Musician's dystonia (MD) is a neurological motor disorder characterized by involuntary contractions of those muscles involved in the play of a musical instrument. It is task-specific and initially only impairs the voluntary control of highly practiced musical motor skills. MD can lead to a severe decrement in a musician's ability to perform. While the etiology and the neurological pathomechanism of the disease remain unknown, it is known that MD like others forms of focal dystonia is associated with somatosensory deficits, specifically a decreased precision of tactile and proprioceptive perception. The sensory component of the disease becomes also evident by the patients' use of “sensory tricks” such as touching dystonic muscles to alleviate motor symptoms. The central premise of this paper is that the motor symptoms of MD have a somatosensory origin and are not fully explained as a problem of motor execution. We outline how altered proprioceptive feedback ultimately leads to a loss of voluntary motor control and propose two scenarios that explain why sensory tricks are effective. They are effective, because the sensorimotor system either recruits neural resources normally involved in tactile-proprioceptive (sensory) integration, or utilizes a fully functioning motor efference copy mechanism to align experienced with expected sensory feedback. We argue that an enhanced understanding of how a primary sensory deficit interacts with mechanisms of sensorimotor integration in MD provides helpful insights for the design of more effective behavioral therapies.
Keywords: human, motor control, movement disorder, proprioception, sensorimotor integration, sensory integration
Citation: Konczak J and Abbruzzese G (2013) Focal dystonia in musicians: linking motor symptoms to somatosensory dysfunction. Front. Hum. Neurosci. 7:297. doi: 10.3389/fnhum.2013.00297
Received: 15 March 2013; Paper pending published: 27 March 2013;
Accepted: 05 June 2013; Published online: 25 June 2013.
Edited by:Eckart Altenmüller, University of Music and Drama Hannover, Germany
Reviewed by:Kirsten E. Zeuner, University of Kiel, Germany
Copyright © 2013 Konczak and Abbruzzese. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.
*Correspondence: Jürgen Konczak, Human Sensorimotor Control Laboratory, Center for Clinical Movement Science, School of Kinesiology, University of Minnesota, 1900 University Ave. S.E., Minneapolis, MN 55455, USA e-mail: firstname.lastname@example.org