PERIODIC K-ALPHA SLEEP EEG ACTIVITY AND PERIODIC LIMB MOVEMENTS DURING SLEEP - COMPARISONS OF CLINICAL-FEATURES AND SLEEP PARAMETERS

The K-alpha sleep electroencephalographic (EEG) phenomenon is characte rized by periodic (similar to 20-40 seconds) K-complexes, immediately followed by alpha-EEG activity (7.5-11 Hz) of 0.5- to 5.0-second durat ion. A group of 14 subjects with the periodic K-alpha anomaly was foun d to have a similar distribution pattern of interevent intervals as co mpared with previously published data for sleep-related periodic limb movements during sleep (PLMS). Sleep parameters and somatic symptoms o f 30 patients with K-alpha were compared with 30 patients with PLMS. T he periodic K-alpha group was predominantly female, younger, exhibitin g more slow-wave sleep, gastrointestinal symptoms and muscular complai nts and fewer movement arousals on overnight polysomnography. The K-al pha group presented uniformly with complaints of unrefreshing sleep, o ften associated with fibromyalgia and chronic fatigue syndrome. The PL MS group was predominantly male, showed greater sleep disruption and p resented with a variety of sleep-related symptoms.