Lower-limb muscle synergies in musician's dystonia: a case study of a drummer

Shizuka Sata; Kazuaki Honda; Satoshi Yamaguchi; Mizuki Komine; SungHyek Kim; Makio Kashino; Shota Hagio; Shinya Fujii

doi:10.3389/fneur.2024.1489143

Lower-limb muscle synergies in musician's dystonia: a case study of a drummer

Front Neurol. 2024 Nov 18:15:1489143. doi: 10.3389/fneur.2024.1489143. eCollection 2024.

Authors

Shizuka Sata¹, Kazuaki Honda², Satoshi Yamaguchi³, Mizuki Komine¹, SungHyek Kim⁴, Makio Kashino², Shota Hagio⁵, Shinya Fujii⁶

Affiliations

¹ Graduate School of Media and Governance, Keio University, Fujisawa, Japan.
² NTT Communication Science Laboratories, NTT Corporation, Atsugi, Japan.
³ Keio Research Institute at SFC, Keio University, Fujisawa, Japan.
⁴ Department of Shizuoka Physical Therapy, Faculty of Health Sciences, Tokoha University, Shizuoka, Japan.
⁵ Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
⁶ Faculty of Environment and Information Studies, Keio University, Fujisawa, Japan.

Abstract

Musician's dystonia (MD) is a movement disorder characterized by involuntary muscle contractions specifically triggered by playing an instrument. This condition often leads to a loss of fine motor control, threatening the careers of affected musicians. While MD is commonly associated with the hands, it can also affect the lower limbs, particularly in drummers. Understanding the muscle coordination involved in MD is crucial for comprehending its neurological mechanisms, yet the muscle coordination of lower-limb dystonia has not been thoroughly explored. This study aimed to investigate the differences in lower-limb muscle synergies in a drummer with MD, utilizing non-negative matrix factorization (NMF) to analyze coordinated muscle activity patterns during drumming tasks. A 36-year-old male professional drummer with lower-limb MD was instructed to play a drum set in time with a metronome set at 80 beats per minute. The task involved striking the bass drum pedal in time with the downbeat. Electromyographic (EMG) data were collected from 10 muscles in the right lower limb. The data were analyzed using NMF to extract muscle synergies and compare the number of synergies, spatial modules, and temporal modules between the data with and without dystonia symptoms. The number of muscle synergies did not differ significantly between the data with and without symptoms. Notably, changes were observed in both the spatial and temporal modules of muscle synergies. Spatial modules revealed the appearance of dystonia-specific muscle synergy, which is considered related to compensatory movement. Temporal modules showed significant earlier overactivation in timing, which is considered the direct manifestation of dystonia symptoms. These findings indicate that lower-limb dystonia in drummers affects the spatial and temporal profiles of muscle synergies. This study underscores the importance of considering both spatial and temporal modules of muscle synergy in understanding and treating lower-limb dystonia in drummers. Further research is needed to validate these findings and apply muscle synergy analysis for the clinical assessment of lower-limb dystonia in drummers.

Keywords: coordination; drummer; dystonia; lower limb; muscle synergy.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported by Taikichiro Mori Memorial Research Grants, and JST SPRING Grant (No. JPMJSP2123) (to SS); by a JST COI-NEXT Grant (No. JPMJPF2203), a JST PRESTO Grant (No. JPMJPR23S9), and a KGRI Pre-Startup Grant (to SF).