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Antelmi E, Mogavero MP, Lanza G, Cartella SM, Ferini-Strambi L, Plazzi G, Ferri R, Tinazzi M. Sensory aspects of restless legs syndrome: Clinical, neurophysiological and neuroimaging prospectives. Sleep Med Rev 2024; 76:101949. [PMID: 38749362 DOI: 10.1016/j.smrv.2024.101949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 11/20/2023] [Accepted: 04/29/2024] [Indexed: 07/26/2024]
Abstract
Restless Legs Syndrome (RLS) is a complex sensorimotor disorder, classified among the sleep-related movement disorders. Although sensory symptoms appear as key features of the disorder, they are still poorly characterized from a clinical perspective and conceptualized from a pathophysiological point of view. In this review, we aim to describe the clinical and functional substrates of RLS, focusing mainly on its sensory symptoms and on their neurophysiological and anatomical correlates. Knowledge of both subjective sensory symptoms and objective sensory signs are still controversial. Current data also indicate that the sensory component of RLS seems to be subserved by anomalies of sensorimotor integration and by mechanism of central sensitization. Overall, electrophysiological findings highlight the involvement of multiple generators in the pathogenesis of RLS, eventually resulting in an increased nervous system excitability and/or alterations in inhibition within the somatosensory and nociceptive pathways. Structural and functional neuroimaging data show the involvement of several crucial areas and circuits, among which the thalamus appears to play a pivotal role. A holistic approach looking at brain connectivity, structural or functional abnormalities, and their interplay with molecular vulnerability and neurotransmitter alterations is warranted to disentangle the complex framework of RLS.
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Affiliation(s)
- Elena Antelmi
- Neurology Unit, Parkinson Disease and Movement Disorders Division, DIMI Department of Engineering and Medicine of Innovation, University of Verona, Italy.
| | - Maria P Mogavero
- Vita-Salute San Raffaele University, Milan, Italy; San Raffaele Scientific Institute, Division of Neuroscience, Sleep Disorders Center, Milan, Italy
| | - Giuseppe Lanza
- Clinical Neurophysiology Research Unit, Oasi Research Institute-IRCCS, Troina, Italy; University of Catania, Department of Surgery and Medical-Surgical Specialties, Catania, Italy
| | - Sandy M Cartella
- Movement Disorders Centre, Department of Neurology, Policlinico "Madonna Della Consolazione", Reggio Calabria, Italy
| | - Luigi Ferini-Strambi
- Vita-Salute San Raffaele University, Milan, Italy; San Raffaele Scientific Institute, Division of Neuroscience, Sleep Disorders Center, Milan, Italy
| | - Giuseppe Plazzi
- IRCCS, Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy; Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Raffaele Ferri
- Clinical Neurophysiology Research Unit, Oasi Research Institute-IRCCS, Troina, Italy
| | - Michele Tinazzi
- Neurology Unit, Parkinson Disease and Movement Disorders Division, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Italy
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Antelmi E, Squintani GM, Sandri A, Lippolis M, Segatti A, Tinazzi M. Defect of the Endogenous Inhibitory Pain System in Idiopathic Restless Legs Syndrome: A Laser Evoked Potentials Study. Mov Disord 2023; 38:1688-1696. [PMID: 37314385 DOI: 10.1002/mds.29509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/24/2023] [Accepted: 05/30/2023] [Indexed: 06/15/2023] Open
Abstract
BACKGROUND Restless legs syndrome (RLS) is a complex sensorimotor disorder. Symptoms worsen toward evening and at rest and are temporarily relieved by movement. Symptoms are perceived as painful in up to 45% of cases, and nociception system may be involved. OBJECTIVES To assess the descending diffuse noxious inhibitory control in RLS patients. METHODS Twenty-one RLS patients and twenty age and sex-matched healthy controls (HC) underwent a conditioned pain modulation protocol. Cutaneous heat stimuli were delivered via laser evoked potentials (LEPs) on the dorsum of the right hand (UL) and foot (LL). N2 and P2 latencies, N2/P2 amplitude and pain ratings (NRS) were recorded before (baseline), during, and after a heterotopic noxious conditioning stimulation (HNCS) application. The baseline/HNCS ratio was calculated for both UL and LL. RESULTS N2 and P2 latencies did not vary between groups at each condition and limbs. Both groups showed a physiological N2/P2 amplitude and NRS reduction during the HNCS condition in UL and LL in comparison to baseline and post conditions (all, P < 0.003). Between-groups comparisons revealed a significant lower amplitude reduction in RLS at the N2/P2 amplitude during the HNCS condition only for LL (RLS, 13.6 μV; HC, 10.1 μV; P = 0.004). Such result was confirmed by the significant difference at the ratio (RLS, 69%, HC, 52.5%; P = 0.038). CONCLUSIONS The lower physiological reduction during the HNCS condition at LL in RLS patients suggests a defect in the endogenous inhibitory pain system. Further studies should clarify the causal link of this finding, also investigating the circadian modulation of this paradigm. © 2023 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Elena Antelmi
- Neurology Unit, Parkinson Disease and Movement Disorders Division, DIMI Department of Engineering and Medicine of Innovation, University of Verona, Verona, Italy
| | | | - Angela Sandri
- Neurology Unit, Parkinson Disease and Movement Disorders Division, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | | | - Alessia Segatti
- UOC Neurology A, Department of Neurosciences, AOUI, Verona, Italy
| | - Michele Tinazzi
- Neurology Unit, Parkinson Disease and Movement Disorders Division, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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Xu Y, Wu J, Jiang Q, Lv Y, Pu S, Li C, Du D. Prediction of the Efficacy of Lumbar Sympathetic Block in Patients with Lower Extremity Complex Regional Pain Syndrome Type 1 Based on the Sympathetic Skin Response. Pain Ther 2023; 12:785-796. [PMID: 37014620 PMCID: PMC10199976 DOI: 10.1007/s40122-023-00499-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Accepted: 03/14/2023] [Indexed: 04/05/2023] Open
Abstract
INTRODUCTION Complex regional pain syndrome type 1 (CRPS-1) is prevalent after trauma, with intractable pain being the most prominent clinical symptom. The impact of sympathetic block on CRPS is unclear. The goal of this study was to explore the characteristics that predict successful symptom relief with lumbar sympathetic block (LSB) in patients with lower extremity CRPS-1. METHODS The study was designed as a prospective cohort study. Ninety-eight patients diagnosed with lower extremity CRPS-1 between March 2021 and March 2022 were enrolled as participants. All of the patients received two LSB treatments within a month. Sympthetic skin response (SSR) and numeric rating scale (NRS) were recorded before and after LSB treatment. The procedure was judged as a clinically positive response if the patients a 50% or greater reduction in NRS scores. Patients were divided into positive response and negative response groups after LSB treatment: LSB (+) and LSB (-), and the different characteristics and examination findings of the two groups of patients were compared. Furthermore, a multivariable logistic regression model was utilized to evaluate the predictors of successful symptom relief following LSB treatment. RESULTS A total of 43.9% (43/98) of patients experienced successful symptom relief, while 56.1% (55/98) had unsuccessful symptom relief. After LSB treatment of all subjects, the overall NRS score decreased, the SSR amplitude increased, and the SSR latency shortened in the affected extremity (P < 0.05). There was a significant difference in the change in SSR amplitude between the LSB (-) and LSB (+) groups (P = 0.000). A 12-month disease duration had an OR (odds ratio) of 4.477 (P = 0.009), and a 510-µV baseline SSR amplitude of the affected extremity had an OR of 7.508 (P = 0.000) in the multivariable analysis that included these explanatory variables. CONCLUSIONS Patients with lower extremity CRPS-1 can experience significant pain relief after LSB treatment. The predictors of successful symptom relief after LSB treatment were a baseline SSR amplitude of the affected extremity < 510 µV and a disease duration < 12 months. TRIAL REGISTRATION The study was registered in the Chinese Clinical Trial Registry (ID: ChiCTR2000037755, date of registration: September 4, 2020).
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Affiliation(s)
- Yongming Xu
- Department of Pain Management Center, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 600 Yishan Road, Shanghai, 200233, China
| | - Junzhen Wu
- Department of Pain Management Center, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 600 Yishan Road, Shanghai, 200233, China
| | - Qingqing Jiang
- Department of Neurology, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yingying Lv
- Department of Pain Management Center, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 600 Yishan Road, Shanghai, 200233, China
| | - Shaofeng Pu
- Department of Pain Management Center, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 600 Yishan Road, Shanghai, 200233, China
| | - Chen Li
- Department of Pain Management Center, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 600 Yishan Road, Shanghai, 200233, China
| | - Dongping Du
- Department of Pain Management Center, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, 600 Yishan Road, Shanghai, 200233, China.
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Idiaquez J, Casar JC, Arnardottir ES, August E, Santin J, Iturriaga R. Hyperhidrosis in sleep disorders - A narrative review of mechanisms and clinical significance. J Sleep Res 2023; 32:e13660. [PMID: 35706374 DOI: 10.1111/jsr.13660] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/10/2022] [Accepted: 05/13/2022] [Indexed: 02/03/2023]
Abstract
Hyperhidrosis is characterized by excessive sweating beyond thermoregulatory needs that affects patients' quality of life. It results from an excessive stimulation of eccrine sweat glands in the skin by the sympathetic nervous system. Hyperhidrosis may be primary or secondary to an underlying cause. Nocturnal hyperhidrosis is associated with different sleep disorders, such as obstructive sleep apnea, insomnia, restless legs syndrome/periodic limb movement during sleep and narcolepsy. The major cause of the hyperhidrosis is sympathetic overactivity and, in the case of narcolepsy type 1, orexin deficiency may also contribute. In this narrative review, we will provide an outline of the possible mechanisms underlying sudomotor dysfunction and the resulting nocturnal hyperhidrosis in these different sleep disorders and explore its clinical relevance.
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Affiliation(s)
- Juan Idiaquez
- Departamento de Neurología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Carlos Casar
- Departamento de Neurología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Erna S Arnardottir
- Reykjavik University Sleep Institute, School of Technology, Reykjavik University, Reykjavik, Iceland.,Internal Medicine Services, Landspitali, The National University Hospital of Iceland, Reykjavik, Iceland
| | - Elias August
- Reykjavik University Sleep Institute, School of Technology, Reykjavik University, Reykjavik, Iceland.,Department of Engineering, School of Technology, Reykjavik University, Reykjavik, Iceland
| | - Julia Santin
- Departamento de Neurología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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Abnormal Circadian Modification of A δ-Fiber Pathway Excitability in Idiopathic Restless Legs Syndrome. Pain Res Manag 2019; 2019:5408732. [PMID: 31827655 PMCID: PMC6885267 DOI: 10.1155/2019/5408732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/06/2019] [Accepted: 10/16/2019] [Indexed: 11/17/2022]
Abstract
Restless legs syndrome (RLS) is characterized by unpleasant sensations generally localized to legs, associated with an urge to move. A likely pathogenetic mechanism is a central dopaminergic dysfunction. The exact role of pain system is unclear. The purpose of the study was to investigate the nociceptive pathways in idiopathic RLS patients. We enrolled 11 patients (mean age 53.2 ± 19.7 years; 7 men) suffering from severe, primary RLS. We recorded scalp laser-evoked potentials (LEPs) to stimulation of different sites (hands and feet) and during two different time conditions (daytime and nighttime). Finally, we compared the results with a matched control group of healthy subjects. The Aδ responses obtained from patients did not differ from those recorded from control subjects. However, the N1 and the N2-P2 amplitudes' night/day ratios after foot stimulation were increased in patients, as compared to controls (N1: patients: 133.91 ± 50.42%; controls: 83.74 ± 34.45%; p = 0.016; Aδ-N2-P2: patients: 119.15 ± 15.56%; controls: 88.42 ± 23.41%; p = 0.003). These results suggest that RLS patients present circadian modifications in the pain system, which are not present in healthy controls. Both sensory-discriminative and affective-emotional components of pain experience show parallel changes. This study confirms the structural integrity of Aδ nociceptive system in idiopathic RLS, but it also suggests that RLS patients present circadian modifications in the pain system. These findings could potentially help clinicians and contribute to identify new therapeutic approaches.
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Erdal Y, Akdogan O, Nalbantoglu M, Kavasoglu G, Emre U. Autonomic dysfunction in restless legs syndrome. Sleep Breath 2019; 24:995-999. [DOI: 10.1007/s11325-019-01939-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 08/10/2019] [Accepted: 09/07/2019] [Indexed: 02/07/2023]
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Abstract
Clinical neurophysiologic investigation of pain pathways in humans is based on specific techniques and approaches, since conventional methods of nerve conduction studies and somatosensory evoked potentials do not explore these pathways. The proposed techniques use various types of painful stimuli (thermal, laser, mechanical, or electrical) and various types of assessments (measurement of sensory thresholds, study of nerve fiber excitability, or recording of electromyographic reflexes or cortical potentials). The two main tests used in clinical practice are quantitative sensory testing and pain-related evoked potentials (PREPs). In particular, PREPs offer the possibility of an objective assessment of nociceptive pathways. Three types of PREPs can be distinguished depending on the type of stimulation used to evoke pain: laser-evoked potentials, contact heat evoked potentials, and intraepidermal electrical stimulation evoked potentials (IEEPs). These three techniques investigate both small-diameter peripheral nociceptive afferents (mainly Aδ nerve fibers) and spinothalamic tracts without theoretically being able to differentiate the level of lesion in the case of abnormal results. In routine clinical practice, PREP recording is a reliable method of investigation for objectifying the existence of a peripheral or central lesion or loss of function concerning the nociceptive pathways, but not the existence of pain. Other methods, such as nerve fiber excitability studies using microneurography, more directly reflect the activities of nociceptive axons in response to provoked pain, but without detecting or quantifying the presence of spontaneous pain. These methods are more often used in research or experimental study design. Thus, it should be kept in mind that most of the results of neurophysiologic investigation performed in clinical practice assess small fiber or spinothalamic tract lesions rather than the neuronal mechanisms directly at the origin of pain and they do not provide objective quantification of pain.
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Affiliation(s)
- Jean-Pascal Lefaucheur
- Excitabilité Nerveuse et Thérapeutique, Faculté de Médecine de Créteil, Université Paris-Est-Créteil, Hôpital Henri Mondor, Créteil, France; Service de Physiologie-Explorations Fonctionnelles, Hôpital Henri Mondor, Créteil, France.
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Fila M, Stasiołek M, Markiewicz A, Bogucki A. Functional Evaluation of Small Fiber Pathways in Primary Restless Legs Syndrome: Aδ Pathway Study. J Clin Sleep Med 2017; 13:1455-1462. [PMID: 29117885 DOI: 10.5664/jcsm.6848] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 10/04/2017] [Indexed: 11/13/2022]
Abstract
STUDY OBJECTIVES The aim of this study was to provide a neurophysiological evaluation of the function of large and small fibers, particularly the peripheral part of the thermonociceptive Aδ pathway in patients with primary restless legs syndrome (RLS). METHODS The main evaluation was based on an analysis of the parameters of laser-evoked potentials (LEPs), N2 and P2 components, and an assessment of thermonociceptive thresholds (pain thresholds; PThs). Routine nerve conduction studies (NCS) were also performed. RESULTS No essential or important differences of clinical significance were observed in the parameters of large fiber conduction between the study and the control groups. Prolonged latencies of N2 and P2 potentials were obtained during foot stimulation in patients with primary RLS when compared to controls (N2, P2-lower right limb, and N2-lower left limb). We also observed higher amplitudes of LEPs evaluated as P2 and N2-P2 potentials in patients with primary RLS in comparison with the control group. Significantly higher (normal distribution P < .05) thermonociceptive thresholds in both lower and upper limbs were found in the RLS group. CONCLUSIONS On the basis of the analysis of LEPs and their comparison with the respective results from the control group, the presence of functional disability of the thermonociceptive Aδ pathway was confirmed in patients with primary RLS. The results indicated the presence of changes in the conduction of small fiber pathways in the pathomechanism of idiopathic RLS.
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Affiliation(s)
- Michał Fila
- Clinical Neurophysiology Unit, Neurology Department, Polish Mother's Memorial Hospital - Research Institute, Lodz, Poland
| | - Mariusz Stasiołek
- Neurology Department, Polish Mother's Memorial Hospital - Research Institute, Lodz, Poland
| | - Adam Markiewicz
- Neurology Department, Polish Mother's Memorial Hospital - Research Institute, Lodz, Poland
| | - Andrzej Bogucki
- Department of Extrapyramidal Diseases, Central University Hospital, Medical University of Lodz, Poland
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Koo BB, Bagai K, Walters AS. Restless Legs Syndrome: Current Concepts about Disease Pathophysiology. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2016; 6:401. [PMID: 27536462 PMCID: PMC4961894 DOI: 10.7916/d83j3d2g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/07/2016] [Indexed: 01/31/2023]
Abstract
Background In the past few decades, much has been learned about the pathophysiology of restless legs syndrome (RLS). Investigators have studied neuropathology, imaging, electrophysiology, and genetics of RLS, identifying brain regions and biological systems affected in RLS. This manuscript will review RLS pathophysiology literature, examining the RLS state through consideration of the neuroanatomy, then the biological, organ, and genetic systems. Methods Pubmed (1966 to April 2016) was searched for the term “restless legs syndrome” cross-referenced with “pathophysiology,” “pathogenesis,” “pathology,” or “imaging.” English language papers were reviewed. Studies that focused on RLS in relation to another disease were not reviewed. Results Although there are no gross structural brain abnormalities in RLS, widespread brain areas are activated, including the pre- and post-central gyri, cingulate cortex, thalamus, and cerebellum. Pathologically, the most consistent finding is striatal iron deficiency in RLS patients. A host of other biological systems are also altered in RLS, including the dopaminergic, oxygen-sensing, opioid, glutamatergic, and serotonergic systems. Polymorphisms in genes including BTBD9 and MEIS1 are associated with RLS. Discussion RLS is a neurologic sensorimotor disorder that involves pathology, most notably iron deficiency, in motor and sensory brain areas. Brain areas not subserving movement or sensation such as the cingulate cortex and cerebellum are also involved. Other biological systems including the dopaminergic, oxygen-sensing, opioid, glutamatergic, and serotonergic systems are involved. Further research is needed to determine which of these anatomic locations or biological systems are affected primarily, and which are affected in a secondary response.
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Affiliation(s)
- Brian B Koo
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA; Department of Neurology, Connecticut Veterans Affairs Health System, West Haven, CT, USA; Yale Center for Neuroepidemiology & Clinical Neurological Research, New Haven, CT, USA
| | - Kanika Bagai
- Department of Neurology, Vanderbilt University, Nashville, TN, USA
| | - Arthur S Walters
- Department of Neurology, Vanderbilt University, Nashville, TN, USA
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Winkelman JW, Gagnon A, Clair AG. Sensory symptoms in restless legs syndrome: the enigma of pain. Sleep Med 2013; 14:934-42. [DOI: 10.1016/j.sleep.2013.05.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 04/12/2013] [Accepted: 05/18/2013] [Indexed: 01/18/2023]
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Stiasny-Kolster K, Pfau DB, Oertel WH, Treede RD, Magerl W. Hyperalgesia and functional sensory loss in restless legs syndrome. Pain 2013; 154:1457-63. [DOI: 10.1016/j.pain.2013.05.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 04/19/2013] [Accepted: 05/03/2013] [Indexed: 11/17/2022]
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Martini M, Valentini E, Aglioti SM. Emotional conflict in a model modulates nociceptive processing in an onlooker: a laser-evoked potentials study. Exp Brain Res 2012; 225:237-45. [PMID: 23241906 DOI: 10.1007/s00221-012-3365-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 11/27/2012] [Indexed: 12/27/2022]
Abstract
Observing models displaying facial expressions of pain elicits neural activity in onlookers' neural structures involved in first-hand experience of pain and in monitoring conflicting information. We investigated whether the purported conflict between the pain and its emotional expression in a model modulates cortical responses elicited by nociceptive laser stimuli in an onlooker. Seeing happy facial expressions, incongruent with the perceptual status attributed to the model, determined a significant reduction in the laser-evoked N2 potential. One of the main sources of this response is the anterior cingulate cortex, an area involved in pain perception, empathy for pain and conflict detection. A pre-activation of the anterior cingulate cortex due to the detection of the emotional conflict may, therefore, be responsible for the reduction of nociceptive-related response in the same brain area. Thus, top-down variables, like the appraisal of the others' emotional status, modulate onlookers' nociceptive-related neural activity.
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Affiliation(s)
- Matteo Martini
- Department of Psychology, University of Rome La Sapienza, Via dei Marsi 78, 00185, Rome, Italy.
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Effect of pramipexole on cutaneous-silent-period parameters in patients with restless legs syndrome. Clin Neurophysiol 2012; 123:154-9. [DOI: 10.1016/j.clinph.2011.05.027] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2011] [Revised: 05/06/2011] [Accepted: 05/29/2011] [Indexed: 11/23/2022]
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Edwards RR, Quartana PJ, Allen RP, Greenbaum S, Earley CJ, Smith MT. Alterations in pain responses in treated and untreated patients with restless legs syndrome: associations with sleep disruption. Sleep Med 2011; 12:603-9. [PMID: 21570347 DOI: 10.1016/j.sleep.2010.09.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 09/03/2010] [Accepted: 09/17/2010] [Indexed: 12/29/2022]
Abstract
OBJECTIVE There has been recent interest in characterizing potential abnormalities of pain processing in patients with sleep disorders such as Restless Legs Syndrome (RLS). The aim of this study was to evaluate psychophysical responses to noxious heat and pressure stimuli in both treated and untreated RLS patients, compared to matched controls. METHODS This study is a cross-sectional group comparison of RLS patients with matched controls. A total of 31 patients (15 treated, 16 untreated) with a confirmed diagnosis of RLS were compared to 18 controls with no history of RLS or related sleep disorders. RESULTS RLS patients (both treated and untreated) demonstrated reduced pain thresholds and reported greater clinical pain relative to controls. Moreover, RLS patients demonstrated enhanced temporal summation of heat pain (p<.05), which may reflect aberrant central nervous system facilitation of pain transmission. Both treated and untreated RLS patients reported disrupted sleep relative to controls, and mediation analyses suggested that the reduced pain thresholds in RLS were attributable to sleep disturbance. However, the effect of RLS on the magnitude of temporal summation of heat pain was independent of sleep disturbance. CONCLUSIONS These findings suggest that central nervous system pain processing may be amplified in RLS, perhaps partially as a consequence of sleep disruption. RLS patients, even those whose symptoms are managed pharmacologically, may be at elevated long-term risk for the development or maintenance of persistent pain conditions. Further studies in larger samples could help to improve the prospects for pain management in RLS patients.
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Affiliation(s)
- Robert R Edwards
- Department of Anesthesiology, Perioperative and Pain Medicine, Harvard Medical School, Brigham & Women's Hospital, Chesnut Hill, MA 02467, USA.
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Bachmann CG, Rolke R, Scheidt U, Stadelmann C, Sommer M, Pavlakovic G, Happe S, Treede RD, Paulus W. Reply: Sensory profile in primary restless legs syndrome and restless legs syndrome associated with small fibre neuropathy. Brain 2011. [DOI: 10.1093/brain/awq292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Monaca C. [Pathophysiology of restless legs syndrome]. Presse Med 2010; 39:587-91. [PMID: 20346613 DOI: 10.1016/j.lpm.2009.09.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 08/14/2009] [Accepted: 09/02/2009] [Indexed: 11/16/2022] Open
Abstract
Restless legs syndrome (RLS) could be the consequence of sensorimotor dysfunction. Dopaminergic treatment has been successful in RLS, suggesting dopaminergic abnormalities. The specific pathophysiology of idiopathic RLS is not well known but recent studies have raised the hypothesis of diencephalospinal pathway dysfunction. This pathway includes spinal, subcortical and cortical structures. In idiopathic RLS, an implication of A11 neurons has been evoked, but further studies are needed to confirm this hypothesis. Brain iron is reduced in RLS. This decrease plays a major role in RLS occurrence. Genetic analyses are necessary to better understand the pathophysiological mechanisms of RLS.
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Affiliation(s)
- Christelle Monaca
- Service de neurophysiologie clinique, hôpital Roger-Salengro, 59037 Lille cedex, France.
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