Intermuscular coherence during co-contraction eliciting tasks as a biomarker for dystonia and GPi-DBS efficacy

S A J E A Lagerweij; J C van Zijl; M Smit; H Eggink; D L M Oterdoom; J M C van Dijk; M E van Egmond; J W Elting; M A J Tijssen

doi:10.1016/j.clinph.2024.12.011

Intermuscular coherence during co-contraction eliciting tasks as a biomarker for dystonia and GPi-DBS efficacy

Clin Neurophysiol. 2024 Dec 14:170:70-79. doi: 10.1016/j.clinph.2024.12.011. Online ahead of print.

Authors

S A J E A Lagerweij¹, J C van Zijl¹, M Smit¹, H Eggink¹, D L M Oterdoom², J M C van Dijk², M E van Egmond³, J W Elting³, M A J Tijssen⁴

Affiliations

¹ Department of Neurology, University Medical Center Groningen (UMCG), University of Groningen, Hanzeplein 1, 9700 RB Groningen, the Netherlands; Expertise Center Movement Disorders Groningen, University Medical Center Groningen (UMCG), the Netherlands.
² Department of Neurosurgery, University Medical Center Groningen (UMCG), University of Groningen, Hanzeplein 1, 9700RB Groningen, the Netherlands.
³ Department of Neurology, University Medical Center Groningen (UMCG), University of Groningen, Hanzeplein 1, 9700 RB Groningen, the Netherlands; Department of Clinical Neurophysiology, University Medical Center Groningen (UMCG), University of Groningen, Hanzeplein 1, 9700 RB Groningen, the Netherlands; Expertise Center Movement Disorders Groningen, University Medical Center Groningen (UMCG), the Netherlands.
⁴ Department of Neurology, University Medical Center Groningen (UMCG), University of Groningen, Hanzeplein 1, 9700 RB Groningen, the Netherlands; Expertise Center Movement Disorders Groningen, University Medical Center Groningen (UMCG), the Netherlands. Electronic address: [email protected].

PMID: 39700629
DOI: 10.1016/j.clinph.2024.12.011

Abstract

Objective: Clinical rating scales often fail to capture the full spectrum of dystonic symptoms. Deep brain stimulation of the globus pallidus interna (GPi-DBS) effectively treats dystonia, but response variability necessitates a reliable biomarker. Intermuscular coherence (4-12 Hz) has been linked to abnormal activity in the cortico-basal ganglia-thalamo-cortical (CBGTC) loop and may serve as an objective measure of dystonia and GPi-DBS effectiveness.

Methods: A retrospective cohort study included 12 dystonia patients undergoing GPi-DBS implantation. Clinical rating scales and a neurophysiological assessment were performed before and one year post-DBS. Coherence in the 4-12 Hz range was analyzed from electromyography (EMG) of antagonistic arm muscles. Comparisons were made between patients with and without arm dystonia, t-tests evaluated the differences between pre- and post-DBS, and correlations between coherence and clinical scales were performed.

Results: Seven patients with arm dystonia appeared to have higher pre-operative intermuscular coherence compared to those without. Coherence was significantly decreased after GPi-DBS in the arm dystonia group. No strong correlations were found between coherence and clinical rating scales.

Conclusion: Intermuscular coherence is present in dystonic muscles and decreases following GPi-DBS. Correlations with motor scores were inconclusive due to patient heterogeneity and ill-fitting clinical scales.

Significance: Intermuscular coherence has potential to aid GPi-DBS patient selection and optimization but larger studies are needed to validate its use.

Keywords: Biomarker; DBS efficacy; Dystonia; GPi-DBS; Intermuscular coherence.