Objective: To characterize and quantify pediatric tics and DCD according to specific movement disorder features.

Background: Until now, it has been impossible to attribute the pathophysiology of pediatric tics and developmental coordination disorders (DCD) to one uniform genetic cause, neuro-transmitter deficiency or cerebral structure. Our hypothesis is that idiopathic tics and DCD do not concern a homogeneous disorder, but rather a heterogeneous presentation of symptoms caused by various pathophysiologic abnormalities somewhere within the basal ganglia- and/or basal ganglia cerebellar network.

Methods: In children with idiopathic tics (n=30; aged 4-17 years) and DCD (n=10; aged 6-13 years) we phenotyped and quantified motor performances. Separate panels of 3-5 pediatric neurologists performed the phenotypic (indication of primary and/or secondary comorbid movement disorder features) and quantitative assessments by strict adherence to ataxia (SARA), dystonia (BFMMS) and chorea (Dyskinesia Impairment Scale–Chorea subscale (DIS-C)) rating scale guidelines. We determined (comorbid) movement disorder features that were recognized by the majority of assessors.

Results: Phenotypic assessment of pediatric tics revealed comorbid movement disorder features in 9/30 (30%) children with tics consisting of chorea, dystonia and myoclonus, but no ataxia. Phenotypic assessment of children with DCD revealed comorbid movement disorder features of ataxia and dystonia in 5/10 children (50%). The children with tics and DCD revealed significantly higher rating scale scores than age-related controls (Tics: SARA, BFMMS and DIS-C p<0.05, and DCD: SARA and DIS-C p<0.05), either still within (SARA, BFMMS) or just outside (DIS-C) the range of age-related normal values. Regression analysis showed that specifically tic phenotypes with choreatic features obtained higher total BFMMS and DIS-C scores (β=0.31, p=0.04 and β=0.43, p=0.014, respectively) than the other tic phenotypes.

Conclusions: Children with tics and DCD reveal heterogeneous features of comorbid movement disorders, potentially due to abnormal signal processing at different locations within the basal ganglia-, respectively cerebellar-thalamic-basal ganglia network connections. Future delineation of phenotypic sub-types may (1) contribute to the pathologic expression of these network connections and (2) aid genetic studies to elucidate underlying (modifying) gene defects.

« Back to 2018 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/pediatric-tics-and-dcd-motor-network-disorders/