Brain regions associated with periodic leg movements during sleep in restless legs syndrome

Tae-Joon Kim,Sang Kun Lee,Jung-Ah Lim,Jung-Won Shin,Jin-Sun Jun,Jun-Sang Sunwoo,Keun Tae Kim,Sanghun Lee,Tae-Won Yang,Kyung Hwan Kim,Ki-Young Jung,Byeong-Su Park,Jung-Ick Byun,Kwang Su Cha

doi:10.1038/s41598-020-58365-0

Abstract

The neural substrates related to periodic leg movements during sleep (PLMS) remain uncertain, and the specific brain regions involved in PLMS have not been evaluated. We investigated the brain regions associated with PLMS and their severity using the electroencephalographic (EEG) source localization method. Polysomnographic data, including electromyographic, electrocardiographic, and 19-channel EEG signals, of 15 patients with restless legs syndrome were analyzed. We first identified the source locations of delta-band (2–4 Hz) spectral power prior to the onset of PLMS using a standardized low-resolution brain electromagnetic tomography method. Next, correlation analysis was conducted between current densities and PLMS index. Delta power initially and most prominently increased before leg movement (LM) onset in the PLMS series. Sources of delta power at −4~−3 seconds were located in the right pericentral, bilateral dorsolateral prefrontal, and cingulate regions. PLMS index was correlated with current densities at the right inferior parietal, temporoparietal junction, and middle frontal regions. In conclusion, our results suggest that the brain regions activated before periodic LM onset or associated with their severity are the large-scale motor network and provide insight into the cortical contribution of PLMS pathomechanism.

Highlights

Periodic leg movements during sleep (PLMS) are repetitive, involuntary, and jerky movements that typically involve dorsiflexion of the ankle, extension of great toe, and occasional flexion of the knee and hip[1]
Previous studies investigating the PLMS pathophysiology revealed that changes in electroencephalography (EEG) accompanied by an increase in heart rate precede the occurrence of leg movements (LMs) during PLMS and that cortical and autonomic activations are regarded to lead these changes[2,3,4,5,6,7,8], supporting the association between PLMS and cardiovascular risks[9]
A total of 1,550 periodic LM (pLM) obtained from 14 subjects and 251 isolated LM (iLM) obtained from another 14 subjects were subjected to subsequent analyses

Summary

Introduction

Periodic leg movements during sleep (PLMS) are repetitive, involuntary, and jerky movements that typically involve dorsiflexion of the ankle, extension of great toe, and occasional flexion of the knee and hip[1]. An initial slow potential shift in EEG, begins approximately two seconds before voluntary motor movement onset in the contralateral supplementary motor area This feature precedes the self-intention to move[12]. The aims of the present study were (1) to identify brain regions associated with intracerebral oscillatory activity preceding PLMS and (2) to find neural substrates related to the severity of PLMS at a sub-lobar level. To address these issues, the brain regions related to PLMS were identified by applying standardized low-resolution brain electromagnetic tomography (sLORETA)[21], an EEG source localization method, from the initial EEG changes prior to PLMS onset. The severity of PLMS was investigated by correlation with PLMSI

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