Alternating Leg Muscle Activation Research Articles

Fragmentary Hypnic Myoclonus and Other Isolated Motor Phenomena of Sleep.

Excessive fragmentary hypnic myoclonus, hypnic jerks, hypnagogic foot tremor, alternating leg muscle activation, and sleep-related cramps are less known sleep-related motor disorders (SRMDs). These manifestations are frequently missed or misinterpreted polygraphic findings that can be frequently confused with the more frequent SRMDs. These symptoms can present as isolated motor symptoms but can be also the cause of otherwise cryptogenic insomnias and somnolence. Expanding the knowledge on these isolated symptoms and defining their polygraphic and clinical features are essential for their identification. However, clear cut-offs to discern between the isolated phenomenon and the disorder are still to be found.

0942 Alternating Leg Muscle Activation and Hypnagogic Foot Tremor in Children: Comparative Study of Polysomnographic and Clinico-Demographic Variables

Abstract Introduction The clinical and polysomnographic meaning of the Alternating Leg Muscle Activation (ALMA) and Hypnagogic Foot Tremor (HFT) patterns in children is not known. Methods A descriptive study was carried out to identify the prevalence and polysomnographic characteristics of ALMA and HFT sequences in a sample of 122 children sequentially admitted in the sleep laboratory, with the analysis of clinical and demographic characteristics of the ALMA/HFT group in relation to a comparison group without this condition, paired by age and gender. Results Sample prevalence was 14.8% for any HFT/ALMA event, 13.1% for ALMA and 10.7% for HFT. In the HFT/ALMA group, the mean age was 8 years old (2-12 years old), 66.7% of males. Obstructive Sleep Apnea was observed in 75% of children, but HFT / ALMA sequences only occasionally occurred in association with respiratory events. The use of medications with monoaminergic activity was associated with the occurrence of HFT/ALMA, p=0,019. There was higher N1 sleep content in the HFT / ALMA group, p=0,0301. There was no significant difference between both groups regarding the other clinical-demographic or polysomnographic parameters analyzed. Autonomic activation represented by heart rate fluctuations often occurred in association with the HFT / ALMA sequences, irrespective of the occurrence of arousals, awakenings, other motor or respiratory events. Conclusion HFT / ALMA is a frequent condition in children that are referred to the sleep lab.The stereotypy of the HFT / ALMA series suggests that their origin might be motor central pattern generators, which are potentially influenced by substances with monoaminergic effect. The finding of higher superficial sleep content in children with HFT / ALMA may indicate greater susceptibility to alteration of pediatric sleep architecture by such subtle motor events. The possibility of clinical consequences and cardiovascular diseases should be considered in relation to the association of HFT / ALMA with observed autonomic activation. Support None.

0811 Polysomnographic Characteristics of Alternating Leg Muscle Activation in Children

0811 Polysomnographic Characteristics of Alternating Leg Muscle Activation in Children

Hypnagogic Foot Tremor, Alternating Leg Muscle Activation or High Frequency Leg Movements: clinical and phenomenological considerations in two cousins

Hypnagogic Foot Tremor, Alternating Leg Muscle Activation or High Frequency Leg Movements: clinical and phenomenological considerations in two cousins

Quantifying Leg Movement Activity During Sleep.

Currently, 2 sets of similar rules for recording and scoring leg movement (LM) exist, including periodic LM during sleep (PLMS) and periodic LM during wakefulness. The former were published in 2006 by a task force of the International Restless Legs Syndrome Study Group, and the second in 2007 by the American Academy of Sleep Medicine. This article reviews the basic recording methods, scoring rules, and computer-based programs for PLMS. Less frequent LM activities, such as alternating leg muscle activation, hypnagogic foot tremor, high-frequency LMs, and excessive fragmentary myoclonus are briefly described.

Central Pattern Generator for Locomotion: Anatomical, Physiological, and Pathophysiological Considerations

This article provides a perspective on major innovations over the past century in research on the spinal cord and, specifically, on specialized spinal circuits involved in the control of rhythmic locomotor pattern generation and modulation. Pioneers such as Charles Sherrington and Thomas Graham Brown have conducted experiments in the early twentieth century that changed our views of the neural control of locomotion. Their seminal work supported subsequently by several decades of evidence has led to the conclusion that walking, flying, and swimming are largely controlled by a network of spinal neurons generally referred to as the central pattern generator (CPG) for locomotion. It has been subsequently demonstrated across all vertebrate species examined, from lampreys to humans, that this CPG is capable, under some conditions, to self-produce, even in absence of descending or peripheral inputs, basic rhythmic, and coordinated locomotor movements. Recent evidence suggests, in turn, that plasticity changes of some CPG elements may contribute to the development of specific pathophysiological conditions associated with impaired locomotion or spontaneous locomotor-like movements. This article constitutes a comprehensive review summarizing key findings on the CPG as well as on its potential role in Restless Leg Syndrome, Periodic Leg Movement, and Alternating Leg Muscle Activation. Special attention will be paid to the role of the CPG in a recently identified, and uniquely different neurological disorder, called the Uner Tan Syndrome.

Sleep-related movement disorders

Several movement disorders may occur during nocturnal rest disrupting sleep. A part of these complaints is characterized by relatively simple, non-purposeful and usually stereotyped movements. The last version of the International Classification of Sleep Disorders includes these clinical conditions (i.e. restless legs syndrome, periodic limb movement disorder, sleep-related leg cramps, sleep-related bruxism and sleep-related rhythmic movement disorder) under the category entitled sleep-related movement disorders. Moreover, apparently physiological movements (e.g. alternating leg muscle activation and excessive hypnic fragmentary myoclonus) can show a high frequency and severity impairing sleep quality. Clinical and, in specific cases, neurophysiological assessments are required to detect the presence of nocturnal movement complaints. Patients reporting poor sleep due to these abnormal movements should undergo non-pharmacological or pharmacological treatments.

Neuroethological approach to frontolimbic epileptic seizures and parasomnias: The same central pattern generators for the same behaviours

The aim of this report is not to make a differential diagnosis between epileptic nocturnal seizures and non-epileptic sleep-related movement disorders, or parasomnias. On the contrary, our goal is to emphasize the commonly shared semiological features of some epileptic seizures and parasomnias. Such similar features might be explained by the activation of the same neuronal networks (so-called ‘central pattern generators’ or CPG). These produce the stereotypical rhythmic motor sequences – in other words, behaviours – that are adaptive and species-specific (such as eating/alimentary, attractive/aversive, locomotor and nesting habits). CPG are located at the subcortical level (mainly in the brain stem and spinal cord) and, in humans, are under the control of the phylogenetically more recent neomammalian neocortical structures, according to a simplified Jacksonian model. Based on video-polygraphic recordings of sleep-related epileptic seizures and non-epileptic events (parasomnias), we have documented how a transient “neomammalian brain” dysfunction – whether epileptic or not – can ‘release’ (disinhibition?) the CPG responsible for involuntary motor behaviours. Thus, in both epileptic seizures and parasomnias, we can observe: (a) oroalimentary automatisms, bruxism and biting; (b) ambulatory behaviours, ranging from the classical bimanual–bipedal activity of ‘frontal’ hypermotor seizures, epileptic and non-epileptic wanderings, and somnambulism to periodic leg movements (PLM), alternating leg muscle activation (ALMA) and restless legs syndrome (RLS); and (c) various sleep-related events such as ictal fear, sleep terrors, nightmares and violent behaviour.

A Woman with Rhythmic Foot Movements

A Woman with Rhythmic Foot Movements

The neurophysiology of the alternating leg muscle activation (ALMA) during sleep: Study of one patient before and after treatment with pramipexole

Background and purposes To report the neurophysiological features of a patient with alternating leg muscle activation (ALMA) during sleep, a quickly alternating pattern of anterior tibialis activation which might represent transient facilitation of a spinal central pattern generator for locomotion, perhaps due to the serotonergic effects of antidepressant medication. Patient and methods A 33-year-old male patient with ALMA. The patient underwent a complete and detailed study of his neurophysiological parameters during sleep, before and after treatment with pramipexole. Results The treatment with pramipexole was followed by a significant reduction in the rate of occurrence of ALMA, in reported insomnia, and in daytime sleepiness. The ALMA generally were preceded by cyclic alternating pattern A phases and increased heart rate in most instances. Visual scoring and spectral analyses suggested that after pramipexole more intense arousal was required to trigger ALMA. Conclusion The evident beneficial effect induced by the treatment with pramipexole indicates that the spinal networks involved in the generation of ALMA might also be under the inhibitory control of dopaminergic networks. We suggest that ALMA can be seen even in the absence of other factors such as antidepressant therapy, sleep apnea or periodic leg movements during sleep, and might be considered as an additional phenomenon influenced by sleep instability. Our patient seems to indicate also that treatment with dopamine agonists can be useful in such patients because the treatment can be followed by a good clinical response.

Propriospinal myoclonus: A motor phenomenon found in restless legs syndrome different from periodic limb movements during sleep

Three patients presented with a 25-, 15-, and 5-year history of restless legs syndrome (RLS) and periodic limb movements during sleep (PLMS). For 1, 4, and 5 years, they reported additional involuntary trunk and limbs jerks preceding falling asleep and occasionally during intrasleep wakefulness. Videopolysomnography revealed jerks during relaxed wakefulness arising in axial muscles with a caudal and rostral propagation at a slow conduction velocity, characteristic of propriospinal myoclonus (PSM). Jerk-related EEG-EMG back-averaging did not disclose any preceding cortical potential. During relaxed wakefulness preceding falling asleep and during intrasleep wakefulness, PSM coexisted with motor restlessness and sensory discomfort in the limbs. PSM disappeared when spindles and K-complexes appeared on the EEG. At this time, typical PLMS appeared every 20 to 40 seconds, especially during light sleep stages. PLMS EMG activity was limited to leg, especially tibialis anterior muscles, and did not show propriospinal propagation. In one patient, alternating leg muscle activation was also present. Jerks with a PSM pattern represent another motor phenomenon associated with RLS and different from the more usual PLMS.

Alternating leg muscle activation during sleep and arousals: a new sleep-related motor phenomenon?

We describe a quickly alternating pattern of anterior tibialis activation, recorded during nocturnal polysomnography in 16 patients. Polysomnography, usually for sleep-disordered breathing, included surface electromyograms over the anterior tibialis of each leg. Cases were identified from approximately 1,500 studies reviewed in the course of standard clinical care. Patients were 12 men and 4 women (mean age, 41 +/- 15 years; range, 12-70 years). Brief activation of the anterior tibialis in one leg alternated with similar activation in the other leg. Activations occurred at a frequency of approximately 1 to 2 Hz, each lasted between 0.1 and 0.5 seconds, and sequences of alternating activations usually lasted between several and 20 seconds. The phenomenon occurred in all sleep stages but particularly during arousals. Ten of the 16 patients had periodic leg movements during sleep at a rate >/= 5.0 per hour, and 12 of the 16 patients were taking antidepressant medication. Alternating leg muscle activation (ALMA) during sleep, at this relatively high frequency, may be a newly described phenomenon. We speculate that ALMA could represent transient facilitation of a spinal central pattern generator for locomotion, perhaps due to serotonergic effects of antidepressant medication.