Hippocampal Volume in Provisional Tic Disorder Predicts Tic Severity at 12-Month Follow-up

Abstract

Previous studies have investigated differences in the volumes of subcortical structures (e.g., caudate nucleus, putamen, thalamus, amygdala, and hippocampus) between individuals with and without Tourette syndrome (TS), as well as the relationships between these volumes and tic symptom severity. These volumes may also predict clinical outcome in Provisional Tic Disorder (PTD), but that hypothesis has never been tested. This study aimed to examine whether the volumes of subcortical structures measured shortly after tic onset can predict tic symptom severity at one-year post-tic onset, when TS can first be diagnosed. We obtained T1-weighted structural MRI scans from 41 children with PTD (25 with prospective motion correction (vNavs)) whose tics had begun less than 9 months (mean 4.04 months) prior to the first study visit (baseline). We re-examined them at the 12-month anniversary of their first tic (follow-up), assessing tic severity using the Yale Global Tic Severity Scale. We quantified the volumes of subcortical structures using volBrain software. Baseline hippocampal volume was correlated with tic severity at the 12-month follow-up, with a larger hippocampus at baseline predicting worse tic severity at follow-up. The volumes of other subcortical structures did not significantly predict tic severity at follow-up. Hippocampal volume may be an important marker in predicting prognosis in Provisional Tic Disorder.

Tourette syndrome research highlights from 2020

“…Hippocampal volume was increased both in TS and in 41 children with PTD compared to tic-free control children ( Kim et al . 2020 ).…”

“…Since the PTD group was studied a mean of only 4 months after tic onset, this difference cannot be due to living with or adapting to tics for years, an advantage over all studies in TS itself. Excitingly, in the PTD group, a larger hippocampus at the initial visit predicted worse tic severity at one-year follow-up, comprising the first predictive biomarker identified for PTD ( Kim et al . 2020 ).…”

“…Hippocampal volume was increased both in TS and in 41 children with PTD compared to tic-free control children (Kim et al 2020). Since the PTD group was studied a mean of only 4 months after tic onset, this difference cannot be due to living with or adapting to tics for years, an advantage over all studies in TS itself.…”

Recent progress on Tourette syndrome

“…Several neuroimaging studies have investigated anatomical changes as well as structural and functional connectivity 32 . A follow-up study using high-resolution magnetic resonance imaging (MRI) in 41 children with new-onset tics showed that larger hippocampal volume at the baseline visit predicted higher tic severity at 1-year follow-up 33 . A high-resolution MRI study using voxel-based cerebellar morphometry and seed-to-voxel structural covariance mapping (structural connectivity) demonstrated reduced cerebellar gray matter volume in patients with TS, which was considered to affect higher-order cognitive and motor processing 34 .…”

Comparison of Hippocampal Subfield Segmentation Agreement between 2 Automated Protocols across the Adult Life Span

“…11 An increasing number of studies are using the volBrain protocol as an alternative. 16,17 The main advantage that volBrain provides over FreeSurfer is its considerably shorter processing time because the segmentation results are produced in approximately 15 minutes compared with several hours for FreeSurfer. The agreement of HPSF volumes from both protocols has never been directly compared in a single study.…”