Periodic limb movements in sleep and periodic limb movement disorder

Neurological Sciences - Previously referred to as “nocturnal myoclonus”, periodic limb movements in sleep (PLMS) is regarded as a distinct nosologic entity, although it overlaps a great...     

Periodic limb movement disorder : a clinical and polysomnographic study.

Periodic limb movement disorder (PLMD) is one of the commonest neurological disorders and causes significant disability, if left untreated. However, it is rarely diagnosed in clinical practice, probably due to lack of awareness and/or lack of necessary diagnostic facilities. Restless leg syndrome (RLS), aging, pregnancy, uraemia, iron deficiency, polyneuropathy are some of the common causes of secondary PLMD. Clinical presentation, polysomnographic findings and management of six patients of PLMD have been discussed in this report.     

Periodic limb movement counting in polysomnography: effects of amplitude

BACKGROUND AND PURPOSE: This study investigates the relationship between periodic limb movement (PLM) counts obtained with standard scoring criteria and PLM counts scored without amplitude criterion (AC). PATIENTS AND METHODS: Twenty-four sleep laboratory patients with a PLM index (PLMI) >5 per hour of sleep in a previous polysomnography (PSG) underwent a full night of digital PSG. PLM were twice scored manually: first, according to standard criteria, and second, without AC. RESULTS: The overall PLMI for time in bed was 34.4+/-30.7 with AC and 50.2+/-36.4 without AC. The PLMI in non-rapid eye movement (NREM) sleep was 45.3+/-40.1 versus 63.4+/-47.6 (P<0.001), in REM sleep 11.5+/-15.1 versus 25.7+/-35.4 (P=0.001) and in wakefulness 29.0+/-31.1 versus 46.0+/-36.1 (P<0.001) with and without AC (Wilcoxon tests). CONCLUSIONS: In comparison to PLM counts obtained with standard criteria, PLM counts obtained without consideration of amplitude are remarkably higher. Counting without AC increases the sensitivity to detect small PLM and probably allows for identification of PLM sequences which would not have fulfilled the periodicity criteria otherwise. PLM counts without AC might be more useful to investigate the periodicity of PLM and possible changes with treatment.     

Periodic limb movement during sleep developed after pontine lesion.

We describe 2 patients who suffered a pontine infarction and subsequently developed periodic leg movement (PLM). The temporal relationship between a stroke and subsequent PLM, as well as the absence of sleep-related disorders in patients' histories, favors the argument of a cause-and-effect relationship, with the observed association providing evidence for an anatomic substrate for PLM.     

Periodic limb movements and other movement disorders in sleep: neuropsychiatric dimensions

Movement disorders such as Parkinson's disease and Tourette's syndrome, primarily manifest during wakefulness, intrude into sleep. There are some disorders, however, such as periodic limb movements in sleep, restless legs syndrome, paroxysmal nocturnal dystonia, bruxism, and somnambulism, which occur primarily during sleep. The diagnosis and management of these disorders pose a challenge to neuropsychiatric practice, not only because they may be difficult to distinguish from other neuropsychiatric disorders, but also because psychiatric disorders are often co-morbid with them. Study of these disorders is necessary for an understanding of the interaction of sleep and movement, and how disturbance in one may affect the other.     

Agreement between sleep diary and actigraphy in a highly educated Brazilian population

ObjectiveThis study evaluated the agreement between a sleep diary and actigraphy on the assessment of sleep parameters among school teachers from Brazil.MethodsA total of 163 teachers (66.3% women; aged 45 ± 9 years) filled out a sleep diary and wore a wrist actigraph device for seven consecutive days. Data were collected from August 2014 to March 2015 in Londrina, a large city in southern Brazil. Intraclass correlation coefficients (ICC) and Pearson correlation coefficients (r) were used to compare self-reported and actigraphic data.ResultsSelf-reported total sleep time (TST), sleep onset latency (SOL), and sleep efficiency were higher than measured by actigraphy (mean difference: 22.6 ± 46.9 min, 2.6 ± 13.3 min, and 7.3± 5.7%, respectively). Subjective total time in bed (TIB) and wake-up time were lower than measured by actigraphy (mean difference: −10.7 ± 37.6 and −19.7 ± 29.6, respectively). Moderate or good agreement and correlation were found between the sleep diary and the actigraphic data for TST (ICC = 0.70; r = 0.60), TIB (ICC = 0.83; r = 0.73), bedtime (ICC = 0.95; r = 0.91), sleep start time (ICC = 0.94; r = 0.88), and wake-up time (ICC = 0.87; r = 0.78). However, SOL (ICC = 0.49; r = 0.38) and sleep efficiency (ICC = 0.16; r = 0.22) showed only fair or poor agreement and correlation.ConclusionIn this highly educated population, the sleep diary and the actigraphy showed moderate or good agreement to assess several sleep parameters. However, these methods seemed to measure different dimensions of sleep regarding sleep onset latency and efficiency. These findings moderately varied according to the individual's subjective sleep quality.     

Periodic leg movements during sleep and periodic limb movement disorder in patients presenting with unexplained insomnia

ObjectiveThe aim of this study was to evaluate quantitatively the presence and the characteristics of periodic leg movements during sleep (PLMS) in a group of consecutive patients presenting with daytime impairment related to insomnia of unknown etiology and whose polysomnographic features differ from those of healthy individuals only for a significantly increased arousal index in NREM sleep.MethodsWe recruited 20 consecutive adult patients with insomnia according to the ICSD-2 criteria, 20 patients with RLS, and 12 age-matched normal controls. The time structure of their polysomnographically recorded leg movements during sleep was analyzed by means of an approach particularly able to consider their periodicity.ResultsA subgroup of 12 patients with a relatively high number of periodic LM activity was detected with a statistically based approach using two indexes: total LM index and Periodicity index. This subgroup had high PLMS index, Periodicity index was also high and PLMS showed a progressive decrease during the night, being highest in the first hours of sleep. The characteristics of PLMS were identical within this insomnia subgroup and RLS patients.ConclusionsPLMS was a common finding in our patients with insomnia and a detailed analysis of their periodicity revealed that a subgroup of these patients had to be finally diagnosed with Periodic Limb Movement Disorder.SignificancePolysomnography with the subsequent analysis of PLMS periodicity is able to differentiate between insomnia patient subgroups.     

Periodic leg movements in sleep and periodic limb movement disorder: prevalence, clinical significance and treatment

Periodic leg movements in sleep (PLMS) are a frequent finding in polysomnography. The prevalence of PLMS is estimated to be 4-11% in adults. In childhood, PLMS rarely occur although medical conditions like sleep apnea syndrome or neuropsychiatric disorders can lead to high rates of PLMS. In the elderly, PLMS are also common in subjects without sleep disturbances. In sleep studies, PLMS are found most frequently in restless legs syndrome (RLS) and often occur in narcolepsy, sleep apnea syndrome and REM sleep behavior disorder. Some patients with otherwise unexplained insomnia or hypersomnia reveal an elevated number of PLMS, a condition defined as periodic limb movement disorder (PLMD). PLMS were found also in various medical and neurological disorders that do not primarily affect sleep. A summary of these is presented. In sleep disorders related to dopaminergic dysfunction such as RLS, PLMS are considered to be a symptom of the disease. In other disorders like primary insomnia, the clinical relevance of PLMS is still being controversially discussed. Studies with findings both pro and contra are referred. To date, only a few studies have evaluated the efficacy of therapeutic substances in reducing PLMS in PLMD patients. Their results need to be confirmed in controlled randomized trials.     

Prevalence of restless legs syndrome and periodic limb movement disorder in the general population

BACKGROUND: Periodic limb movement disorder (PLMD) and restless legs syndrome (RLS) are two sleep disorders characterized by abnormal leg movements and are responsible for deterioration in sleep quality. However, the prevalence of these disorders is not well known in the general population. This study aims to document the prevalence of RLS and PLMD in the general population and to identify factors associated with these conditions. METHODS: Cross-sectional studies were performed in the UK, Germany, Italy, Portugal and Spain. Overall, 18,980 subjects aged 15 to 100 years old representative of the general population of these five European countries underwent telephone interviews with the Sleep-EVAL system. A section of the questionnaire assessed leg symptoms during sleep. The diagnoses of PLMD and RLS were based on the minimal criteria provided by the International Classification of Sleep Disorders. RESULTS: The prevalence of PLMD was 3.9% and RLS was 5.5%. RLS and PLMD were higher in women than in men. The prevalence of RLS significantly increased with age. In multivariate models, being a woman, the presence of musculoskeletal disease, heart disease, obstructive sleep apnea syndrome, cataplexy, doing physical activities close to bedtime and the presence of a mental disorder were significantly associated with both disorders. Factors specific to PLMD were: being a shift or night worker, snoring, daily coffee intake, use of hypnotics and stress. Factors solely associated with RLS were: advanced age, obesity, hypertension, loud snoring, drinking at least three alcoholic beverages per day, smoking more than 20 cigarettes per day and use of SSRI. CONCLUSIONS: PLMD and RLS are prevalent in the general population. Both conditions are associated with several physical and mental disorders and may negatively impact sleep. Greater recognition of these sleep disorders is needed.     

Periodic limb movement disorders and spells of profound muscle weakness due to airborne and dietary factors in humans

Periodic limb movement disorders and the restless legs syndrome, generally considered to be sleep disorders, have a combined prevalence of almost 10% of the general population and are more common in women than in men. Although reduced dopamine activity in central nervous system motor control pathways seems to play a role, little, other than a list of associated risk factors, is known about the conditions that initiate the episodes. We report three patients, two teenage girls and one female teacher, who developed periodic limb movement disorders associated with high mold counts in a classroom and the gymnasium in the girls' school, and in the ventilating system in the teacher's school. Their disorders occurred when they attended their schools and cleared when they did not. These findings, combined with an earlier report of three cases where the disordered movements were triggered by dietary factors, suggest that in some patients, periodic limb movement disorders may be induced by inhalant as well as by dietary factors. Although these 6 patients may represent a subgroup of people with periodic limb movement disorders, potential dietary and environmental triggers should be considered in the clinical evaluation of patients seeking treatment for periodic limb movement disorders.     

Somatization disorder in a community population

The data recently collected in the Piedmont region of North Carolina as part of the National Institute of Mental Health Epidemiologic Catchment Area Program were used to examine somatization disorder in a community population. The authors found an adjusted prevalence of 0.38% for somatization disorder diagnosed according to the Diagnostic Interview Schedule and DSM-III. Respondents with somatization disorder demonstrated demographic characteristics (female, unmarried, nonwhite, from a rural area, less educated) that are consistent with findings from past clinical and epidemiologic studies of somatization disorder. The adjusted prevalence is higher than that of other Epidemiologic Catchment Area sites, and possible explanations for this findings are discussed.     

A new limb movement detector enabling people with multiple disabilities to control environmental stimulation through limb swing with a gyration air mouse

This study assessed whether two persons with multiple disabilities would be able to control environmental stimulation using limb swing with a gyration air mouse and a newly developed limb movement detection program (LMDP, i.e., a new software program that turns a gyration air mouse into a precise limb movement detector). The study was performed according to an ABAB design, A representing baseline and B representing intervention phases. Data showed that during the intervention phases both participants significantly increased their target response to produce environmental stimulation by activating the control system through limb swing. Practical and developmental implications of the findings are discussed.     

Periodic limb movements in syringomyelia and syringobulbia.

Twenty-six patients with syringomyelia were studied with polysomnography to determine the frequency of periodic limb movements (PLM) and its relationship to the presence of a Chiari anomaly, the severity of corticospinal tract involvement, and localization of the syrinx. Sixteen patients showed PLM in stages I and II of non-REM sleep and three PLM also while awake. There were no statistically significant differences in overall disability, corticospinal signs, presence of an associated Chiari anomaly, and disease duration between patients with and without PLM, although there was a trend for patients with PLM to have more severe disease. There was preservation of the lumbosacral enlargement of the spinal cord by the syrinx in all patients with PLM. The latency delay between lower and upper limb muscles was suggestive of conduction along propriospinal pathways. Syringomyelia may lead to an abnormal state of spinal hyperexcitability favoring the appearance of PLM. Detailed magnetic resonance image studies of patients with different localizations of the syrinx cavities may help to determine which tracts are involved in the production of PLM.     

A study of cerebellar cortical involvement in motor learning using a new avoidance conditioning paradigm involving limb movement

These experiments were performed to examine the relationship between the simple and complex spike responses of 3-5 simultaneously recorded Purkinje cells during the acquisition, performance and extinction of a conditioned forelimb movement in decerebrate, unanesthetized ferrets. The data demonstrate parallel, correlated changes in simple and complex spike responses throughout the experimental period. Since the evaluated Purkinje cells were examined in the cerebellar cortical region that contains neurons highly modulated by the intermittent application of the conditioning stimulus, these findings argue against an induction of a long-lasting modification in simple spike responses by the climbing fiber input as the basis for this type of motor learning.