Sleep-related periodic leg movements (nocturnal myoclonus) due to spinal cord lesion

Dopamine and the spinal cord in restless legs syndrome: Does spinal cord physiology reveal a basis for augmentation?

The pathophysiology of restless legs syndrome (RLS) is incompletely understood. L-DOPA, as the precursor of dopamine, as well as dopamine agonists, plays an essential role in the treatment of RLS leading to the assumption of a key role of dopamine function in the pathophysiology of RLS. Periodic limb movements in sleep are a key feature of RLS. They are generated in the spinal cord. Here we review RLS phenomenology on the basis of known dopaminergic influence on spinal control, which has been studied a great deal in recent decades in animals. In particular, we propose that the differential effects of l-DOPA and opioids on early and late flexor reflexes may be linked to the phenomenon of augmentation.

Spinal myoclonus after spinal cord injury

BACKGROUND/OBJECTIVE

In the course of examining spinal motor function in many hundreds of people with traumatic spinal cord injury, we encountered 6 individuals who developed involuntary and rhythmic contractions in muscles of their legs. Although there are many reports of unusual muscle activation patterns associated with different forms of myoclonus, we believe that certain aspects of the patterns seen with these 6 subjects have not been previously reported. These patterns share many features with those associated with a spinal central pattern generator for walking.

METHODS

Subjects in this case series had a history of chronic injury to the cervical spinal cord, resulting in either complete (ASIA A; n = 4) or incomplete (ASIA D; n = 2) quadriplegia. We used multi-channel electromyography recordings of trunk and leg muscles of each subject to document muscle activation patterns associated with different postures and as influenced by a variety of sensory stimuli.

RESULTS

Involuntary contractions spanned multiple leg muscles bilaterally, sometimes including weak abdominal contractions. Contractions were smooth and graded and were highly reproducible in rate for a given subject (contraction rates were 0.3-0.5 Hz). These movements did not resemble the brief rapid contractions (ie, "jerks") ascribed to some forms of spinal myoclonus. For all subjects, the onset of involuntary muscle contraction was dependent upon hip angle; contractions did not occur unless the hips (and knees) were extended (ie, subjects were supine). In the 4 ASIA A subjects, contractions occurred simultaneously in all muscles (agonists and antagonists) bilaterally. In sharp contrast, contractions in the 2 ASIA D subjects were reciprocal between agonists and antagonists within a limb and alternated between limbs, such that movements in these 2 subjects looked just like repetitive stepping. Finally, each of the 6 subjects had a distinct pathology of their spinal cord, nerve roots, distal trunk, or thigh; in 4 of these subjects, treatment of the pathology eliminated the involuntary movements.

CONCLUSION

The timing, distribution, and reliance upon hip angle suggest that these movement patterns reflect some elements of a central pattern generator for stepping. Emergence of these movements in persons with chronic spinal cord injury is extremely rare and appears to depend upon a combination of the more rostrally placed injury and a pathologic process leading to a further enhancement of excitability in the caudal spinal cord.

The restless legs syndrome

The restless legs syndrome (RLS) is one of the commonest neurological sensorimotor disorders at least in the Western countries and is often associated with periodic limb movements (PLM) during sleep leading to severe insomnia. However, it remains largely underdiagnosed and its underlying pathogenesis is presently unknown. Women are more affected than men and early-onset disease is associated with familial cases. A genetic origin has been suggested but the mode of inheritance is unknown. Secondary causes of RLS may share a common underlying pathophysiology implicating iron deficiency or misuse. The excellent response to dopaminegic drugs points to a central role of dopamine in the pathophysiology of RLS. Iron may also represent a primary factor in the development of RLS, as suggested by recent pathological and brain imaging studies. However, the way dopamine and iron, and probably other compounds, interact to generate the circadian pattern in the occurrence of RLS and PLM symptoms remains unknown. The same is also the case for the level of interaction of the two compounds within the central nervous system (CNS). Recent electrophysiological and animals studies suggest that complex spinal mechanisms are involved in the generation of RLS and PLM symptomatology. Dopamine modulation of spinal reflexes through dopamine D3 receptors was recently highlighted in animal models. The present review suggests that RLS is a complex disorder that may result from a complex dysfunction of interacting neuronal networks at one or several levels of the CNS and involving numerous neurotransmitter systems.

Changes in cerebral and autonomic activity heralding periodic limb movements in sleep

BACKGROUND AND PURPOSE

Periodic limb movement disorder (PLMD) is frequently accompanied by awakenings or signs of EEG arousal. However, it is matter of debate whether EEG arousals trigger leg movements or both EEG arousal and leg movements are separate expressions of a common pathophysiological mechanism. Previous studies showed that cardiac and cerebral changes occur in association with periodic limb movements (PLMs), and that a combining increase in delta activity and in heart rate (HR) occurs before the onset of PLMs.

PATIENTS AND METHODS

This paper presents some preliminary data, obtained from a sample of 5 subjects with PLMD not associated to restless legs syndrome. To describe the temporal pattern of cardiac and EEG activities changes concomitant with PLMs in NREM sleep we used time frequency analysis technique.

RESULTS

PLM onset is heralded by a significant activation of HR and delta activity power, beginning 4.25 and 3 s respectively before PLMs onset, with PLMs onset and arousal onset falling together.

DISCUSSION

Delta and HR variations herald PLMs and activation of fast EEG frequencies. Such a stereotyped pattern is common in PLMs and in spontaneous or stimuli-induced arousals. Moreover a similar pattern seems to encompass the CAP phenomenon. The whole of these phenomena can be linked to the activity of a common brainstem system, which receives peripheral inputs, regulating the vascular, cardiac and respiratory activities and synchronizing them to cortical oscillations of EEG.

Influence of sleep stage and wakefulness on spectral EEG activity and heart rate variations around periodic leg movements

OBJECTIVE

Typical changes in spectral electroencephalographic (EEG) activity and heart rate (HR) have been described in periodic leg movements (PLM) associated with or without microarousals (MA). We aimed to determine the effects of sleep stage and wakefulness on these responses to ascertain whether a common pattern of EEG and HR activation takes place.

METHODS

The time course of EEG spectral activity and HR variability associated with PLM was analysed in 13 patients during light NREM sleep, rapid-eye-movement (REM) sleep and wakefulness. The same analysis was also conducted for PLM without MA occurring in stage 2.

RESULTS

A significant EEG and electrocardiogram (ECG) activation was found associated with PLM during sleep, but not during wakefulness. While in light NREM sleep, an increase in delta and theta bands was detected before the PLM onset, in REM sleep the EEG activation occurred simultaneously with the PLM onset. Moreover, during stage 1 and REM sleep, alpha and fast frequencies tended to remain sustained after the PLM onset. In contrast, during wakefulness, a small and not significant increase in cerebral activity was present, starting at the PLM onset and persisting in the post-movement period. A typical pattern of cardiac response was present during NREM and REM sleep, the autonomic activation being lesser and prolonged during wakefulness.

CONCLUSIONS

We conclude that the EEG and HR responses to PLM differ between sleep stages and wakefulness with lesser changes found during wakefulness.

SIGNIFICANCE

These findings suggest that specific sleep state-dependent mechanisms may underlie the occurrence of PLM.

Occurrence of limb movement during sleep in rats with spinal cord injury

Several studies have shown the occurrence of Periodic Leg Movement (PLM) in spinal cord injury patients. The aim of this study was to identify the occurrence of limb movements during sleep in spinal cord injury rats and the possible involvement of the spinal cord in causing these movements. The animals were allocated to spinal cord injury (SCI) and SHAM groups. The two groups were submitted to surgery and electrodes inserted to analyze sleep patterns (electroencephalogram-ECoG) and muscular activity patterns (eletromyogram-EMG). After baseline sleep recording (24 h), the spinal cord injury surgery (level T9) was performed on the SCI group rats and sleep was recorded for seven consecutive days. After spinal cord injury, 10 of the 11 rats began to present limb movements during sleep, while the SHAM group showed no limb movements during the 8-day sleep-recording period. In relation to sleep efficiency, the SCI group presented alterations during the first few days after spinal cord injury but returned to normal values at the end of the 7-day experimental period. The data suggest that spinal cord injury rats may be used as models to study PLM in paraplegic patients, and that these movements may be generated in the spinal cord itself, without the involvement of the cortical structures.

Neurophysiological investigations in restless legs syndrome and other disorders of movement during sleep

Besides polysomnographic techniques, other neurophysiological methods have been utilized in order to understand the pathophysiology of restless legs and periodic limb movement syndromes. By using electromyography with nerve conduction velocity (EMG-CV) and somatosensory evoked potentials (SEPs) it has been possible to determine how frequently each muscle was involved in periodic limb movements, how frequently EMG activity started in a given muscle and the time delay and pattern of activation between the first and the other activated muscles. The etiology of symptoms does not involve structural lesions since brainstem and spinal pathways are intact. Recent evidence from paired transcranial magnetic stimulation suggests that the pathophysiological key in sleep motor disorders is a modified global excitability of corticospinal pathways. The next neurophysiological goal will be to localize the unresolved anatomical level of sleep disorder movement generators and to describe their mechanism.

Comparison between dopaminergic agents and physical exercise as treatment for periodic limb movements in patients with spinal cord injury

STUDY DESIGN

Randomized controlled trial of physical exercise and dopaminergic agonist in persons with spinal cord injury and periodic leg movement (PLM).

OBJECTIVE

The objective of the present study was to compare the effectiveness of physical exercise and of a dopaminergic agonist in reducing the frequency of PLM.

SETTING

Centro de Estudos em Psicobiologia e Exercício. Universidade Federal de São Paulo, Brazil.

METHODS

A total of 13 volunteers (mean age: 31.6+/-8.3 years) received L-DOPA (200 mg) and benserazide (50 mg) 1 h before sleeping time for 30 days and were then submitted to a physical exercise program on a manual bicycle ergometer for 45 days (3 times a week).

RESULTS

Both L-DOPA administration (35.11-19.87 PLM/h, P<0.03) and physical exercise (35.11-18.53 PLM/h, P<0.012) significantly reduced PLM; however, no significant difference was observed between the two types of treatment.

CONCLUSIONS

The two types of treatment were found to be effective in the reduction of PLM; however, physical exercise is indicated as the first treatment approach, while dopaminergic agonists or other drugs should only be recommended for patients who do not respond to this type of treatment.

Restless legs syndrome: an overview of the current understanding and management

Over the last few years, major progress in research has improved our understanding of the restless legs syndrome (RLS). Although frequently under-diagnosed, several epidemiological studies have estimated its prevalence in western countries at 4-10% of the general population. Its diagnosis is usually made on a clinical basis, according to the criteria established by the International RLS Study Group (Mov Disord 1995; 10:634). Furthermore, major advances have also been achieved regarding our understanding of the pathophysiology of the disorder. Thus, several brain imaging studies, as well as pharmacological challenges, suggest the presence of a dopaminergic dysfunction playing a major role in its causation. In addition, a strong association has been discovered between brain iron deficiency and RLS. Eventually, dopaminergic drugs have shown therapeutic efficacy in various large-scale therapeutic trials, and, today, dopaminergic agonists represent the first line of treatment. In conclusion, these and other recent findings shed light on our understanding and management of one of the most common movement disorders.

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.

Neurophysiological study of corticomotor pathways in restless legs syndrome

OBJECTIVE

To test the variations in cerebral motor excitability in patients with primary restless legs syndrome (RLS) by using electrophysiological techniques. In RLS patients periodic legs movements (PLMs) in sleep and wake have been described and it is hypothesised that PLMs result from a sleep-related disinhibition of descending central motor inhibitory pathways. Moreover, in primary RLS, these modifications are still debated.

METHODS

In 15 patients with primary RLS, transcranial magnetic stimulation (TMS) was carried out using several paradigms, particularly paired pulse TMS with short interstimulus intervals (ISI) in abductor digiti minimi (ADM) and tibialis anterior (TA) muscles.

RESULTS

Short ISI paired TMS showed a significant decrease in inhibition and increase in facilitation in ADM muscles. This result was even more evident in TA muscles of patients as compared to the controls and these modifications were more evident in the limbs which were more affected by PLM. Moreover, intracortical (corticocortical) inhibition (ICI) and intracortical facilitation (ICF) unchanged their biphasic time course.

CONCLUSIONS

In our study the changes in short paired-pulse ICI and ICF revealed the presence of an altered excitability of central motor pathways, with good correlation with asymmetric distribution of symptoms.

Different sleep characteristics in restless legs syndrome and periodic limb movement disorder

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.

Reduction of periodic leg movement in individuals with paraplegia following aerobic physical exercise

PURPOSE

According to the American Association of Sleep Disorders, periodic leg movements (PLM) are classified into the group of intrinsic sleep disorders. Studies on PLM in individuals with spinal cord injury are very recent. The objective of the present study was to assess the efficacy of aerobic training in reducing the index/score of PLM in individuals with complete spinal cord injury.

METHODS

Twelve male volunteers with complete spinal cord injury between T7 and T12 were submitted to six polysonographies (PSG Oxford Medilog SAC system; EEG, EMG and EOG: (1) basal night, (2) 12 h after a maximum effort test, (3) 36 h after a maximum effort test, (4) after 44 days of aerobic physical training, (5) 12 h after the last training session, and (6) 36 h after the last training session. All volunteers participated in a physical training program for 44 days using an arm crank ergometer. Data were analyzed statistically by the Wilcoxon test, with the level of significance set at alpha5%.

RESULTS

The results demonstrated a statistically significant reduction (P < or = 0.05) in the comparison of first evaluation (35.1 PLM/h) with fifth (12.70 PLM/h) and sixth evaluation (18.5 PLM/h).

CONCLUSION

This study suggests that a program of regular and systematized physical activity promotes an effective reduction of PLM in individuals with spinal cord injury.

Motor pattern of periodic limb movements in sleep in idiopathic RLS patients

OBJECTIVE

Periodic limb movements in sleep (PLMS) are recurrent sleep-related movements that often occur in association with restless legs syndrome (RLS). The purpose of the present study was to examine the pathophysiology of PLMS in patients with idiopathic RLS.

METHODS

Ten patients with idiopathic RLS who were medication-free or who had withdrawn from medication at least 2 weeks prior to the study underwent an extensive neurophysiological investigation that included nocturnal video-polysomnographic recording (VPSG), EMG recording, and the Multiple Sleep Latency Test (MSLT). Sleep efficiency and PLMS index were calculated during VPSG.

RESULTS

All patients had an increased PLMS index, decreased sleep efficiency, and a pathological MSLT score. Leg muscles were the first to be activated, often with alternation of side, and no constant recruitment pattern could be found from one episode of PLMS to another, even in the same patient. No ordinate caudal or rostral spread of the EMG activity was observed.

CONCLUSIONS

The results suggest that there are different, independent, and unsynchronized generators for PLMS. The direct participation of the cerebral cortex in the origin of PLMS is unlikely, suggesting that abnormal spinal cord hyperexcitability may act as the primary cause of PLMS, triggered by unidentified sleep-related factors.

Clinical and electrophysiologic correlates of quantitative sensory testing in patients with incomplete spinal cord injury

OBJECTIVE

To determine the degree of association among indices of preserved sensation derived from quantitative sensory testing (QST), somatosensory evoked potentials (SEPs), and the clinical characteristics of patients with spinal cord injury (SCI).

DESIGN

A controlled correlational study of diverse measures of preserved sensory function.

SETTING

Regional SCI rehabilitation center in Ontario, Canada.

PARTICIPANTS

Thirty-three patients with incomplete SCI and 14 able-bodied controls.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

QST measures of perceptual threshold for temperature and vibration, American Spinal Injury Association sensory scores (light touch, pinprick), and tibial nerve SEPs.

RESULTS

There was a low degree of association (kappa) between QST results and sensory scores (|kappa|=.05-.44). QST measures yielded greater numbers of patients with SCI being classified as impaired, suggesting a greater sensitivity of QST to detect more subtle sensory deficits. QST measures of vibration threshold generally corresponded to the patients' SEP recordings. QST measures of modalities conveyed within the same tract were significantly (P<.05) correlated (|r|=.46-.84) in patients with SCI, but not in controls, whereas those modalities mediated by different pathways had lower and generally nonsignificant correlations (|r|=.05-.44) in both patients and controls.

CONCLUSIONS

The low degree of association between QST measures and sensory scores is likely attributable to measurement limitations of both assessments, as well as various neuroanatomic and neuropathologic factors. QST provides more sensitive detection of preserved sensory function than does standard clinical examination in patients with incomplete SCI.

Characteristics of sleep apnea syndrome in tetraplegic patients

OBJECTIVE

To include a larger number of tetraplegics than in previous studies, in order to more reliably characterize the pathogenesis and predisposing factors of sleep apnea in tetraplegia.

METHODS

Sleep breathing data and oxymetric values were investigated in 50 randomly selected tetraplegic patients and discussed in context with age, gender, BMI, neck circumference, type and height of lesion, time after injury, spirometric values and medication. A non-validated short questionnaire on daytime complaints was added.

RESULTS

Thirty-one patients out of 50 had an RDI > or =15, defined as sleep disordered breathing (SDB); 24 of them combined with an apnea index of 5 or more, these cases were diagnosed as sleep apnea syndrome (SAS). SAS was apparent in 55% and 20% of the studied men and women, respectively. Regression analyses showed no significant correlation between RDI and lesion level, ASIA impairment scale or spirometric values. In contrast, a significant correlation between RDI and age, BMI, neck circumference and time after injury could be shown. Kruskal-Wallis test for dichotomous non-parametric factors, such as gender, cardiac medication and daytime complaints, showed significant differences with regard to RDI. In contrast to able-bodied people with SAS, daytime complaints were only present in tetraplegic patients with severe pathology (RDI>40).

CONCLUSION

Incidence of SAS is high in tetraplegia, particularly in older male patients with large neck circumference, long standing spinal cord injury and under cardiac medication. As tetraplegics with RDI between 15 and 40 reported no daytime complaints and often have normal BMI, these tetraplegics are not clinically suspicious for SAS. The increased use of cardiac medication in tetraplegics with SAS may implicate a link between SAS and cardiovascular morbidity, one of the leading causes of death in tetraplegia.

Avaliação do padrão e das queixas relativas ao sono, cronotipo e adaptação ao fuso horário dos atletas brasileiros participantes da paraolimpíada em Sidney - 2000

Diversas metodologias têm sido desenvolvidas para investigar a qualidade e as principais queixas e distúrbios relacionados ao sono. Uma forma conhecida de investigar as características temporais dos organismos é a cronobiologia, ciência divide a população em três cronotipos básicos para avaliar as diferenças individuais na prevalência pelos horários de vigília e de sono: os matutinos, os vespertinos e os indiferentes. Outro ponto importante, é que existem poucos estudos relacionando o padrão do sono em indivíduos com necessidades especiais e a atividade física. O sono é considerado como restaurador e o exercício está associado diversas alterações no padrão de sono. A maioria dos estudos referente ao feito do exercício sobre o sono podem ser abordados ou correlacionados com a teoria de restauração das funções do sono. O objetivo deste estudo foi o de avaliar o padrão, queixas relativas ao sono, cronotipo e adaptação ao fuso horário de Sidney dos atletas brasileiros que disputaram a paraolimpíada em 2000. Participaram da avaliação 64 atletas paraolímpicos, com idades de 26,3 (± 5,9). Todos os atletas responderam aos questionários de padrão e queixas relativas ao sono e cronotipo, passando também por uma adaptação ao fuso horário de Sidney. Oprocesso de sincronização ao fuso horário foi realizado de forma abrupta, na tentativa de romper com o ciclo claro-escuro que estava relacionado ao horário brasileiro. Os resultados demonstram que 34,4% dos atletas apresentavam uma insatisfação com o seu próprio sono, sendo que os distúrbios de sono mais relatados foram: apnéia (14%), refluxo gástrico (15,6%), dor de cabeça (14,1%), ansiedade pós-pesadelo (39,1%), caimbras (20,3%), sonilóquio (26,6%), pânico noturno (9,4%), PLM (9,4%) e bruxismo (9,4%). Em relação a avaliação do cronotipo dos atletas, 73,43% se demonstraram indiferentes, 6,22% vespertinos moderados e 20,31% matutinos moderados. Observou-se boa aceitação com todo o trabalho e o mesmo deve ter contribuído e refletido nos resultados finais dos jogos, visto que a equipe paraolímpica obteve um excelente resultado final.

Effects of apomorphine on flexor reflex and periodic limb movement

It has been suggested that periodic leg movements (PLM) and spinal flexor reflex (FR) share common mechanisms. Although dopaminergic agents improve PLM in humans and strongly influence spinal FR circuitry in animal studies, its effects on FR have not been documented in humans. We describe a 65-year-old man with PLM after overnight withdrawal of dopaminergic agents. The electromyographic pattern of spontaneous PLM closely resembled that of the FR elicited by medial plantar nerve stimulation. Thirty minutes after subcutaneous injection of apomorphine, both PLM and FR were completely abolished. These findings demonstrate that dopaminergic agents can suppress exaggerated FR in humans, and support the hypothesis of common mechanisms for PLM and FR.

Sleep and periodic limb movements in corticobasal degeneration

Corticobasal degeneration (CBD) exhibits distinct features of akinesia, the 'alien limb' sign and cortical myoclonus. We report a 63-year old woman with a history of CBD for 18 months who was studied twice using all-night polysomnography with an interval of 13 months. Both recordings revealed frequent periodic arm and leg movements predominantly during non-REM sleep. To our knowledge this has not been described in a patient with CBD so far. Similar to a previous report we found REM sleep without atonia (RWA) in all REM episodes. However, the patient showed RWA and some non violent movements that fulfilled the diagnosis of subclinical REM sleep behavior disorder only in the second investigation. These observations may be due to the underlying degenerative process that involves not only cortical but also thalamic and brainstem structures.

Restless legs syndrome: a review of clinical and pathophysiologic features

Restless legs syndrome (RLS), although long ignored and still much underdiagnosed, disrupts the life and sleep considerably of those who have it. Recent clinical and basic research provides for better definition and pathophysiologic understanding of the disorder. The body of knowledge about this disorder has been expanding rapidly during the past decade and it has altered our concepts of this disorder. This review of RLS covers history, diagnosis, morbidity of sleep disturbance, relation to periodic limb movements in both sleep and waking, secondary causes, severity assessment methods, phenotypes for possible genetic patterns, epidemiology, pathophysiology, and medical treatment considerations. The emphasis on pathophysiology includes consideration of central nervous system localization, neurotransmitter and other systems involved, and the role of iron metabolism. Studies to date support the authors' recently advanced iron-dopamine model of RLS.

Sleep laboratory studies in periodic limb movement disorder (PLMD) patients as compared with normals and acute effects of ropinirole

Periodic limb movement disorder (PLMD) occurs in a variety of sleep disorders and can cause insomnia as well as hypersomnia with daytime somnolence. The aim of this study was to investigate 12 untreated PLMD patients as compared with 12 normal controls and to measure the acute effects of 0.5 mg ropinirole (Requip((R))) - a non-ergoline dopamine agonist - as compared with placebo. In three nights (adaptation, placebo, ropinirole night) objective and subjective sleep and awakening quality were evaluated. In the target variable 'periodic leg movements per hour of sleep' (PLM/(hTST)) PLMD patients showed an increased value of 42/h (normal 0-5/h) with a greater number of arousals due to periodic leg movements (PLM) in sleep. They further demonstrated an increased number of awakenings, sleep stage S1, S4, stage shifts and decreased S2, but there were no significant differences concerning total sleep time, sleep efficiency (SE), subjective sleep quality and morning measures of mood, drive and drowsiness. However, measures of attention variability, numerical memory, fine motor activity and reaction time performance were impaired. Ropinirole 0.5 mg was shown to significantly improve the index PLM/(hTST) by 64% and arousals due to PLM, increase spontaneous arousals, REM-latency, stage 2 and stage shifts and decrease SREM. In the morning attention variability was attenuated and numerical memory augmented. Thus, ropinirole improved some sleep architecture and early morning measures of performance but specifically all PLM variables, which suggests a dopaminergic pathogenesis in PLMD. Copyright 2001 John Wiley & Sons, Ltd.

Periodic arm movements in patients with the restless legs syndrome

A high proportion of patients with restless legs syndrome (RLS) also complain of arm paresthesia but the presence of periodic arm movements (PAM) has never been documented in a sleep laboratory in these patients. We investigated the prevalence of PAM during nocturnal sleep and awakenings in 22 RLS patients. Fifteen patients had a PAM index >5 movements per hour during wakefulness and among them only 3 had a PAM index >5 during sleep. Twenty patients had a periodic leg movement (PLM) index >5 during wakefulness and 17 had a PLM index >5 during sleep. In 42.8% of cases, PAM showed temporal relationship with PLM during wakefulness. These results show that PAM is frequent in RLS and suggest that the basic neurological dysfunction responsible for RLS is probably not located exclusively at the level of the lumbar spinal cord but involves neuronal systems located at upper levels.

CSF dopamine, serotonin, and biopterin metabolites in patients with restless legs syndrome

PURPOSE

To evaluate the role of CNS dopaminergic systems in Restless Legs Syndrome (RLS), homovanillic acid (HVA), tetrahydrobiopterin (BH4), and neopterin (NEOP), were assayed in CSF from RLS patients. The serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA), was also measured.

METHODS

CSF was taken from 16 RLS patients after 2 weeks off medication and from 14 control subjects. The CSF metabolites were determined using HPLC techniques.

RESULTS

There was no significant difference in HVA or 5-HIAA, but NEOP and BH4 were higher in RLS patients. The RLS group was significantly older than the control group (64.2 +/- 9.2 years vs. 51.4 +/- 6.3 years; P < 0.001). A multiple regression analysis showed a strong correlation between age and 5-HIAA (r = 0.46, P = 0.04) and between age and NEOP (r = 0.61, P < 0.01). To eliminate the potential error created by the age difference between groups, an age-adjusted subgroup of RLS and control subjects were compared. There was still no difference found for HVA; however, 5-HIAA was now significantly lower (P < 0.01) in the RLS subgroup. Age-adjustment eliminated the differences previously found for NEOP, (P = 0.12), but BH4 continued to remain higher in the RLS group (P < 0.01).

CONCLUSION

Differences in CSF HVA concentrations were not found. The changes in 5-HIAA and BH4 are of unclear clinical significance and require further assessment with appropriate age-matched controls.

Sleep laboratory studies in restless legs syndrome patients as compared with normals and acute effects of ropinirole. 2. Findings on periodic leg movements, arousals and respiratory variables

The restless legs syndrome (RLS) is a common sensorimotor disorder which leads to severe sleep disturbances and showed a prevalence of 7.9% in our sleep laboratory. The aim of this study was to investigate periodic leg movements (PLM), arousal and respiratory variables in 12 untreated RLS patients and to measure the acute effects of 0.5 mg ropinirole, a nonergoline dopamine agonist, as compared with placebo. In the target variable PLM/h of total sleep time (PLM/h TST), RLS patients showed an increased value of 40/h (normal 0-5/h). Further, we found an increased number of PLM (368), PLM/h of time in bed (49/h), PLM/h of REM sleep (11), PLM/h of non-REM sleep (46) and PLM/h awake (61). The arousal index was also increased (32/h; normal 0-25/h), as were arousals due to PLM. In the confirmatory part of our descriptive data analysis, ropinirole 0.5 mg significantly improved, as compared with placebo, the index PLM/h TST by 75%. In the descriptive part, all the other PLM variables were improved as well. Arousals due to PLM decreased, while spontaneous arousals increased. Respiratory variables, which had a priori been in the normal range, showed a slight but significant improvement after the dopamine agonist. Thus, 0.5 mg ropinirole significantly improved the target variable PLM/h TST, along with objective and subjective sleep quality and morning noopsychic performance, as described in the preceding paper. Our data encourage further sleep studies including all above-mentioned variables in a larger group of RLS/PLM during sleep patients as well as long-term efficacy trials.

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.

The influence of sex, age and sleep/wake state on characteristics of periodic leg movements in restless legs syndrome patients

Restless legs syndrome (RLS) patients experience periodic stereotyped leg movements while awake and during sleep. The aim of the present study was to measure the effects of sex, age and the sleep/wake state on several characteristics (frequency, duration and periodicity) of these periodic leg movements (PLM). One hundred unrelated patients diagnosed with primary RLS were studied. During wakefulness, frequency of PLM increased and the mean inter-movement interval decreased with advancing age. The modal value of inter-movement interval distribution was also altered suggesting that aging influences rhythm-generation mechanisms. Sleep/wake states had a profound effect on leg movement characteristics. Movements of longer duration were seen during wakefulness, while REM sleep was characterized by the shorter duration and the lowest frequency of PLM, due most likely to the inhibition of spinal motoneurons that prevails in REM sleep. States of vigilance also modulated the periodicity of PLM. Intervals were shorter during wakefulness and increased progressively from stage 1 to stage 2 sleep, and to slow wave sleep (SWS). During REM, the duration of sleep intervals returned to values obtained in stage 1 sleep; these two stages sharing similar patterns of EEG activity. These results indicate that a single state dependent mechanism may be responsible for the periodicity of PLM noted both during sleep and wakefulness.

Positron emission tomographic studies in restless legs syndrome

We studied six restless legs syndrome (RLS) patients with [F18]fluorodeoxyglucose (FDG) positron emission tomography (PET). We also studied four of these same patients with [F18]fluorodopa (FDOPA) PET. The patients' FDG and FDOPA PET scans were compared with those from age-matched healthy control subjects. No significant differences between the two groups were found for any regional blood flow values derived from the FDG scans or for any binding constants derived from the FDOPA scans. These results suggest that any abnormal resting brain metabolic activity or putative presynaptic dopaminergic defect in RLS is likely either to be so subtle that it is below the threshold for ready detection by PET or that it is located in an area of neural tissue inaccessible to the current scanner. No substantial defect is likely to involve the dopaminergic nigrostriatal axis.

Neural control of locomotion; The central pattern generator from cats to humans

In the last years it has become possible to regain some locomotor activity in patients suffering from an incomplete spinal cord injury (SCI) through intense training on a treadmill. The ideas behind this approach owe much to insights derived from animal studies. Many studies showed that cats with complete spinal cord transection can recover locomotor function. These observations were at the basis of the concept of the central pattern generator (CPG) located at spinal level. The evidence for such a spinal CPG in cats and primates (including man) is reviewed in part 1, with special emphasis on some very recent developments which support the view that there is a human spinal CPG for locomotion. Copyright 1997 Elsevier Science B.V.

Parasomnias including the restless legs syndrome

The three states of mammalian being, W, REM sleep, and NREM sleep, are not mutually exclusive, and may occur simultaneously, oscillate rapidly, or appear in dissociated or incomplete form to produce primary sleep parasomnias. In addition, dysfunctions of a wide variety of organ systems may take adwide variety of organ systems may take advantage of the sleeping state to declare themselves, resulting in secondary sleep parasomnias. Contrary to popular opinion, the majority of the often bizarre and frightening experiences are not the manifestation of underlying psychological or psychiatric conditions. There is an interesting interaction between sleep-disordered breathing and parasominas. Formal study in an experienced sleep disorders center will usually reveal a diagnosable and treatable condition that explains the spells. Continued study of unusual sleep-related events undoubtedly will reveal more fascinating conditions, expanding our knowledge of sleep physiology, and strengthening the bonds between clinicians and basic-science sleep researchers.

Restless legs and periodic leg movements in sleep syndromes

Restless legs syndrome (RLS) is a common sensorimotor disorder with an estimated prevalence of between 1% and 5%. The symptomatology is characterized by unpleasant sensations experienced predominantly in the legs and rarely in the arms. The symptoms occur only at rest and become more pronounced in the evening or at night. In addition, the patients suffer from a strong urge to move the limbs, typically manifest as walking around, which leads to complete but only temporary relief of the symptoms. Most of the patients with RLS have periodic leg movements (PLMS) during sleep and relaxed wakefulness that are characterized by repetitive flexions of the extremities. PLMS can occur as an isolated phenomenon, but often they occur together with other sleep disorders including RLS, narcolepsy, sleep apnoea syndrome or REM sleep behaviour disorder. In all these disorders, PLMS, contribute considerably to disturbed sleep, as the movements may lead to brief arousals or repeated full awakenings. The aetiology of RLS and PLMS is unknown. It is hypothesized that periodic leg movements result from a suprasegmental disinhibition of descending inhibitory pathways. Based on the efficacy of the drugs listed below, the dopaminergic, adrenergic and opiate systems are thought to play a major role in the pathogenesis of RLS/PLMS. Since the cause is unclear, therapy of RLS and PLMS remains symptomatic except for some secondary forms. Studies on the pharmacological treatment of RLS have shown the efficacy of levodopa, dopamine agonists, benzodiazepines, opioids, clonidine and carbamazepine. With regard to the drug treatment of PLMS in other sleep disorders including their isolated occurrence, indications and efficacy have been poorly defined until now.

Sleep-related periodic leg movements associated with spinal cord lesions

We describe three patients who developed progressive paraparesis and sleep-related periodic leg movements (SRPLM) associated with thoracic spinal cord lesions; one patient had a schwannoma and two had intramedullary lesions. The patients showed periodic repetitive involuntary movements involving one or both lower limbs. The involuntary movements consisted of a single rapid dorsiflexion of the great toe or ankle, two to four repetitive dorsiflexions of the toes and ankle, and a mixture of repetitive jerks and prolonged spasms causing flexion of the hip and knee and dorsiflexion of the ankle and toes. In the patient with a schwannoma, paraparesis and SRPLM improved completely after surgical removal of the mass lesion. In one patient the SRPLM associated with an intramedullary lesion improved markedly after levodopa treatment. We suspect that thoracic spinal lesions partially disinhibit the lumbosacral generator. Such disinhibition seems to be enhanced by the activation of the neuronal systems related to periodic somatic and vegetative phenomena during sleep.

Periodic limb movements and restless legs syndrome

The criteria that characterize restless legs syndrome (RLS) and the differential diagnoses are discussed. Clinical signs include sleep disturbance, involuntary movements in sleep or wakefulness, a normal neurologic examination, a chronic clinical course, and, in some cases, a positive family history. Periodic limb movements during sleep, which also may occur as an isolated finding, may or may not cause frequent arousals or awakenings. Clinical diagnosis of idiopathic or symptomatic forms of RLS can be supported with polysomnography. Treatment of first choice consists of dopaminergic drugs or dopamine agonist followed by opioids or benzodiazepines.

The cyclic alternating pattern plays a gate-control on periodic limb movements during non-rapid eye movement sleep

Periodic limb movements in sleep (PLMS) is a disorder characterized by a cyclic pattern of motor phenomena and EEG changes (mostly arousals), both recurring at approximately 20- to 40-s intervals. The periodicity of the PLMS phenomena recalls the physiological EEG arousal rhythm of non-rapid eye movement (NREM) sleep known as the cyclic alternating pattern (CAP). During CAP, arousals and arousal-equivalent features do not appear as isolated events but periodically intrude (phase A) between intervals of background EEG activity (phase B). Though the A phases can be expressed by a variety of EEG patterns, each with a different arousal impact on polygraphic parameters, overall CAP is a sequence of biphasic cycles reflecting a condition of unstable sleep. Twelve middle-aged PLMS subjects complaining of poor sleep were polygraphically compared with 12 age-matched and gender-matched healthy volunteers (controls). With respect to controls, the PLMS recordings showed an enhancement of the more powerful arousals and presented significantly increased amounts of CAP time (+45 min) and CAP rate (+15%). Of all the jerks detected in NREM sleep, 92% occurred in CAP, with the great majority of limb movements (96%) associated with phase A. Ninety-four percent of the nocturnal jerks coupled with phase A started jointly with the onset of the phase or when the latter had already begun. In particular, most of the myoclonic events (67%) occurred in the first 2.5 s of the A phase. The CAP cycles coupled with periodic movements were significantly longer than those without motor events (+6.4 s). Compared to the American Sleep Disorders Association's rules for scoring EEG arousals, the CAP framework offers a more extensive insight into PLMS. In effect, the present study indicates an entrainment of nocturnal myoclonus by means of CAP and sheds light on the complex interactions between arousal mechanisms and motor phenomena during sleep.

Incidence of periodic leg movements and of the restless legs syndrome during sleep following acute physical activity in spinal cord injury subjects

The purpose of the present study was to evaluate sleep patterns and complaints, and Periodic Limb Movement (PLM) and the Restless Legs Syndrome (RLS) in subjects with complete spinal cord injury. Volunteers were submitted to two polysomnograms (Oxford Medilog SAC system--EEG, EMG, EOC): (1) basal night, when the volunteer arrived at the Sleep Center, and (2) after a maximal physical test (Cybex Met 300/increase of 12.5 watts/2 min until exhaustion). Eleven volunteers with complete spinal cord injury between T7-T12 were evaluated. Data were analyzed by the paired Student's test (total sleeping time) and by the Wilcoxon matched paired test (change of sleep states, number of awakenings during sleep, latency to REM sleep and leg movements--PLM + RLS). Comparison of sleep recordings from the night before with that from the night after (12 h) practice of physical activity, showed a significant reduction in all of the sleep parameters. The results indicate that physical activity improves the sleep patterns of spinal cord injured volunteers. In particular, we noticed that PLM and RLS after physical activity were inhibited during sleep.

Electrophysiological pattern of involuntary limb movements in the restless legs syndrome

Patients with restless legs syndrome (RLS) suffer from involuntary limb movements during the day. We studied these leg movements in 18 idiopathic (n = 8) and uremic (n = 10) patients at rest. Electromyographically measured muscle contractions were preceded by sensory discomfort in all patients. The mean duration of the contractions ranged between 0.67 and 5.71 s with a mean frequency of 244 epochs of muscle activity per hour. Seven of 18 patients showed a constant order of recruitment with propagation of muscle activity up or down spinal segments (L3 to S1 and vice versa). No difference in electrophysiologically recorded patterns was observed between patients with idiopathic and uremic RLS. We suggest a brainstem disinhibition phenomenon as the pathological mechanism that activates a spinal generator. The spinal origin of the involuntary limb movements in patients with RLS is confirmed by the long duration of jerks, the recruitment characteristics, and the periodicity of the jerks. No jerk could be elicited by sensory reflexes.

Toward a better definition of the restless legs syndrome. The International Restless Legs Syndrome Study Group

A large International Restless Legs Syndrome (RLS) Study Group has been formed. As its first task, the group has taken upon itself the role of defining the clinical features of the RLS. As minimal criteria for diagnosis, the group proposes the following four features: (a) desire to move the extremities, often associated with paresthesias/dysesthesias; (b) motor restlessness; (c) worsening of symptoms at rest with at least temporary relief by activity, and (d) worsening of symptoms in the evening or night. Other features commonly seen in RLS include sleep disturbance, periodic limb movements in sleep and similar involuntary movements while awake, a normal neurological examination in the idiopathic form, a tendency for the symptoms to be worse in middle to older age, and, in some cases, a family history suggestive of an autosomal dominant mode of inheritance.

Nocturnal sleep study in multiple sclerosis: correlations with clinical and brain magnetic resonance imaging findings

It has been suggested that sleep disturbances in multiple sclerosis (MS) may be related to periodic leg movements (PLM) during sleep, but to date polysomnographic studies were conducted only on small and unselected patient groups. Aim of this study was to evaluate 8-hour polysomnography in MS patients and to correlate sleep results with clinical and brain magnetic resonance imaging (MRI) data. Twenty-five clinically definite MS patients, without mood disorders and drug-free, entered the study. The patients were compared to 25 age- and sex-matched subjects. MS patients had significantly reduced sleep efficiency and experienced more awakenings during sleep. No difference was found in sleep architecture parameters between MS patients and controls. PLM was found in 9 patients (36%) and 2 controls (8%; p = 0.02). Of the six patients who complained of insomnia two had PLM and 2 others presented with PLM and central sleep apnea. In patients with PLM greater MRI lesion loads were detected in the infratentorial regions, particularly in cerebellum and brainstem. Larger studies in neurological diseases that produce focal lesions in these brain areas could provide useful information on the PLM pathogenesis.