS care with patients and families.

Altered REM sleep architecture in patients with Myotonic dystrophy type 1: is related to sleep apnea?

OBJECTIVE

To determine the sleep architecture and sleep respiratory abnormalities and to correlate with sleep symptoms in patients with Myotonic dystrophy type 1 (DM1).

METHODS

We recruited a cohort of genetically confirmed patients with DM1, who attended the Neuromuscular clinic between July 2016 and December 2019. Clinical, sleep and whole night polysomnography data were collected. The analysis of sleep architecture, sleep respiratory parameters and comparison with healthy controls (HC) was performed in our sleep laboratory.

RESULTS

A total of 59 patients with DM1 underwent sleep evaluation. Hypersomnolence in 42 (77.8%), ESS>10 in 23 (39%), and PSQI>5 in 18 (30.5%) were found in patients with DM1. Thirty-one (68.89%) patients with DM1 and 22 (95.65%) HC had more than 4-h of total sleep time (TST). More than 4 h of TST was taken to compare respiratory and sleep architecture parameters. Patients with DM1 had reduced sleep efficiency, reduced N2 sleep, and increase in N1 sleep, wake index, stage shift index, nocturnal sleep-onset REM periods compared to HC. AHI>15 was found in 16 (51.61%) DM1 and in 3 HC (13.64%). AHI had positive correlation with BMI, but not with age, ESS or disease progression (MIRS). All DM1 with AHI>15; 8(80%) and 1(33.33%) in AHI5to15, and AHI<5 groups, respectively had hypersomnolence.

CONCLUSION

In this first study on Indian cohort, daytime hypersomnolence, poor nocturnal sleep quality, sleep architecture irregularities are identified to be common in patients with DM1. These abnormalities may be explained by sleep-related breathing disorders that are highly prevalent in these patients.

Central Nervous System Involvement as Outcome Measure for Clinical Trials Efficacy in Myotonic Dystrophy Type 1

Increasing evidences indicate that in Myotonic Dystrophy type 1 (DM1 or Steinert disease), an autosomal dominant multisystem disorder caused by a (CTG)n expansion in DMPK gene on chromosome 19q13. 3, is the most common form of inherited muscular dystrophy in adult patients with a global prevalence of 1/8000, and involvement of the central nervous system can be included within the core clinical manifestations of the disease. Variable in its severity and progression rate over time, likely due to the underlying causative molecular mechanisms; this component of the clinical picture presents with high heterogeneity involving cognitive and behavioral alterations, but also sensory-motor neural integration, and in any case, significantly contributing to the disease burden projected to either specific functional neuropsychological domains or quality of life as a whole. Principle manifestations include alterations of the frontal lobe function, which is more prominent in patients with an early onset, such as in congenital and childhood onset forms, here associated with severe intellectual disabilities, speech and language delay and reduced IQ-values, while in adult onset DM1 cognitive and neuropsychological findings are usually not so severe. Different methods to assess central nervous system involvement in DM1 have then recently been developed, these ranging from more classical psychometric and cognitive functional instruments to sophisticated psycophysic, neurophysiologic and especially computerized neuroimaging techniques, in order to better characterize this disease component, at the same time underlining the opportunity to consider it a suitable marker on which measuring putative effectiveness of therapeutic interventions. This is the reason why, as outlined in the conclusive section of this review, the Authors are lead to wonder, perhaps in a provocative and even paradoxical way to arise the question, whether or not the myologist, by now the popular figure in charge to care of a patient with the DM1, needs to remain himself a neurologist to better appreciate, evaluate and speculate on this important aspect of Steinert disease.

Consensus-Based Care Recommendations for Pulmonologists Treating Adults with Myotonic Dystrophy Type 1

PURPOSE OF REVIEW

Myotonic dystrophy type 1 (DM1) is a severe, progressive genetic disease that affects approximately 1 in 2,500 individuals globally [Ashizawa et al.: Neurol Clin Pract 2018;8(6):507-20]. In patients with DM1, respiratory muscle weakness frequently evolves, leading to respiratory failure as the main cause of death in this patient population, followed by cardiac complications [de Die-Smulders et al.: Brain 1998;121(Pt 8):1557-63], [Mathieu et al.: Neurology 1999;52(8):1658-62], [Groh et al.: Muscle Nerve 2011;43(5):648-51]. This paper provides a more detailed outline on the diagnostic and management protocols, which can guide pulmonologists who may not have experience with DM1 or who are not part of a neuromuscular multidisciplinary clinic. A group of neuromuscular experts in DM1 including pulmonologists, respiratory physiotherapists and sleep specialists discussed respiratory testing and management at baseline and during follow-up visits, based on their clinical experience with patients with DM1. The details are presented in this report.

RECENT FINDINGS

Myotonic recruited 66 international clinicians experienced in the treatment of people living with DM1 to develop and publish consensus-based care recommendations targeting all body systems affected by this disease [Ashizawa et al.: Neurol Clin Pract. 2018;8(6):507-20]. Myotonic then worked with 12 international respiratory therapists, pulmonologists and neurologists with long-standing experience in DM respiratory care to develop consensus-based care recommendations for pulmonologists using a methodology called the Single Text Procedure. This process generated a 7-page document that provides detailed respiratory care recommendations for the management of patients living with DM1. This consensus is completely based on expert opinion and not backed up by empirical evidence due to limited clinical care data available for respiratory care management in DM patients. Nevertheless, we believe it is of relevance for professionals treating adults with myotonic dystrophy because it addresses practical issues related to respiratory management and care, which have been adapted to meet the specific issues in patients with DM1.

SUMMARY

The resulting recommendations are intended to improve respiratory care for the most vulnerable of DM1 patients and lower the risk of untoward respiratory complications and mortality by providing pulmonologist who are less experienced with DM1 with practical indications on which tests and when to perform them, adapting the general respiratory knowledge to specific issues related to this multiorgan disease.

Sleep in Huntington's disease: a systematic review and meta-analysis of polysomongraphic findings

STUDY OBJECTIVES

Disturbed overnight sleep is a prominent feature of advanced stage Huntington's disease (HD). Several polysomnography (PSG) studies have reported significant changes of sleep in HD patients, but the findings are not unequivocal. To date, no meta-analysis has investigated the PSG changes in HD patients. The present study meta-analyzed results from studies examining the PSG changes in HD patients compared with controls.

METHODS

A literature search performed in MEDLINE, EMBASE, All EBM databases, PsycINFO, and CINAHL databases identified seven studies involving 152 HD patients and 144 controls which were included in our meta-analysis.

RESULTS

Pooled results indicated decreased sleep efficiency, percentage of slow wave sleep and rapid eye movement sleep, and increased percentage of N1 sleep, wake time after sleep onset, and rapid eye movement sleep latency in HD patients compared with controls. We found high heterogeneity in the effect sizes and no indication of systematic publication biases across studies. Meta-regression analyses showed that some of the heterogeneity was explained by age, body mass index (BMI), CAG repeat length, and disease severity of HD patients.

CONCLUSIONS

Our study showed that polysomnographic abnormalities are present in HD. Our findings also underscore the need for a comprehensive PSG assessment of sleep changes in patients with HD. Furthermore, the effects of age, BMI and CAG repeat length on sleep changes should be carefully considered and closely monitored in the management of HD.

Health-related quality of life and its correlates in Japanese patients with myotonic dystrophy type 1

PURPOSE

Myotonic dystrophy type 1 (DM1) is a common form of muscular dystrophy that presents with a variety of symptoms that can affect patients' quality of life (QoL). Despite the importance of clarifying patients' subjective experience in both physical and psychosocial aspects for improved symptom management, there is lack of evidence concerning QoL of patients with DM1 in Japan.

PATIENTS AND METHODS

A cross-sectional study was performed with 51 DM1 patients who completed questionnaires that measured health-related QoL (HRQoL), depression, and daytime sleepiness. Activities of daily living, body mass index (BMI), and genetic information were also collected, together with general demographic information. Correlation analyses using these variables were performed. Furthermore, regression analysis was utilized to assess the relationship that HRQoL, depression, and daytime sleepiness scores have with other variables.

RESULTS

Physical component summary (PCS) score was affected by the disease more than the mental component summary (MCS) score among study participants. Moderate correlation was observed between PCS and depression, PCS and Barthel index, and depression and daytime sleepiness. Regression analysis revealed that age, sex, cytosine-thymine-guanine repeats, and BMI did not predict the aforementioned dependent variables.

CONCLUSION

DM1 symptoms influenced physical component scores more than mental component scores, although the state of physical wellness seemed to affect patients' mood. Explaining the QoL of these patients only using biologic and genetic characteristics was not sufficient. We conclude that social and psychological aspects of these patients' lives and the nature of adjustments made by patients due to DM1 to require further examination in order to improve the standard of care.