Beyond the surface: A prospective case-control study of electromyography in cervical dystonia

To identify potential EMG monitoring biomarkers for CD by comparing cervical muscle activity in patients and controls.

Fifteen CD patients and fifteen controls underwent bilateral EMG recordings from the sternocleidomastoid (SCM) and splenius capitis (SPL) muscles during rest and motor tasks. Power spectral density (PSD) in the 4-12 Hz range, co-contraction, overflow and intermuscular coherence were analyzed. Group differences were assessed with Mann-Whitney U tests and associations between EMG features and clinical severity scores were evaluated using Spearman correlations.

CD patients showed significantly increased 4-12 Hz PSD across all neck muscles and tasks. Co-contraction and overflow were consistently observed and quantifiable. Intermuscular coherence was notably elevated in SCM pairs during active tasks. Preliminary correlations were found between PSD measures and clinical scores.

The study confirms four distinct EMG characteristics in CD: elevated 4-12 Hz PSD, co-contraction, overflow and intermuscular coherence, supporting their potential as objective monitoring biomarkers.

These findings provide electrophysiological validation of key EMG features in CD and highlight their potential for integration into research and clinical assessment, pending further methodological standardization.