Abstract
ObjectiveSensorimotor processing is abnormal in Idiopathic/Genetic dystonias, but poorly studied in Acquired dystonias. Beta-Corticomuscular coherence (CMC) quantifies coupling between oscillatory electroencephalogram (EEG) and electromyogram (EMG) activity and is modulated by sensory stimuli. We test the hypothesis that sensory modulation of CMC and intermuscular coherence (IMC) is abnormal in Idiopathic/Genetic and Acquired dystonias. MethodsParticipants: 11 children with Acquired dystonia, 5 with Idiopathic/Genetic dystonia, 13 controls (12–18 years). CMC and IMC were recorded during a grasp task, with mechanical perturbations provided by an electromechanical tapper. Coherence patterns pre- and post-stimulus were compared across groups. ResultsBeta-CMC increased post-stimulus in Controls and Acquired dystonia (p = 0.001 and p = 0.010, respectively), but not in Idiopathic/Genetic dystonia (p = 0.799). The modulation differed between groups, being larger in both Controls and Acquired dystonia compared with Idiopathic/Genetic dystonia (p = 0.003 and p = 0.022). Beta-IMC increased significantly post-stimulus in Controls (p = 0.004), but not in dystonia. Prominent 4–12 Hz IMC was seen in all dystonia patients and correlated with severity (rho = 0.618). ConclusionIdiopathic/Genetic and Acquired dystonia share an abnormal low-frequency IMC. In contrast, sensory modulation of beta-CMC differed between the two groups. SignificanceThe findings suggest that sensorimotor processing is abnormal in Acquired as well as Idiopathic/Genetic dystonia, but that the nature of the abnormality differs.
Highlights
Deep Brain Stimulation (DBS) of the Globus pallidus internus is a well-established management for medically refractory dystonias
Numbers of children showing significant beta-range Corticomuscular coherence (CMC) at baseline and post-stimulus are given in Table 2 and Supplementary Table S2
Our findings show some similarities between intermuscular coherence (IMC) and CMC patterns, indicating a degree of overlap, but the differences we observe suggest that EMG:EMG coherence cannot be assumed to be a pure surrogate of CMC
Summary
Deep Brain Stimulation (DBS) of the Globus pallidus internus is a well-established management for medically refractory dystonias. The success of pallidal DBS in alleviating painful disabling muscle spasms and improving motor control in dystonia has triggered a rapid expansion in the field of neuromodulation and has intensified interest in the underlying physiology of these conditions, including their developmental aspects (Ismail et al, 2017; Lin and Nardocci, 2016). V.M. McClelland et al / Clinical Neurophysiology 131 (2020) 967–977
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