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Corpus callosum abnormalities in Tourette syndrome: an MRI-DTI study of monozygotic twins
  1. Andrea E Cavanna1,2,3,
  2. Alessandro Stecco1,4,
  3. Hugh Rickards3,
  4. Serena Servo1,
  5. Emanuela Terazzi1,
  6. Bradley Peterson5,
  7. Mary M Robertson6,7,
  8. Alessandro Carriero4,
  9. Francesco Monaco1
  1. 1Department of Neurology, Amedeo Avogadro University, Novara, Italy
  2. 2Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, UK
  3. 3Department of Neuropsychiatry, Birmingham and Solihull Mental Health NHS Foundation Trust, Birmingham, UK
  4. 4Department of Radiology, Amedeo Avogadro University, Novara, Italy
  5. 5Columbia College of Physicians & Surgeons and the New York State Psychiatric Institute, New York, USA
  6. 6Department of Mental Health Sciences, University College London, UK
  7. 7Department of Neurology, St Georges Hospital and Medical School, London, UK
  1. Correspondence to Dr Andrea Cavanna, Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London WC1N 3BG, UK; a.cavanna{at}


Background Tourette syndrome (TS) is a chronic neurodevelopmental disorder characterised by the presence of multiple motor and phonic tics. Recent brain imaging investigations with diffusion tensor imaging (DTI) techniques found reduced measures of connectivity in the corpus callosum of children with TS compared with healthy controls, thus raising the hypothesis that the reduced interhemispherical connectivity in TS reflects neural plasticity processes.

Methods We assessed corpus callosum white-matter connectivity with fractional anisotropy (FA) index from magnetic resonance-DTI in two monozygotic twins (male sex; age 20) discordant for the diagnosis of TS.

Results Both conventional morphological magnetic resonance images and fibre-tracking reconstruction failed to show any difference between the two twins. On the other hand, mean corpus callosum FA values were significantly lower in the affected twin than in the unaffected twin (p<0.01). The differences in FA values were highest in the posterior portions of the corpus callosum, and lowest in the central area.

Conclusions Our findings of reduced interhemispherical white-matter connectivity in the affected twin support the hypothesis that plastic remodelling in the corpus callosum possibly represents an adaptation mechanism in TS.

  • MRI
  • Tourette syndrome

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  • All authors contributed equally to this manuscript.

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.