Sensory Attenuation Assessed by Sensory Evoked Potentials in Functional Movement Disorders.

Panagiotis Kassavetis,Bogdan Draganski,Jui-Cheng Chen,Antonella Macerollo,Isabel Pareés,James Morvan Kilner,Mark John Edwards

doi:10.1371/journal.pone.0129507

Abstract

BackgroundFunctional (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.MethodsWe 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.ResultsPatients 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).ConclusionsPatients 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.

Highlights

Functional movement disorders (FMD) are part of the spectrum of functional neurological symptoms, one of the most frequent diagnoses made in neurological practice [1]
Sensory attenuation (SA) describes a phenomenon associated with normal movement where there is a different perception of identical sensory inputs depending on whether they are self-generated or externally generated [2].Stimuli which are self-generated are associated with a reduction in the perceived intensity of the stimulus; for example while one cannot tickle oneself, one can be tickled by others [3,4,5,6,7,8]
We hypothesised that patients with FMD would have less sensory evoked potentials (SEPs) suppression at the onset of movement compared to healthy controls

Summary

Background

Editor: Bogdan Draganski, Centre Hospitalier Universitaire Vaudois Lausanne - CHUV, UNIL, SWITZERLAND. Data Availability Statement: All relevant data are within the paper. 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

Results

Conclusions

Introduction

Participants

Procedure and experimental design

Discussion