title: Alteration of cortical excitability in patients with fibromyalgia.
abstract: We assessed cortical excitability and intracortical modulation systematically, by transcranial magnetic stimulation (TMS) of the motor cortex, in patients with fibromyalgia. In total 46 female patients with fibromyalgia and 21 normal female subjects, matched for age, were included in this study. TMS was applied to the hand motor area of both hemispheres and motor evoked potentials (MEPs) were recorded for the first interosseous muscle of the contralateral hand. Single-pulse stimulation was used for measurements of the rest motor threshold (RMT) and suprathreshold MEP. Paired-pulse stimulation was used to assess short intracortical inhibition (SICI) and intracortical facilitation (ICF). Putative correlations were sought between changes in electrophysiological parameters and major clinical features of fibromyalgia, such as pain, fatigue, anxiety, depression and catastrophizing. The RMT on both sides was significantly increased in patients with fibromyalgia and suprathreshold MEP was significantly decreased bilaterally. However, these alterations, suggesting a global decrease in corticospinal excitability, were not correlated with clinical features. Patients with fibromyalgia also had lower ICF and SICI on both sides, than controls, these lower values being correlated with fatigue, catastrophizing and depression. These neurophysiological alterations were not linked to medication, as similar changes were observed in patients with or without psychotropic treatment. In conclusion, fibromyalgia is associated with deficits in intracortical modulation involving both GABAergic and glutamatergic mechanisms, possibly related to certain aspects of the pathophysiology of this chronic pain syndrome. Our data add to the growing body of evidence for objective and quantifiable changes in brain function in fibromyalgia.
authors.affiliation: INSERM U-987, CHU Ambroise Paré, APHP, F-92100 Boulogne-Billancourt, France Department of Neurology, Hospital das Clinicas, University of São Paulo, Brazil CHU Hôtel Dieu, Assistance Publique Hôpitaux de Paris, F-75001 Paris, France Université Paris Descartes, F-75005 Paris, France.
authors.forename: Alaa
authors.initials: A
authors.lastname: Mhalla
authors.forename: Daniel Ciampi
authors.initials: DC
authors.lastname: de Andrade
authors.forename: Sophie
authors.initials: S
authors.lastname: Baudic
authors.forename: Serge
authors.initials: S
authors.lastname: Perrot
authors.forename: Didier
authors.initials: D
authors.lastname: Bouhassira
mesh_terms: D000328:Adult; D001007:Anxiety / Q000503:physiopathology; D002540:Cerebral Cortex / Q000503:physiopathology*; D003863:Depression / Q000503:physiopathology; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D005356:Fibromyalgia / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009433:Neural Inhibition / Q000502:physiology; D009434:Neural Pathways / Q000503:physiopathology; D010146:Pain / Q000503:physiopathology; D011712:Pyramidal Tracts / Q000503:physiopathology; D009435:Synaptic Transmission / Q000502:physiology; D050781:Transcranial Magnetic Stimulation