Neurophysiological Determinants of Tic Severity in Children with Chronic Motor Tic Disorder

Abstract

Tics wax and wane in severity. Although the understanding of the natural course of symptoms in tic disorder (TD) is important for planning and assessing therapeutic interventions, neurophysiological mechanisms and predictors of tic exacerbation and remission have not been sufficiently investigated. In each of seven children suffering from TD, contingent negative variation (CNV) was recorded on 10 occasions over a period of 2 months. CNV parameters of children with TD were compared with CNV data of healthy, age-matched children. During the entire time of observation, tic severity was assessed by parents and the investigator using a scale developed from the Yale Global Tic Severity Scale. Moreover, tic severity was also evaluated using video assessments. Patients with TD were characterized by significantly lower amplitude of the total CNV and more pronounced habituation of the early CNV component as compared to healthy children. Correlation analysis between tic severity and CNV parameters demonstrated that the more severe the tics were, the lower the amplitude of the total CNV. Since CNV amplitude represents processes of resource mobilization and control over neuronal excitability, tic severity may result from less ability to control neurophysiological functions in patients with TD.

Neurofeedback and its possible relevance for the treatment of Tourette syndrome

“…Beyond that and similar to the ADHDtypical impairments in the regulation of voluntary movements (Ganos et al, 2013;Segawa, 2003), deviant slow cortical potentials in the form of reduced CNVs have been reported for patients with GTS (Berardelli et al, 2003;Van Woerkom et al, 1988;Weate et al, 1993). Those have also been attributed to dysfunctional corticobasal-ganglia-thalamo-cortical projections (Berardelli et al, 2003;Siniatchkin and Kuppe, 2011;Van Woerkom et al, 1988). This thalamo-cortical overactivity may also be responsible for the difficulties GTS patients show in suppressing unwanted behaviors and impulses (Berardelli et al, 2003;Segawa, 2003;Weate et al, 1993).…”

“…In this respect, NF could constitute a very useful supplementation for ERP-based treatment approaches and components of awareness training in HRT protocols. Respective NF protocols should further aim for the positive modification of the repeatedly reported theta excess and/or the reduced SMR and CNVs (Berardelli et al, 2003;Siniatchkin and Kuppe, 2011;Van Woerkom et al, 1988;Yordanova and Kolev, 1996) in the attempt to counteract associated symptoms such as hyperactivity and inattention. In the course of NF training, patients may learn how to execute top-down control by applying cognitive strategies (Arns et al, 2014;Butnik, 2005;Van Boxtel and Gruzelier, 2014).…”

Tics: neurological disorders determined by a deficit in sensorimotor gating processes

“…Such type of studies has consistently identified a diminished amplitude of the contingent negative variation (CNV) component, which can be considered as a marker of cognitive anticipation for a forthcoming sensory event, in both adults and children affected by TS [ 74 ]. Additionally, patients with more severe tics have lower CNV amplitudes, indicating a reduced pre-conscious capacity to anticipate environmental stimuli [ 75 ].…”

Pathophysiology of ADHD and associated problems—starting points for NF interventions?

“…However, this may not hold for electrophysiological parameters of preparation and self-regulation after decision making, as children with ADHD + Tic may be more similar to children with pure Tic disorder, following a sub-additive model (Yordanova et al, 1996 , 1997 ). Diminished preparatory slow-wave CNV in children with Tics was furthermore associated with tic severity, suggesting a possible functional link with tic suppression (Siniatchkin and Kuppe, 2011 ).…”