Disruption of sleep-wake rhythmicity and daytime sleepiness in myotonic dystrophy

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.

Predicting daytime sleepiness and fatigue: a 9-year prospective study in myotonic dystrophy type 1

OBJECTIVE

Daytime sleepiness and fatigue are prominent symptoms of myotonic dystrophy type I (DM1) that exact a heavy toll on patients' quality of life, but information is scarce on their predictive factors. This study aimed to determine factors that may influence levels of daytime sleepiness and fatigue in a large cohort of DM1 patients followed for 9 years.

METHODS

This study included 115 patients with DM1 at baseline (Time 1, T1) and at Time 2 (T2) who were questioned for daytime sleepiness, fatigue, history of depression, psychological distress, pain, hypothyroidism, and sleep habits. Also, their muscular impairment and intellectual quotient were evaluated. Regression models were used to identify correlates of daytime sleepiness and fatigue while controlling for time effect.

RESULTS

Both daytime sleepiness and fatigue increased between T1 and T2, but their rate of change are higher when CTG repeat number is higher (p < 0.05). Also, higher psychological distress level is associated with higher daytime sleepiness and fatigue levels both at T1 and T2 (p < 0.01). Moreover, patients with a history of depression report higher daytime sleepiness levels both at T1 and T2 (p < 0.05). In addition, patients with higher fatigue levels both at T1 and T2 have more severe muscular impairment (p < 0.01) and report a longer habitual sleep duration (p < 0.05). Finally, a higher BMI and a history of hypothyroidism predict higher daytime sleepiness levels at T2 (p < 0.05).

CONCLUSION

This study identified potentially modifiable risk factors of future daytime sleepiness and fatigue in DM1 patients, including BMI, psychological distress, hypothyroidism, and sleep habits.

The multiple sleep latency test

The measurement of daytime sleepiness is important in the evaluation of patients with excessive sleepiness. The multiple sleep latency test (MSLT) is an objective test that measures the tendency to fall asleep under controlled conditions. It is based on the notion that sleep latency reflects underlying physiological sleepiness. The MSLT consists of four to five naps given 2h apart during the day, following a standardized procedure. The mean sleep latency from all naps is used as the measure of sleepiness. The test has been shown to be valid and reliable and is part of the diagnostic criteria for narcolepsy and idiopathic hypersomnia. However, the MSLT is affected by numerous variables including insufficient sleep, drugs, activity, and arousal level. Adherence to the established protocol is necessary to limit the effect of these extraneous factors on the MSLT. While the test is a valuable and widely used diagnostic tool for narcolepsy and idiopathic hypersomnia, the use of MSLT in other sleep disorders is not well established.

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.

Impact of dronabinol on quantitative electroencephalogram (qEEG) measures of sleep in obstructive sleep apnea syndrome

STUDY OBJECTIVES

To determine the effects of dronabinol on quantitative electroencephalogram (EEG) markers of the sleep process, including power distribution and ultradian cycling in 15 patients with obstructive sleep apnea (OSA).

METHODS

EEG (C4-A1) relative power (% total) in the delta, theta, alpha, and sigma bands was quantified by fast Fourier transformation (FFT) over 28-second intervals. An activation ratio (AR = [alpha + sigma] / [delta + theta]) also was computed for each interval. To assess ultradian rhythms, the best-fitting cosine wave was determined for AR and each frequency band in each polysomnogram (PSG).

RESULTS

Fifteen subjects were included in the analysis. Dronabinol was associated with significantly increased theta power (p = 0.002). During the first half of the night, dronabinol decreased sigma power (p = 0.03) and AR (p = 0.03), and increased theta power (p = 0.0006). At increasing dronabinol doses, ultradian rhythms accounted for a greater fraction of EEG power variance in the delta band (p = 0.04) and AR (p = 0.03). Females had higher amplitude ultradian rhythms than males (theta: p = 0.01; sigma: p = 0.01). Decreasing AHI was associated with increasing ultradian rhythm amplitudes (sigma: p < 0.001; AR: p = 0.02). At the end of treatment, lower relative power in the theta band (p = 0.02) and lower AHI (p = 0.05) correlated with a greater decrease in sleepiness from baseline.

CONCLUSIONS

This exploratory study demonstrates that in individuals with OSA, dronabinol treatment may yield a shift in EEG power toward delta and theta frequencies and a strengthening of ultradian rhythms in the sleep EEG.

Sleep-Wake Cycle and Daytime Sleepiness in the Myotonic Dystrophies

Myotonic dystrophy is the most common type of muscular dystrophy in adults and is characterized by progressive myopathy, myotonia, and multiorgan involvement. Two genetically distinct entities have been identified, myotonic dystrophy type 1 (DM1 or Steinert's Disease) and myotonic dystrophy type 2 (DM2). Myotonic dystrophies are strongly associated with sleep dysfunction. Sleep disturbances in DM1 are common and include sleep-disordered breathing (SDB), periodic limb movements (PLMS), central hypersomnia, and REM sleep dysregulation (high REM density and narcoleptic-like phenotype). Interestingly, drowsiness in DM1 seems to be due to a central dysfunction of sleep-wake regulation more than SDB. To date, little is known regarding the occurrence of sleep disorders in DM2. SDB (obstructive and central apnoea), REM sleep without atonia, and restless legs syndrome have been described. Further polysomnographic, controlled studies are strongly needed, particularly in DM2, in order to clarify the role of sleep disorders in the myotonic dystrophies.

Daytime sleepiness and myotonic dystrophy

Myotonic dystrophy type 1 (DM1) represents the 1 chronic neuromuscular disease with the most prominent sleep disorders, including excessive daytime sleepiness (EDS), sleep apneas, periodic leg movements during sleep, and rapid eye movement sleep dysregulation. The large majority of DM1 patients complain about EDS, which may have a deleterious impact on work, domestic responsibilities, social life, and quality of life. Here, we review the extant literature and report that studies are largely supportive of the view that DM1-related EDS is primarily caused by a central dysfunction of sleep regulation rather than by sleep-related disordered breathing (SRDB) or sleep fragmentation. The pathogenesis of EDS in DM1 still remains unclear but several arguments favor a model in which brain/brainstem nuclear accumulations of toxic expanded DM protein kinase (DMPK) gene are responsible for aberrant genes expression in modifying alternative splicing. Regarding management, early recognition, and treatment of SRDB with nocturnal noninvasive mechanical ventilation is first mandatory. However, despite its appropriate management, EDS often persists and may require a psychostimulant but no consensus has been yet established. Further studies are needed to clarify the discrepancies between daytime sleepiness/fatigue complaints and subjective/objective measurement of daytime sleepiness, the role of cognitive impairment and apathy in this relationship, and its reversibility with appropriate management.

Myotonic dystrophy type 1, daytime sleepiness and REM sleep dysregulation

Myotonic dystrophy type 1 (DM1), or Steinert's disease, is the most common adult-onset form of muscular dystrophy. DM1 also constitutes the neuromuscular condition with the most significant sleep disorders including excessive daytime sleepiness (EDS), central and obstructive sleep apneas, restless legs syndrome (RLS), periodic leg movements in wake (PLMW) and periodic leg movements in sleep (PLMS) as well as nocturnal and diurnal rapid eye movement (REM) sleep dysregulation. EDS is the most frequent non-muscular complaint in DM1, being present in about 70-80% of patients. Different phenotypes of sleep-related problems may mimic several sleep disorders, including idiopathic hypersomnia, narcolepsy without cataplexy, sleep apnea syndrome, and periodic leg movement disorder. Subjective and objective daytime sleepiness may be associated with the degree of muscular impairment. However, available evidence suggests that DM1-related EDS is primarily caused by a central dysfunction of sleep regulation rather than by sleep fragmentation, sleep-related respiratory events or periodic leg movements. EDS also tends to persist despite successful treatment of sleep-disordered breathing in DM1 patients. As EDS clearly impacts on physical and social functioning of DM1 patients, studies are needed to identify the best appropriate tools to identify hypersomnia, and clarify the indications for polysomnography (PSG) and multiple sleep latency test (MSLT) in DM1. In addition, further structured trials of assisted nocturnal ventilation and randomized trials of central nervous system (CNS) stimulant drugs in large samples of DM1 patients are required to optimally treat patients affected by this progressive, incurable condition.

Daytime sleepiness and REM sleep characteristics in myotonic dystrophy: a case-control study

STUDY OBJECTIVES

Excessive daytime sleepiness (EDS) and high daytime REM sleep pressure are important sleep features of myotonic dystrophy (DM1). Small and uncontrolled studies have focused on EDS phenotype; none have focused on nocturnal REM sleep characteristics in DM1. Our objectives were to compare polysomnographic and multiple sleep latency test (MSLT) parameters, and both tonic and phasic components of REM sleep between DM1 and controls.

DESIGN AND PATIENTS

Forty consecutive DM1 patients and 40 sex- and age-matched controls were included. All subjects underwent overnight polysomnography followed by a MSLT.

RESULTS

About 80% of DM1 patients complained of EDS through clinical interview: 31.4% had Epworth scores > 10, and 12.5% had objective sleepiness (latency < 8 min). Higher apnea and central apnea indexes, and a greater proportion of subjects with severe apnea/hypopnea syndrome were found in DM1. The number of SOREMP differed between DM1 and controls, one and two SOREMPs being present in 47.5% and 32.5%, and one control had one SOREMP. Higher percentages of slow wave sleep and REM sleep were found in DM1. DM1 patients had significantly more PLMW, PLMS in both NREM and REM sleep, and PLMS-associated microarousals. Higher REM density was found in DM1 with similar tendencies for either REM sleep without atonia or phasic EMG activity.

CONCLUSIONS

This is the first case-control sleep study in DM1 to demonstrate higher frequency of daytime sleepiness and abnormalities in REM sleep regulation, with an increased daytime and nighttime REM sleep propensity, REM density, and PLMS. These data suggest a primary central sleep regulation dysfunction in DM1.

Fatigue and daytime sleepiness in patients with myotonic dystrophy type 1: to lump or split?

We assessed the relationship and clinical correlates of fatigue and Excessive Daytime Sleepiness (EDS) in 200 myotonic dystrophy type 1 (DM1) patients by means of questionnaire and neuropsychological evaluation. Fatigue levels were higher in patients with EDS and daytime sleepiness levels higher in patients with excessive fatigue. However, EDS without fatigue was rarely observed. Also, DM1 patients with fatigue (with or without EDS) showed greater muscular impairment, CTG repeats, abnormalities regarding personality, depressive symptoms and lower health-related quality of life (HRQoL) than patients without these symptoms. These findings do not readily support the contention that fatigue and EDS constitute distinct clinical manifestations in DM1. Clinicians should systematically evaluate both symptoms since fatigue and EDS have a greater impact on HRQoL than fatigue alone. However, specific rating scales for fatigue in DM1 have yet to be devised.

Towards an integrative approach to the management of myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is the most common type of muscular dystrophy in adults. Approximately 60% of individuals report either having difficulty performing or being unable to carry out some activities related to home management, mobility and transportation, work and leisure. Employment, educational level and income are, on average, lower than in the general population. The complexity and variability of disease manifestations in DM1 undoubtedly pose a challenge as regards anticipating all potential problems and developing a plan for health and community management. This article presents a conceptual model for DM1 management as well as a brief discussion of an approach for developing interdisciplinary health and community services.

Objective measures of sleepiness and wakefulness: application to the real world?

The impact of excessive sleepiness on the individual and on society is immense, and chronic sleepiness is one of the most common complaints evaluated by sleep medicine specialists. The author explores how measures of sleepiness and wakefulness using the Multiple Sleep Latency Test (MSLT) and the Maintenance of Wakefulness Test (MWT) can be clinically useful. A companion article presents a counterpoint discussion of the limitations and drawbacks associated with the MSLT and MWT. Both presentations use an evidence-based approach to understanding the operating characteristics of these tests, and the overall goal is to clarify for sleep medicine specialists the positive and negative attributes of the MSLT and MWT. The MSLT and MWT are the most widely accepted objective measures of an individual's ability to fall asleep and ability to remain awake, respectively. The MSLT is a well-validated and extensively published objective measure of the speed at which a subject falls asleep under standardized laboratory conditions, and it is associated with good to excellent interrater and intrarater reliability, and excellent test-retest reliability. The MSLT is indicated as part of the evaluation of suspected narcolepsy and it may be helpful in differentiating narcolepsy from idiopathic hypersomnia. Mean sleep latency values less than 5 minutes are observed in the majority of subjects with narcolepsy, and the presence of two or more sleep-onset rapid eye movement periods is strongly correlated with a diagnosis of narcolepsy. An MSLT should be performed to address specific clinical questions, and should not be used as a screening tool. The MWT has clinical usefulness in evaluating response to treatment following intervention for conditions associated with excessive sleepiness, and in assessing individuals who must remain awake for safety reasons. However, the sleep medicine specialist should not rely solely on mean sleep latency values as a single indicator of impairment or risk of accidents, but findings should be integrated with the clinical history, compliance, patient judgment, and other factors to form a global impression regarding the individual's response to treatment. Future challenges include refinement of normative ranges in different populations using rigorous statistical methods, and improved understanding of the specific operating characteristics of the MSLT and MWT in different age groups. Additional study is necessary regarding the impact of MSLT and MWT findings on clinical decision-making, patient outcome, and patient and physician satisfaction. From a safety and regulatory standpoint, additional study is needed to establish the correlation between MWT findings and the risk of adverse consequences of sleepiness such as accidents. Because the MSLT and MWT are in-laboratory tests, it is important that investigators also develop novel techniques that provide reliable assessment of sleepiness and wakefulness in the actual work environment over extended periods. In summary, the MSLT and MWT are not perfect tests, but they are the best objective measures currently available for characterization of ability to fall asleep and ability to remain awake.

Excessive daytime sleepiness: an unusual presentation of myotonic dystrophy

Two middle-aged women presented with excessive daytime sleepiness. Examination revealed features of myotonic dystrophy with a positive family history. Sleep studies revealed frequent awakenings, central apnoeas with significant oxygen desaturation.

Excessive daytime sleepiness in myotonic dystrophy

The aim of the present study was to assess whether or not there is any correlation between magnetic resonance imaging (MRI) abnormalities and excessive daytime sleepiness (EDS) in a consecutive series of patients with myotonic dystrophy (MD). The influences of nocturnal breathing abnormalities and sleep morphology on EDS were also evaluated. Ten MD patients were studied by means of an all-night polysomnographic recording, the multiple sleep latency test (MSLT) and MRI. Diagnosis of MD was established on the basis of the clinical and electrophysiological evidence of myotonia as well as of the characteristic genetic pattern. No patient had respiratory failure. Polysomnography and MSLT were also evaluated in ten healthy age-matched controls under the same environmental conditions. The mean MSLT value was significantly lower in patients than in controls. Five of the ten patients were found to have pathological EDS. The quantitative sleep variables and the nocturnal apnoeas in these five patients were not significantly different from those of the patients without EDS. As two patients did not undergo MRI because of claustrophobia, the MRI data were considered in eight patients. Corpus callosum (CC) atrophy was detected in four patients, whereas three patients showed hyperintense areas in the white matter. No correlation was found between EDS and MRI indexes of subcortical atrophy as well as volume of the hyperintense areas. By contrast, a correlation was found between the MSLT value and the reduction in the anterior area of the CC. Our data suggest that CC atrophy might occur in MD patients, and that the size of the CC anterior area might be associated with EDS.

Selegiline in the treatment of hypersomnolence in myotonic dystrophy: a pilot study

Patients with myotonic dystrophy frequently complain of hypersomnolence, a symptom which seriously restricts their social life. The pathogenesis of this symptom is a matter of debate: it has been attributed to both alveolar hypoventilation and pathological changes in the brainstem. As selegiline has been shown to reduce the number of sleep attacks in nacrolepsy, we tested whether hypersomnolence in myotonic dystrophy would respond to the same treatment. Ten patients with myotonic dystrophy received selegiline/placebo (20 mg daily) in a double-blind crossover trial. We monitored daytime sleepiness by means of a multiple sleep latency test. Treatment appeared to be well tolerated but did not alter hypersomnolence in myotonic dystrophy. Further studies to assess the effect of higher doses of selegiline are warranted.

Myotonic dystrophy with alveolar hypoventilation and hypersomnia: a clinicopathological study

We present a case of myotonic dystrophy accompanied by alveolar hypoventilation and hypersomnia. Case history, pulmonary function tests, polygraphic recording, and multiple sleep latency test, concomitant with a restrictive ventilatory abnormality, suggested a central origin of alveolar hypoventilation and hypersomnia in our case. The most significant neuropathological findings were in the tegmentum of the brain stem. Severe neuronal loss and gliosis were observed in the midbrain and pontine raphe, particularly in dorsal raphe nucleus and superior central nucleus. Pontine and medullary reticular formation also showed a marked cell loss and fibrillary gliosis. The alveolar hypoventilation and the hypersomnia in our case may be attributed to these morphological abnormalities, and would appear to be central in nature.

Neuronal cell loss in the dorsal raphe nucleus and the superior central nucleus in myotonic dystrophy: a clinicopathological correlation

A quantitative study of neurons in the dorsal raphe nucleus (DRN) and the superior central nucleus (SCN) was performed in seven patients with myotonic dystrophy (MyD), five of whom showed hypersomnia, and in eight age-matched controls. The densities of neurons in the DRN and the SCN were significantly lower in MyD patients with hypersomnia than in MyD patients without hypersomnia and control subjects. There was an appreciable positive correlation in the density of neurons between the DRN and the SCN in all MyD patients. These data suggest that the neuronal loss of the DRN and the SCN is associated with the presence of hypersomnia in MyD.