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Drakatos P, Olaithe M, Verma D, Ilic K, Cash D, Fatima Y, Higgins S, Young AH, Chaudhuri KR, Steier J, Skinner T, Bucks R, Rosenzweig I. Periodic limb movements during sleep: a narrative review. J Thorac Dis 2022; 13:6476-6494. [PMID: 34992826 PMCID: PMC8662505 DOI: 10.21037/jtd-21-1353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 10/20/2021] [Indexed: 01/02/2023]
Abstract
Objective Using narrative review techniques, this paper evaluates the evidence for separable underlying patho-mechanisms of periodic limb movements (PLMs) to separable PLM motor patterns and phenotypes, in order to elucidate potential new treatment modalities. Background Periodic limb movement disorder (PLMD) is estimated to occur in 5–8% of the paediatric population and 4–11% of the general adult population. Due to significant sleep fragmentation, PLMD can lead to functional impairment, including hyperactivity and delayed language development in children, and poor concentration and work performance in adults. Longitudinal data demonstrate that those with PLMD are at greater risk of depression and anxiety, and a 4-fold greater risk of developing dementia. PLMD has been extensively studied over the past two decades, and several key insights into the genetic, pathophysiological, and neural correlates have been proposed. Amongst these proposals is the concept of separable PLM phenotypes, proposed on the basis of nocturnal features such as the ratio of limb movements and distribution throughout the night. PLM phenotype and presentation, however, varies significantly depending on the scoring utilized and the nocturnal features examined, across age, and co-morbid clinical conditions. Furthermore, associations between these phenotypes with major neurologic and psychiatric disorders remain controversial. Methods In order to elucidate potential divergent biological pathways that may help clarify important new treatment modalities, this paper utilizes narrative review and evaluates the evidence linking PLM motor patterns and phenotypes with hypothesised underlying patho-mechanisms. Distinctive, underlying patho-mechanisms include: a pure motor mechanism originating in the spinal cord, iron deficiency, dopamine system dysfunction, thalamic glutamatergic hyperactivity, and a more cortical-subcortical interplay. In support of the latter hypothesis, PLM rhythmicity appears tightly linked to the microarchitecture of sleep, not dissimilarly to the apnoeic/hypopneic events seen in obstructive sleep apnea (OSA). Conclusions This review closes with a proposal for greater investigation into the identification of potential, divergent biological pathways. To do so would require prospective, multimodal imaging clinical studies which may delineate differential responses to treatment in restless legs syndrome (RLS) without PLMS and PLMS without RLS. This could pave the way toward important new treatment modalities.
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Affiliation(s)
- Panagis Drakatos
- Sleep and Brain Plasticity Centre, CNS, IoPPN, King's College London, London, UK.,Sleep Disorders Centre, Guy's and St Thomas' Hospital, GSTT NHS, London, UK.,Faculty of Life and Sciences Medicine, King's College London, London, UK
| | - Michelle Olaithe
- School of Psychological Science, University of Western Australia, Perth, Western Australia, Australia
| | - Dhun Verma
- Sleep and Brain Plasticity Centre, CNS, IoPPN, King's College London, London, UK
| | - Katarina Ilic
- Sleep and Brain Plasticity Centre, CNS, IoPPN, King's College London, London, UK.,BRAIN, Imaging Centre, CNS, King's College London, London, UK
| | - Diana Cash
- Sleep and Brain Plasticity Centre, CNS, IoPPN, King's College London, London, UK.,BRAIN, Imaging Centre, CNS, King's College London, London, UK
| | - Yaqoot Fatima
- Institute for Social Science Research, University of Queensland, Brisbane, Australia.,Centre for Rural and Remote Health, James Cook University, Mount Isa, Australia
| | - Sean Higgins
- Sleep and Brain Plasticity Centre, CNS, IoPPN, King's College London, London, UK.,Sleep Disorders Centre, Guy's and St Thomas' Hospital, GSTT NHS, London, UK
| | - Allan H Young
- School of Academic Psychiatry, King's College London, London, UK
| | - K Ray Chaudhuri
- King's College London and Parkinson's Foundation Centre of Excellence, King's College Hospital, London, UK
| | - Joerg Steier
- Sleep Disorders Centre, Guy's and St Thomas' Hospital, GSTT NHS, London, UK.,Faculty of Life and Sciences Medicine, King's College London, London, UK
| | - Timothy Skinner
- Institute of Psychology, University of Copenhagen, Copenhagen, Denmark.,La Trobe Rural Health School, La Trobe University, Bendigo, Victoria, Australia
| | - Romola Bucks
- School of Psychological Science, University of Western Australia, Perth, Western Australia, Australia.,The Raine Study, University of Western Australia, Perth, Australia
| | - Ivana Rosenzweig
- Sleep and Brain Plasticity Centre, CNS, IoPPN, King's College London, London, UK.,Sleep Disorders Centre, Guy's and St Thomas' Hospital, GSTT NHS, London, UK
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