title: Sensory Attenuation Assessed by Sensory Evoked Potentials in Functional Movement Disorders.
abstract: BACKGROUND
  Functional (psychogenic) movement disorders (FMD) have features associated with voluntary movement (e.g. distractibility) but patients report movements to be out of their control. One explanation for this phenomenon is that sense of agency for movement is impaired. The phenomenon of reduction in the intensity of sensory experience when movement is self-generated and a reduction in sensory evoked potentials (SEPs) amplitude at the onset of self-paced movement (sensory attenuation) have been linked to sense of agency for movement.
  
  
  METHODS
  We compared amplitude of SEPs from median nerve stimulation at rest and at the onset of a self-paced movement of the thumb in 17 patients with FMD and 17 healthy controls.
  
  
  RESULTS
  Patients showed lack of attenuation of SEPs at the onset of movement compared to reduction in amplitude of SEPs in controls. FMD patients had significantly different ratios of movement onset to rest SEPs than did healthy controls at each electrode: 0.79 in healthy controls and 1.35 in patients at F3 (t = -4.22, p<0.001), 0.78 in healthy controls and 1.12 at patients C3 (t = -3.15, p = 0.004) and 0.77 in healthy controls and 1.05 at patients P3 (t = -2.88, p = 0.007).
  
  
  CONCLUSIONS
  Patients with FMD have reduced sensory attenuation as measured by SEPs at onset of self-paced movement. This finding can be plausibly linked to impairment of sense of agency for movement in these patients.
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, The National Hospital of Neurology and Neurosurgery, Institute of Neurology, University College London, London, United Kingdom; Department of Neuroscience and Sense Organs, Aldo Moro University of Bari, Bari, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Macerollo
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, The National Hospital of Neurology and Neurosurgery, Institute of Neurology, University College London, London, United Kingdom.
authors.forename: Jui-Cheng
authors.initials: JC
authors.lastname: Chen
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, The National Hospital of Neurology and Neurosurgery, Institute of Neurology, University College London, London, United Kingdom.
authors.forename: Isabel
authors.initials: I
authors.lastname: Pareés
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, The National Hospital of Neurology and Neurosurgery, Institute of Neurology, University College London, London, United Kingdom.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Kassavetis
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, The National Hospital of Neurology and Neurosurgery, Institute of Neurology, University College London, London, United Kingdom.
authors.forename: James Morvan
authors.initials: JM
authors.lastname: Kilner
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, The National Hospital of Neurology and Neurosurgery, Institute of Neurology, University College London, London, United Kingdom.
authors.forename: Mark John
authors.initials: MJ
authors.lastname: Edwards
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D009069:Movement Disorders / Q000503:physiopathology*; D012146:Rest