Enlargement of Thalamic Nuclei in Tourette Syndrome

Abstract

Context The basal ganglia and thalamus together connect in parallel closed-loop circuits with the cortex. Previous imaging studies have shown modifications of the basal ganglia and cortical targets in individuals with Tourette syndrome (TS), but less is known regarding the role of the thalamus in TS pathogenesis. Objective To study the morphological features of the thalamus in children and adults with TS. Design A cross-sectional, case-control study using anatomical magnetic resonance imaging. Setting University research center. Participants The 283 participants included 149 with TS and 134 normal control individuals aged 6 to 63 years. Main Outcome Measures Conventional volumes and measures of surface morphology of the thalamus. Results Analyses of conventional volumes and surface morphology were consistent in demonstrating an enlargement in TS-affected thalami. Overall volumes were 5% larger in the group composed of children and adults with TS. Statistical maps of surface contour demonstrated enlargement over the lateral thalamus. Post hoc testing indicated that differences in IQ, comorbid illnesses, and medication use did not account for these findings. Conclusions Morphological abnormalities in the thalamus, together with the disturbances reported in the sensorimotor cortex, striatum, and globus pallidus, support the hypothesis of a circuit wide disorder within motor pathways in TS. The connectivity and function of the numerous and diverse thalamic nuclei within cortical-subcortical circuits constitute an anatomical crossroad wherein enlargement of motor nuclei may represent activity-dependent hypertrophy within this component of cortical-subcortical motor circuits, or an adaptive response within a larger putative compensatory system that could thereby directly modulate activity in motor circuits to attenuate the severity of tics.

Morphology and microstructure of subcortical structures at birth: A large-scale Asian neonatal neuroimaging study

“…However, sexual dimorphism in the deep gray matter becomes pronounced in children, adolescents, and adults. Sowell et al (2002) and Giedd et al (1997) described that females actually had larger volumes in the caudate and thalamus than the males in childhood and adulthood, which is intriguing given the involvement of the basal ganglia and thalamus in disorders with pronounced sex differences in incidence such as attention deficit hyperactivity disorder (ADHD), autism, Tourette's syndrome, and schizophrenia (Castle et al, 1998;Ivanov et al, 2010;Miller et al, 2010;Qiu et al, 2009Qiu et al, , 2010. Interestingly, regional gray matter volumes followed an inverted-U shaped maturational curve and peaked earlier in females.…”

Neurobiology of Tourette Syndrome: Current Status and Need for Further Investigation: Table 1.

“…A third study, using an automated computational anatomy technique, showed no difference in thalamic size between a small group of TS patients and healthy controls, although this study did not control for numerous variables . In the largest MRI analysis, including 149 children and adults, there was a 5% increase in thalamic volume, primarily the lateral thalamus (Miller et al, 2010). Post hoc testing suggested that the differences observed were not due to IQ, treatment history, or comorbid conditions.…”

Longitudinal Magnetic Resonance Imaging (MRI) Analysis of the Developmental Changes of Tourette Syndrome Reveal Reduced Diffusion in the Cortico-Striato-Thalamo-Cortical Pathways

“…16, 17 Bloch et al 18 found smaller caudate volumes in children with persisting tics into early adulthood, but the caudate volume was not correlated with tic score at the time of scan. Cross-sectional studies in adults with Tourette syndrome have shown changed volumes of corpus callosum, 13,19 increased dorsal prefrontal areas, 20 and decreased gray matter in prefrontal areas.…”