A Quantitative Study of Electroencephalography, Eye Movements and Neck Electromyography Characterizing the Sleep—Wake Cycle of the Guinea-pig

The qualitative and quantitative characteristics of cerebral cortex electrical activity, ocular motility and muscular activity were studied in six head-restrained guinea-pigs during wakefulness, slow-wave and paradoxical sleep. Animals were chronically implanted with bipolar electrodes in the obliquus capitis muscle for electromyographic recordings and epidurally through the parietal bones for electroencephalographic (EEG) recordings. Eye movements were recorded using the scleral search-coil technique. After postoperative recovery and a short period of habituation to immobilization, head-restrained animals exhibited a polyphasic sleep–wake cycle similar to what has already been described in the unrestrained guinea-pig. Paradoxical sleep periods of mean duration 110 ± 42 s occurred at a mean interval of 32.2 ± 7.2 min. Amplitude and frequency components of EEG activity were different for each state of vigilance. EEG amplitude was highest and frequency range lowest—with two well-defined peaks at 4 and 10 Hz—during slow-wave sleep. During paradoxical sleep, frequencies were higher and amplitudes lower than during wakefulness. Three types of eye movement intermingled with periods of ocular fixation were recorded: saccadic movements during wakefulness and paradoxical sleep, slow drifts during slow-wave sleep and paradoxical sleep, and a new type of eye movement—bursts of high-velocity eye oscillations during paradoxical sleep. Saccadic eye movements during paradoxical sleep were more frequent and showed higher velocities and amplitudes than during wakefulness. During paradoxical sleep the episodes of eye oscillation (8–14 Hz) occurred quite regularly every 1.6 s and had a mean duration of 1.4 s. During wakefulness, the obliquus muscle activity displayed a burst-tonic pattern. Bursting components were closely related to saccadic eye movements directed to the side of the recorded muscle. The muscle activity was predominantly tonic during slow-wave sleep and was completely absent during paradoxical sleep except for small bursts or twitches. These twitches were tightly synchronized with the occurrence of the rapid eye movements oriented towards the side of the recorded obliquus muscle, as during wakefulness. These results strongly suggest that paradoxical sleep is characterized by the oscillatory discharge of at least two neuronal populations: the brainstem saccadic generators and the tecto-reticular spinal network which underlies gaze-orienting behaviour during wakefulness. The occurrence of rhythmic discharges at ?11 Hz may explain the spinal motoneurons’ inhibition during paradoxical sleep in order to avoid anarchic motor behaviour. Whether these neuronal oscillations are simply an epiphenomenon or have functional implications remains to be determined.     

Temporal coupling of rapid eye movements and cerebral activities during REM sleep

ObjectivesWe investigated event-related potentials time locked to the onset and offset of rapid eye movements during rapid eye movement (REM) sleep.MethodNine healthy university students participated in this study. Data were collected in a sleep laboratory. Rapid eye movements during REM sleep were recorded during natural nocturnal sleep. Saccades during wakefulness were recorded during a visually triggered task. Event-related potentials were averaged, time-locked to the onset and offset of eye movements.ResultsDuring REM sleep, a lambda-like response occurred over the occipital region, time-locked to the offset of rapid eye movements (similar to what occurs during wakefulness). Moreover, we found that a positive potential (P200r) occurred at about 200 ms, with the maximal amplitude over the central region and time-locked to the onset of rapid eye movements during REM sleep; this potential was not observed during wakefulness.ConclusionsDuring REM sleep, the P200r occurs with the start of rapid eye movements, and then the lambda-like response occurs after termination of the movements.SignificanceWe demonstrated temporal coupling of rapid eye movements and cerebral activities during REM sleep. These activities might provide a useful basis for future investigations of brain functions during REM sleep.     

Periodic leg movements in RLS patients as compared to controls: Are there differences beyond the PLM index?

ObjectiveTo characterize periodic leg movements (PLM) and their association with sleep disturbances in drug-free patients with restless legs syndrome (RLS) and healthy subjects without sleep complaints.MethodsPolysomnographic recordings of 95 patients with idiopathic RLS and 31 age-matched controls were compared, and correlation analysis between sleep efficiency and PLM variables was performed. All patients and controls were free of medication for 10 days prior to polysomnography.ResultsPLM measures revealed a significantly longer mean duration of single PLM during wakefulness and non rapid eye movement (NREM) sleep in RLS patients as compared to controls. PLM indices were higher in RLS patients than in controls during all sleep stages, but not during wakefulness and slow wave sleep. A significantly higher number of PLM sequences was found in RLS patients than in controls. In RLS patients decreased sleep efficiency was associated with a higher number and a shorter duration of PLM sequences.ConclusionsThe mean duration of single PLM might be an appropriate parameter to discriminate between healthy subjects with PLM and patients with RLS. High numbers of PLM sequences of short duration might be an indicator for the decreased sleep quality in RLS patients.     

Lower number of K-complexes and K-alphas in sleep bruxism: a controlled quantitative study.

OBJECTIVES: Although patients with sleep bruxism (SB) show a higher incidence of rhythmic masticatory muscle activity (RMMA) during sleep than matched normal controls, they are good sleepers. Sleep macrostructure (e.g. total sleep time, sleep latency, number of awakenings or sleep stage shifts and sleep stage duration) is similar between groups. Differences in sleep microstructure between SB patients and normals have been investigated only in few studies. The aim of the present study was to quantify number of microarousals, K-complexes, K-alphas, EEG spindles, and the density of slow wave activity, in both groups, in order to better understand the pathophysiology of SB. METHODS: Ten normal sleepers were matched for age and gender with 10 patients who exhibited frequent tooth-grinding during sleep. Using quantitative polysomnographic measures, we compared the above-mentioned sleep variables in both groups. Data are presented as indices for total sleep and for consecutive non-rapid eye movement (non-REM) episodes over non-REM to rapid eye movement (REM) cycles and per hour of sleep. RESULTS: SB patients showed 6 times more RMMA episodes per hour of sleep than normals (P<0.001), with a higher frequency in the second and third non-REM to REM cycles. SB patients presented 42.7% fewer K-complexes per hour of stage 2 sleep, but only normals showed a decline from the first to fourth non-REM episode. Only 24% of SB-RMMA episodes were associated with K-complexes in 60 s. The number of K-alphas was 61% lower in SB patients, no change across non-REM episodes was noted. While no difference in electroencephalographic (EEG) spindles or slow wave activity (SWA) was observed between groups, EEG spindles increased and SWA decreased linearly over consecutive non-REM to REM cycles. CONCLUSIONS: According to our observations, good sleep in SB patients is characterized by a low incidence of K-complexes or K-alphas and by the absence of any difference in other sleep microstructure variables or SWA.     

First night effect on polysomnographic sleep bruxism diagnosis varies among young subjects with different degrees of rhythmic masticatory muscle activity

ObjectiveThis study investigated the first night effect on the polysomnographic diagnosis of sleep bruxism (SB).MethodsPolysomnographic recordings were performed for two consecutive nights in forty-three subjects (mean age 23.7 ± 0.32 years [range: 20.0–33.0]). Sleep variables and rhythmic masticatory muscle activity (RMMA) were scored for two nights. The diagnosis of SB was graded by the frequency of RMMA with cut-off values of two and four times per hour of sleep.ResultsParticipants were classified into control (n = 15), low (n = 13) and moderate-high (n = 15) groups. Among the three groups, the concordance of the SB diagnosis was compared between the two nights. Sleep variables showed a significant first-night effect with lower sleep efficiency, longer sleep latency and higher frequency of arousals. The frequency of RMMA significantly increased from the first to the second night in the moderate-high SB group only. The concordance rate of the severity between the two nights was 93.3% (14/15) in the control group, 76.9% (10/13) in the low SB group and 60% (9/15) in the moderate-high SB group. When the severity was determined on the first night, it remained the same on the second night in 77.8% (14/18) of the control group, 66.7% (10/15) of the low SB group and 90.0% (9/10) of the moderate-high SB group.ConclusionThe results showed that the first night effect on the occurrence of RMMA differed among the different degrees of the RMMA frequency, and suggest that, due to the first night effect, single-night polysomnography may underestimate the moderate-high level of SB but differentiate the low level of SB from controls.     

Time trends and periodic cycles in REM sleep eye movements.

Eye movements during REM sleep episodes were tabulated in 16 young adults. REM episodes were then broken down into four ranges according to length in min: (1) 11.0-21.3; (2) 21.7-29.7; (3) 30.0-42.3; (4) 42.7 or longer. These data were then analyzed for linear and quadratic trends. Eight episodes had a significant linear trend, 10 had a significant quadratic trend, 7 had both linear and quadratic trends, while 12 had no trend. The residuals from the best-fitting polynomial curve were then subject to a spectral analysis. In addition, 2 long periods of pre-sleep wakefulness (approximately 2 h each) were also analyzed. In general, the spectral analysis revealed the dominant presence of a slow cycle (period of 10 min to about 30 min) the exact period of which varied according to the length of the REM episode. A binomial probability test indicated that the presence of slow cycles was significant in REM episodes except for those in the 21-30 min range. For the episodes of wakefulness, a dominant slow cycle was found in both cases. The results give the impression of similarity in the periodic organization of eye movements during REM sleep and waking. The data also indicated that an ultradian (70-150 min) cycle was present in eye movements during sleep and waking. Further, the finding of a decrease in eye movements before sleep onset, coupled with previous reports of an increase in eye movement after sleep onset, indicate the presence of a circadian cycle.     

Stridor combined with other sleep breathing disorders in multiple system atrophy: a tailored treatment?

ObjectivesTo determine the frequency of sleep breathing disorders in multiple systemic atrophy (MSA, combining Parkinsonism, cerebellar syndrome, and dysautonomia) and evaluate the benefit/tolerance of various modes of ventilation.MethodsWe retrospectively analyzed 45 patients with MSA having undergone a videopolysomnography. Their sleep characteristics were compared to those of 45 patients with Parkinson's disease and 45 healthy controls, matched for age and sex. Patients with MSA received fixed continuous positive airway pressure (CPAP) when stridor was isolated, auto-adjusting CPAP when it was combined with obstructive sleep apnea, and adaptive servo-ventilation (ASV) when combined with central sleep apnea.ResultsHigher periodic leg movements index and more frequent REM sleep behavior disorder were observed in MSA patients, compared to patients with Parkinson's disease and healthy controls. In MSA, 28/45 (62.2%) patients had sleep breathing disorders, including (overlapping samples) stridor (n = 17, 38%), obstructive sleep apnea (n = 14, 31%), central sleep apnea (n = 4, 9%), and ataxic breathing (n = 1). Except for three initial refusals and two yet untreated patients, fixed CPAP (n = 9), auto-adjusting CPAP (n = 8) and ASV (n = 2) were well-tolerated (limited leaks and good compliance) and successfully controlled stridor plus sleep apnea. Treated patients had survival times similar to those of patients without any sleep breathing disorder.ConclusionIn this small group, tailored management of stridor in MSA as an independent issue or combined with obstructive and central sleep apnea, yields a survival similar to survival in patients without sleep breathing disorders.     

Challenges in sleep stage R scoring in patients with autosomal dominant spinocerebellar ataxias (SCA1, SCA2 and SCA3) and oculomotor abnormalities: a whole night polysomnographic evaluation

ObjectivesSpinocerebellar ataxias are progressive neurodegenerative disorders characterized by progressive cerebellar features with additional neuro-axis involvement. Oculomotor abnormality is one of the most frequent manifestations. This study was done to assess the polysomnographic abnormalities in patients with Spinocerebellar ataxia (SCA1, SCA2 and SCA3) and also to evaluate whether oculomotor abnormalities interfere with sleep stage R scoring.MethodsThe study was carried out using 36 genetically positive SCA patients. All patients underwent neurological examination with special focus on oculomotor function (optokinetic nystagmus-OKN and extraocular movement restriction-EOM). The sleep quality was measured with Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS). Disease severity was assessed with International Cooperative Ataxia Rating Scale (ICARS). All the patients underwent over-night video-polysomnography (VPSG).ResultsOut of 36 patients studied, the data of 34 patients [SCA1 (n = 12), SCA2 (n = 13), SCA3 (n = 9)] were used for final analysis. Patients from SCA1, SCA2, and SCA3 category did not show significant differences in age and diseases severity (ICARS). All patients had vertical OKN impairment. Oculomotor impairment was higher in SCA2 patients. Sleep macro-architecture analysis showed absent stage R sleep, predominantly in SCA2 (69%) followed by SCA3 (44%) and SCA1 (8%). Patients showed a strong negative correlation of stage R sleep percentage with disease severity and oculomotor dysfunction.ConclusionVoluntary saccadic eye movement velocity and rapid eye movements (REMs) in sleep are strongly correlated. The more severe the saccadic velocity impairment, the less likely was it to generate REMs (rapid eye movements) during stage R. Accordingly 69% of SCA2 patients with severe occulomotor impairments showed absent stage R as per the AASM sleep scoring. We presume that the impaired REMs generation in sleep could be due to oculomotor abnormality and has resulted in spuriously low or absent stage R sleep percentage in SCA patients with conventional VPSG scoring rules. The present study recommends the modification of AASM scoring rules for stage R in patients with oculomotor abnormalities.     

Leg movements during wakefulness in restless legs syndrome: time structure and relationships with periodic leg movements during sleep

Background and objectiveApproximately one third of patients with restless legs syndrome (RLS) also show periodic leg movements (PLM) during relaxed wake fulness (PLMW). In contrast with the large amount of data published on periodic leg movements during sleep (PLMS), PLMW have received less attention from the scientific community. The objective of this study was to evaluate the correlations/differences of time–structure and response to a dopamine-agonist between PLMW and PLMS in patients with RLS.MethodsNinety idiopathic RLS patients and 28 controls were recruited. Subjects underwent clinical and neurophysiological evaluation, hematological screening, and one or two consecutive full-night polysomnographic studies. A subset of patients received 0.25 mg of pramipexole or placebo before the second recording. Polysomnographic recordings were scored and LM activity was analyzed during sleep and during the epochs of wakefulness occurring during the first recording hour.ResultsRLS patients had higher LM activity during wakefulness than controls, but with a similar periodicity. Even if correlated, the ability of the PLMW index to predict the PLMS index decreased with increasing LM activity. Intermovement intervals during wakefulness showed one peak only at approximately 4 s, gradually decreasing with increasing interval in both patients and controls. The effect of pramipexole was very limited and involved the small periodic portion of LM activity during wakefulness.ConclusionsPLMW index and PLMS index were correlated; however, the magnitude of this correlation was not sufficient to suggest that PLMW can be good predictors of PLMS. Short-interval LM activity during wakefulness and sleep might be linked to the severity of sleep disruption in RLS patients and the differences between their features obtained during wakefulness or sleep might be relevant for the diagnosis of sleep disturbances in RLS.     

Spontaneous nystagmus across the sleep-wake cyc̀le in vegetative state patients

The presence of spontaneous CNS nystagmus during wakefulness was documented for the first time in 6 vegetative-state (VS) patients. Nystagmus of smaller amplitude as compared to the awake state was consistently detected in each patient during stage 1 of sleep. There was complete absence of nystagmus during stage 2 and slow wave sleep (SWS) in all the patients. Clear nystagmus episodes were observed during rapid eye movement (REM) sleep in all patients. Some nystagmus episodes followed rapid eye movements (REMs), some were unrelated to REMs while others were superimposed on REMs. It is suggested that spontaneous neural activation during REM sleep may allow the episodic emergence of nystagmus during this sleep stage.     

Do periodic arm movements during sleep exist in healthy subjects? A polysomnographic study

BackgroundDespite several polysomnographic studies on periodic leg movements (PLM) in healthy sleep, data on the prevalence and characteristics of periodic arm movements (PAM) in normal subjects are lacking. We aimed to investigate PAM and their association with PLM during wakefulness and sleep in healthy subjects.MethodsNinety-one participants underwent video-polysomnography according to American Academy of Sleep Medicine 2007 criteria. In addition to standard electromyographic registration, data for both flexor digitorum superficialis muscles were recorded.ResultsSixty-two subjects (68.1%) had a PAM index during wakefulness >5/h (median PAM index during wakefulness, 8.8/h; range, 0–77). Seven subjects (7.7%) had a PAM index >5/h during sleep (median PAM index during sleep, 0.7/h; range, 0–47.4). In 14% of cases, PAM during wakefulness were coincident with PLM during wakefulness. During sleep, this coincidence was not evident. The correlation between PAM and PLM was weak to moderate (during wakefulness: Spearman's ρ = 0.576, P < 0.001; during sleep: Spearman's ρ = 0.222, P = 0.036).ConclusionIn healthy subjects, PAM occur predominantly during wakefulness with no apparent true periodicity. In contrast to classical PLM, some PAM may not present a true periodic phenomenon, but rather random voluntary movements meeting the wide range of periodicity criteria for PLM.     

Sleep disorders in Wilson’s disease

Background: Wilson’s disease (WD) is an autosomal recessive inherited disease with copper accumulation; neurodegeneration is associated with dopaminergic deficit. The aim of the study is to verify sleep co‐morbidity by questionnaire and objective sleep examinations (polysomnography, multiple sleep latency test). Methods: Fifty‐five patients with WD (22 hepatic, 28 neurological, five asymptomatic form) and 55 age‐ and sex‐matched control subjects completed a questionnaire concerning their sleep habits, sleep co‐morbidity, Epworth sleepiness scale (ESS), and answered screening questions for rapid eye movement (REM) behaviour disorder (RBD‐SQ). Twenty‐four patients with WD and control subjects underwent polysomnographic examination. Results: Unlike the controls, patients with WD were more prone to daytime napping accompanied by tiredness and excessive daytime sleepiness, cataplexy‐like episodes and poor nocturnal sleep. Their mean ESS as well as RBD‐SQ was higher than that of the controls. Total sleep time was lower, accompanied by decreased sleep efficiency and increased wakefulness. Patients with WD had lower latency of stage 1 and stage 2 of non‐rapid eye movement (NREM) sleep and less amount of NREM sleep stage 2. One‐third of the patients with WD were found to have short or borderline multiple sleep latency test (MSLT) values independent of nocturnal pathology (sleep apnoea, periodic leg movements and/or restless leg syndrome). Conclusions: Patients with WD often suffer from sleep disturbances (regardless of the clinical form). The spectrum of sleep/wake symptoms raises the suspicion that altered REM sleep function may also be involved.     

Characterization of sleep in six patients with pantothenate kinase-associated neurodegeneration

BackgroundPantothenate kinase-associated neurodegeneration (PKAN) is a rare neurologic disorder included in the group of neurodegeneration with brain iron accumulation diseases (NBIA). Information regarding sleep in patients with PKAN is limited.ObjectivesTo describe the clinical and polysomnographic characteristics of sleep in six patients with genetically confirmed PKAN.MethodsThe evaluation included a clinical interview, sleep questionnaires -Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI) and Hospital Anxiety and Depression Scale (HADS)- and a video-polysomnography (VPSG). In addition to standard sleep measures we manually quantified sleep spindle density in stage N2 and rapid eye movements in REM sleep comparing the results with matched controls. Quantification of EMG activity in REM sleep was performed following standard criteria.ResultsAll the patients reported at least one sleep complaint, most commonly sleep fragmentation (4/6) and sleep onset insomnia (3/6). ESS and PSQI were abnormal in 3/6 and 4/6, respectively. VPSG showed in 4/6 decreased ocular movements during REM sleep, an increase in sleep spindles in 3/6 (all of them with deep brain pallidal stimulation), an absence of slow wave sleep in 2 and undifferentiated NREM sleep and delayed sleep phase in one. Three patients had an abnormal sleep apnea/hypopnea index, and 2 periodic limb movements of sleep. REM sleep muscular atonia was preserved in all.ConclusionsSleep disorders are common in patients with PKAN. Although our sample is small and heterogeneous, with different symptomatic treatments possibly influencing the results, it suggests that evaluation of sleep should be considered in their management.     

Sleep bruxism and its associations with insomnia and OSA in the general population of Sao Paulo

Sleep bruxism (SB) is characterized by recurrent masticatory muscle activity during sleep with occasional tooth grinding. SB can be concomitant with sleep apnea although its association with insomnia is understudied.Study objectiveAssess the strength of the associations between SB, insomnia and sleep apnea in a general population.MethodsData from the 2007 EPISONO general population study (n = 1042; Sao Paulo, Brazil) were reused for the present analyses. The data was collected from polysomnography (PSG) and from a questionnaire. SB could only be assessed as “possible” with self-report questionnaires, but as “definitive” with both self-reports and PSG. Logistic regression and decision tree analyses were performed.ResultsLogistic regression analyses revealed that being male, overweight, obese, having an apnea/hypopnea index (AHI) above 30 and insomnia syndrome are among risk factors for SB (prevalence ratio (PR): 1.5–3.3). A high AHI and insomnia syndrome had similar PRs, 2.7 and 2.8, respectively. Decision tree analysis showed that insomnia syndrome contributed to the predictive accuracy of SB self-report (88%). A similar estimate (91%) was observed with SB PSG data. Correspondence analysis illustrated three age profiles in participants: (1) good sleepers aged 20–35 years, (2) females aged 35–50 years with SB and concomitant insomnia syndrome, and (3) participants aged ≥ 50 years with obesity and sleep apnea.ConclusionsInsomnia is likely a condition associated with SB, especially in middle-age females, while sleep apnea seems age and gender dependent. Such overlap may influence the treatment decision to achieve best outcomes.Clinical trial registrationEPISONO study; Clinical trials.gov ID # NCT00596713.     

Paroxysmal nocturnal dystonia presenting as excessive daytime somnolence

We describe the clinical and electrophysiologic findings in seven patients referred for evaluation of excessive daytime somnolence. These patients had none of the usual causes of excessive daytime somnolence but during sleep exhibited stereotypic body movements, tachycardia, respiratory disturbances, somniloquy, and transient arousals in a repetitive fashion. These episodes induced fragmentation of sleep. The polysomnograms revealed an increase in wakefulness and stage I decreased rapid eye movement during sleep in addition to the episodes of abnormal body movements. No epileptiform features were present either in the electroencephalogram or in the nocturnal polysomnogram. Four of the seven patients were treated with anticonvulsants, with both subjective and objective improvement on subsequent follow-up polysomnograms. Because of the pronounced functional deficits associated with the sleep disorder in these patients, it is of great importance to recognize the disorder and treat it appropriately.     

Systematic assessment of autonomic symptoms in restless legs syndrome

ObjectivesTo compare the clinical features of autonomic dysfunction using the SCOPA-AUT questionnaire in untreated patients with restless legs syndrome (RLS) with controls, to identify factors associated with more severe autonomic symptoms, and to assess the effect of medication in patients.MethodsThe SCOPA-AUT questionnaire that evaluates cardiovascular, gastrointestinal, urinary, thermoregulatory, pupillomotor, and sexual dysfunctions was completed by 409 consecutive untreated patients with RLS (54.1 ± 14.5 y.o; 265 women) and 331 controls (59.0 ± 17.0; 161 women). Clinical and polysomnographic data were assessed in all patients. A subgroup of 57 patients were evaluated a second time after treatment (mostly dopaminergic agonist) after an interval of 0.88 ± 1.42 year.ResultsCompared to controls, untreated patients with RLS were younger, more often women, obese, with increased cardiovascular diseases (CVD). The SCOPA-AUT total score was higher in patients than controls in unadjusted and adjusted models. Patients had more autonomic symptoms in all subdomains of the scale (except for sexual dysfunction in men). These results were confirmed in a subgroup of 259 cases and age-sex-matched controls. Female gender, obesity, RLS severity, diabetes mellitus, CVD, sleepiness, insomnia and depressive symptoms but neither periodic legs movements during sleep (PLMS) nor objective sleep parameters were associated with high scores. Despite RLS and PLMS improvement, medication did not change total and subdomain scores.ConclusionsPatients with RLS have frequent and large spectrum of autonomic symptoms, without effect of PLMS, sleep fragmentation and medication. These results suggest a global autonomic dysfunction in RLS that should be assessed more systematically in severe patients.     

Eye movements in the human fetus and newborn

The human oculomotor system becomes active long before birth. At about 16 weeks (post-menstrual age) the first slow changes of eye position can be observed with the aid of real time ultrasonography. At 18-20 weeks more rapid eye movements are detectable. There is a gradual decline in the percentage of time spent in rapid and slow eye movements from 32-40 weeks. These eye movements are organized in episodes of activity, divided by episodes of quiescence which are at first unrelated to cyclical changes in other variables (such as breathing movements, body movements and fetal heart rate patterns). At about 36 weeks gestation, REM and non-REM episodes become linked with other changes and then represent behavioural states identical to those seen in the newborn infant. This organization of behavioral states in the fetus is identical with that found in preterm infants of comparable age. Opening of eyelids is difficult to see before birth but the existence of episodes of wakefulness seems most probable. Hence fetal eye movements will be in part related to wakefulness. In the newborn at term, the interval distributions of REMs during sleep and of scanning eye movements during wakefulness are statistically different.     

Recent data on rapid eye movement sleep behavior disorder in patients with Parkinson disease: analysis of behaviors,movements, and periodic limb movements

Rapid eye movement (REM) sleep behavior disorder (RBD) is a fascinating parasomnia in which patients are able to enact their dreams because of a lack of muscle atonia during REM sleep. RBD represents a unique window into the dream world. Frequently associated with Parkinson’s disease (PD), RBD raises various issues about dream modifications in this pathology and about aggressiveness during RBD episodes in placid patients during wakefulness. Studies on these behaviors have underlined their non-stereotyped, action-filled and violent characteristics but also their isomorphism with dream content. Complex, learnt behaviors may reflect the cortical involvement in this parasomnia but the more frequent elementary movements and the associated periodic limb movements during sleep also implicate the brainstem. Surprisingly, patients with PD have an improvement of their movements during their RBD as if they were disease-free. Also not yet understood, this improvement of movement during REM sleep raises issues about the pathways involved in RBD and about the possibility of using this pathway to improve movement in PD during the day.     

Benign EEG variants in the sleep–wake cycle: A prospective observational study using the 10–20 system and additional electrodes

ObjectivesTo study the prevalence of benign EEG variants (BEVs) in the sleep–wake cycle among 1163 consecutive patients.MethodsProspective, observational EEG study using the 10–20 system with systematically two additional anterior-temporal electrodes. Depending on clinical indications, other electrodes were added. REM sleep identification was based on its characteristic EEG grapho-elements and rapid eye movements, clearly detectable with the additional anterior-temporal and fronto-polar electrodes due to eye proximity. The video-EEG monitoring duration was between 24 hours and eight days.ResultsWe identified 710 patients (61%) with BEVs. Positive occipital sharp transients of sleep (POSTs) were observed in 36.4% of participants, mu rhythm in 22.4%, lambda waves in 16.7%, wicket spikes (WS) in 15%, 14- and 6-Hz positive bursts in 8.3%, benign sporadic sleep spikes (BSSS) in 3.3%, rhythmic mid-temporal theta burst of drowsiness (RMTD) in 2.15%, midline theta rhythm in 2.1% and six-Hz spike and wave (SW) bursts in 0.1%. WS and RMTD were present during wakefulness, NREM (14.1%, 1.3%, respectively) and REM sleep (3.3%, 1.1%, respectively). Mu rhythm was also observed during NREM (1.5%) and REM sleep (7.7%). Fourteen- and 6-Hz positive bursts were present during NREM (4.5%) and REM sleep (6.5%). BSSS and six-Hz SW bursts were only observed during NREM sleep.ConclusionsThe prevalence of BEVs is much higher than current estimates. POSTs and WS can no longer be considered as unusual patterns but physiological patterns of NREM sleep. RMTD and mu rhythm may be observed during NREM and REM sleep.