World Association of Sleep Medicine (WASM) 2016 standards for recording and scoring leg movements in polysomnograms developed by a joint task force from the International and the European Restless Legs Syndrome Study Groups (IRLSSG and EURLSSG).

This report presents the results of the work by a joint task force of the International and European Restless Legs Syndrome Study Groups and World Association of Sleep Medicine that revised and updated the current standards for recording and scoring leg movements (LM) in polysomnographic recordings (PSG). First, the background of the decisions made and the explanations of the new rules are reported and then specific standard rules are presented for recording, detecting, scoring and reporting LM activity in PSG. Each standard rule has been classified with a level of evidence. At the end of the paper, Appendix 1 provides algorithms to aid implementation of these new standards in software tools. There are two main changes introduced by these new rules: 1) Candidate LM (CLM), are any monolateral LM 0.5-10 s long or bilateral LM 0.5-15 s long; 2) periodic LM (PLM) are now defined by runs of at least four consecutive CLM with an intermovement interval ≥10 and ≤ 90 s without any CLM preceded by an interval <10 s interrupting the PLM series. There are also new options defining CLM associated with respiratory events. The PLM rate may now first be determined for all CLM not excluding any related to respiration (providing a consistent number across studies regardless of the rules used to define association with respiration) and, subsequently, the PLM rate should also be calculated without considering the respiratory related events. Finally, special considerations for pediatric studies are provided. The expert visual scoringof LM has only been altered by the new standards to require accepting all LM > 0.5 s regardless of duration, otherwise the technician scores the LM as for the old standards. There is a new criterion for the morphology of LM that applies only to computerized LM detection to better match expert visual detection. Available automatic scoring programs will incorporate all the new rules so that the new standards should reduce technician burden for scoring PLMS.

Further studies on periodic limb movement disorder and restless legs syndrome in children with attention-deficit hyperactivity disorder.

Fourteen consecutive children who were newly diagnosed with attention-deficit hyperactivity disorder (ADHD) and who had never been exposed to stimulants and 10 control children without ADHD underwent polysomnographic studies to quantify Periodic Limb Movements in Sleep (PLMS) and arousals. Parents commonly gave both false-negative and false-positive reports of PLMS in their children, and a sleep study was necessary to confirm their presence or absence. The prevalence of PLMS on polysomnography was higher in the children with ADHD than in the control subjects. Nine of 14 (64%) children with ADHD had PLMS at a rate of >5 per hour of sleep compared with none of the control children (p <0.0015). Three of 14 children with ADHD (21%) had PLMS at a rate of >20 per hour of sleep. Many of the PLMS in the children with ADHD were associated with arousals. Historical sleep times were less for children with ADHD. The children with ADHD who had PLMS chronically got 43 minutes less sleep at home than the control subjects (p = 0.0091). All nine children with ADHD who had a PLMS index of >5 per hour of sleep had a long-standing clinical history of sleep onset problems (>30 minutes) and/or maintenance problems (more than two full awakenings nightly) thus meeting the criteria for Periodic Limb Movement Disorder (PLMD). None of the control children had a clinical history of sleep onset or maintenance problems. The parents of the children with ADHD were more likely to have restless legs syndrome (RLS) than the parents of the control children. Twenty-five of 28 biologic parents of the children with ADHD and all of the biologic parents of the control children were reached for interview. Eight of twenty-five parents of the children with ADHD (32%) had symptoms of RLS as opposed to none of the control parents (p = 0.011). PLMS may directly lead to symptoms of ADHD through the mechanism of sleep disruption. Alternative explanations for the association between ADHD and RLS/PLMS are that they are genetically linked, they share a common dopaminergic deficit, or both.

Moderate to severe periodic limb movement disorder in childhood and adolescence.

The purpose of this study is to review clinical features of children with moderate to severe Periodic Limb Movement Disorder (PLMD). Because of our interest in both Restless Legs Syndrome (RLS) and Attention-Deficit Hyperactivity Disorder (ADHD), many of our patients had one or both of these conditions. We did a retrospective review of 129 children and adolescents who were found to have Periodic Limb Movements in Sleep (PLMS) > 5/hour of sleep. Sixty five had PLMS of 5-10/hour of sleep, 48 had PLMS of 10-25/hour of sleep and 16 had PLMS > 25/hour of sleep. One hundred and seventeen of the original 129 had ADHD. Stimulant medication did not seem to play a role in the production of PLMS. In only 25 of the 129 cases did parents note the presence of PLMS before being specifically asked to look, and even after specific instructions to look, PLMS were not noted by the parents in 39 patients. The sub-group of 16 children and adolescents--6 female, 10 male (average age 11.1 years--range 6-17 years) with moderate to severe PLMS > 25/hour of sleep are described in more detail. Fifteen of the 16 patients had ADHD. Four of the 16 had RLS and 10 of 13 patients for whom a family history was available had a parent with RLS. Two of the 16 patients had their PLMS initially misdiagnosed as seizures. Sleep disturbance was present in all 16 patients and 7 of the 16 had daytime somnolence which resolved with dopaminergic medications. To our knowledge this is the first clinical series of moderate to severe PLMS in children and adolescents to be fully described in the literature.

Studies of penetrance and anticipation in five autosomal-dominant restless legs syndrome pedigrees.

Restless legs syndrome (RLS) can occur with an autosomal-dominant mode of inheritance. To determine if there are distinguishing features of RLS pedigrees which might clarify molecular mechanisms of pathogenesis, five pedigrees with 81 affected members were analyzed for age of onset, sex ratio, and transmission pattern. One-factor analysis of variance of ages of onset between generations was carried out, and segregation ratios were calculated for each generation. These kindreds showed an autosomal-dominant mode of inheritance and a male:female ratio of 1:1.4 (p = 0.15). One of the five analyzed pedigrees shows some evidence of reduced penetrance. In two of the five analyzed pedigrees, there is statistical support for anticipation (p<0.05). These variations in penetrance and anticipation suggest possible genetic heterogeneity.

Periodic limb movement disorder and restless legs syndrome in children with attention-deficit hyperactivity disorder.

Sleep disruption can lead to symptoms of attention-deficit hyperactivity disorder (ADHD) in children. Since periodic limb movement disorder and/or restless legs syndrome can cause sleep disruption, we assessed whether these two specific sleep disorders are likely to occur in children with ADHD. We asked a series of 69 consecutive parents of children with ADHD questions about the symptoms of periodic limb movement disorder. Based on a positive response to these periodic limb movement disorder queries, 27 children underwent all-night polysomnography. Eighteen children (aged 2 to 15 years) of the 27 (26% of the 69 children with ADHD) had 5 or more periodic leg movements in sleep per hour of sleep and had complaints of sleep disruption, thus fulfilling the criteria for periodic limb movement disorder. A comparably age- and sex-matched group of children referred to a sleep laboratory for sleep complaints but without ADHD showed only a 5% prevalence (2 of 38 subjects) of periodic leg movements in sleep (P=.017). Eight of the 18 children with ADHD and periodic limb movement disorder and one of the two control patients with periodic limb movement disorder had both a personal and parental history of restless legs syndrome symptomatology. This study further documents the occurrence of periodic limb movement disorder and restless legs syndrome in children and is the first large-scale study establishing a possible comorbidity between ADHD and periodic limb movement disorder. We propose that the sleep disruption associated with periodic limb movement disorder and restless legs syndrome and the motor restlessness of restless legs syndrome while awake could contribute to the inattention and hyperactivity seen in a subgroup of ADHD-diagnosed children.

Restless legs syndrome in childhood and adolescence.

Restless legs syndrome (RLS) is believed to be a condition primarily of middle to older age. However, it can have its onset in childhood. Five illustrative case histories with an autosomal dominant mode of inheritance are described. A mother and her 3 children (age: 6 1/2, 4 and 1 1/2 years) as well as a 16-year-old patient from a second family have typical RLS signs of leg discomfort (paresthesias) and motor restlessness prevalent at night and at rest, with temporary relief by activity. Polysomnography or videotaping revealed periodic limb movements in sleep (PLMS) and, in some cases, involuntary jerking of the legs was present during wakefulness as well. Clinicians should be aware that RLS can occur in childhood and adolescence and may be more common than heretofore recognized. "Growing pains" and attention deficit hyperactivity disorder (ADHD) are in the differential diagnosis of RLS in childhood.

A variant of Fukuyama congenital muscular dystrophy in a non-Japanese child.

We report a case of Fukuyama congenital muscular dystrophy with inflammatory infiltrate on muscle biopsy in an American girl of non-Japanese ancestry. The child was hypotonic, had decreased muscle strength in all extremities, and poor head control. Her mental and motor development were delayed. She developed generalized seizures at 19 months of age. Her muscle enzymes were abnormal; cranial computed tomography demonstrated hypoplasia of the cerebellum. Electromyogram was normal. Deltoid muscle biopsy documented scattered basophilic regenerating myofibers and focal atrophic fibers with focal increases of endomysial connective tissue, small endomysial foci of inflammatory cells, and occasional perimysial, perivenular lymphocytic infiltrates. Prednisone therapy produced some decrease in serum muscle enzyme levels.

Intrathecal interferon in subacute sclerosing panencephalitis.

Five patients with clinically advanced subacute sclerosing panencephalitis (SSPE) were given human leukocyte interferon (IFN) by the lumbar route, 1 million IU every other day for a total of 30 days. Intrathecal IFN produced a meningeal inflammatory reaction in all patients and was associated with transient hemiparesis in 1. It persisted in the cerebrospinal fluid at measurable levels for 48 hours after a single injection. Although improvement was temporally related to intrathecal IFN in 1 patient, it is not clear whether this was induced by IFN or a spontaneous remission. A randomized controlled trial would be necessary to evaluate IFN critically as a therapy for SSPE.