Somatosensory–motor bodily representation cortical thinning in Tourette: Effects of tic severity, age and gender

Fahim, Cherine; Yoon, Uicheul; Das, Samir; Lyttelton, Oliver; Chen, John; Arnaoutelis, Rozie; Rouleau, Guy; Sandor, Paul; Frey, Kirk; Brandner, Catherine; Evans, Alan C.

doi:10.1016/j.cortex.2009.06.008

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Volume 46, Issue 6 , Pages 750-760, June 2010

Somatosensory–motor bodily representation cortical thinning in Tourette: Effects of tic severity, age and gender

Cherine Fahim
- Department of Neurology and Neurosurgery, McGill University, Montréal, Canada
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montréal, Canada
- Laboratory for the Experimental Research on Behaviour (LERB), Faculty of Social Sciences and Politics, University of Lausanne, Switzerland
- CHU Sainte-Justine Research Centre, Department of Medicine, University of Montréal, Canada
Uicheul Yoon
- Department of Neurology and Neurosurgery, McGill University, Montréal, Canada
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montréal, Canada
Samir Das
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montréal, Canada
Oliver Lyttelton
- Department of Neurology and Neurosurgery, McGill University, Montréal, Canada
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montréal, Canada
John Chen
- Department of Neurology and Neurosurgery, McGill University, Montréal, Canada
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montréal, Canada
Rozie Arnaoutelis
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montréal, Canada
Guy Rouleau
- CHU Sainte-Justine Research Centre, Department of Medicine, University of Montréal, Canada
Paul Sandor
- Department of Psychiatry, Division of Child Psychiatry, University of Toronto, Canada
- Division of Brain Imaging & Behaviour Systems – Neuroscience Toronto Western Research Institute, University Health Network, Toronto, Canada
Kirk Frey
- Department of Radiology, Mental Health Research Institute, Ann Arbor, University of Michigan, United States
- Department of Neurology, Mental Health Research Institute, Ann Arbor, University of Michigan, United States
Catherine Brandner
- Laboratory for the Experimental Research on Behaviour (LERB), Faculty of Social Sciences and Politics, University of Lausanne, Switzerland
Alan C. Evans
- Department of Neurology and Neurosurgery, McGill University, Montréal, Canada
- McConnell Brain Imaging Centre, Montreal Neurological Institute, Montréal, Canada
- Corresponding author. McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, 3081 University Street, Montréal, Quebec, H3A 2B4 Canada.

Received 25 February 2009; received in revised form 22 April 2009 and 27 May 2009; accepted 10 June 2009. published online 07 September 2009.

Action editor Jordan Grafman

Abstract

Introduction

Tourette syndrome (TS) implicates the disinhibition of the cortico-striatal-thalamic-cortical circuitry (CSTC). Previous studies used a volumetric approach to investigate this circuitry with inconsistent findings. Cortical thickness may represent a more reliable measure than volume due to the low variability in the cytoarchitectural structure of the grey matter.

Methods

66 magnetic resonance imaging scans were acquired from 34 TS subjects (age range 10–25, mean 17.19±4.1) and 32 normal controls (NC) (age range 10–20, mean 16.33±3.56). Brain morphology was assessed using the fully automated CIVET pipeline at the Montreal Neurological Institute.

Results

We report (1) significant cortical thinning in the fronto-parietal and somatosensory–motor cortices in TS relative to NC (p<.05); (2) TS boys showed thinner cortex relative to TS girls in the fronto-parietal cortical regions (p<.05); (3) significant decrease in the fronto-parietal mean cortical thickness in TS subjects with age relative to NC and in the pre-central cortex in TS boys relative to TS girls; (4) significant negative correlations between tic severity and the somatosensory–motor cortical thickness.

Conclusions

TS revealed important thinning in brain regions particularly involved in the somatosensory/motor bodily representations which may play an important role in tics. Our findings are in agreement with Leckman et al. (1991) hypothesis stating that facial tics would be associated with dysfunction in an orofacial subset of the motor circuit, eye blinking with the occulo-motor circuit, whereas lack of inhibition to a dysfunction in the prefrontal cortex. Gender and age differences may reflect differential etiological factors, which have significant clinical relevance in TS and should be considered in developing and using diagnostic and therapeutic interventions.

Keywords: Tourette syndrome, Cortical thickness, Neuroimaging, Magnetic resonance imaging, Gender, Age