Abstract
Dystonia is a disorder of sensorimotor integration associated with abnormal oscillatory activity within the basal ganglia-thalamo-cortical networks. Event-related changes in spectral EEG activity reflect cortical processing but are sparsely investigated in relation to sensorimotor processing in dystonia. This study investigates modulation of sensorimotor cortex EEG activity in response to a proprioceptive stimulus in children with dystonia and dystonic cerebral palsy (CP).Proprioceptive stimuli, comprising brief stretches of the wrist flexors, were delivered via a robotic wrist interface to 30 young people with dystonia (20 isolated genetic/idiopathic and 10 dystonic CP) and 22 controls (mean age 12.7 years). Scalp EEG was recorded using the 10–20 international system and the relative change in post-stimulus power with respect to baseline was calculated for the alpha (8–12 Hz) and beta (14–30 Hz) frequency bands.A clear developmental profile in event-related spectral changes was seen in controls. Controls showed a prominent early alpha/mu band event-related desynchronisation (ERD) followed by an event-related synchronisation (ERS) over the contralateral sensorimotor cortex following movement of either hand. The alpha ERD was significantly smaller in the dystonia groups for both dominant and non-dominant hand movement (ANCOVA across the 3 groups with age as covariate: dominant hand F(2,47) = 4.45 p = 0.017; non-dominant hand F(2,42) = 9.397 p < 0.001. Alpha ERS was significantly smaller in dystonia for the dominant hand (ANCOVA F(2,47) = 7.786 p = 0.001). There was no significant difference in ERD or ERS between genetic/idiopathic dystonia and dystonic CP. ConclusionModulation of alpha/mu activity by a proprioceptive stimulus is reduced in dystonia, demonstrating a developmental abnormality of sensorimotor processing which is common to isolated genetic/idiopathic and acquired dystonia/dystonic CP.
Highlights
Dystonia is a network disorder involving dysfunction within the basal ganglia, cortex, cerebellum or their inter-connections as part of the sensorimotor network (Corp et al, 2019; Neychev et al, 2011)
Our key a-priori hypotheses were that levels of alpha event-related desynchronization (ERD) and event-related synchronisation (ERS) over sensorimotor cortex in response to the proprioceptive stimulus would differ between the three groups: controls, isolated genetic/idio pathic dystonia and dystonic cerebral palsy (CP)
Whilst the current study used limited scalp EEG and is unable to more precisely localise the alpha and beta changes seen over the sensorimotor cortex, previously reported magneto encephalogram (MEG) studies using beamforming methodologies have demonstrated that alpha ERD is localised to the post-central gyrus while beta ERD and ERS are localised more anteriorly in pre-central primary motor cortex (Trevarrow et al, 2019)
Summary
Dystonia is a network disorder involving dysfunction within the basal ganglia, cortex, cerebellum or their inter-connections as part of the sensorimotor network (Corp et al, 2019; Neychev et al, 2011). We focus on the alpha/mu spectral frequency band (8–12 Hz) since desynchronised activity in this range is typically seen over sensorimotor cortex during passive movement or somatosensory stim ulation (Pfurtscheller, 2001; Pineda, 2005) This band co incides in part with the 4–12 Hz range in which abnormal cortical, subcortical and intermuscular oscillatory activity has been reported in ge netic/idiopathic dystonia (Neumann et al, 2012; Sharott et al, 2008; Barow et al, 2014; Miocinovic et al, 2017) (McClelland et al, 2020; Sharott et al, 2008; Neumann et al, 2015; Doldersum et al, 2019). We test the hypothesis that levels of alpha ERD and ERS over sensori motor cortex in response to the proprioceptive stimulus will differ be tween controls, isolated genetic/idiopathic dystonia and dystonic CP
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