Absent movement‐related cortical potentials in children with primary motor stereotypies

Abstract

Background The underlying pathophysiologic mechanism for complex motor stereotypies in children is unknown with hypotheses ranging from an arousal to a motor control disorder. Movement-related cortical potentials (MRCPs), representing the activation of cerebral areas involved in the generation of movements, precede and accompany self-initiated voluntary movements. The goal of this study was to compare cerebral activity associated with stereotypies to that seen with voluntary movements in children with primary complex motor stereotypies. Methods Electroencephalographic (EEG) activity synchronized with video recording was recorded in 10 children diagnosed with primary motor stereotypies and 7 controls. EEG activity related to stereotypies and self-paced arm movements were analyzed for presence or absence of early or late MRCP, a steep negativity beginning about one second before the onset of a voluntary movement. Results Early MRCPs preceded self-paced arm movements in 8 out of 10 children with motor stereotypies and in 6 out of 7 controls. Observed MRCPs did not differ between groups. No MRCP was identified before the appearance of a complex motor stereotypy. Conclusions Unlike voluntary movements, stereotypies are not preceded by MRCPs. This indicates that premotor areas are likely not involved in the preparation of these complex movements and suggests that stereotypies are initiated by mechanisms different from voluntary movements. Further studies are required to determine the site of the motor control abnormality within cortico-striatal-thalamo-cortical pathways and to identify whether similar findings would be found in children with secondary stereotypies.

Hand stereotypies

“…Future investigations focusing on broadening the genotype-phenotype correlations regarding HS and hand function would help improve mutation-specific prognosis. Although several hypotheses regarding the underlying pathophysiology of stereotypies in general have been postulated, 33,34 the neurobiological bases of HS are still unknown. Mouse models of Mecp2 deficiency show features similar to HS in RTT (hind-limb clasping).…”

Stereotypic movement disorder: a case for Procrustes?

“…The neurobiological underpinnings of stereotypy are being investigated with newer technologies. Houdayer et al . have reported a difference in the initial movement‐related cortical potentials preceding normal movements and those in SMD.…”

GABA and Glutamate in Children with Primary Complex Motor Stereotypies: An1H-MRS Study at 7T

“…The absence of premotor movement-related cortical potentials in children with primary CMS during these stereotypic movements suggests that motor stereotypies are initiated by different neural mechanisms than voluntary, purposeful movements 12 . Current research suggests that stereotypies, similar to many other movement disorders, likely involve cortico-striatal-thalamo-cortical (CSTC) circuits and their interconnecting brain regions.…”