Abnormalities of spatial and temporal sensory discrimination in writer's cramp

Authors

  • Terence D. Sanger MD PhD,

    1. Department of Child Neurology and Movement Disorders, Stanford University Medical Center, Stanford, California, USA
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  • Daniel Tarsy MD,

    1. Behavioral Neurology Unit and Movement Disorders Center, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
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  • Alvaro Pascual-Leone MD PhD

    Corresponding author
    1. Behavioral Neurology Unit and Movement Disorders Center, Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
    • Behavioral Neurology Unit, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215
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Abstract

Clinical observations of patients with writer's cramp suggest that abnormalities of the sensory system may be a frequent finding in this disorder. Neurophysiological data from an animal model of focal dystonia have revealed cells in somatosensory cortex with enlarged and overlapping tactile receptive fields. However, psychophysical studies so far have been unable to document a clinical correlate supporting a similar enlargement of receptive fields in humans. We compared the fingertip discrimination of the orientation of fine spatial gratings between writer's cramp and control subjects and found a significant decrease in grating sensitivity in the patients, consistent with the possibility of enlarged tactile receptive fields. In addition, we duplicated previous experiments showing an abnormality of tactile temporal discrimination. The results provide psychophysical measures which may relate to the development of sensory cortical reorganization in patients with writer's cramp. Mov. Disord. 16:94–99, 2001. © 2001 Movement Disorder Society.

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