The sensory consequences of repetitive strain injury in musicians: focal dystonia of the hand¹

Issue title: Feature Section: Alternative Medicine

Article type: Research Article

Authors: Byl, Nancy^{*; a} | Hamati, Debra^b | Melnick, Marsha^{a; c} | Wilson, Frank^{d; e} | McKenzie, Alison^{a; f}

Affiliations: [a] Graduate Program in Physical Therapy, University of California, San Francisco, CA 94122, USA | [b] Department of Physical Therapy, Kaiser Permanente Medical Center, Oakland, CA, USA | [c] San Francisco State University, San Francisco, CA, USA | [d] Department of Neurology, University of California, San Francisco, CA 94122, USA | [e] Department of Neurology, Kaiser Permanente Northern California, San Francisco, CA, USA | [f] Division of Physical Therapy, Chapman University, San Francisco, CA, USA

Correspondence: [*] Corresponding author. UCSF/SFSU Graduate Program in Physical Therapy, 374 Parnassus Ave., University of California, San Francisco, School of Medicine, San Francisco, CA 94143-0736, USA. Tel.: +1 415 476-3452. Fax: + 1 415 502-0323.

Note: [1] This project was carried out as partial fulfillment of the MPT degree for DH.

Abstract: Some individuals with repetitive strain injury (RSI) develop focal dystonia of the hand (FDh), a disorder of motor control manifested in a specific context during skilled, hand movements. This descriptive study was designed to determine if musicians with FDh had reduced tactile discrimination. Ten healthy adults and ten patients with FDh participated in the study. From the standardized Sensory Integration and Praxis Test, five subtests were selected to measure tactile discrimination. The Paired Wilcoxon Test was used to analyze, meaningful, planned pairwise differences by side and by group. The two groups performed similarly on the three tests measuring tactile motor perception (Finger Identification, Localization and Kinesthesia). However, those with FDh performed significantly worse than the healthy comparison group on two tactile perceptual tasks: (1) Graphesthesia, right affected (P < 0.003) and left unaffected (P < 0.005); and (2) Manual Form Perception (stereognosis) on the right affected (P < 0.002) and left unaffected (P < 0.002). It is possible that the somatosensory differences as measured by tactile discrimination tasks represent some degradation of the hand representation following prolonged, repetitive, near simultaneous sensory stimulation of adjacent digits. Tactile discrimination should be tested in patients with RSI to detect potential risks for developing FDh. Effective treatment of patients with RSI including FDh may need to target the somatosensory deficits in order to restore stress-free motor movements.

Keywords: Writer's cramp, Task specific dystonia, Musician, Repetitive injury syndrome, Repetitive strain injury Cumulative trauma disorder, Focal dystonia of the hand

DOI: 10.3233/BMR-1996-7105

Journal: Journal of Back and Musculoskeletal Rehabilitation, vol. 7, no. 1, pp. 27-39, 1996