Quantification of electromyographic activity during REM sleep in multiple muscles in REM sleep behavior disorder

STUDY OBJECTIVES: The aim of our study was to determine which muscle or combination of muscles (either axial or limb muscles, lower or upper limb muscles, or proximal or distal limb muscles) provides the highest rates of rapid eye movement (REM) sleep phasic electromyographic (EMG) activity seen in patients with REM sleep behavior disorder (RBD). SETTING: Two university hospital sleep disorders centers. PARTICIPANTS: Seventeen patients with idiopathic RBD (n = 8) and RBD secondary to Parkinson disease (n = 9). INTERVENTIONS: Not applicable. MEASUREMENTS AND RESULTS: Patients underwent polysomnography, including EMG recording of 13 different muscles. Phasic EMG activity in REM sleep was quantified for each muscle separately. A mean of 1459.6 +/- 613.8 three-second REM sleep mini-epochs were scored per patient. Mean percentages of phasic EMG activity were mentalis (42 +/- 19), flexor digitorum superficialis (29 +/- 13), extensor digitorum brevis (23 +/- 12), abductor pollicis brevis (22 +/- 11), sternocleidomastoid (22 +/- 12), deltoid (19 +/- 11), biceps brachii (19 +/- 11), gastrocnemius (18 +/- 9), tibialis anterior (right, 17 +/- 12; left, 16 +/- 10), rectus femoris (left, 11 +/- 6; right, 9 +/- 6), and thoraco-lumbar paraspinal muscles (6 +/- 5). The mentalis muscle provided significantly higher rates of excessive phasic EMG activity than all other muscles but only detected 55% of all the mini-epochs with phasic EMG activity. Simultaneous recording of the mentalis, flexor digitorum superficialis, and extensor digitorum brevis muscles detected 82% of all mini-epochs containing phasic EMG activity. This combination provided higher rates of EMG activity than any other 3-muscle combination. Excessive phasic EMG activity was more frequent in distal than in proximal muscles, both in upper and lower limbs. CONCLUSION: Simultaneous recording of the mentalis, flexor digitorum superficialis, and extensor digitorum brevis muscles provided the highest rates of REM sleep phasic EMG activity in subjects with RBD.     

Lack of effects of pramipexole on REM sleep behavior disorder in Parkinson disease

STUDY OBJECTIVES: REM sleep behavior disorder (RBD) is a common manifestation of Parkinson disease (PD) which is characterized by dream-enacting behaviors, unpleasant dreams, and loss of muscle atonia during REM sleep. Dopaminergic mechanisms are thought to play a role in RBD pathogenesis. To further asses such a role, we have evaluated the effect of pramipexole, a dopamine receptor agonist, on RBD features in PD patients. SETTING: University hospital sleep disorder center. PARTICIPANTS: Eleven PD patients with untreated RBD. interventions: Not applicable. MEASUREMENTS AND RESULTS: In a prospective study, 11 consecutive PD patients with untreated RBD on levodopa monotherapy were placed on pramipexole to further ameliorate their parkinsonism. The effects on RBD were evaluated before and 3 months after stable pramipexole therapy through patient and bed partner interviews and blind assessment of video-polysomnographic measures. Pramipexole improved parkinsonism in all patients. Patients and bed partners reported no significant changes in frequency and severity of the abnormal RBD related motor and vocal sleep behaviors or the frequency of unpleasant dreams. Video-polysomnography analyses showed no differences in RBD related sleep measures including tonic submental electromyographic activity, phasic submental electromyographic activity, percentage of REM sleep time spent with abnormal behaviors, and severity of the abnormal behaviors detected on the videotapes. CONCLUSION: In PD, pramipexole improved parkinsonism but did not modify RBD related symptoms and objective video-polysomnographic abnormalities. This observation suggests that in PD, dopamine mechanisms do not play a central role in the pathogenesis of RBD.     

A quantitative statistical analysis of the submentalis muscle EMG amplitude during sleep in normal controls and patients with REM sleep behavior disorder

The aim of this study was to evaluate quantitatively the amplitude of the submentalis muscle EMG activity during sleep in controls and in patients with idiopathic REM sleep behavior disorder (RBD) or with RBD and multiple system atrophy (MSA). We recruited 21 patients with idiopathic RBD, 10 with MSA, 10 age-matched and 24 young normal controls. The average amplitude of the rectified submentalis muscle EMG signal was used for the assessment of atonia and a Sleep Atonia Index was developed; moreover, also chin muscle activations were detected and their duration and interval analyzed. The Sleep Atonia Index was able to distinguish clearly REM from NREM sleep in normal controls with values very close to 1 in young normal subjects and only slightly (but significantly) lower in old controls. Idiopathic RBD patients showed a further significant decrease of this index; MSA patients showed the lowest values of REM Sleep Atonia Index, which were very well distinguishable from those of normal controls and of idiopathic RBD patients. The distribution of the duration of chin activations was monomodal in all groups, with idiopathic RBD patients showing the highest levels. This study is a really quantitative attempt to provide practical indices for the objective evaluation of EMG atonia during REM sleep and of EMG activations. Our proposed Sleep Atonia Index can have a practical application in the clinical evaluations of patients and represents an additional useful parameters to be used in conjunction with the other criteria for the diagnosis of this sleep motor disorder.     

Searching for a marker of REM sleep behavior disorder: submentalis muscle EMG amplitude analysis during sleep in patients with narcolepsy/cataplexy

STUDY OBJECTIVES: To evaluate the amplitude of submentalis muscle EMG activity during sleep in patients with narcolepsy/cataplexy with or without REM sleep behavior disorder (RBD). DESIGN: Observational study with consecutive recruitment. SETTINGS: Sleep laboratory. PATIENTS: Thirty-four patients with narcolepsy/cataplexy and 35 age-matched normal controls. MEASUREMENTS AND RESULTS: Half the patients (17 subjects) had a clinical and video polysomnographic diagnosis of RBD. The average amplitude of the rectified submentalis muscle EMG signal was used to assess muscle atonia, and the new REM sleep Atonia Index was computed. Chin muscle activations were detected and their duration and interval analyzed. REM sleep Atonia Index was lower in both patient groups (with narcolepsy patients with RBD showing the lowest values) with respect to controls, and it did not correlate with age as it did in controls. The total number of chin EMG activations was significantly higher in both patient groups than controls. No significant differences were found between the two groups of patients, although more chin EMG activations were noted in narcolepsy patients with RBD than those without. CONCLUSIONS: Elevated muscle activity during REM sleep is the only polysomnographic marker of RBD. This study shows that polysomnographically evident RBD is present in many patients with narcolepsy/ cataplexy. This condition might be specific to narcolepsy/cataplexy, reflecting a peculiar form of REM sleep related motor dyscontrol (i.e., status dissociatus), paving the way to enacting dream behaviors, and correlated with the specific neurochemical and neuropathological substrate of narcolepsy/cataplexy.     

Time structure analysis of leg movements during sleep in REM sleep behavior disorder

STUDY OBJECTIVES: To compare the time structure of leg movements (LM) during sleep of patients with rapid eye movement (REM) sleep behavior disorder (RBD) with that of patients with restless legs syndrome (RLS) or control subjects. DESIGN: The polysomnographically recorded tibialis anterior activity during sleep was analyzed by means of a new approach able to consider duration, intermovement interval, sleep stage and time of night distribution, and periodicity. PATIENTS AND PARTICIPANTS: Twenty patients with idiopathic RBD, 37 with idiopathic RLS and 14 age-matched control subjects were consecutively recruited. MEASUREMENTS AND RESULTS: Most patients with RBD (85%) presented periodic leg movements during sleep (PLMS). PLMS occurred more frequently during non-REM sleep in patients with RLS and during REM sleep in patients with RBD. PLMS were shorter in duration, less often bilateral, and with a higher intermovement interval in patients with RBD compared to those with RLS. The number of PLMS decreased across the night in patients with RBD and in those with RLS, but not in control subjects. In all subjects, LM periodicity clearly depended on sleep state, with higher values during non-REM than during REM sleep. Patients with RBD showed a lower LM periodicity, compared with patients with RLS, in each of the sleep states. CONCLUSIONS: Significant differences, together with some similarities in LM time structure, were observed between patients with RBD and those with RLS; for this reason, our approach seems to indicate that their phenotype might be dependent on 2 factors: disease and sleep stage.     

123I-MIBG cardiac scintigraphy provides clues to the underlying neurodegenerative disorder in idiopathic REM sleep behavior disorder

OBJECTIVE: RBD is considered to be a manifestation of an evolving synucleinopathy, such as Parkinson disease (PD), dementia of Lewy bodies (DLB), and multiple system atrophy (MSA). We tested whether the degree of accumulation of cardiac 123I-MIBG scintigraphy can distinguish the clinical syndromes associated with Lewy body-related disease from the syndrome of PSP (a tauopathy) and MSA. DESIGN: Cross-sectional. SETTING: University-based sleep disorders laboratory. PATIENTS: Subjects comprised 95 patients (31, idiopathic RBD; 26, PD; 10, MSA; 6, DLB; 13, progressive supranuclear palsy [PSP]) and 9 control subjects. INTERVENTION: To compare tracer uptake of cardiac 123I-MIBG between idiopathic RBD, PD, MSA, DLB, and PSP and control subjects. MEASUREMENTS AND RESULTS: Cardiac 123I-MIBG accumulation was evaluated by the heart/mediastinum (H/M) ratio. Mean value of the H/M ratio (early, delayed) was significantly reduced in patients with idiopathic RBD compared to MSA patients, PSP patients, control subjects (P < 0.001 in each group) and PD patients in early images (P < 0.05). There was a correlation between the H/M ratio and disease duration in the idiopathic RBD group. ROC analysis revealed that an H/M cut-off value of 1.9 was useful for differentiating RBD from MSA and PSP as well as distinguishing control subjects from those with RBD in both early and delayed images. CONCLUSION: Cardiac 123I-MIBG findings are similar among idiopathic RBD and the syndromes of PD and DLB, but differ from those of PSP and MSA.     

Cognitive dysfunction and REM sleep behavior disorder: Key findings in the literature and preliminary longitudinal findings

A considerable proportion of subjects initially diagnosed with idiopathic REM sleep behavior disorder (iRBD) are reported to convert to a neurodegenerative disorder, mainly synucleinopathies.     

Increased muscle activity during sleep and more RBD symptoms in H1N1-(Pandemrix)-vaccinated narcolepsy type 1 patients compared with their non-narcoleptic siblings

Study ObjectivesNarcolepsy type 1 (NT1) is characterized by unstable sleep-wake and muscle tonus regulation during sleep. We characterized dream enactment and muscle activity during sleep in a cohort of post-H1N1 NT1 patients and their siblings, and analyzed whether clinical phenotypic characteristics and major risk factors are associated with increased muscle activity.MethodsRBD symptoms and polysomnography m. tibialis anterior electromyographical signals [long (0.5–15 s); short (0.1–0.49 s)] were compared between 114 post-H1N1 NT1 patients and 89 non-narcoleptic siblings. Association sub-analyses with RBD symptoms, narcoleptic symptoms, CSF hypocretin-1 levels, and major risk factors [H1N1-(Pandemrix)-vaccination, HLA-DQB1*06:02-positivity] were performed.ResultsRBD symptoms, REM and NREM long muscle activity indices and REM short muscle activity index were significantly higher in NT1 patients than siblings (all p < 0.001). Patients with undetectable CSF hypocretin-1 levels (<40 pg/ml) had significantly more NREM periodic long muscle activity than patients with low but detectable levels (40–150 pg/ml) (p = 0.047). In siblings, REM and NREM sleep muscle activity indices were not associated with RBD symptoms, other narcolepsy symptoms, or HLA-DQB1*06:02-positivity. H1N1-(Pandemrix)-vaccination status did not predict muscle activity indices in patients or siblings.ConclusionIncreased REM and NREM muscle activity and more RBD symptoms is characteristic of NT1, and muscle activity severity is predicted by hypocretin deficiency severity but not by H1N1-(Pandemrix)-vaccination status. In the patients’ non-narcoleptic siblings, neither RBD symptoms, core narcoleptic symptoms, nor the major NT1 risk factors is associated with muscle activity during sleep, hence not indicative of a phenotypic continuum.