Changes in Corticomuscular Coupling After Microneedle-Knife Therapy in Patients With Ankle Sprain: An EEG-EMG caCOH Analysis

This was a single-group, pre-post interventional study involving participants with ankle sprain. Each participant received one session of microneedle-knife therapy targeting relevant soft-tissue regions of the lower leg and foot. No other therapeutic intervention was administered as part of the study during the treatment period.

Synchronous EEG and EMG recordings were performed before and after microneedle-knife therapy. EEG signals were recorded using a NeuSen W64 wireless EEG acquisition system at a sampling frequency of 1,000 Hz. EMG signals were recorded using a Trigno Wireless EMG System. A common trigger was used to temporally align the EEG and EMG signals.

The motor assessment included three ankle tasks: dorsiflexion, eversion, and inversion or isometric contraction. Participants performed the tasks while seated and began each movement after an instruction from the researcher. Each movement lasted approximately 3 seconds and was repeated at least five times. A 1-minute rest period was provided between tasks to reduce fatigue. The tasks were performed in a fixed order: dorsiflexion, eversion, and inversion or isometric contraction.

EEG signals from frontal, central, and parietal scalp regions were analyzed, with particular attention to the motor-related C3, C4, and Cz channels. EMG signals were recorded from the tibialis anterior, peroneus longus, extensor digitorum longus, medial gastrocnemius, lateral gastrocnemius, and soleus muscles.

For each movement event, the signal segment from 0.5 to 2.0 seconds after the movement instruction was used for analysis. Corticomuscular coupling was assessed using the covariance-based coherence (caCOH) index. The principal analysis focused on mean caCOH within the beta frequency band of 15 to 30 Hz and compared measurements obtained before and after treatment across the three ankle motor tasks.