title: Fragmentary myoclonus in sleep revisited: a polysomnographic study in 62 patients.
abstract: OBJECTIVE
  To investigate the frequency of fragmentary myoclonus (FM) in a sleep-disorder population, to analyze its distribution across sleep stages and to examine potential associations with clinical correlates and night-to-night variability.
  
  
  METHODS
  Retrospective review of 102 polysomnographic records.
  
  
  METHODS
  Sleep laboratory at a University Hospital Neurology Department.
  
  
  METHODS
  Sixty-two sleep-disorder patients.
  
  
  METHODS
  None.
  
  
  RESULTS
  Fragmentary myoclonus (FM) was counted according to published criteria. Sleep stage specific FM indices (FMI) were calculated for each patient. Median FMI was 39.5/h sleep. FMI was the highest in REM sleep, followed by similar indices in wakefulness, S1 and S2 sleep, and was the lowest in S3/S4 sleep (n.s.). FMI increased with age (ρ=0.350, P=0.005). Men had a higher FMI than women (median 55.8/h vs. 24.1/h, P=0.042). In addition, FMI was positively correlated with the presence of sleep-related breathing disorders (ρ=0.270, P=0.036), respiratory indices (apnea-hypopnea index: ρ=0.403, P=0.002; oxygen desaturation index: ρ=0.378, P=0.004) and body mass index (ρ=0.28, P=0.028). In a linear regression model, age, male sex and oxygen desaturation index were significant (P<0.05). FMI night-to-night variability was 1.6 (range: 1.0-3.9).
  
  
  CONCLUSIONS
  Fragmentary myoclonus was present in every patient of this sleep-disorder population. Its clinical significance is unknown, but the association with oxygen desaturation index points to an association with sleep-related breathing disorders. Since FMI was similar during wakefulness and light sleep, these data challenge the concept of a primarily sleep-related phenomenon.
authors.affiliation: Department of Neurology, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Frauscher
authors.forename: Alexander
authors.initials: A
authors.lastname: Kunz
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Brandauer
authors.forename: Hanno
authors.initials: H
authors.lastname: Ulmer
authors.forename: Werner
authors.initials: W
authors.lastname: Poewe
authors.forename: Birgit
authors.initials: B
authors.lastname: Högl
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D002940:Circadian Rhythm / Q000502:physiology; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009207:Myoclonus / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood; D017286:Polysomnography; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012894:Sleep Stages / Q000502:physiology; D012893:Sleep Wake Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D010100:Oxygen