British Society for Clinical Neurophysiology

...to promote and encourage for the public benefit the science and practice of clinical neurophysiology and related sciences

Abstract Details

Abnormal event-related modulation of sensorimotor cortex alpha/mu activity in children with dystonia and dystonic cerebral palsy

Objectives
Abnormal sensorimotor processing is present in adult genetic dystonia, but is sparsely studied in acquired or childhood dystonia.  This study investigates sensorimotor processing by measuring event-related synchronisation (ERS) and desynchronization (ERD) in response to a proprioceptive stimulus in children with dystonia/dystonic cerebral palsy (CP).

Methods
30 young people with dystonia (20 genetic/idiopathic; 10 dystonic CP) and 22 controls participated, age 5-21years.  Proprioceptive stimuli, comprising a brief stretch of the wrist flexors, were delivered to each hand using a robotic wrist interface, (for 5 patients, dominant hand only was tested). Scalp EEG was recorded, filtered (DC-500Hz) and sampled at 2500Hz.   Wrist position was monitored and movement onset synchronised with EEG recordings. Up to 160 EEG epochs (1s pre- and 3.5s post-stimulus) were averaged per subject to produce a Stretch Evoked Potential. Time-frequency analyses were performed using continuous Morlet wavelet transforms to compute power in 1Hz bins between 5-40Hz, using 8 wavelet cycles. The relative change in post-stimulus power with respect to pre-stimulus/baseline, was calculated for the alpha/mu (8-12Hz) band for each time point.

Results
Mean age was 12.7years and was comparable across groups. Controls showed a clear developmental profile in event-related spectral changes. Findings were compared between control and dystonia groups using age as a covariate.  Controls showed a prominent early alpha/mu ERD (0.5-1s post-stimulus) and a prominent alpha/mu ERS (1.5–2.5s post-stimulus) over contralateral sensorimotor cortex following movement of either hand. Alpha ERD was significantly smaller in the dystonia group for both the dominant hand (ANCOVA F(2,47)=4.45 p=0.017) and the non-dominant hand (ANCOVA F(2,42)=9.397 p<0.001). Alpha ERS was significantly smaller in dystonia for the dominant hand (ANCOVA F(1,48)=13.132 p=0.001).  The findings were similar for genetic/idiopathic dystonia and dystonic CP.

Conclusions
The impaired alpha/mu modulation indicates a developmental abnormality of sensorimotor processing which is common to genetic/idiopathic dystonia and dystonic CP.

TitleForenamesSurnameInstitutionLead AuthorPresenter
DrVerityMcClellandKing's College London
DrPetraFischerUniversity of Oxford
DrSofiaDall'OrsoImperial College London
ProfessorPeterBrownUniversity of Oxford
DrJean-PierreLinGuys and St Thomas' NHS Foundation Trust
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