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Impaired sensorimotor integration in focal hand dystonia patients in the absence of symptoms
  1. C Carolyn Wu1,
  2. Scott L Fairhall2,
  3. Nicolas A McNair1,
  4. Jeff P Hamm1,
  5. Ian J Kirk1,
  6. Ross Cunnington3,
  7. Tim Anderson4,
  8. Vanessa K Lim1
  1. 1Department of Psychology, The University of Auckland, Auckland, New Zealand
  2. 2Neuroimaging Laboratory, Fondazione Santa Lucia IRCCS, Rome, Italy
  3. 3Queensland Brain Institute and School of Psychology, The University of Queensland, Brisbane, Australia
  4. 4Van der Veer Institute for Parkinson's & Brain Research, The University of Otago, Christchurch, New Zealand
  1. Correspondence to Dr Vanessa K Lim, Department of Psychology, Research Centre for Cognitive Neuroscience, The University of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand; v.lim{at}auckland.ac.nz

Abstract

Background Functional imaging studies of people with focal hand dystonia (FHD) have indicated abnormal activity in sensorimotor brain regions. Few studies however, have examined FHD during movements that do not provoke symptoms of the disorder. It is possible, therefore, that any differences between FHD and controls are confounded by activity due to the occurrence of symptoms. Thus, in order to characterise impairments in patients with FHD during movements that do not induce dystonic symptoms, we investigated the neural correlates of externally paced finger tapping movements.

Methods Functional MRI (fMRI) was used to compare patients with FHD to controls with respect to activation in networks modulated by task complexity and hand used to perform simple and complex tapping movements.

Results In the ‘complexity network,’ patients with FHD showed significantly less activity relative to controls in posterior parietal cortex, medial supplementary motor area (SMA), anterior putamen and cerebellum. In the ‘hand network,’ patients with FHD showed less activation than controls in primary motor (M1) and somatosensory (S1) cortices, SMA and cerebellum. Conjunction analysis revealed that patients with FHD demonstrated reduced activation in the majority of combined network regions (M1, S1 and cerebellum).

Conclusion Dysfunction in FHD is widespread in both complexity and hand networks, and impairments are demonstrated even when performing tasks that do not evoke dystonic symptoms. These results suggest that such impairments are inherent to, rather than symptomatic of, the disorder.

  • Dystonia
  • functional imaging
  • movement disorders

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Footnotes

  • Funding This research was supported by P Baines Trust (VKL), an Early Careers Research Award (JPH) and a New Zealand Lotteries Grant.

  • Competing interests None.

  • Ethics approval Ethics approval was provided by the Northern X Regional Ethics Committee, Auckland, New Zealand.

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

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