Enhanced broad-band intermuscular coherence in myoclonus: a targeted characterization study

Area of Science:

• Neuroscience
• Motor Control
• Biomedical Engineering

Background:

• Cortical myoclonus (CM) is a neurological disorder characterized by involuntary muscle jerks.
• Intermuscular coherence (IMC) reflects the synchronization of motor unit activity between muscles.
• Enhanced broad-band intermuscular coherence (eIMC) is a specific pattern of IMC.

Purpose of the Study:

• To investigate the occurrence of eIMC in patients with CM.
• To determine if eIMC represents a physiological synchronization mechanism or a CM-associated alteration.
• To compare eIMC patterns across CM, essential tremor (ET), and healthy controls (HC).

Main Methods:

• eIMC was assessed in 19 CM patients, 19 ET patients, and 39 HC during three standardized postures.
• Signal quality was rigorously evaluated to rule out artifacts.
• Prevalence and coherence values in 4-12 Hz, 12-30 Hz, and 30-100 Hz bands were analyzed across groups and postures.

Main Results:

• eIMC was observed in all participant groups (CM, ET, HC) and was more frequent with stronger muscle activation.
• The prevalence of eIMC was higher in CM patients compared to ET and HC groups.
• Median IMC values were elevated in CM, particularly in the 4-12 Hz and 12-30 Hz frequency bands.

Conclusions:

• eIMC is a physiological aspect of motor control detectable in CM, ET, and HC.
• The heightened eIMC in CM may stem from pathological synchronous discharges or amplified physiological synchronization due to cortical hyperexcitability.
• eIMC shows potential as a supportive diagnostic marker for CM.