Periodic limb movement disorder of sleep in children VALERIE MCLAUGHLIN CRABTREE, ANNA IVANENKO, LOUISE MARGARET O’BRIEN and DAVID GOZAL Kosair Children’s Hospital Research Institute, and Division of Pediatric Sleep Medicine, Department of Pediatrics, University of Louisville, Louisville, USA Accepted in revised form 25 November 2002; received 24 September 2002 SUMMARY To characterize periodic limb movement disorder (PLMD) in a cohort of prepubertal children we examined sleep-related identifiable differences between children with PLMD and attention-deficit ⁄ hyperactivity disorder (ADHD), PLMD alone, and age- matched controls. Children were selected from a chart review of all children referred to a pediatric sleep medicine center and from a community survey of 5–7-year-old- children. Polysomnography (PSG) and parental report data from all children identified as having periodic limb movement index (PLMI) >5 were reviewed and compared with a cohort of age-matched controls. A total of 8.4% of children in the clinic-referred sample, and 11.9% of the children recruited from the community had PLMI >5. Of those, 44.4% were identified as having ADHD. Children with PLMD had significantly lower percentage of rapid eye movement (REM) than control children (P < 0.001). Children in the PLMD ⁄ ADHD group had a significantly greater number of arousals associated with PLM (PLMa) than children with PLMD only (P < 0.05). While a relationship between ADHD and PLMD was observed, it was weaker than previous reports (Chervin, R. D. et al. Sleep, 2002; 25: 213; Chervin, R. D. and Archbold, K. H. Sleep, 2001; 24: 313; Picchietti et al. J. Child Neurol., 1999; 13: 588; Picchietti et al. Mov. Disord., 1999; 14: 1000; Picchietti and Walters Sleep, 1999; 22: 297). Children in the PLMD ⁄ ADHD group were more likely to have PLMas than were children with PLMD only. We postulate that rather than a direct relationship between ADHD and PLMD, this link may be mediated by the presence of reduced REM sleep and more importantly by the sleep fragmentation associated with PLM-induced arousals. keywords behavior, hyperactivity, inattention, periodic limb movement disorder, restless leg syndrome, sleep fragmentation INTRODUCTION Periodic limb movement disorder of sleep (PLMD), while previously well-documented in adults, has only recently emerged as a relatively frequent and markedly underdiagnosed condition affecting children. PLMD is defined as the occur- rence of periodic episodes of repetitive and highly stereotyped limb movements during sleep. In adult patients with PLMD, complaints of insomnia and ⁄ or excessive daytime sleepiness are commonly present in the absence of any other explanatory disorders (Chesson et al. 1999). Initial evidence strongly supporting the occurrence of PLMD in children was derived from surveys of adults with restless leg syndrome (RLS) that revealed a high percentage of patients with onset of symptoms during childhood (Walters et al. 1996). Furthermore, a genetic linkage analysis study of RLS revealed an autosomal domin- ant mode of inheritance in a number of families with RLS (Walters et al. 1994). These initial reports were since followed by a number of studies on the prevalence of PLMD among the general pediatric population and among children referred to specialized sleep centers (Chervin et al. 2002; Chervin and Archbold 2001; Chervin and Hedger 2001; Picchietti and Walters 1999; Picchietti et al. 1998). As more children were diagnosed with PLMD, a potential relationship between PLMD and attention-deficit ⁄ hyperactivity disorder (ADHD) was uncovered as evidenced by the fact that the vast majority Correspondence: David Gozal, MD, Kosair Children’s Hospital Research Institute, University of Louisville School of Medicine, 571 S. Preston Street Suite 321, Louisville, KY 40202, USA. Tel.: (502) 852 2323; fax: (502) 852 2215; e-mail: david.gozal@louisville.edu J. Sleep Res. (2003) 12, 73–81 Ó 2003 European Sleep Research Society 73