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Somatosensory Representation of the Digits and Clinical Performance in Patients with Focal Hand Dystonia

McKenzie, A. L. PT, PhD; Nagarajan, S. S. PhD; Roberts, T. P. L. PhD; Merzenich, M. M. PhD; Byl, N. N. PT, PhD

American Journal of Physical Medicine & Rehabilitation: October 2003 - Volume 82 - Issue 10 - p 737-749
doi: 10.1097/01.PHM.0000087458.32122.14
Research Articles: Focal Hand Dystonia

McKenzie AL, Nagarajan SS, Roberts TPL, Merzenich MM, Byl NN: Somatosensory representation of the digits and clinical performance in patients with focal hand dystonia. Am J Phys Med Rehabil 2003;82:737–749.

Objective The purpose of this study was to incorporate magnetoencephalography and clinical testing to describe differences in somatosensory organization and sensorimotor function of the hand in patients with focal hand dystonia, a target-specific disorder of voluntary movement that interferes with fine motor control during the performance of rapid, repetitive, skilled movements.

Design This descriptive study included prospective, quasi-experimental comparisons between groups.

Results Patients with focal hand dystonia demonstrated deficits in physical variables, sensory processing, and motor control when compared with age- and sex-matched controls. They also had altered patterns of firing (amplitude and latency integrated over time) and abnormal somatosensory representations on magnetoencephalography.

Conclusions These study findings suggest that there are alterations in both somatosensory representation of the digits and clinical performance in patients with focal hand dystonia. Future studies to determine if alterations in the sensorimotor feedback loop contribute to the development of focal hand dystonia are indicated. If so, intervention strategies may need to include specific types of somatosensory retraining as part of the rehabilitation program for patients with focal hand dystonia.

From the Department of Physical Therapy, Chapman University, Orange, California (ALM); the Department of Bioengineering, University of Utah, Salt Lake, Utah (SSN); the Scientific Learning Corporation, Berkeley, California (SSN, MMM); and the Department of Radiology, Biomagnetic Imaging Laboratory (TPLR), the Keck Center for Neuroscience, Department of Physiology (MMM), and the Department of Physical Therapy and Rehabilitation Science (NNB), University of California, San Francisco, California.

Supported, in part, by a UCSF Resource Allocation Committee Grant (N. N. Byl), a Chapman University Faculty Development Grant (A. L. McKenzie), and NIH Program Project Grant P01NS34835 (M. M. Merzenich).

All correspondence and requests for reprints should be addressed to A. L. McKenzie, PT, PhD, Department of Physical Therapy, Chapman University, One University Drive, Orange, CA 92866.

© 2003 Lippincott Williams & Wilkins, Inc.