The Neurologic Phenotype of Idiopathic Tic Disorders in Children

Sinnige, P.F. (2015) The Neurologic Phenotype of Idiopathic Tic Disorders in Children. thesis, Medicine.

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Abstract

Aim Our aim was to describe the neurologic phenotype of pediatric idiopathic tic disorders. Method We performed an electronic search in the UMCG’s patient files and identified patients with tics that had been referred to the pediatric neurology outpatient clinic. 30 patients aged 4 to 17 years (mean: 11.7, standard deviation, SD: 3.6) who had persisting tics and whose parents were willing to participate were included. All children had previously been examined by a pediatric neurologist and had no relevant neurologic diagnoses (besides tics). We videotaped the motor behavior of all children using a standardized protocol. 5 neurologists analyzed the recorded motor behavior for the presence of concurrent movement disorders (in addition to tics). 3 pediatric neurologists and 3 research trainees quantified dystonic, ataxic and choreatic features according to standardized rating scales [respectively the Burke Fahn Marsden Movement Scale (BFMMS), Scale for the Assessment and Rating of Ataxia (SARA) and Dyskinesia Impairment Scale (DIS)]. We performed reliability analyses on all measurements, correlated the phenotype with movement scale outcomes and corrected outcomes for the potentially confounding effect of the child’s age. We compared rating scale outcomes with healthy age-matched controls in order to establish subgroups of rater scores. Physiological scores were defined as the 95% confidence interval of the mean score in healthy children. We used the intraclass correlation coefficient (ICC) to assess reliability of the DIS because no normative data are available. Results 9 out of 30 children were phenotyped with a concurrent hyperkinetic movement disorder by at least 2 out of 5 observing neurologists. The identified movement disorders were: chorea n=4, dystonia n=2 and myoclonus n=3. Percentage agreement on recognition of additional neurologic features varied between 66 and 95%. The percentage agreement on the distinction between physiological and non-physiological rating scale outcomes was 66% for the BFMMS and 88% for the SARA. The ICCs between all observers on the total ‘original’ DIS and ‘expanded’ DIS scores were 0.46 and 0.43, respectively. All three movement scales showed strong age dependency (p<0.001 R2=0.46, p<0.001 R2=0.59 and p<0.001, R2=0.41 for the BFMMS, SARA and ‘expanded’ DIS scores, respectively). Tic duration had no effect on the rating scale scores. Rating scale outcomes in children without a concurrent movement disorder (n=21) were similar to the hyperkinetic movement disorder group. However, after correcting for age, a regression analysis showed that the subgroup of participants who were phenotyped with choreatic features (n=4) had higher total BFMMS, ‘original’ DIS and ‘expanded’ DIS scores: (p=0.045, β=0.31), (p=0.014, β=0.43) and (p=0.018, β=0.38), respectively. Summary In children with idiopathic tics but no other relevant neurologic diagnosis, a substantial amount (30%) revealed features of a concurrent hyperkinetic movement disorder. This confirms our hypothesis that there is an association between tics and other hyperkinetic features. Based on current data on tic pathophysiology, an anatomical substrate (in the basal ganglia) for this association seems likely. Our findings imply that a subgroup of children with idiopathic tic disorders shows features of additional hyperkinetic movement disorders. Recognition of this subgroup is important for optimal diagnostic and therapeutic decision-making, as well as for the interpretation of innovative genetic techniques such as Whole Exome Sequencing.

Item Type:	Thesis (Thesis)
Supervisor name:	Sival, DA MD and Department of Pediatric Neurology, Beatrix Children’s Hospit and University of Groningen, University Medical Centre Groningen
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 10:47
Last Modified:	25 Jun 2020 10:47
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/881

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