Slow-Down Exercise Reverses Sensorimotor Reorganization in Focal Hand Dystonia: A Case Study of a Pianist

Abstract

Focal hand dystonia in musicians, which is characterized by involuntary flexion and/or extension of fingers while playing musical instruments, is a disabling neurological disorder that can even threaten their careers. The present study investigated whether or how a non-invasive intervention for focal hand dystonia called “slow-down exercise” affects motor performance, muscular activity, and somatosensation in a dystonic pianist. The patient was asked to performa simple five-finger exercise at three different tempi on a digital piano, just prior to, 1, 2, 3, 6, and 12 months after the onset of the slow-down exercise training. As the rehabilitation proceeded, the patient improved the regularity of piano keystrokes, as objectively quantified using musical instrument digital interface signals. Measurements of surface electromyographic activity from the forearm muscles demonstrated that the patient gradually regained the inherent bilateral difference in the co-contraction level of the extensor digitorum communis and flexor digitorum superficialis muscles. Furthermore, the practice of slow-down exercise lowered the two-point discrimination thresholds of affected fingers, indicating the restoration of tactile spatial resolution. These findings not only confirm the effectiveness of slow-down exercise for the treatment of focal hand dystonia but also provide objective evidence that a simple behavioral intervention can reverse the reorganization of sensorimotor neural networks in dystonic patients.