Altered frontal-mediated inhibition and white matter connectivity in pediatric chronic tic disorders

• Published in: Experimental brain research 2021-03, Vol.239 (3), p.955-965
• Main Authors: Bruce, Adrienne B., Yuan, Weihong, Gilbert, Donald L., Horn, Paul S., Jackson, Hannah S., Huddleston, David A., Wu, Steve W.
• Format: Article
• Language: English
• Subjects: Analysis; Anatomy; Anisotropy; Biomedical and Life Sciences; Biomedicine; Child; Children; Corpus callosum; Cortex (frontal); Cortex (motor); Development and progression; Diagnosis; Diffusion Tensor Imaging; Diseases; Humans; Inhibition (Neurophysiology); Inhibition, Psychological; Magnetic fields; Magnetic resonance imaging; Motor Cortex - diagnostic imaging; Motor task performance; Movement disorders; Neural networks; Neuroimaging; Neurology; Neurosciences; Presupplementary motor area; Research Article; Substantia alba; Supplementary motor area; Tic disorders; Tic Disorders - diagnostic imaging; Transcranial magnetic stimulation; White Matter - diagnostic imaging
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-020-06017-0

Tics are unique from most movement disorders, in that they are partially suppressible. As part of the inhibitory motor network, the pre-supplementary motor area is engaged in motor control and may be involved in tic physiology. We used dual-site transcranial magnetic stimulation to assess inhibitory connectivity between right pre-supplementary motor area and left primary motor cortex, which has previously been demonstrated in healthy adults. We also used diffusion tensor imaging to investigate white matter connectivity in children with chronic tics. Twelve children with chronic tic disorder and fourteen typically developing controls underwent MRI with diffusion tensor imaging indices analysis followed by single and paired-pulse transcranial magnetic stimulation with conditioning pulse over the right pre-supplementary motor area followed by left motor cortex test pulse. Neurophysiologic and imaging data relationships to measures of tic severity and suppressibility were also evaluated in tic patients. Pre-supplementary motor area-mediated inhibition of left motor cortex was present in healthy control children but not in chronic tic disorder participants. Less inhibition correlated with worse tic suppressibility ( ρ  = − 0.73, p  = 0.047). Imaging analysis showed increased fractional anisotropy in the right superior longitudinal fasciculus, corpus callosum, corona radiata and posterior limb of the internal capsule ( p