An Evidence-based Analysis of the Association between Periodic Leg Movements during Sleep and Arousals in Restless Legs Syndrome

Raffaele Ferri; Francesco Rundo; Marco Zucconi; Mauro Manconi; Oliviero Bruni; Luigi Ferini-Strambi; Stephany Fulda

doi:10.5665/sleep.4740

An Evidence-based Analysis of the Association between Periodic Leg Movements during Sleep and Arousals in Restless Legs Syndrome

Sleep. 2015 Jun 1;38(6):919-24. doi: 10.5665/sleep.4740.

Authors

Raffaele Ferri¹, Francesco Rundo¹, Marco Zucconi², Mauro Manconi³, Oliviero Bruni⁴, Luigi Ferini-Strambi², Stephany Fulda³

Affiliations

¹ Sleep Research Centre; Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina, Italy.
² Sleep Disorders Center, Department of Neurology, Scientific Institute and University Ospedale San Raffaele, Vita-Salute University, Milan, Italy.
³ Sleep and Epilepsy Center, Neurocenter of Southern Switzerland, Civic Hospital (EOC) of Lugano, Lugano, Switzerland.
⁴ Department of Social and Developmental Psychology, Sapienza University, Rome, Italy.

Abstract

Study objectives: To analyze statistically the association between periodic leg movements during sleep (PLMS) and arousals, in order to eventually support or challenge the current scoring rules and to further understand their reciprocal influence.

Setting: Sleep research center.

Patients: Twenty untreated consecutive patients with restless legs syndrome (RLS) (13 women and 7 males, mean age 60.9 y).

Methods: In each recording, we selected all PLMS/arousal pairs that met the following inclusion criteria: (a) PLMS events that were separated from another PLMS event (preceding or following) by at least 10 s of EMG inactivity; (b) arousal events separated from another arousal event (preceding or following) by at least 10 s of stable EEG baseline activity; (c) PLMS/arousal pairs were then selected among events identified according to the previous two criteria, when PLMS and arousals were separated (offset-to-onset) by no more than 10 s, regardless of which was first.

Measurements and results: We selected a mean of 46.1 (SD 25.55) PLMS/arousal pairs per subject; in these pairs, average PLMS duration was 3.2 s (0.65) and average arousal duration was 6.5 s (0.92). Within these event pairs, the great majority (on average 98.4%, SD 3.88) was separated by less than 0.5 s (i.e., between the end of one event and the onset of the other, regardless of which was first). Arousal onsets preceded PLMS onset in 41.2% of pairs, while the opposite was true for the remaining 58.8% of pairs. A significant correlation between PLMS duration and arousal duration was also found (r = 0.447, P < 0.000001).

Conclusion: The results of this study support the current rule for the definition of the association between periodic leg movements during sleep (PLMS) and arousals. The tight time relationship between PLMS and arousals and their correlated durations seem to indicate that both events might be regulated by a complex mechanism, rather than being connected by a simple reciprocal cause/effect relationship.

Keywords: PLMS; arousals; periodic leg movements during sleep; restless legs syndrome; sleep scoring.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Arousal*
Electromyography
Female
Humans
Leg / physiopathology*
Male
Middle Aged
Movement*
Polysomnography
Restless Legs Syndrome / physiopathology*
Sleep*
Time Factors