Picchietti D, Allen RP, Walters AS, Davidson JE, Myers A, Ferini-Strambi L.

University of Illinois School of Medicine and Carle Clinic Association, Department of Pediatrics, 602 W University Ave, Urbana, IL 61801, USA. dpicchie@uiuc.edu

OBJECTIVES: Restless legs syndrome, a common neurologic sleep disorder, occurs in 5% to 10% of adults in the United States and Western Europe. Although approximately 25% of adults with restless legs syndrome report onset of symptoms between the ages of 10 and 20 years, there is very little literature looking directly at the prevalence in children and adolescents. In this first population-based study to use specific pediatric diagnostic criteria, we examined the prevalence and impact of restless legs syndrome in 2 age groups: 8 to 11 and 12 to 17 years. METHODS: Initially blinded to survey topic, families were recruited from a large, volunteer research panel in the United Kingdom and United States. Administration was via the Internet, and results were stratified by age and gender. National Institutes of Health pediatric restless legs syndrome diagnostic criteria (2003) were used, and questions were specifically constructed to exclude positional discomfort, leg cramps, arthralgias, and sore muscles being counted as restless legs syndrome. RESULTS: Data were collected from 10,523 families. Criteria for definite restless legs syndrome were met by 1.9% of 8- to 11-year-olds and 2.0% of 12- to 17-year-olds. Moderately or severely distressing restless legs syndrome symptoms were reported to occur > or = 2 times per week in 0.5% and 1.0% of children, respectively. Convincing descriptions of restless legs syndrome symptoms were provided. No significant gender differences were found. At least 1 biological parent reported having restless legs syndrome symptoms in > 70% of the families, with both parents affected in 16% of the families. Sleep disturbance was significantly more common in children and adolescents with restless legs syndrome than in controls (69.4% vs 39.6%), as was a history of “growing pains” (80.6% vs 63.2%). Various consequences were attributed to restless legs syndrome, including 49.5% endorsing a “negative effect on mood.” Data were also collected on comorbid conditions and restless legs diagnosis rates. CONCLUSIONS: These population-based data suggest that restless legs syndrome is prevalent and troublesome in children and adolescents, occurring more commonly than epilepsy or diabetes.

• “Motor restlessness, expressed as activity, that relieves the urge to move.”

Movement will usually bring immediate relief, however, often only temporary and partial. Walking is most common; however, doing stretches, yoga, biking, or other physical activity may relieve the symptoms. Constant and fast up-and-down movement of the leg, coined “sewing machine legs” by at least one RLS sufferer, is often done to keep the sensations at bay without having to walk. Sometimes a specific type of movement will help a person more than another.

• “Worsening of symptoms by relaxation.”

Any type of inactivity involving sitting or lying – reading a book, a plane ride, watching TV or a movie, taking a nap - can trigger the sensations and urge to move. This depends on several factors: the severity of the person’s RLS, the degree of restfulness, the duration of the inactivity, etc.

• “Variability over the course of the day-night cycle, with symptoms worse in the evening and early in the night.”

While some only experience RLS at bedtime and others experience it throughout the day and night, most sufferers experience the worst symptoms in the evening and the least in the morning.

Picchietti D, Allen RP, Walters AS, Davidson JE, Myers A, Ferini-Strambi L.

OBJECTIVES: Restless legs syndrome, a common neurologic sleep disorder, occurs in 5% to 10% of adults in the United States and Western Europe. Although approximately 25% of adults with restless legs syndrome report onset of symptoms between the ages of 10 and 20 years, there is very little literature looking directly at the prevalence in children and adolescents. In this first population-based study to use specific pediatric diagnostic criteria, we examined the prevalence and impact of restless legs syndrome in 2 age groups: 8 to 11 and 12 to 17 years. METHODS: Initially blinded to survey topic, families were recruited from a large, volunteer research panel in the United Kingdom and United States. Administration was via the Internet, and results were stratified by age and gender. National Institutes of Health pediatric restless legs syndrome diagnostic criteria (2003) were used, and questions were specifically constructed to exclude positional discomfort, leg cramps, arthralgias, and sore muscles being counted as restless legs syndrome. RESULTS: Data were collected from 10,523 families. Criteria for definite restless legs syndrome were met by 1.9% of 8- to 11-year-olds and 2.0% of 12- to 17-year-olds. Moderately or severely distressing restless legs syndrome symptoms were reported to occur > or = 2 times per week in 0.5% and 1.0% of children, respectively. Convincing descriptions of restless legs syndrome symptoms were provided. No significant gender differences were found. At least 1 biological parent reported having restless legs syndrome symptoms in > 70% of the families, with both parents affected in 16% of the families. Sleep disturbance was significantly more common in children and adolescents with restless legs syndrome than in controls (69.4% vs 39.6%), as was a history of “growing pains” (80.6% vs 63.2%). Various consequences were attributed to restless legs syndrome, including 49.5% endorsing a “negative effect on mood.” Data were also collected on comorbid conditions and restless legs diagnosis rates. CONCLUSIONS: These population-based data suggest that restless legs syndrome is prevalent and troublesome in children and adolescents, occurring more commonly than epilepsy or diabetes.

Eisensehr I, Ehrenberg BL, Noachtar S.

Department of Neurology, Klinikum Grosshadern, Ludwig-Maximilians, University of Munich, Marchioninistrasse 15, 81377, Munich, Germany. eisen@nefo.med.unio-muenchen.de

OBJECTIVE: Periodic limb movements in sleep (PLMS) may or may not be associated with restless legs syndrome (RLS). The number of PLMS is commonly used to assess the clinical severity and sleep quality of patients with RLS. It is still unclear whether the sleep disorder of periodic limb movement disorder (PLMD) is different from the sleep disorder in RLS. METHODS: We compared the polysomnograms (PSGs) of 27 prospectively recruited RLS patients and 26 retrospectively recruited age- and sex-matched PLMD patients without RLS symptoms. RESULTS: The PLM index and the index of arousal-associated PLMS (PLMAI) were significantly higher in PLMD, whereas the index of EEG arousals not associated with any sleep-related event was significantly higher in RLS. In PLMD patients, the PLMI correlated negatively with the percentage of PLMS associated with an arousal, whereas this correlation was positive in RLS patients. Further, RLS patients spent significantly more time in wake-after-sleep onset, had more rapid eye movement sleep (REM) and less sleep stage I. CONCLUSIONS: We conclude that the sleep disorder in RLS differs from that in PLMD. Spontaneous, not PLM associated EEG arousals should be included in the assessment of the sleep structure of patients with RLS, particularly in studies concerned with drug-efficacy.

Sforza E, Haba-Rubio J.

Sleep laboratory, Department of Psychiatry, University Hospital, Geneva, Switzerland. emilia.sforza@hcuge.ch

BACKGROUND AND PURPOSE: Although a night-to-night variability in periodic leg movements (PLM) occurrence has been described in patients with primary PLM disorder and sleep apnea syndrome, no study has apparently considered the inter-night effect on PLM index during wakefulness and sleep in patients with Restless Legs Syndrome (RLS). Moreover, no study has examined the night-to-night variability in PLM index according to sleep stage and time of night. We therefore examined changes in PLM index during wakefulness and sleep during two consecutive nights in a group of untreated RLS patients. PATIENTS AND METHODS: Twenty-eight drug-free RLS patients, aged 53.4+/-2.3 yr, with a mean International Restless Legs Syndrome Study Group (IRLSSG) severity score of 20.2+/-1.6, were studied during two consecutive nights. PLM duration and interval, PLM index during wakefulness (PLMWI), during total sleep time (PLMSI), as well as during each sleep stage were measured. Analysis was also extended to examine PLM occurrence during sleep cycles. RESULTS: In the group of patients as a whole, the PLMW and PLMS index, duration and interval did not show significant difference between nights, these measures being consistently similar for both nights. Comparison of PLMS index between different sleep stages did not reveal inter-night differences. Nocturnal variation in PLM number, duration and interval for total recording time and sleep period revealed a progressive decline across the night for PLM index (P</=0.0001) but no interaction, the changes being similar in first and second nights. However, a large intra-individual variability was present with a correlation coefficient between nights of 0.60 for the PLMWI (P=0.001) and 0.54 (P=0.003) for the PLMSI. The individual inter-night changes in PLM index were independent of age, IRLSSG severity score, duration of the disease and changes in sleep parameters. CONCLUSIONS: This study shows that the index and the nocturnal pattern of PLM occurrence are highly reliable across nights in RLS patients, suggesting that a single-night study may be sufficiently sensitive to confirm diagnosis and associated sleep disturbances in these patients. However, an individual inter-night variability is present, independent of age, severity and duration of the disease, which should be considered in the clinical evaluation.

Birinyi PV, Allen RP, Hening W, Washburn T, Lesage S, Earley CJ.

Department of Neuroscience, Baltimore, The Johns Hopkins University School of Art and Sciences, MD, USA.

BACKGROUND AND PURPOSE: To evaluate periodic limb movements during sleep (PLMS) in first-degree relatives of both restless legs syndrome (RLS) patients and matched controls without RLS in order to analyze patterns of this motor sign of RLS. PATIENTS AND METHODS: First-degree relatives of a consecutive case series of RLS patients and matched community controls without RLS were evaluated for diagnosis of primary RLS and for PLMS as determined by a leg activity meter. The data were analyzed to determine whether or not PLMS rates are higher than expected for RLS subjects in these families, who have mostly milder disease, and family members of early-onset RLS patients not themselves diagnosed with RLS. RESULTS: PLMS activity in family members was significantly higher for those diagnosed as RLS compared to those diagnosed as not-RLS. This difference was greater for older than younger subjects. In family members older than the median study age (52 years old) who were diagnosed as not-RLS, PLMS were significantly more frequent in those related to an early-onset RLS proband than in those related to either a control or late-onset RLS proband. CONCLUSIONS: PLMS are elevated even in those with mild RLS and reveal an age-related worsening of the motor component of RLS. PLMS may represent an incomplete expression of RLS tendencies in families of patients with early-onset RLS, but this needs to be confirmed in future longitudinal studies. The increase in PLMS with age, reported in healthy controls, may in fact occur in part as a partial expression of familial or genetic factors associated with RLS.

Whittom S, Dauvilliers Y, Pennestri MH, Vercauteren F, Molinari N, Petit D, Montplaisir J.

Sleep Disorders Center, Centre d’étude du sommeil et des rythmes biologiques, Hôpital du Sacré-Coeur de Montréal, 5400 boul. Gouin Ouest, Montréal, Que., Canada H4J 1C5; Department of Psychology, Université de Montréal, Canada.

OBJECTIVE: 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. METHODS: 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. RESULTS: Age-at-onset showed a significant bimodal distribution with a large peak occurring at 20years of age and a smaller peak in the mid-40s. Early- and late-onset RLS could be separated with a cut-off at 36years 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). CONCLUSIONS: 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.

Often sufferers think they are the only ones to be afflicted by this peculiar condition and are relieved when they find out that many others also suffer from it. The severity and frequency of the disorder vary tremendously. Many people only experience symptoms when they try to sleep, while others experience symptoms during the day. It is common to have symptoms on long car rides or during any long period of inactivity (like watching television or a movie, attending a musical or theatrical performance, etc.) Approximately 80-90% of people with RLS also have PLMD, Periodic Limb Movement Disorder, which causes slow “jerks” or flexions of the affected body part. These occur during sleep (PLMS = Periodic Limb Movement while Sleeping) or while awake (PLMW - Periodic Limb Movement while Waking).

About 10 percent of adults in North America and Europe may experience RLS symptoms, according to the National Sleep Foundation, which reports that “lower prevalence has been found in India, Japan and Singapore,” indicating that ethnic factors, including diet, may play a role in the prevalence of this syndrome

• Restlessness – An inability to sit still because the leg sensations are too annoying or painful
• Insomnia – Difficulty falling asleep or staying asleep
• Daytime sleepiness

Restless Legs Syndrome is most common in:

• Middle-aged or older people
• Women, slightly more than men
• Pregnant women during last months of pregnancy
• Relatives of people who have RLS