Etiological musculo-skeletal factor in focal dystonia in a musician's hand: A case study of the right hand of a guitarist

Authors

  • Joris N.A.L. Leijnse PhD,

    Corresponding author
    1. Laboratory for Clinical Biomechanics and Reconstructive Surgery of Hand and Upper Limb, Department of Mechanical Engineering, Speed School for Engineering & Price Institute for Surgical Research, Department of Surgery, University of Louisville, Louisville, Kentucky, USA
    • Assistant Professor of Research, Department of Mechanical Engineering, 200 Sackett Hall, University of Louisville, Louisville, KY 40292
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  • Mark Hallett MD

    1. Human Motor Control Section, NINDS, National Institutes of Health, Bethesda, Maryland, USA
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Abstract

A case study is presented in which a focal hand dystonia seems to have developed in the right hand of a classical guitarist as a result of a neuromuscular peripheral defect caused by trauma. The trauma was a near total perforation of the first web space by a splinter. Healing was uneventful without apparent functional complications. Two years later the patient noticed difficulties in extending the index in playing, for which he received various unsuccessful treatments during seven years. However, we found more severe dystonic symptoms (cocontractions) in the thumb than in the index during playing, which correlated with an undiagnosed insufficiency in the flexor pollicis brevis (FPB). This defect allowed proposing a biomechanical analysis of compensations for diminished thumb control in playing, which would explain the dysfunction in the index in playing as overcompensation for the thumb problem. If this analysis is correct, the etiology of the case can be traced back to underlying multiarticular control problems in the thumb caused by an insufficient FPB. This defect was considered irrepairable. It was concluded that even with knowledge of the underlying cause, a potentially successful treatment of the dystonia might not exist in this case. The case would demonstrate that task-specific hand dystonias can arise as overcompensations for (peripheral) neuro-musculoskeletal defects. The case is illustrated by videos of playing and functional thumb tests. © 2007 Movement Disorder Society

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