title: Periodic leg movements during sleep and periodic limb movement disorder in patients presenting with unexplained insomnia.
abstract: OBJECTIVE
  The 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.
  
  
  METHODS
  We 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.
  
  
  RESULTS
  A 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.
  
  
  CONCLUSIONS
  PLMS 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.
  
  
  CONCLUSIONS
  Polysomnography with the subsequent analysis of PLMS periodicity is able to differentiate between insomnia patient subgroups.
authors.affiliation: Sleep Research Centre, Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Via C. Ruggero 73, 94018 Troina, Italy. rferri@oasi.en.it
authors.forename: Raffaele
authors.initials: R
authors.lastname: Ferri
authors.forename: Viola
authors.initials: V
authors.lastname: Gschliesser
authors.forename: Birgit
authors.initials: B
authors.lastname: Frauscher
authors.forename: Werner
authors.initials: W
authors.lastname: Poewe
authors.forename: Birgit
authors.initials: B
authors.lastname: Högl
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D020189:Nocturnal Myoclonus Syndrome / Q000150:complications*; D010507:Periodicity; D017286:Polysomnography / Q000379:methods; D012148:Restless Legs Syndrome / Q000150:complications* / Q000175:diagnosis; D007319:Sleep Initiation and Maintenance Disorders / Q000150:complications*; D012894:Sleep Stages / Q000502:physiology; D055815:Young Adult