Spectral <scp>EEG</scp> and heart rate changes associated with leg movements during the suggested immobilization test in patients with restless legs syndrome

Restless legs syndrome is usually associated with periodic limb movements during sleep, which are defined as repetitive, stereotyped movements in sleep. Changes in spectral analysis of electroencephalography and heart rate were shown to be associated with periodic limb movements during sleep and non-periodic leg movements in sleep. Considering the circadian distribution of symptoms of restless legs syndrome, we investigated spectral electroencephalography and heart rate accompanying periodic limb movements, isolated leg movements and short-interval leg movements during suggested immobilization test. The mean age of 53 patients was 51.9 ± 13 years, 54.7% were females. Prominent increases in electroencephalography activation were associated with periodic limb movements, isolated leg movements and short-interval leg movements during the suggested immobilization test, which were significant in all spectral bands (p < 0.001). An increase in all electroencephalography bands started ~10 s before periodic limb movements, isolated leg movements and short-interval leg movements; increases in delta and theta band activities ended ~10 s after the movements, while increases in alpha and beta band activities lasted for about ~20 s. Maximum increases in delta, theta, alpha and beta bands were all observed after periodic limb movements and short-interval leg movements, but before isolated leg movements in theta and alpha bands, and after isolated leg movements in delta and beta bands. A notably longer increase in alpha and beta bands was evident for periodic limb movements and short-interval leg movements. An increase in heart rate was prominent at 4-12 s after movement onset in short-interval leg movements, being significantly higher than those associated with periodic limb movements and isolated leg movements. Our study shows that, in patients with restless legs syndrome, periodic limb movements, isolated leg movements and short-interval leg movements during suggested immobilization test are associated with prominent cortical and cardiac activation, which warrants confirmation in larger restless legs syndrome cohorts and requires long-term follow-up studies to delineate its possible clinical consequences.