title: Periodic K-alpha sleep EEG activity and periodic limb movements during sleep: comparisons of clinical features and sleep parameters.
abstract: The K-alpha sleep electroencephalographic (EEG) phenomenon is characterized by periodic (approximately 20-40 seconds) K-complexes, immediately followed by alpha-EEG activity (7.5-11 Hz) of 0.5- to 5.0-second duration. A group of 14 subjects with the periodic K-alpha anomaly was found to have a similar distribution pattern of interevent intervals as compared with previously published data for sleep-related periodic limb movements during sleep (PLMS). Sleep parameters and somatic symptoms of 30 patients with K-alpha were compared with 30 patients with PLMS. The periodic K-alpha group was predominantly female, younger, exhibiting more slow-wave sleep, gastrointestinal symptoms and muscular complaints and fewer movement arousals on overnight polysomnography. The K-alpha group presented uniformly with complaints of unrefreshing sleep, often associated with fibromyalgia and chronic fatigue syndrome. The PLMS group was predominantly male, showed greater sleep disruption and presented with a variety of sleep-related symptoms.
authors.affiliation: University of Toronto, Centre for Sleep and Chronobiology, Toronto Hospital (Western Division), Ontario, Canada.
authors.forename: J G
authors.initials: JG
authors.lastname: MacFarlane
authors.forename: B
authors.initials: B
authors.lastname: Shahal
authors.forename: C
authors.initials: C
authors.lastname: Mously
authors.forename: H
authors.initials: H
authors.lastname: Moldofsky
mesh_terms: D000328:Adult; D004569:Electroencephalography; D004576:Electromyography; D015673:Fatigue Syndrome, Chronic; D005260:Female; D005356:Fibromyalgia; D006801:Humans; D007866:Leg; D008297:Male; D008875:Middle Aged; D009068:Movement; D010507:Periodicity; D012894:Sleep Stages; D012895:Sleep, REM