[Show abstract][Hide abstract] ABSTRACT: To test the hypothesis of autonomic nervous system dysfunction in patients with narcolepsy-cataplexy (NC) by assessing the physiologic activations associated with periodic limb movements during sleep (PLMS).
Sleep and heart rate (HR) were recorded during 1 night of polysomnography.
Data were collected at the Sleep Disorders Center, Sacre-Coeur Hospital, Montreal, Canada.
Data from 14 patients with NC (6 men, 8 women, mean age: 52.5 ± 11.9 years) were compared with data from 14 healthy control subjects matched for age and sex.
Analyses included sleep stages, PLMS, microarousals, RR intervals converted into beats per minute on segments lasting 25 heartbeats (10 RR intervals before PLMS and 15 after), and cardiac-activation amplitudes. A Group-by-Heartbeat interaction was noted for PLMS without microarousals; the patients had a tachycardia of lower amplitude and a delayed and lower-amplitude bradycardia, compared with normal control subjects. Similar significant HR modifications were observed for PLMS with microarousals between patients with NC and control subjects. Patients with NC had a reduced magnitude of cardiac activation associated with PLMS with and without microarousals, as compared with control subjects. A negative correlation was noted between cardiac-activation amplitude and age in patients with NC, but no correlation with PLMS index was found in either patients with NC or control subjects.
A significant reduction in the amplitude of PLMS-related HR responses in both tachycardia and bradycardia was found in patients with NC. These findings favor the physiologic relevance of the action of hypocretin on autonomic function that may be of clinical significance, i.e., increasing the risk of cardiovascular diseases.
[Show abstract][Hide abstract] ABSTRACT: A close temporal relationship was shown between the onset of melatonin secretion at night and the worsening of restless legs syndrome (RLS) symptoms, suggesting that melatonin may play a role in the genesis of this phenomenon. To test this hypothesis we studied the effects of the administration of exogenous melatonin and, conversely, the suppression of endogenous melatonin secretion by bright light exposure on the severity of RLS symptoms.
Eight RLS subjects were studied in three conditions: at baseline, after administration of melatonin and during bright light exposure. The severity of RLS symptoms was assessed by the suggested immobilization test (SIT), which allows quantification of both sensory and motor manifestations (SIT-PLM) of RLS.
Analyses showed a significant increase of SIT-PLM index when subjects received exogenous melatonin compared to both baseline and bright light conditions, but bright light exposure had no effect on leg movements compared to the baseline condition. Analyses also revealed a small but significant decrease in sensory symptoms with bright light exposure compared to baseline.
Exogenous melatonin may have a detrimental effect on motor symptoms, and bright light exposure produced small but significant improvement of leg discomfort. The study shows the interest of using the SIT to measure outcome of intervention in RLS. Further studies will be needed to assess the therapeutic value of bright light in RLS.
[Show abstract][Hide abstract] ABSTRACT: To determine the distribution of age-at-onset in a large cohort of patients with restless legs syndrome (RLS) and to compare clinical and polysomnographic characteristics of patients with early and late age-at-onset of RLS.
Two hundred and fifty patients with RLS were studied. Information on age-at-onset, etiology, familial history and symptoms severity of RLS was obtained. Age-at-onset density functions were determined from bootstrap methods and kernel density estimators.
Age-at-onset showed a significant bimodal distribution with a large peak occurring at 20 years of age and a smaller peak in the mid-40s. Early- and late-onset RLS could be separated with a cut-off at 36 years of age. Distributions of age-at-onset differed as a function of presence/absence of a familial history and etiology of RLS. Age-at-onset clearly differentiated patients with a primary RLS (early onset) from those with secondary RLS. Finally, early-onset RLS was associated with increased RLS severity with higher indices of periodic leg movements in sleep (PLMS) associated with microarousals and periodic leg movements during wakefulness (PLMW).
Early- and late-onset RLS could be distinguished depending on familial history and etiology of RLS. Our data suggest that different pathological processes are involved in these two groups, the early-onset group being highly genetically determined.
[Show abstract][Hide abstract] ABSTRACT: Several studies have demonstrated a positive correlation between periodic leg movements during sleep (PLMS) and age in healthy subjects. However, little is known about periodic leg movements during wakefulness (PLMW) in this population. Although the definitions of PLMS and PLMW specify a typical intermovement interval of 20 to 40 seconds, scoring criteria allow an intermovement interval of 4 to 90 seconds. The aim of the present study was to look at the prevalence and interval distribution of PLMS and PLMW in relationship with age in a population of healthy subjects.
Periodic leg movements were recorded during 1 night.
Sleep laboratory, Hôpital du Sacré-Coeur de Montréal.
Sixty-seven healthy subjects aged between 5 and 76 years (32 F, 35 M).
The presence of PLMS was rare before the age of 40, but then the index increased dramatically. PLMW index was higher in younger subjects compared with middle-aged subjects. Interval histograms of PLMS did not revealed a clear peak in younger subjects. With advancing age, PLMS interval histograms show a peak around 15 to 35 seconds, which is not observed in younger subjects. On the other hand, despite high indexes, PLMW interval histograms do not show a clear peak for any age group.
These results illustrate that interval evaluation is an important feature of the calculation of periodic movements to discriminate spontaneous motor activity from PLMS or PLMW.